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Research Interests: Materials Engineering, Condensed Matter Physics, Materials Science, Metallurgy, Surface Coatings, and 10 moreDifferential scanning calorimetry, Coatings, Magnetic Properties, Nickel, Surface and Coatings Technology, Phase Transformation, X ray diffraction, Low Temperature, Thermal Properties, and Vibrating Sample Magnetometer
Electroless NiCoP ternary alloy deposits were prepared by varying the metallic ratio and were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and vibration sample... more
Electroless NiCoP ternary alloy deposits were prepared by varying the metallic ratio and were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and vibration sample magnetometer. The plating rate of electroless ...
Research Interests: Materials Engineering, Condensed Matter Physics, Materials Science, Metallurgy, Surface Coatings, and 12 moreDifferential scanning calorimetry, Coatings, Magnetic Properties, Cobalt, Nickel, Alloy, Surface and Coatings Technology, Structural Properties, Thermal Properties, Elsevier, Coercivity, and Ternary Alloy
Abstract Surface mechanical attrition treatment (SMAT) was carried out on Ti-6Al-4 V. Fretting wear tests were conducted using two counterbody materials (alumina and steel). SMAT resulted in surface nanocrystallization. Due to high... more
Abstract Surface mechanical attrition treatment (SMAT) was carried out on Ti-6Al-4 V. Fretting wear tests were conducted using two counterbody materials (alumina and steel). SMAT resulted in surface nanocrystallization. Due to high hardness, low tangential force coefficient (TFC) and more TiO 2 layer, fretting wear resistance of SMAT treated samples was higher than that of the untreated samples. TFC values obtained with alumina counterbody were higher than those obtained with steel counterbody. The fretting wear ...
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Abstract Microarc oxidation (MAO) of magnesium is performed in a single stage using an alkaline silicate electrolyte and acidic zirconate electrolyte as well as in two stages, sequentially using the alkaline silicate followed by the... more
Abstract Microarc oxidation (MAO) of magnesium is performed in a single stage using an alkaline silicate electrolyte and acidic zirconate electrolyte as well as in two stages, sequentially using the alkaline silicate followed by the acidic zirconate electrolyte. The morphological characteristics, surface roughness, phase content, corrosion behaviour and bioactivity were compared. The surface morphology, thickness, average surface roughness (Ra), and phase composition of the MAO coatings show a strong dependence on the type of electrolytes used and the methodology employed for deposition. Based on the corrosion protective ability in Hank’s balanced salt solution, the uncoated and MAO coated Mg are ranked as follows: Uncoated Mg
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The idea of codepositing various second-phase particles in electrodeposited (ED) or electroless deposited (EL) metal or alloy matrix and thereby taking advantage of their desirable qualities, such as hardness, wear and abrasion... more
The idea of codepositing various second-phase particles in electrodeposited (ED) or electroless deposited (EL) metal or alloy matrix and thereby taking advantage of their desirable qualities, such as hardness, wear and abrasion resistance, and corrosion resistance, has led to the development of ED and EL composite coatings with a wide range of possible combinations and properties [1–3]. ED and EL composite coatings can be prepared by codepositing various second-phase particles in the respective metal or alloy ...
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ABSTRACT The effect of surface mechanical attrition treatment (SMAT) and its duration on fatigue lives of alloy 718 has been studied. The SMAT process was carried out in vacuum (−0.1 MPa) with SAE 52100 steel balls of 5 mm diameter for 30... more
ABSTRACT The effect of surface mechanical attrition treatment (SMAT) and its duration on fatigue lives of alloy 718 has been studied. The SMAT process was carried out in vacuum (−0.1 MPa) with SAE 52100 steel balls of 5 mm diameter for 30 and 60 min at a vibrating frequency of 50 Hz. SMAT resulted in surface nanocrystallization, higher surface roughness, higher surface hardness, higher compressive residual stress, higher tensile strength, reduced ductility and superior fatigue lives. The enhancement in the fatigue lives of treated samples can be attributed to the positive influence of nanostructured surface layer, compressive residual stress and work hardened layer, which surpassed the negative effect of increased surface roughness. There was no significant difference between the fatigue lives of samples treated for 30 and 60 min.
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The effectiveness of hydroxyapatite (HA) coating prepared by electrodeposition technique in improving the corrosion resistance of commercially pure magnesium (CP-Mg) in simulated body fluid (SBF) is addressed. The coating formed in... more
The effectiveness of hydroxyapatite (HA) coating prepared by electrodeposition technique in improving the corrosion resistance of commercially pure magnesium (CP-Mg) in simulated body fluid (SBF) is addressed. The coating formed in as-deposited condition is identified as dicalcium phosphate dehydrate (DCPD) (Brushite), which is converted to HA after immersion in 1 M NaOH at 80°C for 2 h. The XRD patterns and FTIR spectra confirm the formation of DCPD and HA. During electrodeposition, the H2PO4− ion is reduced and the reaction between Ca2+ ions and the reduced phosphate ions leads to the formation of DCPD, which is converted to HA following treatment in NaOH. The deposition of HA coating enables a threefold increase in the corrosion resistance of CP-Mg. The ability to offer a significant improvement in corrosion resistance coupled with the bioactive characteristics of the HA coating establish that electrodeposition of HA is a viable approach to engineer the surface of CP-Mg in the development of Mg-based degradable implant materials.
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Abstract The present study investigates the influence of gum ghatti (GG) concentration on the porosity of hydroxyapatite (HAP), where the final composite has been tested for the effects of drug delivery, antibacterial activity, and in... more
Abstract The present study investigates the influence of gum ghatti (GG) concentration on the porosity of hydroxyapatite (HAP), where the final composite has been tested for the effects of drug delivery, antibacterial activity, and in vitro cytotoxicity. Following the synthesis of GG-HAP composite by a simple chemical precipitation method, the various analyses were employed to understand the crystallinity, morphology, chemical composition, surface functionality and internal bonding, etc. From the comparison of physical properties among the sintered and un-sintered GG-HAP composites and that too with different concentrations of GG (1%, 5%, and 10%), we observed the superior properties for the samples formed from higher GG concentration (10%) with sintering. We observed the lowest crystal size of 30 nm with 95% crystallinity, a surface area of 108 m2/g, a total pore volume of 0.2 mL/g, an average pore diameter of 33 A for the Sin-10% GG-HAP composite. In addition, the biocompatibility test performed on the Sin-GG-HAP pellet confirmed the in-built bioactivity and biostability of the composites in simulated body fluid. Further, the Naringenin drug delivery profiles confirmed for the stable and controlled release of loaded drug from the Sin-GG-HAP composites (with 1, 5, and 10% of GG). We observed the highest release of 96% from the Sin-10% GG-HAP matrix in just 90 min and T50% of 416 h, and a mean diffusion time period of 459 h. Finally, the antimicrobial (using both gram-positive and gram-negative bacteria) and cytotoxic activities (with the use of healthy normal and diseased cells) of the drug-loaded and un-loaded GG-HAP composites confirm the potential role of the formed Sin-10% GG-HAP composite towards biomedical applications.
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The present study reports the development of multi-functional coatings on titanium for orthopaedic implant applications.
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Faster degradation of iron based degradable implants in physiological media, particularly during the initial stages of implantation, poses difficulties in directly using them for clinical applications.
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Abstract The effects of surface mechanical attrition treatment (SMAT) of EN8 steel on the growth of phosphate coatings, morphological features and corrosion resistance of the resultant coatings have been studied. SMAT enabled the... more
Abstract The effects of surface mechanical attrition treatment (SMAT) of EN8 steel on the growth of phosphate coatings, morphological features and corrosion resistance of the resultant coatings have been studied. SMAT enabled the formation of a uniform surface profile although the average surface roughness is increased after treatment. SMAT increased the extent of metal dissolution and the rate of growth of phosphate coating. In spite of the similarity in phase composition, the phosphate crystallite size is relatively high for samples treated by SMAT. Compared to the untreated one, a cathodic shift in Ecorr with a corresponding decrease in icorr is observed for SMAT treated EN8 steel after phosphating. For all tested samples, zinc phosphate coatings deposited on EN8 steel after SMAT using 8 mm Ø balls for 30 min offers the highest corrosion resistance. The increase in surface roughness by SMAT is partly compensated by the expected improvement in corrosion resistance.
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Résumé/Abstract A cold zinc phosphating bath was formulated and optimized to study the effect of some cotionic surfactants viz.. Dodecylamine (DDA), Tetradecylamine (TDA), Hexadecylamine (HDA) and Octadecylamine (OCA) on the growth and... more
Résumé/Abstract A cold zinc phosphating bath was formulated and optimized to study the effect of some cotionic surfactants viz.. Dodecylamine (DDA), Tetradecylamine (TDA), Hexadecylamine (HDA) and Octadecylamine (OCA) on the growth and the crystal habit of zinc phosphote coating on mild steel. Studies have been carried out regarding the mode of adsorption and how these additives modify the crystallization kinetics. The properties of the coated layer and corrosion performance were also investigated to correlate with the effect ...
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Abstract The effect of SMAT on pack boronizing of EN8 steel is addressed. SMAT induced plastic deformation, enabled nanocrystallization at the surface, reduced the grain size and increased the volume fraction of non-equilibrium gain... more
Abstract The effect of SMAT on pack boronizing of EN8 steel is addressed. SMAT induced plastic deformation, enabled nanocrystallization at the surface, reduced the grain size and increased the volume fraction of non-equilibrium gain boundaries, accumulation of defects and dislocations at the grain boundaries and within the grains. These features helped to promote the diffusion of boron. The present study demonstrates for the first time that SMAT treated EN8 steel can be boronized with a reasonable case depth at 923 K for 7 h. It also addresses the benefits of duplex treatment methodology to achieve the desired case depth and a dense boronized layer. Formation of an FeB phase along with an Fe 2 B phase for SMAT treated EN8 steel has also been reported for the first time. The findings of the study recommend that SMAT can be used as a pretreatment for boronizing of steel, provided necessary precautions are made on boron concentration, to control the volume fraction of the deleterious FeB phase.
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ABSTRACT The influence of surface mechanical attrition treatment (SMAT) on pack boronizing of AISI 304 stainless steel (304 SS) is addressed. SMAT of 304 SS was performed using 8 mm Ø 316L stainless steel balls for 60 min. Untreated and... more
ABSTRACT The influence of surface mechanical attrition treatment (SMAT) on pack boronizing of AISI 304 stainless steel (304 SS) is addressed. SMAT of 304 SS was performed using 8 mm Ø 316L stainless steel balls for 60 min. Untreated and SMATed 304 SS samples were pack boronized by single stage (at 1223 K for 1, 3 5 and 7 h) and duplex (973 K for 1 h and 1223 K for 1 h) treatments. SMATed 304 SS increased the kinetics of boron diffusion, enabled the formation of a higher volume fraction of alloy borides and increased the hardness of the borided layer. Duplex treatment increased the case depth than the single stage treatment. The findings of this study suggest that SMAT can be used as an effective pretreatment for boronizing of 304 SS.
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The formation of Ni-B alloy films by electrodeposition route and evaluation of their structural characteristics, phase transformation behavior and corrosion resistance are discussed. The Ni-B alloy films were prepared using... more
The formation of Ni-B alloy films by electrodeposition route and evaluation of their structural characteristics, phase transformation behavior and corrosion resistance are discussed. The Ni-B alloy films were prepared using Watt's nickel bath containing dimethylamine borane (DMAB) as the source of boron. The ratio of rate of reduction of nickel and rate of decomposition of DMAB determines the boron content of the films. The Ni-B films electrodeposited in the current density range of 1-4 A/dm (2) are found to be crystalline in ...
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Research Interests: Materials Science, Fluoride, Metallurgy, Corrosion, Coating, and 3 moreAlloy, Passivation, and Springer Ebooks
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Abstract Developing homogeneous TiO2 nanoporous arrays (NPAs) and nanotubular arrays (NTAs) on biphasic Ti alloys is challenging. The present study used large-pulse electron-beam (LPEB) irradiation prior to anodizing, and ascertained its... more
Abstract Developing homogeneous TiO2 nanoporous arrays (NPAs) and nanotubular arrays (NTAs) on biphasic Ti alloys is challenging. The present study used large-pulse electron-beam (LPEB) irradiation prior to anodizing, and ascertained its effectiveness for developing homogeneous TiO2 NPAs and NTAs on a dual (α + β)-phase Ti–6Al–4V alloy for the first time. The morphological features, structural characteristics, and corrosion resistance of the TiO2 NTAs formed on the LPEB-irradiated Ti–6Al–4V alloy were compared to those obtained on the untreated alloy. The irradiation transformed the dual (α + β)-phase structure into a single α′-martensite phase with a uniform distribution of alloying elements, and enabled the formation of a smooth surface finish with reduced surface roughness. The modified surface facilitated the formation of homogenous NPAs and NTAs. Annealing in air at 500 °C for 2 h transformed the amorphous as-prepared TiO2 NTAs into a mixture of anatase and rutile phases. Despite the appearance of cracks and an increase in intertubular spacing, the NTAs did not collapse. The NTAs formed on the untreated and LPEB-irradiated Ti–6Al–4V alloy provided better corrosion protection than their nonanodized counterparts.
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In this study, pure hydroxyapatite (HAP) and lithium substituted hydroxyapatite (Li-HAP) nanoparticles were synthesized by a sonochemical synthesis process and investigated for their antimicrobial and hemolytic activities.
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The failure of a turbine blade of a 60 MW thermal power plant is addressed in this paper. The findings of this study, based on the operating conditions and the characteristics of failed turbine blade, suggest a corrosion fatigue-related... more
The failure of a turbine blade of a 60 MW thermal power plant is addressed in this paper. The findings of this study, based on the operating conditions and the characteristics of failed turbine blade, suggest a corrosion fatigue-related failure. The paper addresses the key elements that could have possibly lead to the failure of the turbine blade and highlights the importance of scrutinizing the operating conditions to eliminate the occurrence of such failures.
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ABSTRACT
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Cathodic electrochemical treatment is a facile approach for the deposition of iron–manganese phosphate composite coatings on Al.
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Deposition of electroless (EL) Ni-B-Si3N4 composite coating and its characteristic properties are addressed. Hydrogen evolution limits the level of incorporation of Si3N4 particles in the EL Ni-B matrix to 2 wt%. Incorporation Si3N4... more
Deposition of electroless (EL) Ni-B-Si3N4 composite coating and its characteristic properties are addressed. Hydrogen evolution limits the level of incorporation of Si3N4 particles in the EL Ni-B matrix to 2 wt%. Incorporation Si3N4 particles increased the surface roughness of the matrix but did not influence its structure. The microhardness of EL Ni-B-Si3N4 composite coating in its as-plated condition is 632±17 HV0. 1. Heat treatment at 350 and 450° C for 1 h increased its hardness. Adhesive wear is the predominant wear mechanism of EL Ni-B- ...
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ABSTRACT The fretting corrosion behaviour of Ti?6Al?4V alloy in Ringer’s solution was evaluated and compared with that of commercially pure titanium (CP-Ti). Free corrosion potential, morphology of the fretted zone, extent of formation... more
ABSTRACT The fretting corrosion behaviour of Ti?6Al?4V alloy in Ringer’s solution was evaluated and compared with that of commercially pure titanium (CP-Ti). Free corrosion potential, morphology of the fretted zone, extent of formation and accumulation of debris and wear volume were used as parameters of evaluation. Both Ti?6Al?4V alloy and CP-Ti behave similarly in terms of change in free corrosion potential as a function of time, morphological features and wear mechanism. Ti?6Al?4V alloy, however, exhibits an increase in corrosion susceptibility, decrease in tendency for repassivation, higher amount of formation and accumulation of debris and an increase in wear volume compared with CP-Ti. The study points out the importance of material selection for implants that would encounter fretting corrosion.
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ABSTRACT a b s t r a c t In the present work, multi layer perceptron feed forward artificial neural network (ANN) technique was employed to predict the fretting wear behavior of surface mechanical attrition treated and untreated Ti–... more
ABSTRACT a b s t r a c t In the present work, multi layer perceptron feed forward artificial neural network (ANN) technique was employed to predict the fretting wear behavior of surface mechanical attrition treated and untreated Ti– 6Al–4V fretted against alumina and steel counterbodies. A three-layer neural network with a gradient descent learning algorithm was used to train the network. Three input parameters normal load (L), sur-face hardness of the test material (H) and hardness of counterbody material (CB) were employed in con-struction of ANN. Tangential force coefficient (TFC), fretting wear volume and wear rate obtained from a series of fretting wear tests were used in the training and testing data sets of ANN. Ranking of the impor-tance of input parameters on the output TFC was found to be in the order of L > CB > H. For wear volume and wear rate, it was found in the order of L > H > CB. The degrees of accuracy of predictions were 96.6%, 96.1% and 92.2% for TFC, wear volume and wear rate respectively. Owing to the good correlation between the predicted values and the experimental results, ANN can be used in the prediction of fretting wear behavior.
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The formation of electroless Ni–Co–B ternary alloy deposits was studied using varying bath parameters and operating conditions. Variation in metallic ratio of the bath enables the formation of electroless Ni–Co–B deposits with varying... more
The formation of electroless Ni–Co–B ternary alloy deposits was studied using varying bath parameters and operating conditions. Variation in metallic ratio of the bath enables the formation of electroless Ni–Co–B deposits with varying contents of nickel, cobalt and boron. The Ni–Co–B deposits were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM) to assess the phase constituents, phase transition behaviour, thermal behaviour ...
Research Interests: Materials Engineering, Condensed Matter Physics, Materials Science, Metallurgy, Differential scanning calorimetry, and 11 moreCoatings, Magnetic Properties, Phase transition, Nickel, Alloy, Surface and Coatings Technology, Thermogravimetric Analysis, Structural Properties, Thermal Properties, Vibrating Sample Magnetometer, and thermal behaviour
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The corrosion behaviour of leaded brasses with 2, 2.4, 2.8, and 4.85 wt.% of lead in both neutral (pH 6.5) and acidified (pH 3.0) 3.5% NaCl solution was studied. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS),... more
The corrosion behaviour of leaded brasses with 2, 2.4, 2.8, and 4.85 wt.% of lead in both neutral (pH 6.5) and acidified (pH 3.0) 3.5% NaCl solution was studied. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), currenttime transient, and ...
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The formation of electrodeposited NiB alloy coatings using a dimethylamine borane (DMAB) modified Watt's nickel bath and evaluation of their structural characteristics, hardness and wear resistance are discussed. The boron content... more
The formation of electrodeposited NiB alloy coatings using a dimethylamine borane (DMAB) modified Watt's nickel bath and evaluation of their structural characteristics, hardness and wear resistance are discussed. The boron content in the electrodeposited NiB alloy ...
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The corrosion resistance of Ti–Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5–25% sulphuric acid was evaluated. The Ti–Mo alloys offered a better corrosion resistance than commercially pure titanium (CP‐Ti). The higher impedance values,... more
The corrosion resistance of Ti–Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5–25% sulphuric acid was evaluated. The Ti–Mo alloys offered a better corrosion resistance than commercially pure titanium (CP‐Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti–Mo alloys. The study recommends the use of Ti–Mo alloys, particularly Ti–25Mo alloy, as a suitable material of construction for sulphuric acid medium.
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The possibility of utilizing hydrochloric acid-based waste pickle liquor (WPL) and medium-grade pyrolusite ore to synthesize manganese zinc ferrite was explored. The excess acidity of the WPL was neutralized using mild steel turnings. The... more
The possibility of utilizing hydrochloric acid-based waste pickle liquor (WPL) and medium-grade pyrolusite ore to synthesize manganese zinc ferrite was explored. The excess acidity of the WPL was neutralized using mild steel turnings. The unreacted mild steel scrap and suspended solids were removed by filtration. Partial precipitation technique was employed to reduce the impurities. The purified WPL was treated with
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Research Interests: Materials Engineering, Condensed Matter Physics, Materials Science, Metallurgy, Heat Treatment, and 11 moreTribology, Surface Coatings, Coatings, Nickel, Surface and Coatings Technology, Phase Transformation, X ray diffraction, Structural Properties, Wear resistance, Coefficient of Friction, and Wear Mechanism
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Research Interests: Materials Engineering, Mechanical Engineering, Materials Science, Metallurgy, Scanning Electron Microscopy, and 15 moreFretting, Corrosion, Surface Roughness, Copper, Tin, Laser Scanning, Coatings, High Temperature, Alloy, Contact Zone, Scanning Electron Microscope, Contact Resistance, Copper Alloy, Elevated Temperature, and Intermetallic Compound
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Research Interests: Materials Engineering, Materials Science, Scanning Electron Microscopy, Heat Treatment, Corrosion, and 9 moreStainless Steel, Grain size, Hydrogen Embrittlement, Temperature measurement, Nanocrystalline, X ray diffraction, Microstructures, Corrosion Resistance, and Surface Mechanical Attrition Treatment
Research Interests: Materials Engineering, Mechanical Engineering, Materials Science, Scanning Electron Microscopy, Differential scanning calorimetry, and 9 moreThermogravimetry, Glass Transition Temperature, Thermal Stability, Thermogravimetric Analysis, Polydimethylsiloxane, Epoxy Resin, Thermal Properties, Elsevier, and thermal behaviour
Titanium oxide films with different morphologies have for the first time been fabricated through hydrothermal reactions between a titanium substrate and iodine powder in water or ethanol. SEM revealed that iodine supported titanium... more
Titanium oxide films with different morphologies have for the first time been fabricated through hydrothermal reactions between a titanium substrate and iodine powder in water or ethanol. SEM revealed that iodine supported titanium (Ti-I2) surface shows different morphologies with variable treatment conditions. The mean surface roughness (Ra) was increased in the different groups. Use of surfactant has a role to increase the roughness of the film. The surface roughness was in the range of 0.15 μm-0.42 μm. Furthermore, the electrochemical examinations showed that the Ti-I2 surface fabricated in alcoholic medium has high corrosion resistance than in aqueous medium. Keywords—Corrosion, Hydrothermal, Surface roughness, Titanium oxide.
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This presentation provides an overview of graphene, methods of preparation of graphene, important applications and its role in energy storage devices, namely, fuel cells, supercapacitors, lithium batteries and hydrogen storage.
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Tribocorrosion is the degradation of materials caused by simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion, resulting in irreversible transformation of materials or of their functions.... more
Tribocorrosion is the degradation of materials caused by simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion, resulting in irreversible transformation of materials or of their functions. The present chapter addresses the role of nanomaterials on tribocorrosion. It focuses on the ability of nanoparticles in providing a lubricating effect and the usefulness of nanostructured coatings such as, thermally sprayed FeCu/WC-Co and WC-Co coatings, electrodeposited Ni-Co alloy, Ni-nano SiC, electroless Ni-P-nano SiC coatings, and, nanostructured titanium, in improving the tribocorrosion performance of materials. The limitations of using nanoparticles and nanostructured coatings under tribocorrosion conditions are also addressed.
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The effects of surface mechanical attrition treatment (SMAT) of H11 steel on the growth of phosphate coating and, morphological features and corrosion resistance of the resultant coatings are addressed. SMAT enabled the formation of a... more
The effects of surface mechanical attrition treatment (SMAT) of H11 steel on the growth of phosphate coating and, morphological features and corrosion resistance of the resultant coatings are addressed. SMAT enabled the formation of a uniform surface profile although the average surface roughness is increased after treatment. SMAT increased the extent of metal dissolution and the rate of growth of phosphate coating. In spite of the similarity in phase composition, the phosphate crystallite size is relatively high for samples treated by SMAT. Compared to the untreated one, a cathodic shift in Ecorr with a corresponding decrease in icorr is observed for SMATed H 11 steel after phosphating. Among all, zinc phosphate coatings deposited at pH 3.20 on H 11 steel after SMAT using 8 mm balls for 30 min ranks higher in offering a better corrosion resistance. The increase in surface roughness by SMAT partly compensates the expected improvement in corrosion resistance.
Phosphating is the most widely used metal pretreatment process for the surface treatment and finishing of ferrous and non-ferrous metals. Due to its economy, speed of operation and ability to afford excellent corrosion resistance, wear... more
Phosphating is the most widely used metal pretreatment process for the surface treatment and finishing of ferrous and non-ferrous metals. Due to its economy, speed of operation and ability to afford excellent corrosion resistance, wear resistance, adhesion and lubricative properties, it plays a significant role in the automobile, process and appliance industries. Though the process was initially developed as a simple method of preventing corrosion, the changing end uses of phosphated articles have forced the modification of the existing processes and development of innovative methods to substitute the conventional ones. To keep pace with the rapid changing need of the finishing systems, numerous modifications have been put forth in their development - both in the processing sequence as well as in the phosphating formulations. This review addresses the various aspects of phosphating in detail. In spite of the numerous modifications put forth on the deposition technologies to achieve ...
This presentation provides an overview of the most common type of failures in tin plated contacts - fretting corrosion and whisker growth. The fretting corrosion behaviour of tin plated copper contacts as a function of different... more
This presentation provides an overview of the most common type of failures in tin plated contacts - fretting corrosion and whisker growth. The fretting corrosion behaviour of tin plated copper contacts as a function of different conditions were addressed. The mechamism of fretting corrosion is proposed.
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Corrosion Science and Engineering. Sankara Narayanan, TSN (2010) Corrosion Science and Engineering. [Teaching Resource] (Unpublished). [img], PDF - Presentation 12Mb. Abstract. This presentation provides an overview of corrosion and... more
Corrosion Science and Engineering. Sankara Narayanan, TSN (2010) Corrosion Science and Engineering. [Teaching Resource] (Unpublished). [img], PDF - Presentation 12Mb. Abstract. This presentation provides an overview of corrosion and corrosion prevention methods. ...
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Disclosed is a novel electrochemical method to deposit magnesium fluoride (MgF2) coating on magnesium, in a shorter time. This methodology enables in situ generation of MgF2 and promotes the formation of a uniform and adherent coating on... more
Disclosed is a novel electrochemical method to deposit magnesium fluoride (MgF2) coating on magnesium, in a shorter time. This methodology enables in situ generation of MgF2 and promotes the formation of a uniform and adherent coating on magnesium. In addition, it offers a precise control of thickness and composition of the MgF2 coating by appropriate choice of electrochemical parameters and treatment time. The MgF2 coating deposited using this methodology could be used to achieve a controlled corrosion rate of magnesium towards the development of biodegradable implants. In addition, these coatings could also be used as a pretreatment for the deposition of bioactive coatings, like hydroxyapatite and for depositing electro- and electroless plated coatings.
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This paper addresses the structural characteristics and phase transformation behaviour of plain electroless Ni–P coating and electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings. The X-ray diffraction patterns of electroless... more
This paper addresses the structural characteristics and phase transformation behaviour of plain electroless Ni–P coating and electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings. The X-ray diffraction patterns of electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings are very similar to that of plain electroless Ni–P coating, both in as plated and heat-treated conditions. Selected area electron diffraction (SAED) patterns obtained on the Ni–P matrix of Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 ...
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ABSTRACT a b s t r a c t The role of surface mechanical attrition treatment (SMAT) on pack boronizing of AISI H11 type tool steel is addressed. SMAT induced plastic deformation, enabled nanocrystallization at the surface, reduced the... more
ABSTRACT a b s t r a c t The role of surface mechanical attrition treatment (SMAT) on pack boronizing of AISI H11 type tool steel is addressed. SMAT induced plastic deformation, enabled nanocrystallization at the surface, reduced the grain size and increased the volume fraction of non-equilibrium gain boundaries, increased the accu-mulation of defects and dislocations at the grain boundaries and within the grains. These features helped to promote the diffusion of boron during boronizing and increased the case depth and hardness of the borided layer. Duplex treatment on SMATed H11 steel samples helps to achieve a higher case depth when compared to the single stage treatment. The findings of the study suggest that SMAT can be used as a pre-treatment for boronizing of H11 tool steel.
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... Sci. Eng., 29 (2009) 19421949]. Satendra, Kumar and Sankara Narayanan, TSN and Sundara Raman, Ganesh (2010) Corrigendum to Thermal oxidation of CP-Ti: Evaluation of characteristics and corrosion resistance as a function of treatment... more
... Sci. Eng., 29 (2009) 19421949]. Satendra, Kumar and Sankara Narayanan, TSN and Sundara Raman, Ganesh (2010) Corrigendum to Thermal oxidation of CP-Ti: Evaluation of characteristics and corrosion resistance as a function of treatment time [Mater. Sci. ...
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Abstract The wear resistance of electrodeposited (ED) Ni–B and Ni–B–Si 3 N 4 composite coatings is compared. The effect of incorporation of Si 3 N 4 particles in the ED Ni–B matrix on the surface morphology, structural characteristics and... more
Abstract The wear resistance of electrodeposited (ED) Ni–B and Ni–B–Si 3 N 4 composite coatings is compared. The effect of incorporation of Si 3 N 4 particles in the ED Ni–B matrix on the surface morphology, structural characteristics and microhardness has been evaluated to correlate the wear resistance. The wear mechanism of ED Ni–B and Ni–B–Si 3 N 4 composite coatings appears to be similar; both involve intensive plastic deformation of the coating due to the ploughing action of the hard counter disc. However, the extent of ...
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... Author: Sankara Narayanan, TSN Title Article/Chapter: "Phosphate consversion coatings - a metal pretreating process" Title of Source: Corrosion reviews Volume Number: 12 Issue Number: 3-4 Date of Publication: 1994... more
... Author: Sankara Narayanan, TSN Title Article/Chapter: "Phosphate consversion coatings - a metal pretreating process" Title of Source: Corrosion reviews Volume Number: 12 Issue Number: 3-4 Date of Publication: 1994 Page Numbers: 305-319 Language Text: English ...
The present work aims to evaluate the effect of galvania coupling of mild steel substrate with stainless steel or copper substrate on zinc phosphatability and to evaluate the suitability of zinc phosphate coating to serve as an effective... more
The present work aims to evaluate the effect of galvania coupling of mild steel substrate with stainless steel or copper substrate on zinc phosphatability and to evaluate the suitability of zinc phosphate coating to serve as an effective base for cathodic electrophoretic painting. The study reveals that zinc phosphate coatings obtained under galvanically coupled conditions have higher coating weight and possess better thermal and chemical stabilities compared to those obtained under uncoupled conditions.
This chapter presents an overview of the fundamental aspects of electro-and electroless deposition process, the mechanism of deposition, alloy deposition, etc. and the utility of these coatings for corrosion protection. Both electro-and... more
This chapter presents an overview of the fundamental aspects of electro-and electroless deposition process, the mechanism of deposition, alloy deposition, etc. and the utility of these coatings for corrosion protection. Both electro-and electroless deposition techniques are simple, cost-effective and offer unique advantages for preparing deposits with desirable qualities. In electrodeposition, the plating rate, stability of the bath and the number of turnovers are very high but the resultant coatings lack uniformity on complex shapes and ...
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The present work aims to investigate the effect of galvanic coupling on manganese phosphating process and the possible implications of such a modification in decreasing the processing temperature/time. Coating weight and iron dissolved... more
The present work aims to investigate the effect of galvanic coupling on manganese phosphating process and the possible implications of such a modification in decreasing the processing temperature/time. Coating weight and iron dissolved during phosphating, under both uncoupled and galvanically coupled (with stainless steel or copper substrate) conditions, were used to study the effect of galvanic coupling. The study concludes that galvanic coupling is beneficial in increasing the rate of formation of manganese ...
The wear resistance of electrodeposited (ED) Ni–B and Ni–B–Si 3 N 4 composite coatings is compared. The effect of incorporation of Si 3 N 4 particles in the ED Ni–B matrix on the surface morphology, structural characteristics and... more
The wear resistance of electrodeposited (ED) Ni–B and Ni–B–Si 3 N 4 composite coatings is compared. The effect of incorporation of Si 3 N 4 particles in the ED Ni–B matrix on the surface morphology, structural characteristics and microhardness has been evaluated to correlate the wear resistance. The wear mechanism of ED Ni–B and Ni–B–Si 3 N 4 composite coatings appears to be similar; both involve intensive plastic deformation of the coating due to the ploughing action of the hard counter disc. However, the extent of ...
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Corrosion resistance of electrodeposited (ED) and electroless (EL) composite coatings have been a debatable issue in the published literature. The present paper aims to compare the corrosion resistance of ED Ni–B–Si3N4 composite coating... more
Corrosion resistance of electrodeposited (ED) and electroless (EL) composite coatings have been a debatable issue in the published literature. The present paper aims to compare the corrosion resistance of ED Ni–B–Si3N4 composite coating with its plain counter part.
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Evaluation of the corrosion behavior of commercially pure magnesium (CP-Mg) and ZM21 Mg alloy immersed in Ringer's solution for 92h by electrochemical impedance spectroscopy (EIS) is addressed. The formation of a compact layer of... more
Evaluation of the corrosion behavior of commercially pure magnesium (CP-Mg) and ZM21 Mg alloy immersed in Ringer's solution for 92h by electrochemical impedance spectroscopy (EIS) is addressed. The formation of a compact layer of well-developed rod-like aragonitic CaCO3 crystals and its subsequent thickening with increase in immersion time offers a higher corrosion protective ability for ZM21 Mg alloy.
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Corrigendum to “Thermal oxidation of CP-Ti: Evaluation of characteristics and corrosion resistance as a function of treatment time” [Mater. Sci. Eng., 29 (2009) 1942–1949] Satendra Kumar , T.S.N. Sankara Narayanan ⁎, S. Ganesh Sundara... more
Corrigendum to “Thermal oxidation of CP-Ti: Evaluation of characteristics and corrosion resistance as a function of treatment time” [Mater. Sci. Eng., 29 (2009) 1942–1949] Satendra Kumar , T.S.N. Sankara Narayanan ⁎, S. Ganesh Sundara Raman , S.K. Seshadri b a National Metallurgical Laboratory, Madras Centre, CSIR Complex, Taramani, Chennai-600 113, India b Department of Metallurgical and Materials Engineering Indian Institute of Technology Madras, Chennai-600 036, India
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This paper addresses the structural characteristics and phase transformation behaviour of plain electroless Ni–P coating and electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings. The X-ray diffraction patterns of electroless... more
This paper addresses the structural characteristics and phase transformation behaviour of plain electroless Ni–P coating and electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings. The X-ray diffraction patterns of electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings are very similar to that of plain electroless Ni–P coating, both in as plated and heat-treated conditions. Selected area electron diffraction (SAED) patterns obtained on the Ni–P matrix of Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings exhibit diffuse ring patterns resembling the one obtained for plain electroless Ni–P coating. Phase transformation behaviour studied by differential scanning calorimetry (DSC) indicates that the variation in crystallization temperature and the energy evolved during crystallization of plain electroless Ni–P coating and electroless Ni–P–Si3N4, Ni–P–CeO2 and Ni–P–TiO2 composite coatings is not significant. The study concludes that incorporation of Si3N4, CeO...
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The formation of zinczinc phosphate composite coatings by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed in this paper. The cathodic phosphating process offers some unique advantagesit... more
The formation of zinczinc phosphate composite coatings by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed in this paper. The cathodic phosphating process offers some unique advantagesit requires no specific addition of accelerator in ...
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The present work aims to study the formation and evaluation of characteristic properties of autocatalytically (electroless) deposited Ni-BP ternary alloy coatings. An alkaline plating bath with nickel chloride hexahydrate as the source of... more
The present work aims to study the formation and evaluation of characteristic properties of autocatalytically (electroless) deposited Ni-BP ternary alloy coatings. An alkaline plating bath with nickel chloride hexahydrate as the source of nickel ions and sodium borohydride and sodium hypophosphite as reducing agents was used for the formation electroless Ni-BP coatings.
The influence of various factors on phosphating process using mostly steel substrates and zinc phosphating process are reviewed. The fact evident from such a study is that in an on-line phosphating process, each stage is important in... more
The influence of various factors on phosphating process using mostly steel substrates and zinc phosphating process are reviewed. The fact evident from such a study is that in an on-line phosphating process, each stage is important in determining the phosphatability and ultimate performance of the coating, and one should not overlook a process stage or the variations in the materials used for phosphating and the modifications proposed in the phosphating formulation.
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The methodology of deposition of fluoride conversion coatings is modified with the use of galvanic coupling, agitation of the electrolyte solution, and addition of K2CO3, which helps to provide a better understanding of the mechanism and... more
The methodology of deposition of fluoride conversion coatings is modified with the use of galvanic coupling, agitation of the electrolyte solution, and addition of K2CO3, which helps to provide a better understanding of the mechanism and new avenues to tailor the composition of the coating.
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Résumé/Abstract The present work aims to discuss the effective means of accelerating the low temperature zinc phosphating processes by employing two methodologies and to evaluate the possible implications of adopting such methodologies in... more
Résumé/Abstract The present work aims to discuss the effective means of accelerating the low temperature zinc phosphating processes by employing two methodologies and to evaluate the possible implications of adopting such methodologies in decreasing the processing time. The first one utilizes the galvanic corrosion principle whereas the second one involves the addition of a powerful oxidizing agent, namely, iodine pentoxide to the bath. It is suggested that both methods would impart a higher rate of metal dissolution, ...
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Tribocorrosion is the degradation of materials caused by simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion, resulting in irreversible transformation of materials or of their functions.... more
Tribocorrosion is the degradation of materials caused by simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion, resulting in irreversible transformation of materials or of their functions. The present chapter addresses the role of nanomaterials on tribocorrosion. It focuses on the ability of nanoparticles in providing a lubricating effect and the usefulness of nanostructured coatings such as, thermally sprayed FeCu/WC-Co and WC-Co coatings, electrodeposited Ni-Co alloy, Ni- ...
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ABSTRACT Precipitation and inhibition of calcium carbonate, the most common form of scale in a variety of industrial processes, has been the subject of intense research. Control of scaling by chemical methods is considered to be most... more
ABSTRACT Precipitation and inhibition of calcium carbonate, the most common form of scale in a variety of industrial processes, has been the subject of intense research. Control of scaling by chemical methods is considered to be most effective and economical. The wide anomalies noticed between the actual scale deposition and the rate predicted by the models based on the results of static laboratory test warrant the importance of studying scaling tendency on solid surfaces, rather than in bulk solution. Electrochemical deposition of ...
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Abstract As per the requirements of the customer, the chemical composition and mechanical properties of reinforcement steel bars (8, 12, 20 and 25 mm dia bars) were analyzed and verified for its conformance to Fe 500 HCRM grade of IS... more
Abstract As per the requirements of the customer, the chemical composition and mechanical properties of reinforcement steel bars (8, 12, 20 and 25 mm dia bars) were analyzed and verified for its conformance to Fe 500 HCRM grade of IS 1786: 2008 specification. Besides ...
The corrosion behaviour of Ti-Mo (5 to 25 wt.% Mo) alloys in 0.15 M NaCl containing varying concentration of NaF (0.01, 0.03, 0.06 and 0.5 M) is addressed. The corrostion protective ability of Ti-Mo alloys when comparted to that of CP-Ti... more
The corrosion behaviour of Ti-Mo (5 to 25 wt.% Mo) alloys in 0.15 M NaCl containing varying concentration of NaF (0.01, 0.03, 0.06 and 0.5 M) is addressed. The corrostion protective ability of Ti-Mo alloys when comparted to that of CP-Ti is evaluated using potentiodynamic polarization, EIS and chronoamperometric studies. The microstructure and structural characteristics of the Ti-Mo alloys are also evalated to correlate the corrosion resistance to their microstrucutral characteristics. In 0.15 M NaCl containing 0.01 and 0.03 M NaF, Ti- ...
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Abstract Fretting corrosion is one of the main sources of failure in hip and knee joints. Understanding of the fretting corrosion behaviour of implants becomes an important challenge not only for the medial professionals who perform the... more
Abstract Fretting corrosion is one of the main sources of failure in hip and knee joints. Understanding of the fretting corrosion behaviour of implants becomes an important challenge not only for the medial professionals who perform the surgery but also for the ...
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ABSTRACT The present study addresses the deposition of a duplex coating by microarc oxidation (MAO) treatment and polycaprolactone (PCL) coating to improve the corrosion resistance of Mg. A uniform PCL coating layer is formed by dip... more
ABSTRACT The present study addresses the deposition of a duplex coating by microarc oxidation (MAO) treatment and polycaprolactone (PCL) coating to improve the corrosion resistance of Mg. A uniform PCL coating layer is formed by dip coating method on MAO treated Mg, and the corrosion resistance of MAO-PCL duplex coated Mg is evaluated by potentiodynamic polarization study and immersion test. The results reveal that the porous nature of MAO treated Mg fails to offer a better corrosion resistance in Hanks' balanced salt solution (HBSS). However, deposition of PCL coating (using 4 and 7 wt.% PCL) over MAO treated Mg significantly increased the corrosion resistance of Mg in HBSS for 7 days. The MAO-PCL duplex coating can be a good alternative method of protecting Mg from rapid corrosion for biodegradable implant applications.
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Medication using Siddha drugs has been in practice for a long time. A variety of metallic additives has been added during formulation of the siddha drugs. This has raised concern over the contamination of heavy metals in the human body,... more
Medication using Siddha drugs has been in practice for a long time. A variety of metallic additives has been added during formulation of the siddha drugs. This has raised concern over the contamination of heavy metals in the human body, as they are highly carcinogenic. Following this an ...
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The corrosion behaviour of Ti15Mo alloy in Ringer's solution was evaluated by potentiodynamic polarization, cyclic polarization and chronoamperometric/currenttime transient (CTT) studies. The corrosion protective ability of Ti15Mo... more
The corrosion behaviour of Ti15Mo alloy in Ringer's solution was evaluated by potentiodynamic polarization, cyclic polarization and chronoamperometric/currenttime transient (CTT) studies. The corrosion protective ability of Ti15Mo alloy was compared with that of ...
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This presentation gives an overview of the global challanges and how chemistry can provide a solution for these challanges. Presented for graduate students in chemistry department
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Studies on the catalysis and inhibition of reactions occurring at the electrode/electrolyte interface are of immense interest in both fundamental and applied electrochemical research. A great deal of work was done in studying the relative... more
Studies on the catalysis and inhibition of reactions occurring at the electrode/electrolyte interface are of immense interest in both fundamental and applied electrochemical research. A great deal of work was done in studying the relative rates of the reduction of metal ions and water or hydronium ions both in the presence and absence of numerous organic additives, having in mind that a possible inhibition in the reduction of water or hydronium ions could lead to an increase in the current efficiency of the metal. A variety of organic ...
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ABSTRACT Precipitation and inhibition of calcium carbonate, the most common form of scale in a variety of industrial processes, has been the subject of intense research. Control of scaling by chemical methods is considered to be most... more
ABSTRACT Precipitation and inhibition of calcium carbonate, the most common form of scale in a variety of industrial processes, has been the subject of intense research. Control of scaling by chemical methods is considered to be most effective and economical. The wide anomalies noticed between the actual scale deposition and the rate predicted by the models based on the results of static laboratory test warrant the importance of studying scaling tendency on solid surfaces, rather than in bulk solution. Electrochemical deposition of ...
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ABSTRACT Surface degradation processes such as wear, oxidation, corrosion and fatigue cause failure of many engineering components under varied circumstances. Among the various surface engineering processes, phosphate conversion coatings... more
ABSTRACT Surface degradation processes such as wear, oxidation, corrosion and fatigue cause failure of many engineering components under varied circumstances. Among the various surface engineering processes, phosphate conversion coatings and, electro-and electroless plating processes have received widespread acceptance following their less complex processing sequence and cost-effectiveness. The present review addresses the recent developments in the areas of phosphate conversion coatings, electrodeposition ...
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Electro-and electroless composite coatings offer a cost-effective and efficient way to engineer the surface to achieve desirable qualities, such as hardness, wear and abrasion resistance and corrosion resistance. The present chapter... more
Electro-and electroless composite coatings offer a cost-effective and efficient way to engineer the surface to achieve desirable qualities, such as hardness, wear and abrasion resistance and corrosion resistance. The present chapter provides an overview of electro-and electroless composite coatings, focusing on the scientific fundamental, mechanism of codeposition of particles, factors influencing particle incorporation, characteristics of composite coatings such as, structure, hardness, wear resistance, corrosion, ...
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The fretting corrosion behaviour of CP-Ti in Ringer's solution was studied as a function of normal load, frequency and number of fretting cycles. The restoration ability of CP-Ti after the passive film is damaged due to fretting and... more
The fretting corrosion behaviour of CP-Ti in Ringer's solution was studied as a function of normal load, frequency and number of fretting cycles. The restoration ability of CP-Ti after the passive film is damaged due to fretting and as a function of the on-time/off-time ratio (intermittent ...
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The fretting wear behavior of tin plated copper alloy contacts and its influence on the contact resistance are addressed in this paper. Based on the change in the area of contact zone as well as the wear depth as a function of fretting... more
The fretting wear behavior of tin plated copper alloy contacts and its influence on the contact resistance are addressed in this paper. Based on the change in the area of contact zone as well as the wear depth as a function of fretting cycles, a model was proposed to explain the observed low and stable contact resistance. The extent of wear of tin coating and the formation of wear debris as a function of fretting cycles were assessed by scanning electron microscopy (SEM). Energy dispersive X-ray line scanning (EDX), X-ray mapping, and EDX spot analysis were employed to characterize the nature of changes that occur at the contact zone. The study reveals that the fretted area increases linearly up to 8000 cycles due to the continuous removal of the tin coating and attains saturation when the fretting path length reaches a maximum. The observed low and stable contact resistance observed up to 8000 cycles is due to the common area of contact which provides an electrically conducting are...
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The performance of electroless (EL) Ni – B coated brass contacts under fretting conditions was evaluated. The contact resistance of EL Ni – B coated brass contact was measured as a function of fretting cycles. The surface profile and wear... more
The performance of electroless (EL) Ni – B coated brass contacts under fretting conditions was evaluated. The contact resistance of EL Ni – B coated brass contact was measured as a function of fretting cycles. The surface profile and wear depth of the fretted zone were measured using laser scanning microscope. The study reveals that EL Ni – B coated contacts exhibit better performance under fretting conditions. However, at conditions which are prone for severe oxidation such as, low frequency (3 Hz) or high temperature (155°C), EL Ni – B coated contacts fail to exhibit a better stability. The quick removal of the oxide film by fretting motion, rapid oxidation of the fresh metallic particles and trapping of the oxidation products in the remaining coating, cause the contact resistance to increase to unacceptable levels at such conditions. The study concludes that EL Ni – B coating is not a suitable choice for connector contacts that could experience fretting under highly oxidizing con...
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ABSTRACT The development of biodegradable implants is indeed fascinating and among the various types of materials used in this regard, magnesium and its alloys assume significance. However, the rapid corrosion, generation of a large... more
ABSTRACT The development of biodegradable implants is indeed fascinating and among the various types of materials used in this regard, magnesium and its alloys assume significance. However, the rapid corrosion, generation of a large volume of hydrogen gas, accumulation of the hydrogen bubbles in gas pockets adjacent to the implant, increase in local pH of the body fluid, are the major impediments in using them as an implant material. Hence, development of Mg/Mg alloy based degradable implants requires that (i) they should maintain sufficient mechanical strength and integrity until the affected part of body is healed; (ii) they should exhibit good resistance to corrosion in the body fluid during the initial periods of implantation and subsequently corrode in a controlled and uniform fashion; and (iii) the corrosion products should not exceed the acceptable absorption level of the human body. Reducing the rate of corrosion of Mg is the most appropriate strategy and this can be achieved with the use of alloying, surface treatment/coating and mechanical processing. Surface treatment/coating is a viable approach as it not only enables improvement in corrosion resistance but also provides a suitable surface for better bone bonding and cell growth. Among the various surface modification processes, microarc oxidation (MAO) has received considerable attention since the protective oxide layer would delay the rate of corrosion attack during the initial period of implantation and, the decrease in the extent of hydrogen evolution would enhance the primary neo-formation of bone around the implant. The presence of micropores and cracks on the surface of MAO coatings can be considered as an opportunity or a limitation. The presence of a porous outer layer in MAO coatings would significantly improve the mechanical interlocking effect, the bonding area and stress distribution across the adhesive-substrate interface of the joins, resulting in higher bond strength. However, the presence of a higher pore density on the surface of the MAO coatings increases the effective surface area and thus the tendency of the corrosive medium to adsorb and concentrate into these pores. This would facilitate quicker infiltration of the corrosive medium into the inner regions of the coating and subsequently down to the substrate, thus deteriorating the corrosion resistance of the coating by changing its local pH. The pore density, distribution of pores and interconnectivity of the pores with the substrate are the important factors that decide its corrosion protective ability. In spite of the limitation in corrosion rate, MAO coatings exhibit a slow rate of degradation during the first few weeks and an accelerated degradation in later stages of implantation. Nevertheless, the difficulty in achieving a control over the rate of degradation is still a matter of concern in fabricating implant devices with a desired lifetime. Hence, it is not only essential but also mandatory to increase the corrosion resistance of MAO coatings. In this perspective, this review aims to address the various strategies explored to improve the corrosion resistance of MAO coatings on Mg/Mg alloys. This review provides a detailed outline on how the choice of electrolytes, process parameters, pretreatment, additives, incorporation of ceramic particles and, sealing and post-treatment, influence the porosity and corrosion resistance of MAO coatings on Mg/Mg alloys. In addition, the implications of such modifications/choices on the suitability of the resultant coatings for biomedical applications are discussed. The importance of multifunctional approaches in improving the corrosion resistance as well as imparting a controlled drug delivery, better apatite growth, improved bioactivity, etc. is addressed. The important strategies to improve the corrosion resistance and future prospects are summarized.
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Abstract: Fretting wear tests were carried out at different normal loads on uncoated and diamond-like carbon (DLC)-coated Ti-6Al-4V samples against two counterbody materials: alu-mina and ultra high molecular weight polyethylene (UHMWPE).... more
Abstract: Fretting wear tests were carried out at different normal loads on uncoated and diamond-like carbon (DLC)-coated Ti-6Al-4V samples against two counterbody materials: alu-mina and ultra high molecular weight polyethylene (UHMWPE). Tangential force ...
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In the present study commercially pure titanium (CP Ti) samples were oxidized thermally at three different temperatures (500, 650 and 800°C) for 24h and evaluation of their morphological and structural characteristics, microhardness and... more
In the present study commercially pure titanium (CP Ti) samples were oxidized thermally at three different temperatures (500, 650 and 800°C) for 24h and evaluation of their morphological and structural characteristics, microhardness and corrosion resistance in Ringer's solution was done. The corrosion protective ability of thermally oxidized materials shows a strong dependence on the nature and thickness of the surface
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Abstract Because of the ability of millimolar concentrations of substituted benzyl alcohols to block hydrogen evolution and to form complexes with the cadmium ions, their addition to cadmium sulfate and chloride plating baths increased... more
Abstract Because of the ability of millimolar concentrations of substituted benzyl alcohols to block hydrogen evolution and to form complexes with the cadmium ions, their addition to cadmium sulfate and chloride plating baths increased the current efficiency for depositing cadmium. In sulfate baths there was generally a linear correlation between the concentration of the cadmium‐alcohol complex and the current efficiency. In the cadmium‐chloride system, in which the alcohol could not displace chloride and form a complex, the current efficiency ...
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Abstract Voltammetric and current efficiency studies were made on the effect of benzyl and substituted benzyl alcohols on the competitive deposition of cadmium and evolution of hydrogen. The adsorbed alcohol additives acted as general... more
Abstract Voltammetric and current efficiency studies were made on the effect of benzyl and substituted benzyl alcohols on the competitive deposition of cadmium and evolution of hydrogen. The adsorbed alcohol additives acted as general blocking agents blocking the evolution of hydrogen. In the weakly complexing sulfate system these additives formed complexes with the Cd (II), and in the chloride system they caused a cathodic shift of the cadmium reduction potential, indicating a shift in the distribution of the chloride complex ...
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The corrosion behaviour of Ti-15Mo alloy in 0.15M NaCl solution containing varying concentrations of fluoride ions (190, 570, 1140 and 9500 ppm) is evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS)... more
The corrosion behaviour of Ti-15Mo alloy in 0.15M NaCl solution containing varying concentrations of fluoride ions (190, 570, 1140 and 9500 ppm) is evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and chronoamperometric/current-time transient (CTT) studies to ascertain its suitability for dental implant applications. The study reveals that there is a strong dependence of the corrosion resistance of Ti-15Mo alloy on the concentration of fluoride ions in the electrolyte medium. Increase in fluoride ion concentration from 0 to 9500 ppm shifts the corrosion potential (E(corr)) from -275 to -457 mV vs. SCE, increases the corrosion current density (i(corr)) from 0.31 to 2.30 microA/cm(2), the passive current density (i(pass)) from 0.07 to 7.32 mA/cm(2) and the double-layer capacitance (C(dl)) from 9.63 x 10(-5) to 1.79 x 10(-4)F and reduces the charge transfer resistance (R(ct)) from 6.58 x 10(4) to 6.64 x 10(3)Omega cm(2). In spite of the active dissolution, the Ti-15Mo alloy exhibit passivity at anodic potentials at all concentrations of the fluoride ions studied. In dental implants since the exposure of the alloy will be limited only to its 'neck', the amount of Mo ions released from Ti-15Mo alloy is not likely to have an adverse and hence, in terms of biocompatibility this alloy seems to be acceptable for dental implant applications. The results of the study suggest that Ti-15Mo alloy can be a suitable alternative for dental implant applications.
Research Interests: Dentistry, Electrochemistry, Dental Implants, Corrosion, Polarography, and 15 moreHumans, Electrochemical Impedance Spectroscopy, Fluorides, Current Density, Hardness, Double Layer, Dental Implant, Charge transfer, Materials Testing, Alloys, Biocompatible Materials, Dental Alloys, Electric Impedance, Electric Capacitance, and Corrosion Resistance
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The preparation of NiBSi 3 N 4 composite coatings by electrodeposition technique and evaluation of their characteristic properties are addressed in this paper. The NiBSi 3 N 4 composite coatings were electrodeposited using a... more
The preparation of NiBSi 3 N 4 composite coatings by electrodeposition technique and evaluation of their characteristic properties are addressed in this paper. The NiBSi 3 N 4 composite coatings were electrodeposited using a dimethylamine borane (DMAB)-modified Watt's nickel bath ...
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Research Interests: Materials Engineering, Condensed Matter Physics, Heat Treatment, Amorphous Materials, Differential scanning calorimetry, and 13 moreTEM, Phase transition, Nickel, Phase Transformation, Thermal Analysis, X ray diffraction, Microstructures, Operant Conditioning, Transmission Electron Microscope, Alloys, Sodium Chloride, Vibrating Sample Magnetometer, and Corrosion Resistance
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ABSTRACT A case study on failure analysis of boiler bank tube from a 77 × 2 MW thermal power plant in the Northwest region India is carried out. Visual, optical and stereomicroscopic images were obtained to analyze the type of failure.... more
ABSTRACT A case study on failure analysis of boiler bank tube from a 77 × 2 MW thermal power plant in the Northwest region India is carried out. Visual, optical and stereomicroscopic images were obtained to analyze the type of failure. Scanning electron microscopy (SEM) – coupled with energy dispersive X-ray analysis (EDAX) was used to ascertain the mechanism of failure. The results of the study reveal that the boiler bank tube is failed due to corrosion both from the fireside as well as from the waterside. Ash corrosion is considered to be operative from the fireside while both galvanic and localized corrosion mechanisms are operative from the waterside of the tube. The reason for such failures is addressed. Highlights ► Boiler bank tube is failed due to corrosion from fireside as well as waterside. ► Ash corrosion is operative from the fireside of the tube. ► Galvanic and localized corrosion are operative from the waterside of the tube. ► Accumulation of ash deposits and improper cleaning procedures leads to failure.
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Research Interests: Engineering, Materials Engineering, Mechanical Engineering, Civil Engineering, Condensed Matter Physics, and 15 moreCorrosion Science, Kinetics, Morphology, Atomic Force Microscopy, Corrosion, Electrochemical Impedance Spectroscopy, Physical sciences, Stainless Steel, Magnetron Sputtering, Metals, CHEMICAL SCIENCES, Surface Structure, Nanocrystal, Surface Mechanical Attrition Treatment, and Defect Density
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Page 1. Magnesium: A wonder material? TSN Sankara Narayanan National Metallurgical Laboratory Madras Centre, CSIR Complex Taramani, Chennai-600 113 E-mail: tsnsn@rediffmail.com Page 2. This presentation is aimed to give a glimpse of ...
An overview on the stability of phosphate coating as a base for electropaints, suggests a phosphophyllite-rich coating to provide the best resistance to environments occurring during cathodic electrophoretic painting, curing and under... more
An overview on the stability of phosphate coating as a base for electropaints, suggests a phosphophyllite-rich coating to provide the best resistance to environments occurring during cathodic electrophoretic painting, curing and under service conditions. But coatings on galvanized and other coated steels showed formation of hopeite on phosphating which is unsuitable for protection of the steel substrate. An incorporation of metallic ions, such as nickel and manganese into the zinc phosphating bath, seems to provide a satisfactory ...
Tribocorrosion is the degradation of materials caused by simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion, resulting in irreversible transformation of materials or of their functions.... more
Tribocorrosion is the degradation of materials caused by simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion, resulting in irreversible transformation of materials or of their functions. The present chapter addresses the role of nanomaterials on tribocorrosion. It focuses on the ability of nanoparticles in providing a lubricating effect and the usefulness of nanostructured coatings such as, thermally sprayed FeCu/WC-Co and WC-Co coatings, electrodeposited Ni-Co alloy, Ni- ...
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Surface active agents occupy a predominant role in the metal finishing industry. Being capable of reducing the surface tension and improving the wettability of the surface, the importance of such additives is very well realized and... more
Surface active agents occupy a predominant role in the metal finishing industry. Being capable of reducing the surface tension and improving the wettability of the surface, the importance of such additives is very well realized and phosphating baths have been developed with surfactants as one of the additives. However, surfactant additives could influence the nucleation and growth of phosphate crystals and alter the kinetics of the phosphating process. Addition of surfactants in phosphating baths is beneficial in ...
A cold zinc phosphating bath was formulated and optimised to study the effect of some surfactants as phosphating additives. Potential--time measurements were carried out to evaluate the role of these surfactants in phosphating baths. This... more
A cold zinc phosphating bath was formulated and optimised to study the effect of some surfactants as phosphating additives. Potential--time measurements were carried out to evaluate the role of these surfactants in phosphating baths. This method was found to be simple and versatile in predicting both the kinetics and mechanism of the coating formations. The performance of the coating in the presence of these additives was also assessed. IS 1079 high carbon steel samples were tested.
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Effective monitoring of phosphate baths is difficult since so many parameters control the quality of the plated surface. The results of tests carried out to determine if a more simple monitoring scheme could be developed are reported. The... more
Effective monitoring of phosphate baths is difficult since so many parameters control the quality of the plated surface. The results of tests carried out to determine if a more simple monitoring scheme could be developed are reported. The method must be easily understood and simple to implement so that even the smallest shops could use it. One such method is to measure the potential as a function of time during plating. This has been used to study phosphate baths and develop an understanding of the kinetics and mechanism of ...
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The study explores the utility of the electro-Fenton process for the degradation of o-chlorophenol (o-CP) from aqueous solution. The extent of degradation of o-CP is found to be a function of applied current, electrolysis time,... more
The study explores the utility of the electro-Fenton process for the degradation of o-chlorophenol (o-CP) from aqueous solution. The extent of degradation of o-CP is found to be a function of applied current, electrolysis time, concentration of o-CP and concentration of ferrous ions. Under optimized conditions it is possible to achieve efficiencies higher than 70%. Accelerating the regeneration of Fe2+ ions in the electrolyte determines the efficiency of the process. Addition of goethite as a catalyst in the medium did not significantly ...
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Abstract: The influence of galvanic coupling of mild steel (MS) with titanium, copper, brass, nickel and stainless steel (SS) on the phosphatability is elucidated. The galvanic couple accelerates metal dissolution, enables quicker... more
Abstract: The influence of galvanic coupling of mild steel (MS) with titanium, copper, brass, nickel and stainless steel (SS) on the phosphatability is elucidated. The galvanic couple accelerates metal dissolution, enables quicker consumption of free phosphoric acid and facilitates an earlier attainment of point of incipient precipitation, resulting in higher amount of coating formation. The surface morphology of the coatings exhibit more uniform coating for the mild steel substrates phosphated under coupled conditions. XRD pattern of the zinc ...
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Résumé/Abstract A study of the effect of pH on coating weight of a phosphating bath determined that pH is vital in the determination of the rate and amount of coating formed. Additives undergo changes in activity that greatly influence... more
Résumé/Abstract A study of the effect of pH on coating weight of a phosphating bath determined that pH is vital in the determination of the rate and amount of coating formed. Additives undergo changes in activity that greatly influence the phosphating process as pH is varied.
A literature survey on the types and roles of additives for phosphate coating and their influence on microcrystallinity, adhesion and corrosion resistance of the coating, is presented. The lubricating properties of coatings are enhanced... more
A literature survey on the types and roles of additives for phosphate coating and their influence on microcrystallinity, adhesion and corrosion resistance of the coating, is presented. The lubricating properties of coatings are enhanced by the use of additives of fatty acids mixed with cationic emulsifiers. Phosphating is one of the most common pretreatments for steel, Zn and Al. Data are given for several dozen specific additives.
Electroless NiP coatings provide high hardness and excellent resistance to wear and abrasion. The present work aims to study the formation of electroless NiP graded coatings, with varying nickel and phosphorus contents of the individual... more
Electroless NiP coatings provide high hardness and excellent resistance to wear and abrasion. The present work aims to study the formation of electroless NiP graded coatings, with varying nickel and phosphorus contents of the individual layers and to evaluate their ...