In this study, we introduce a new electrochemical boriding method that results in the formation o... more In this study, we introduce a new electrochemical boriding method that results in the formation of a single-phase Fe2B layer on low carbon steel substrates. Although FeB phase is much harder and more common than Fe2B in all types of boriding operations, it has very poor fracture toughness; hence, it can fracture or delaminate easily from the surface under high
An alternative approach for producing a hard TiB2/TiC multilayer on M2 high-speed steel was intro... more An alternative approach for producing a hard TiB2/TiC multilayer on M2 high-speed steel was introduced by combining cathodic arc physical vapor deposition (CA-PVD) and cathodic reduction and thermal diffusion-based boriding (CRTD-Bor). In this regard, the CRTD-Bor process was applied on CA-PVD Ti-deposited M2 steel and the effects of boriding parameters (i.e., temperatures and durations) on multilayer growth were examined. During boriding, Ti coating on the substrate was converted into Ti-borides on the top surface and a TiC layer was simultaneously formed at the interface of the Ti deposit and the steel matrix. The growth of boride and carbide phases was found to obey the parabolic law. The pre-exponential factors (K0) and the activation energy (Q) values were calculated as 7.50 × 10−9 m2/s and 146.10 kJ/mol for TiB2 growth and 1.81 × 10−7 m2/s and 187.31 kJ/mol for TiC formations, respectively. Additionally, empirical equations for estimating the thicknesses of TiB2 and TiC layers...
This study is focused on the determination of the effects of processing time and temperature on t... more This study is focused on the determination of the effects of processing time and temperature on the thickness, morphology, and hardness of boride layers grown on AISI 304L stainless steels. For boriding, a new molten salt electrolysis method called as CRTD-Bor (Cathodic Reduction and Thermal Diffusion-based boriding) was chosen due to its fast and green nature. CRTD-Bor of AISI 304L substrates was carried out in a borax-based molten electrolyte at temperatures ranging from 950 to 1050 °C for periods of 15 to 60 min at a constant current density of 200 mA/cm 2 . The x-ray diffraction analyses revealed the mixed iron boride phases including Fe 2 B, FeB. Moreover, cross-sectional scanning electron microscopy examinations confirmed the growth of these phases. Additionally, a phase homogenization (PH) step was adapted into CRTD-Bor to eliminate brittle FeB layer. It was founded that after 70 min of treatment at 1000 °C (15 min of CRTD-Bor + 55 min of PH) it is possible to grow ≈ 40-µm-thick Fe 2 B layer exhibiting 1700 ± 100 HV on the surface with excellent adhesion to the substrate (HF1). Besides, kinetic calculations showed the activation energy ( Q ) of boride layer growth as 181.45 kJ/mol.
In this study, sericin extracted from Bombyx mori silk cocoons was integrated into the well-known... more In this study, sericin extracted from Bombyx mori silk cocoons was integrated into the well-known Tollens’ method for synthesizing Ag-NPs. Sericin successfully acted as a stabilizer while silver amine complex [Ag(NH3)2]+ was reduced by maltose. As a result, silver nanoparticles with high stability are formed. Possible functional groups related to the stabilization of NPs were investigated by Fourier-transforms infrared spectroscopy (FT-IR). Ag-Ser NPs were characterized by using particle size measurements based on dynamic light scattering (DLS) and transmission electron microscopy (TEM). According to the characterization investigations, Ag-Ser NPs have characteristic (111) face-centered cubic (FFC) plane and were spherical in shape with a narrow size distribution of 20.23 ±6.25 nm. Overall, the sericin-modified Tollens’ method for synthesizing Ag-NPs offers a simple and non-toxic production method to form nanoparticles. Colloidal stability of nanoparticles displays an essential role...
The necessity of hard and corrosion-resistant surfaces on engineering components becomes progress... more The necessity of hard and corrosion-resistant surfaces on engineering components becomes progressively more vital to provide longer service life with better performance. Transition metal borides, an important subgroup of advanced ceramics, are the perfect candidate for various applications due to their extraordinary properties; i.e., high melting points and extreme hardness along with good wear resistance and fair corrosion resistance as well as excellent thermal and electrical properties. Boriding, a thermal boron diffusion process, is one of the common surface modification technique to form metal borides MeB, MeB2, etc. (Me= metal) on the surface of metallic workpieces. Among several boriding processes, pack and paste boriding are found conventional applications due to their simplicity. However, these processes have many disadvantages, such as expensive powder usage, long process durations and solid waste generations. All these negative sides of currently used boriding techniques ...
In this study, a new environmentally-friendly salt electrolyte was applied for the extraction of ... more In this study, a new environmentally-friendly salt electrolyte was applied for the extraction of copper from Cu2S (white metal- containing approximately 78 wt.% Cu), supplied from KBI Black Sea Copper Works Inc. The effects of process parameters, namely current density and time on the cathodic current efficiency and copper yield were systematically investigated. The molten salt electrolysis was performed at a constant temperature of 1200 °C in a borax electrolyte at current densities ranging from 100 to 800 mA/cm2 for periods of 15 to 60 minutes. The highest cathodic current efficiency (Iii) calculated according to Faraday's Law was found as 40.8% at 600 mA/cm2 for 15 minutes. It was seen that the increase in process time does not have any significant influence on the value of current efficiency (Iii). However, the yield of copper was raised to 79.58% after longer process time; for instance, 38 g Cu was recovered from 60 g Cu2S at 400 mA/cm2 in 1 hour. The cell potential values ...
In this study, we introduce a new electrochemical boriding method that results in the formation o... more In this study, we introduce a new electrochemical boriding method that results in the formation of a single-phase Fe2B layer on low carbon steel substrates. Although FeB phase is much harder and more common than Fe2B in all types of boriding operations, it has very poor fracture toughness; hence, it can fracture or delaminate easily from the surface under high
An alternative approach for producing a hard TiB2/TiC multilayer on M2 high-speed steel was intro... more An alternative approach for producing a hard TiB2/TiC multilayer on M2 high-speed steel was introduced by combining cathodic arc physical vapor deposition (CA-PVD) and cathodic reduction and thermal diffusion-based boriding (CRTD-Bor). In this regard, the CRTD-Bor process was applied on CA-PVD Ti-deposited M2 steel and the effects of boriding parameters (i.e., temperatures and durations) on multilayer growth were examined. During boriding, Ti coating on the substrate was converted into Ti-borides on the top surface and a TiC layer was simultaneously formed at the interface of the Ti deposit and the steel matrix. The growth of boride and carbide phases was found to obey the parabolic law. The pre-exponential factors (K0) and the activation energy (Q) values were calculated as 7.50 × 10−9 m2/s and 146.10 kJ/mol for TiB2 growth and 1.81 × 10−7 m2/s and 187.31 kJ/mol for TiC formations, respectively. Additionally, empirical equations for estimating the thicknesses of TiB2 and TiC layers...
This study is focused on the determination of the effects of processing time and temperature on t... more This study is focused on the determination of the effects of processing time and temperature on the thickness, morphology, and hardness of boride layers grown on AISI 304L stainless steels. For boriding, a new molten salt electrolysis method called as CRTD-Bor (Cathodic Reduction and Thermal Diffusion-based boriding) was chosen due to its fast and green nature. CRTD-Bor of AISI 304L substrates was carried out in a borax-based molten electrolyte at temperatures ranging from 950 to 1050 °C for periods of 15 to 60 min at a constant current density of 200 mA/cm 2 . The x-ray diffraction analyses revealed the mixed iron boride phases including Fe 2 B, FeB. Moreover, cross-sectional scanning electron microscopy examinations confirmed the growth of these phases. Additionally, a phase homogenization (PH) step was adapted into CRTD-Bor to eliminate brittle FeB layer. It was founded that after 70 min of treatment at 1000 °C (15 min of CRTD-Bor + 55 min of PH) it is possible to grow ≈ 40-µm-thick Fe 2 B layer exhibiting 1700 ± 100 HV on the surface with excellent adhesion to the substrate (HF1). Besides, kinetic calculations showed the activation energy ( Q ) of boride layer growth as 181.45 kJ/mol.
In this study, sericin extracted from Bombyx mori silk cocoons was integrated into the well-known... more In this study, sericin extracted from Bombyx mori silk cocoons was integrated into the well-known Tollens’ method for synthesizing Ag-NPs. Sericin successfully acted as a stabilizer while silver amine complex [Ag(NH3)2]+ was reduced by maltose. As a result, silver nanoparticles with high stability are formed. Possible functional groups related to the stabilization of NPs were investigated by Fourier-transforms infrared spectroscopy (FT-IR). Ag-Ser NPs were characterized by using particle size measurements based on dynamic light scattering (DLS) and transmission electron microscopy (TEM). According to the characterization investigations, Ag-Ser NPs have characteristic (111) face-centered cubic (FFC) plane and were spherical in shape with a narrow size distribution of 20.23 ±6.25 nm. Overall, the sericin-modified Tollens’ method for synthesizing Ag-NPs offers a simple and non-toxic production method to form nanoparticles. Colloidal stability of nanoparticles displays an essential role...
The necessity of hard and corrosion-resistant surfaces on engineering components becomes progress... more The necessity of hard and corrosion-resistant surfaces on engineering components becomes progressively more vital to provide longer service life with better performance. Transition metal borides, an important subgroup of advanced ceramics, are the perfect candidate for various applications due to their extraordinary properties; i.e., high melting points and extreme hardness along with good wear resistance and fair corrosion resistance as well as excellent thermal and electrical properties. Boriding, a thermal boron diffusion process, is one of the common surface modification technique to form metal borides MeB, MeB2, etc. (Me= metal) on the surface of metallic workpieces. Among several boriding processes, pack and paste boriding are found conventional applications due to their simplicity. However, these processes have many disadvantages, such as expensive powder usage, long process durations and solid waste generations. All these negative sides of currently used boriding techniques ...
In this study, a new environmentally-friendly salt electrolyte was applied for the extraction of ... more In this study, a new environmentally-friendly salt electrolyte was applied for the extraction of copper from Cu2S (white metal- containing approximately 78 wt.% Cu), supplied from KBI Black Sea Copper Works Inc. The effects of process parameters, namely current density and time on the cathodic current efficiency and copper yield were systematically investigated. The molten salt electrolysis was performed at a constant temperature of 1200 °C in a borax electrolyte at current densities ranging from 100 to 800 mA/cm2 for periods of 15 to 60 minutes. The highest cathodic current efficiency (Iii) calculated according to Faraday's Law was found as 40.8% at 600 mA/cm2 for 15 minutes. It was seen that the increase in process time does not have any significant influence on the value of current efficiency (Iii). However, the yield of copper was raised to 79.58% after longer process time; for instance, 38 g Cu was recovered from 60 g Cu2S at 400 mA/cm2 in 1 hour. The cell potential values ...
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