Introduction: In the present study, the Ti-10Mo-X (TiC & TiB2) composite produced by spark plasma sintering (SPS) with different amounts of ceramic reinforcements (0.5≤ X ≤ 4) was chosen as substrate for development of new biomaterials.... more
Introduction: In the present study, the Ti-10Mo-X (TiC & TiB2) composite produced by spark plasma sintering (SPS) with different amounts of ceramic reinforcements (0.5≤ X ≤ 4) was chosen as substrate for development of new biomaterials. The aim of this study was applying the calcium phosphate (CaP) coating with appropriate quality and phase composition on the Ti-10Mo-X (TiC & TiB2) composite materials for biomedical application. Methods: The Ti-10Mo-X (TiC & TiB2) composites were sintered by SPS method, at an initial pressure of 10 MPa, an intermediate pressure of 20 MPa and a final pressure of 50 MPa at 1150 ℃. Then the CaP coating was applied on the substrates by electrochemical deposition method at three different DC current densities of 0.5, 0.6 and 0.7 mA.cm-2 for 30 minutes. Optical electron microscopy (OM) was used to study the pore structure of the substrates containing the different amounts of ceramic reinforcements. To take a look at the physical properties of the substrates, the sintering density became measured based at the Archimedes method. A tensile test became additionally performed to check the tensile strength of the porous substrates. Scanning electron microscopy (SEM), X-ray energy distribution spectroscopy (EDS) and X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were also used to investigate the morphology, chemical and phase composition of the obtained coatings, respectively. Wettability of the CaP coatings was also investigated using the static droplet contact angle method. At last, the apatite forming ability test of the coated sample were carried out in SBF solution. Findings: By increasing the percentage of ceramic reinforcements because of the removal of porosity, the density and tensile strength of the substrates have raised. Comparing the SEM images showed that, besides the applied current density, the properties of the substrate, such as the percentage of porosity and hydrophilic behavior had an impact on the morphology of the coatings. Moreover, by increasing the current density from 0.5 to 0.6 and 0.7 mA.cm-2 , the apparent quality of the coating decreased and the amount of porosity in the coating increased. In addition, the Ca/P ratio in the coating applied on the 1.0-T1150 and 2.0-T1150 samples at the current density of 0.5 mA .cm-2 was measured to be 1.60 and 1.67, respectively, which is close to that of the natural apatite. Furthermore, the results of XRD and FTIR analysis revealed that the coatings formed on these samples at 0.5 mA cm-2 were mainly containing hydroxyapatite (HA) phase. In addition, after the sample was immersed in simulated body solution (SBF) for 3, 5 and 7 days, a layer of apatite spheres was formed on the surface, indicating the high mineralization ability of the coated sample and hence the prepared sample has a sensible bioactivity.
Introduction: Fitness-for-service (FFS) assessment is one of the standard methods used in oil and gas structures. This method is for assessment the defects of pipes and equipments, which can be operated without repair or replacement if... more
Introduction: Fitness-for-service (FFS) assessment is one of the standard methods used in oil and gas structures. This method is for assessment the defects of pipes and equipments, which can be operated without repair or replacement if the existing defects are within the accepted range of this standard. Methods: During inspection of an 7-km-long pipeline made of API X52 steel carrying hydrocarbons containing wet H2S, hydrogen-induced cracking (HIC) and Lamination was found at different locations along the pipeline length. Microstructural investigations by scanning electron microscopy (SEM) showed stepwise cracking (SWC) as the result of the presence of MnS inclusions. Fitness-for-service (FFS) assessment based on API579-1/ASME FFS-1 was performed to decide on the pipeline serviceability. Findings: The finite element analysis (FEA) results showed that the HICdamaged pipeline was acceptable per level-3 FFS requirements and the pipeline understudy was fit for service. The remaining life of the damaged pipeline should also be periodically monitored using failure assessment diagram (FAD).
Introduction: Nano copper powder is prepared by various methods, which can be mentioned as chemical regeneration, evaporationdeposition, plasma, chemical mechanical, electric explosion, electrolytic deposition and liquid metal atomization... more
Introduction: Nano copper powder is prepared by various methods, which can be mentioned as chemical regeneration, evaporationdeposition, plasma, chemical mechanical, electric explosion, electrolytic deposition and liquid metal atomization methods. Among these, the electrolytic method is more ideal due to the simplicity of the process, low energy consumption, high efficiency, easy control, and low environmental pollution. In this research, the role of electrode material and protective concentration in the electrochemical synthesis of copper nanoparticles was investigated. Methods: constant current density and temperature equal to 0.04 A/cm 2 and 50 C° and the distance between cathode and anode 2.5 cm were considered as research constants. Research variables included copper, gold, steel and rubidium cathode electrodes as well as CTAB protective concentration Findings:. The results showed that smaller crystals can be obtained with copper and gold cathodes. XRD analysis showed that the best purity of copper nanoparticles is obtained by copper cathode. SEM results showed that the gold cathode leads to the formation of spherical and non-cubic particles; and the copper cathode caused the formation of cubic particles. By increasing the amount of CTAB, the purity of copper increased and the growth of copper nanoparticles was effectively prevented. The crystallinity index is more than one and the copper metal is polycrystalline.