91 research outputs found
Effect of PostNitride Annealing on Wear and Corrosion Behavior of Titanium Alloy Ti-6Al-4V
No full textTitanium alloy, Ti-6Al-4V, was plasma nitrided using RF plasma with 100% N at 800 °C and annealed at 850 °C in vacuum. XRD and XPS studies show the formation of titanium nitrides after nitriding and redistribution of nitrogen after annealing. Potentiodynamic polarization and electrochemical impedance spectroscopy studies in Hank’s solution show that nitriding decreases the corrosion resistance of the substrate and postnitride annealing improves the corrosion resistance of the nitrided samples. After nitriding, wear rate has decreased by an order of magnitude in reciprocating wear experiments and decreased further in annealed samples in comparison with that of substrate. Thus, postnitride annealing improves both corrosion and wear resistance of the nitrided sample. These improvements are attributed to redistribution of nitrogen and formation of a thin oxide layer on the sample due to annealing
Similarity Metrics Applied to Graph Based Design Model Authoring
No full textModel reuse is typically facilitated by search and retrieval tools, matching the sought model with models in a database. This research aims at providing similar assistance to users authoring design exemplars, a data structure to represent parametric and geometric design problems. The design exemplar represents design problems in the form of a bi-partite graph consisting of entities and relations. Authoring design exemplars for relatively complex design problems can be time consuming and error prone. This forms the motivation of developing a search and retrieval tool, capable of retrieving exemplars that are similar to the exemplar that a user is trying to author, from a database of previously authored exemplars. In order to develop such a tool, similarity measures have been developed to evaluate the similarity between the exemplar that a user is trying to author and target exemplars in the database. Two exemplars can be considered similar based on the number and types of entities and relations shared by them. However, exemplars meant for th
Corrosion behaviour and effect of surface finishing in the formation of nano structure on NiTi Alloy
No full textNitinol 13 NiTi (Nickel-titanium alloy) is used in orthopaedic and orthodontic applications due to its attractive and exceptional properties such as super elasticity and shape memory effect. Conversely NiTi releases harmful Ni ions from the implants to living tissues that could be toxic to cell, tissue and organs. Thus, it is necessary to have a barrier for such release of ions from the implant. In the present work, we investigate the formation of nano structured oxide layers by anodic oxidation on different surface finished (mirror finished, 600 and 400grit polished) nickel - titanium alloy (NiTi) in electrolyte solution containing Ethylene glycol and NH4F. The anodized surface was characterized by XRD, FESEM and EDS. The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks 19 solution). The investigations show that the native oxide on the sample is replaced by nano structure by anodisation. Corrosion resistance of the anodized sample is comparable with that of the untreated samples
Effect of plasma nitriding on structure and biocompatibility of self organised TiO2 nanotubes on Ti-6Al-7Nb
No full textTiO2 nanotubes formed by anodic oxidation of Ti-6Al-7Nb were nitrided in a nitrogen plasma. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Nano hardness tester (NHT) and Field emission scanning electron microscopy (FESEM). The corrosion behaviour of the substrate, plasma nitrided substrate, substrate with self organised TiO2 nano tubes (TNT) and with plasma nitrided TiO2 nano tubes (TNT+PN) was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks’ solution). The investigations show that the native oxide on the sample is replaced by self assembled nano array by anodisation process. XPS spectra of TNT plasma nitrided sample show the presence of oxy nitride and nitride on the surface. Nano hardness of the samples has increased after nitriding. FESEM images of samples immersed in Hanks’ solution show that growth of calcium phosphate phases is more and the size of deposits are larger on TNT and nitrided TNT samples, as compared to that on the untreated substrate. XPS spectra of TNT and nitrided TNT samples immersed in Hanks’ solution show higher amount of calcium, phosphorous and oxygen than on the substrate. Electrochemical studies show that nitriding decreases the corrosion resistance
Growth, optical, ICP and thermal studies of nonlinear optical single crystal: Sodium acid phthalate (NaAP)
No full textGrowth and electrochemical behaviour of self-organized TiO2 nanotube arrays on Ti-6Al-7Nb
No full textTitanium being bio-inert shows poor bone cell adhesion with an intervening fibrous capsule. It could be made bio- active by several methods including growing in situ TiO2 layer on Ti-surface. In the present work, we investigate the formation of self-organized titanium oxide nanotube layers by anodic oxidation on titanium alloy Ti-6Al-7Nb in electrolyte solution containing HF and H2SO4. The anodized surface was characterized by micro-Raman, XRD and FESEM. The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks’ solution). The investigations show that the native oxide on the sample is replaced by self assembled nano array by anodisation. Corrosion resistance of the anodized sample is comparable with that of the untreated samples. Electrochemical impedance data of the substrate was fitted with two time constant equivalent circuit and that of anodized samples with three time constant equivalent circuit
Electrochemical studies and growth of apatite on Molybdenum doped DLC coatings on titanium alloy β-21S
No full textTitanium alloy β-21S (Ti–15Mo–3Nb–3Al–0.2Si) was coated with molybdenum doped DLC by Plasma-enhanced chemical vapor deposition and sputtering. XRD, XPS and Raman spectroscopy show that Mo is present in the form of carbide in the coating. XPS of samples immersed in Hanks’ solution shows presence of calcium, phosphorous and oxygen in hydroxide/phosphate form on the substrate and Mo-doped DLC. Potentiodynamic polarization studies show that the corrosion resistance and passivation behavior of Mo-doped DLC is better than that of substrate. Electrochemical impedance spectroscopy (EIS) studies show that Mo-doped DLC samples behave like an ideal capacitor in Hanks’ solution
Investigation of electrochemical behavior of plasma nitrided Ti-6Al-7Nb alloy in Hanks’ Solution
No full textTitanium alloy Ti-6Al-7Nb was plasma nitrided using inductively coupled RF Plasma with 100% Nitrogen at 750, 800 and 850°C for 4 h. Micro Raman studies show the formation of titanium nitrides. Potentiodynamic polarization studies in Hanks’ solution show the corrosion resistance of the untreated samples to be better than the treated samples. Electrochemical Impedance Spectroscopy (EIS) studies show higher charge transfer resistance and lower double layer capacitance for the substrate compared to the nitrided samples. FESEM images of samples immersed in SBF show that growth of apatite is more and the size of deposits are larger on nitrided samples as compared to that on the untreated substrate. Nitrided samples immersed in Hanks’ solution for 7 days show higher amount of calcium, phosphorous and oxygen than the substrate
Drug release characteristics of quercetin-loaded TiO2 nanotubes coated with chitosan
No full textTiO2 nanotubes formed by anodic oxidation of Ti-6Al-7Nb were loaded with quercetin (TNTQ) and chitosan was coated on the top of the quercetin (TNTQC) to various thicknesses. Field emission scanning electron microscopy (FESEM), 3D and 2D analyses were used to characterize the samples. The drug release studies of TNTQ and TNTQC were studied in Hanks’ solution for 192 h. The studies showed that the native oxide on the sample is substituted by self assembled nanotube arrays by anodisation. FESEM images of chitosan-loaded TNT samples showed that filling of chitosan takes place in inter-tubular space and pores. Drug release studies revealed that the release of drug into the local environment during that duration was constant. The local concentration of the drug can be controlled and tuned by controlling the thickness of the chitosan (0.6, 1 and 3 μm) to fit into an optimal therapeutic window in order to treat postoperative infections, inflammation and for quick healing with better osseointegration of the titanium implants
Investigation of electrochemical behavior of Plasma nitrided Ti-6Al-7Nb alloy in Hanks’ Solution
No full textTitanium alloy Ti-6Al-7Nb was plasma nitrided using inductively coupled RF Plasma with 100% Nitrogen at 700, 750 and 800°C for 4 h. XRD and micro Raman studies show the formation of titanium nitrides. Potentiodynamic polarization studies in Hanks’ solution show the corrosion resistance of the untreated samples to be better than the treated samples. Electrochemical Impedance Spectroscopy (EIS) studies show higher charge transfer resistance and lower double layer capacitance for the substrate compared to the nitrided samples. FESEM images of samples immersed in SBF show that growth of apatite is more and the size of deposits are larger on nitrided samples as compared to that on the untreated substrate. EDS results show a decrease in nitrogen content and increase in oxygen content after corrosion experiments. XPS spectra from the nitrided samples show the presence of nitride and oxy nitride on the surface. Nitrided samples immersed in Hanks’ solution for one day show higher amount of calcium, phosphorous and oxygen in hydroxide form than the substrate
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