Characterization of Surface-Treated NiTi Alloy by Various Electrochemical Techniques in Phosphate-Buffered Saline

Sol–gel titania thin film coating was prepared on NiTi surfaces, modified with acidified ferric chloride solution. Nanogrids formed on chemical treatment were uniformly covered with titania coating. Cyclic voltammetry studies in phosphate-buffered saline solution revealed that sol–gel titania-coated surface displayed electrochemical properties which were similar to those observed for pure titanium. During polarization, the passive layer formed on modified NiTi was stable for potentials greater than 0.9 V. The overall resistance measured by electrochemical impedance spectroscopy for sol–gel titania surface was in the order of 10⁵ Ω, which was approximately two orders higher than bare NiTi surface. The current noise analyzed using electrochemical noise measurements was minimum after sol–gel coating, which emphasizes the better protection power of the surface from the attack of corrosive species. Dynamic impedance studies carried out on bare and titania-coated NiTi also supports the results obtained from cyclic polarization

Role of powder metallurgical processing and TiB reinforcement on mechanical response of Ti-TiB composites

In this work, titanium–titanium boride (Ti–TiB) composites were synthesized by three different powder metallurgical techniques, namely, spark plasma sintering (SPS), hot iso-static pressing (HIP) and vacuum sintering (VS). The mechanical properties of the composites were determined using the nanoindentation technique. The role of the material processing route and TiB reinforcement employed on the mechanical properties of the composites was investigated. The results revealed that the composites processed by SPS possessed improved mechanical properties relative to those of the composites prepared by the HIP and VS techniques. Furthermore, reinforcement of the composites with TiB enhanced the hardness, elastic modulus and contact stiffness, whereas it reduced the fracture toughness and indentation creep

Effect of chemical treatment on the corrosion and bioactivity of equiatomic NiTi alloy

NiTi alloy in its equiatomic concentration is widely used in biomedical industry owing to its shape memory and superelasticity properties. The main problem facing for using it as implant materials is the possibility of elution of nickel, which is a known carcinogen. However, the elution rate can be reduced from the toxic limit to a reasonably safe level by adopting suitable surface modification techniques. In the present study, the advantage of using ferric chloride, which is a common etchant for nickel was explored to modify the surface of NiTi alloy. NiTi alloy was chemically treated using acidified ferric chloride solution and post treated by annealing at 400 oC and passivation in nitric acid. The alloy surface after chemical treatment resulted in a nanogrid structure with a combination of one dimensional channel and two dimensional network-like patterns. The undulations formed after chemical treatment remained unaltered after annealing, while after passivation process the undulated surface was found to be filled with titanium oxides. XPS analysis revealed that the surface of passivated sample was enriched with oxides of titanium, predominantly as TiO2. The corrosion potential, corrosion current density and breakdown potential were less noble for chemically treated NiTi alloy. The breakdown potential obtained for annealed surface was almost 200 mV higher than the passivated surface (0.8 V). Due to the decrease in surface nickel content and formation of compact titanium oxide, the overall resistance was in the range of mega ohms for passivated surfaces and the amount of nickel released after 14 days of immersion is almost half when compared to untreated NiTi alloy. Thus a combination of chemical treatment, annealing and passivation processes on NiTi alloy exhibits good bioactivity and corrosion resistance and may be considered suitable for biomedical implant applications

Investigation on wear and corrosion behavior of equal channel angular pressed aluminium 2014 alloy

Aluminium 2014 alloy solutionized at 495°C, aged at 195°C was subjected to Equal Channel Angular Pressing (ECAP). Dry sliding wear tests were conducted using pin on disc tribometer system under nominal loads of 10N and 30N with constant speed 2m/s for 2000m in order to investigate their wear behavior after ECAP. The Co-efficient of friction and loss in volume were decreased after ECAP. The dominant wear mechanism observed was adhesion, delamination in addition to these wear mechanisms, oxidation and transfer of Fe from the counter surface to the Al 2014 pin were observed at higher loading condition. The corrosion behavior was evaluated by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results obtained from PDP showed higher corrosion potential and lower corrosion density after ECAP than base. Electrochemical impedance spectroscopy (EIS) showed higher charge transfer resistance after ECAP. Surface morphology showed decreased pit size and increased oxygen content in ECAP sample than base after PDP

Novel TCAP mutation c.32C>A causing limb girdle muscular dystrophy 2G

TCAP encoded telethonin is a 19 kDa protein, which plays an important role in anchoring titin in Z disc of the sarcomere and is known to cause LGMD2G, a rare muscle disorder characterised by proximal and distal lower limb weakness, calf hypertrophy and loss of ambulation. A total of 300 individuals with ARLGMD were recruited for this study. Among these we identified 8 clinically well characterised LGMD2G cases from 7 unrelated Dravidian families. Clinical examination revealed predominantly proximo - distal form of weakness, scapular winging, muscle atrophy, calf hypertrophy and foot drop, immunoblot showed either complete absence or severe reduction of telethonin. Genetic analysis revealed a novel nonsense homozygous mutation c.32C>A, p.(Ser11*) in three patients of a consanguineous family and an 8 bp homozygous duplication c.26_33dupAGGTGTCG, p.(Arg12fs31*) in another patient. Both mutations possibly lead to truncated protein or nonsense mediated decay. We could not find any functionally significant TCAP mutation in the remaining 6 samples, except for two other polymorphisms, c.453A>C, p.( = ) and c.-178G>T, which were found in cases and controls. This is the first report from India to demonstrate TCAP association with LGMD2G

Screening of groundnut interspecific derivatives for resistance to Sclerotium rolfsii

Sclerotium rolfsii is a major constraint for production in most of the groundnut growing areas in India inflicting 28-30 per cent yield losses annually. Irrigated groundnut grown in the post-rainy and summer seasons in India is often infected by this pathogen. The 54 interspecific derivatives and 6 recombinant inbred lines (TAG-24 x R-9227 cross) along with 6 check varieties CDh-86, Dh-216, ICGV 91114, Dh-3-30, R-9227 and TAG-24) were screened for S. rolfsii resistance in sick plots during summer and Kharif2012 seasons. In summer 28 lines and 32 lines in Kharif showed highly resistant reaction to stem rot disease. High genetic variability and heritability was observed for disease and yield attributes viz., number of pods per plant, pod yield, harvest index, disease incidence at harvest, disease severity and disease spread irrespective of seasons. Per cent disease incidence at harvest was having strong significant negative association with dry pod yield per plant in both seasons. The interspecific derivatives viz., ICGV 3649-1, ICGV 4368-1, ICGV 3727-4, ICGV 34-1 and ICGV 4670-7 and recombinant inbred lines viz., RIL 3-14, RIL 6-1 and RIL 6-28 had desirable combination of high level of stem rot resistance and good agronomic attributes. These promising lines can been tested in trials over locations to confirm their superiority and utilized in breeding for Sclerotium disease resistance

Development and certification of chromic acid-free anodizing process for aircraft grade aluminium alloys

21-27Chromic acid (Cr6+) anodization process is widely used for the corrosion protection of aircraft aluminium alloys. Hexavalent chromium being toxic in nature need to be phased out by eco-friendly alternatives. In the present study modified tartaric-sulphuric acid (TSA) process has been developed followed by sealing in permanganate based bath to obtain 4 to 6 µm thick anodic oxide layer on 2024-T3, 6061-T6 and 7075-T6 aluminium alloys. The process was carried out using a pilot scale anodizing plant. The anodized specimens were characterized for visual observation, thickness, adhesion, electrical breakdown voltage, corrosion resistance and tensile behaviour. All the tests were carried out as per MIL-A-8625F specifications. The specimens were also subjected for about 800 hrs to real time corrosion testing, 200 metres away from sea shore at Mandapam Camp, Rameshwaram, India. The performance of the permanganate sealed TSA anodized aluminium alloys are comparable with that of the conventional chromic acid anodized coatings. This chromic acid-free anodization process has been qualified to airworthiness regulating standards by Indian military certification authorities. Efforts are in progress to commercialize this technology for use on aero platforms

Development and certification of chromic acid-free anodizing process for aircraft grade aluminium alloys

Chromic acid (Cr6+) anodization process is widely used for the corrosion protection of aircraft aluminium alloys. Hexavalent chromium being toxic in nature need to be phased out by eco-friendly alternatives. In the present study modified tartaric-sulphuric acid (TSA) process has been developed followed by sealing in permanganate based bath to obtain 4 to 6 µm thick anodic oxide layer on 2024-T3, 6061-T6 and 7075-T6 aluminium alloys. The process was carried out using a pilot scale anodizing plant. The anodized specimens were characterized for visual observation, thickness, adhesion, electrical breakdown voltage, corrosion resistance and tensile behaviour. All the tests were carried out as per MIL-A-8625F specifications. The specimens were also subjected for about 800 hrs to real time corrosion testing, 200 metres away from sea shore at Mandapam Camp, Rameshwaram, India. The performance of the permanganate sealed TSA anodized aluminium alloys are comparable with that of the conventional chromic acid anodized coatings. This chromic acid-free anodization process has been qualified to airworthiness regulating standards by Indian military certification authorities. Efforts are in progress to commercialize this technology for use on aero platforms

Utilization of Glycerol from Biodiesel Industry By-Product into Several Higher Value Product

Since the 1980s the energy demand has been increasing steadily, including diesel fuel. On the other hand the oil reserve in the world was increasingly limited because of being the product that could not be renewed. Therefore, effort was carried out to look for the alternative fuel that could be renewed and environment friendly. The alternative energy from new renewable energy is a solution to reduce the dependence of fossil energy. The renewable energy consists of the energy of water, wind, biomass or biofuels, solar energy, ocean energy, and geothermal energy. One of the biofuels is biodiesel. Biodiesel is diesel fuel which is made from vegetable oil by transesterification. The abundance of glycerol will result in declining sales value of glycerol as a by-product of the biodiesel plant. It should be anticipated to improve the usefulness of glycerol both in terms of quantity and its variants. The increasing usefulness of glycerol will result in the higher price of glycerol that will increase the profitability of biodiesel plants. Among the usefulness of glycerol investigated is as an ingredient in pharmaceutical products, polyether, emulsifiers, fabric softener, stabilizers, preservatives in bread, ice cream, cosmetic ingredients, a propellant binder, and others. This chapter explains the utilization of glycerol to produce triacetin as bioadditive and polyglycidyl nitrate (PGN) as a propellant binder. Triacetin is used to increase octane number of fuel and improve the biodiesel’s performance. Propellant binder consists of two kinds of non-energetic polymers and polymer energetic. The most energetic polymer is PGN. The focus of this chapter is to determine each step of reactions, operating conditions of process and the results of products