Browsing by Author "Mukunda, S."

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Effect of low temperature annealing on the properties of nano Ni-Ti alloys
(Institute of Physics Publishing helen.craven@iop.org, 2019) Mukunda, S.; Mahesh, M.; Narendranath, S.; Herbert, M.A.
Binary 1:1 Ni-Ti alloy has been the work horse for many industrial and of late biomedical applications amongst all shape memory alloys. Apart from being employed for endovascular applications like stents and filters, they are also used as orthodontic braces and in endodontic tools. Ni-Ti drills and files are used in a few procedures with sterilization between uses. However, the effect of these sterilizing heat-treatments on the properties of the tools is not clearly investigated. In addition to this, satisfactory metallurgical explanations for the wear resistance of these alloys in absent in the literature. Therefore, this paper attempts to define the transformational temperatures for the Ni-Ti as-received and low temperature heat-treated conditions have been investigated using Differential Scanning Calorimetry (DSC). Attempts are made to justify their suitability for endodontic applications by evaluating their mechanical strength parameters using the Tensile and Wear tests. It was found that the samples showed did not show much variations in strength when subjected to tensile tests whereas the same was not observed for DSC tests. Ambient temperature x-ray diffraction studies indicate the presence of Austenitic and Martensitic phases in all the samples. DSC results are strongly affected by presence of internal stresses but stress-induced-martensitic forms in all the samples with equal facility. © 2019 IOP Publishing Ltd.
Effect of low temperature annealing on the wear properties of NITINOL
(2016) Mukunda, S.; Naths, N.; Herbert, M.A.; Mukunda, P.G.
NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450�C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450�C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted. � Published under licence by IOP Publishing Ltd.
Effect of low temperature annealing on the wear properties of NITINOL
(Institute of Physics Publishing michael.roberts@iop.org, 2016) Mukunda, S.; Naths, N.; Herbert, M.; Mukunda, P.G.
NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450Â°C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450Â°C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted. Â© Published under licence by IOP Publishing Ltd.
Effect of low-temperature annealing on the superelastic response and electrochemical corrosion behaviour of equi-atomic Ni-Ti alloy
(Taylor and Francis Ltd., 2022) Mukunda, S.; Mahesh, V.; Narendranath, S.; Herbert, M.A.; Pg, M.
Nickel–Titanium (Ni–Ti) alloys have exemplary properties such as good thermo-mechanical response and biocompatibility. Hence, they are one of the prime materials of interest in today’s context for the fabrication of advanced biomedical devices. Such properties can be exemplified with certain techniques such as heat-treatment techniques. However, peer-reviewed literature for the same appears to be inadequate to efficiently quantify the effect of such techniques on the overall performance of such materials. Therefore, the present study focuses on analysing the effect of low-temperature heat treatment on the superelastic behaviour and corrosion resistance of titanium-rich Ni–Ti alloys. The superelastic behaviour has been evaluated for different strains. Meanwhile, the Tafel extrapolation method is incorporated to assess the electrochemical corrosion of these materials. It is noticed that the low-temperature heat treatment has marginal effects on the superelastic behaviour of the alloy. The Ni–Ti alloy annealed at 450°C at 6% predetermined strain rate showed the best enhancement in the superelastic behaviour and the corrosion resistance increased upto treatment temperatures of 350°C. Therefore, the most optimum temperature of annealing is found to be 350°C, resulting in about 35.72% improvement in the corrosion resistance of the alloy when compared to their untreated counterparts. © 2021 Informa UK Limited, trading as Taylor & Francis Group.