Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
3 results
Search Results
Item Aging time correlation in DC magnetron sputtered Ni60Ti40 thin films(Elsevier Ltd, 2017) Reddy, B.; Udayashankar, N.K.In this work, Intermetallic NiTi thin films have been prepared using glancing angle DC magnetron sputtering technique on Si (1 0 0) substrate maintained at room temperature with separate elemental targets Ni and Ti. The films were solution treated (annealed) at 600 °C for 1 h followed by aging at 500 °C for 2 h, 4 h and 6 h. The degree of crystallinity increases with subsequent solution treatment followed by aging at different times. The hardness and elastic modulus increased from 8.32 to 9.41 GPa and from 148.92 to 163.13 GPa, respectively, with respect to the increase in aging time. From HR-XPS (High Resolution X-ray Photoelectron Spectroscopy) investigations, it was found that the films aged at different times have shown strong tendency to form thicker surface layer TiO2 (metal oxide) onto the film surface due to higher thermodynamic reactivity by leaving Ni-rich precipitates in the matrix immediately behind the metal oxide layer. © 2016 Elsevier LtdItem Influence of annealing temperature on the structural, morphological, mechanical and surface properties of near equiatomic NiTi thin films(Elsevier Ltd, 2017) Reddy, B.; Udayashankar, N.K.In this work, we report our studies on near equiatomic NiTi thin films grown on silicon (1 0 0) substrates deposited without intentional heating of the substrate by DC magnetron sputtering technique with separate elemental targets Ni and Ti. The films were annealed for one hour at various temperatures, i.e. 350, 450, 550 and 650 °C. X-ray diffraction (XRD) studies revealed that the degree of crystallinity increases up to 550 °C but decreases at 650 °C. The surface roughness value Rq, Ra and Rmax have been obtained by Atomic Force Microscopy (AFM). The hardness and elastic modulus values increase up to 550 °C and decreases at 650 °C. High Resolution X-ray Photoelectron Spectroscopy (HR-XPS) studies revealed that the annealed near equiatomic NiTi thin films have a strong tendency to form TiO2 (metal oxide) layer onto the film surface. This is due to the higher thermodynamic reactivity of Ti by leaving Ni-rich matrix trapped behind, most likely in the sub layers of NiTi along with Titanium carbide (Ti-C) and Silicon carbide (Si-C) precipitates. © 2017 Elsevier LtdItem Pulsed DC magnetron sputtered titanium nitride thin films for localized heating applications in MEMS devices(Elsevier B.V., 2018) M.a, M.A.; Lakshmi Ganapathi, L.G.; G N V R, V.; Udayashankar, N.K.; Mohan, S.Titanium nitride (TiN) thin films are deposited on Si/SiO2 substratesby using Pulsed DC magnetron sputtering and are characterized for their structural, mechanical and electrical properties for their application as localized heating elements in microsystem devices. The influence of substrate temperature on the properties of TiN films has been investigated. The correlation between the structural orientation with mechanical and electrical properties has been established. The films deposited at a substrate temperature of 300 °C have shown better structural, mechanical and electrical properties. This film has been chosen for the fabrication of microheater and its characterization. A maximum temperature of 250 °C is achieved by applying a power of 2.8 W to the microheater. © 2018 Elsevier B.V.