Rajneesh Tyagi - Academia.edu (original) (raw)

Papers by Rajneesh Tyagi

Surface and Coatings Technology

Journal of Materials Engineering and Performance, 2022

The present investigation has been carried out with the aim of determining the frictional and wea... more The present investigation has been carried out with the aim of determining the frictional and wear behavior of porous copper-based composites. The porous copper-based composites have been prepared by using a novel approach for bearing applications, where the mixture of copper oxide and copper powder is blended with the hybrid 2D material, i.e., reduced graphene oxide-MoS2 (rGO-MoS2) by ball milling. The composites were sintered using microwave sintering technique having different compositions (0, 0.5, 1.0, 1.5 and 2.0 wt.% rGO-MoS2), wherein rGO-MoS2 served as the genesis of porosity. The density and hardness decreased with increase in rGO-MoS2 content, and the relative density up to 62% is achieved. The tribological behavior was studied at the different loads of 4, 6, 8 and 10 N and constant sliding speed of 0.5 m s−1 against EN31 ball counterface, while testing has been conducted under dry sliding and mixed lubricated conditions. Composites exhibit the low frictional characteristics as compared to the base material, and an increase in coefficient of friction and wear rate is observed with increase in load. The worn surface analyzed by the scanning electron microscopy and energy-dispersive x-ray spectroscopy revealed the oxide layer formation, abrasive wear and adhesion as major wear mechanisms in dry sliding conditions. Tribo-oxide layer formation and retention of lubricant in the pores account for the low friction and wear of the composites under single drop lubrication.

Journal of Tribology, 2022

To reveal the effect of carbon content on tribological performance of coatings, TiAlC films havin... more To reveal the effect of carbon content on tribological performance of coatings, TiAlC films having four different amounts of carbon content were synthesized using DC pulse magnetron sputtering. The amount of carbon was varied by using different graphite target powers of 400, 450, 500, and 550 W while keeping the TiAl target power fixed at 80 W. Sliding friction and wear behavior of TiAlC nanostructured coatings deposited on Si (100) substrates by (DC) pulse magnetron sputtering was examined against steel ball using a ball on disk configuration’ at a load of 1 N and sliding speed of 7 mm/s. The coating deposited at 500 W graphite target power attained a hardness of 20.24 GPa and elastic modulus of 246 GPa. Tribological test results indicate that the coating deposited at (500 W, 25 at% C) has the lowest coefficient of friction (COF) of 0.29 as well as the wear-rate of 6.52 × 10−13 (mm3/Nm). The observed behavior has been attributed to the increase in crystalline nano graphite phase, i...

Journal of Materials Engineering and Performance

Materials Today: Proceedings, 2021

Abstract Graphene has drawn the attention of researchers across the globe due to its exceptional ... more Abstract Graphene has drawn the attention of researchers across the globe due to its exceptional properties and has a great potential to reduce friction and wear in machine elements. The present investigation is aimed at exploring the effect of counterface ball materials (Si3N4, ZrO2, and steel) on friction and wear of a multi-layer graphene coating deposited on steel using chemical vapor deposition under reciprocating sliding. Results pointed out that the graphene coating on the steel surface reduces both friction and wear against each ball material in comparison to bare steel. Contact pressure played a vital role in determining tribological performance against different counterparts. Silicon nitride ball exhibited the highest friction and wear as surfaces were subjected to maximum contact stress. However, the minimum friction coefficient was observed for steel slid against multi-layer graphene-coated steel. The higher hardness of the zirconia ball in comparison to the steel ball helped in providing minimum wear.

Journal of Materials Engineering and Performance, 2020

The present study is directed to reveal the effect of density and shape of the dimples on the fri... more The present study is directed to reveal the effect of density and shape of the dimples on the friction and wear characteristics of textured bearing steel (100Cr6) under dry sliding conditions. One untextured and four laser-textured disks of 100Cr6 steel with circular and bi-triangular dimples having 7 and 20% density, respectively, in the spiral layout were tested using a pin-on-disk unidirectional tribometer against a 100Cr6 pin having a flat surface with rounded corners under flat-on-flat configuration. The tests were carried at different speeds of 0.2, 0.6, and 1 m/s at a constant load of 15 N. The results indicate that a higher density of bi-triangular dimples had less wear and a lower coefficient of friction compared to untextured disk or disk with circular dimples, particularly at a relatively higher speed. This has been attributed to a relatively higher number of dimples in the contact zone in case of a spiral array, which increases the entrapment of more wear particles leading to a reduction in wear. The friction coefficient had a relatively higher value at a relatively lower speed but decreased at the highest speed of 1.0 m/s used in the present study. The results suggest that dimples may not be too effective under dry contact because they lose their effectiveness to trap wear debris after getting filled.

Journal of Physics: Conference Series, 2019

The present investigation is on the tribological behaviour of graphene coated bearing steel (EN31... more The present investigation is on the tribological behaviour of graphene coated bearing steel (EN31). Though bearing steel has excellent mechanical properties but its wear properties are inadequate. To enhance its wear properties, bearing steel was coated by graphene. Graphene is a very unique and peculiar material. It has excellent mechanical, chemical, electrical, magnetic and optical properties. Furthermore, it is light in weight which makes it one of the most sought after materials in the research world. To improve the adhesion property between graphene and bearing steel, bearing steel was first coated with nickel using electroplating technique. Then graphene was coated by CVD technique. To analyse the characteristics of graphene, Raman spectroscopy was carried out. The friction and wear tests were performed at constant load of 1 N and different speeds of 0.05 m/s, 0.075 m/s and 0.1 m/s for the tribological analysis of the materials. After wear, the worn out surfaces were further ...

Materials Research Express, 2019

Composites Part B: Engineering, 2019

Copper matrix composites reinforced by rGO-MoS 2 hybrid: Strengthening effect to enhancement of t... more Copper matrix composites reinforced by rGO-MoS 2 hybrid: Strengthening effect to enhancement of tribological properties,

Materials Today: Proceedings, 2018

Aluminium based composites containing 5, 7 and 9 wt.% B 4 C were synthesized with the help of Pot... more Aluminium based composites containing 5, 7 and 9 wt.% B 4 C were synthesized with the help of Potassium Hexaflurotitanate (K 2 TiF 6) following stir casting route. The technique results in good bonding of second phase with the matrix due to improved wettability and good dispersion. Dry sliding friction and wear test were carried out at 9.8N, 19.6 N,29.4 N, 39.2N load at a constant sliding speed of 1m/s and compared with pure Aluminium. The wear rate was observed to vary linearly with normal load following Archard ' s law. However, the wear rate shown by the composites was significantly lower than for the pure Aluminium. Both the wear rate and the average friction coefficient were found to decrease with increasing weight percentage of boron carbide.The wear mechanism appeared to be primarily oxidative for both pure Aluminium and composites under the given condition of load and sliding velocity as indicated by the presence of a well compacted transfer layer of wear debris on the sliding surface as revealed by the scanning electron microscopy of worn surfaces. The said layer inhibits metal-metal contact leading to reduction in both wear rate and friction coefficient.

Vibroengineering PROCEDIA, 2018

Three-point bending test is conducted by help of Finite Element Method to find out mechanical pro... more Three-point bending test is conducted by help of Finite Element Method to find out mechanical properties of Inconel 718 coating on stainless steel. For doing this ANSYS package are employed to visualise exact situation of bending test so that can find out stress field developed during the test. A 3D modelling of coating and substrate material is used. Load versus displacement relationships is compared with reference results. It is noticed that yield stress of substrate material is higher than the tensile stress of substrate and coating. Due to this reason there is initiation of crack at coating-substrate interface and it is propagated which leads to failure with applied load.

Spine, Mar 3, 2017

Biomechanical analysis using a validated nonlinear finite element (FE) model. To combine the stra... more Biomechanical analysis using a validated nonlinear finite element (FE) model. To combine the strategy of two-level hybrid surgery (HS) to explore how prostheses affect cervical biomechanics. Few FE studies have explored differences in biomechanical behavior between combined and stand-alone structured prostheses with HS. No FE studies have considered whether the prosthesis type and hybrid strategy influence two-level HS. Three prostheses-Prodisc-C, PCM, DCI-were analyzed in flexion and extension during HS at C4-C6. There were two HS constructs: (1) ACDF conducted at the C4-C5 levels and ACDR conducted at C5-C6 levels (ACDF/ACDR); (2) ACDR/ACDF. Flexion motion at adjacent levels was greater than that of intact spine. A maximum increase of 80% was observed with PCM in the ACDF/ACDR group. Extension motion at adjacent levels for both hybrid strategies with PCM, however, was similar to that of intact spine (<10% change), whereas it increased by 14%-32% with DCI. The strain energy-stor...

Spine, Jan 14, 2017

Biomechanical study using a three-dimensional nonlinear finite element (FE) model. To analyze bio... more Biomechanical study using a three-dimensional nonlinear finite element (FE) model. To analyze biomechanical changes with three prostheses based on two-level arthroplasty and to verify the biomechanical efficiency of dynamic cervical implants (DCIs) with a stand-alone U-shaped structure. Few studies have compared biomechanical behavior of various prostheses as they relate to clinical results after two-level total disc replacement (TDR). Three arthroplasty devices Mobi-C, PCM and DCI were inserted at the C4-C6 disc space and analyzed. Displacement loading was applied to the center of the endplate at the C3 level to simulate flexion and extension motions. The motion distributions in extension with DCI and in flexion with DCI and Mobi-C were relatively close to that in the intact model. Mobi-C and PCM obviously increased the combined extension range of motion at the index levels, but both resulted in about 45% decrease in extension moment. DCI showed a trend in strain energy similar to ...

Journal of Materials Engineering and Performance, 2016

Galling behavior of three different stainless steels (SS 316, 316 L and 416) was evaluated at roo... more Galling behavior of three different stainless steels (SS 316, 316 L and 416) was evaluated at room temperature and 300°C under a self-mated condition. An indigenously fabricated galling tester was used to evaluate the galling performance of mated materials as per ASTM G196-08 standard. The variation in frictional torque was recorded online during the test to assess the onset of galling. The galling 50 (G 50) stress value was used to compare the galling resistance of a combination of materials, and the results indicate a significant influence of temperature on the galling resistance of the materials tested. This has been attributed to the decrease in hardness and yield strength at elevated temperature which results in softening of the steel and limits its ability to resist severe deformation. Scanning electron micrographs of the galled surface reflected a severe plastic deformation in sliding direction, and a typical adhesive wear mechanism is prevalent during the galling process.