Faculty Publications
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Item An investigation on tribological performance in HVOF sprayed of Amdry1371 and Amdry 1371/WC-Co coatings on Ti6Al4V(Elsevier B.V., 2024) Behera, N.; Srihari, M.; Sharma, Y.K.; Ramesh, M.R.This study investigates the effect of 30 wt% WC addition into Mo-based coating on the microstructure and dry sliding wear performance at elevated temperatures. A ball-on disk tribometer assessed coating wear and friction behavior at room temperature (RT), 300, and 600 °C with loads of 10 and 20 N. The wear rate and mechanism were assessed using SEM-EDX and an optical profilometer. The coating characteristics included density, porosity, surface roughness, microstructure, and microhardness. The bond strength of Amdry1371 and Amdry1371/30%WC-Co coatings is analyzed using the scratch test. During the scratch test, both coatings show cohesive failure at 30-50 N and cohesive along with adhesive failure at 70 N loads. Compared to Amdry1371 coating, Amdry1371/30%WC-Co coating has greater microhardness and bond strength. The wear rate and friction coefficients of Amdry1371 and Amdry1371/30%WC-Co coatings increase with temperatures up to 300 °C and decrease at 600 °C. Wear debris is generated when contact surfaces fracture under the applied load, acting as a third body in the sliding process. This phenomenon, observable from room temperature to 300 °C, increases wear rate and friction coefficients. Protective oxide phases formed on worn surfaces like MoO3, NiMO4, CoWO4, Cr3O8, and WO3 film at 600 °C. This glaze layer is present on worn surfaces, significantly reducing friction coefficients and the wear rate of coatings. Amdry1371/30%WC-Co coating exhibits superior wear resistance and lower friction coefficients than Amdry1371 coating due to MoO3 and WO3. At RT, the dominant abrasive wear mechanism shifts to oxidative wear at 600 °C for both coatings. © 2024 Elsevier B.V.Item Effect of molybdenum on high-temperature tribological performance in HVOF sprayed of WC-based coatings on superni-76(SAGE Publications Ltd, 2025) Behera, N.; Sarmah, P.; Chandramouli, T.V.; Ramesh, M.R.This study examines the effects of Mo on the high-temperature wear and friction behavior of HVOF-sprayed 70%WC-Co/25%Mo/5%C and 70%WC-CrC-Ni/30%Mo coatings on Superni-76. The ball-on-disc tribometer wear tests were conducted at different temperatures (300°C and 600°C) and loads (10 and 30?N) against counter body Al2O3 ball. Microstructures and phase formation were investigated using SEM/EDS and XRD. The characterization of coating microhardness, surface roughness, and coating density was examined. The 70%WC-Co/25%Mo/5%C coating showed lower surface roughness and higher microhardness values than the 70%WC-CrC-Ni/30%Mo coating. The wear rate of the substrate increases with an increase in temperature, whereas 70%WC-Co/25%Mo/5%C and 70%WC-CrC-Ni/30%Mo coatings decrease with temperature from 300°C to 600°C. The coefficient of friction of substrate and coating decreases with increasing temperatures. The worn surfaces of 70%WC-Co/25%Mo/5%C and 70%WC-CrC-Ni/30%Mo coating contain oxide phases (WO3, Cr2O5) and lubrication phases (M0.2W0.8O3, CoMoO4, and MoO3) at 600°C. These oxide phases reduced the coating wear rate and coefficient of friction at 600°C. The 70%WC-Co/25%Mo/5%C coating showed improved resistance to wear and lower friction coefficient than the substrate and 70%WC-CrC-Ni/30%Mo coating. At temperatures of 300°C, the main abrasive wear mechanism changes to oxidative wear when the temperature reaches 600°C for both coatings. © The Author(s) 2025.