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    Effect of temperature on wear and friction performance of WC-Co and Cr3C2 reinforced with 17-4PH Fe-based composite coatings
    (Springer Science and Business Media Deutschland GmbH, 2024) Chandramouli, T.V.; Joladarashi, S.; Ramesh, M.R.; Rahman, M.R.
    Surface protection is crucial in industrial equipment and tools to prevent wear and friction in harsh environments, particularly at high temperatures, where anti-friction coatings are essential for optimal performance. The present research investigates the tribological properties of high-velocity oxy-fuel sprayed coatings of 17-4PH stainless steel reinforced with tungsten carbide and chromium carbide powders. The coatings are deposited onto a maraging steel substrate. A dry sliding wear test was performed using an alumina ball as a counter body under various test temperatures (25 °C, 300 °C, and 600 °C) and loads (10 N and 30 N). The coating is characterized by employing SEM, XRD, micro-hardness tester, particle analyzer, and bond strength tester, and the mechanism of wear reduction was discussed. The post-wear analysis was carried out on the wear track using SEM/EDS and 3D non-contact optical profilometers. The micro-hardness and bond strength of both (17-4PH-30%WC-Co and 17-4PH-30%Cr3C2) coatings are compared. The test results revealed that at all temperatures and loads, 17-4PH-30%WC-Co coating shows better wear resistance and lower friction coefficient than the 17-4PH-30%Cr3C2 coating. The significant influence of the tribo-oxide layer at high temperatures, which contributed to decreasing wear rate and coefficient of friction, was premeditated. © 2023, International Institute of Welding.
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    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.
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    Microstructure, Mechanical Properties, and Tribological Properties of Fe-Based Composite Coatings Reinforced with WC-Co and Cr3C2
    (Springer, 2025) Chandramouli, T.V.; Joladarashi, S.; Ramesh, M.R.; Rahman, M.R.
    Fe-based (stainless steel 316L) coatings are widely employed in the aerospace, chemical processing, petrochemical, and marine industries owing to their low and stable price, excellent corrosion resistance, and durability. However, at elevated temperatures, their performance is limited due to wear. Thus, the current investigation incorporates tungsten carbide (WC-Co) and chromium carbide (Cr3C2) into the Fe-based coating to enhance its wear resistance at high temperatures. SS316L reinforced by 30% of WC-Co and Cr3C2 by mechanical mixture, then sprayed using high-velocity oxy fuel spraying method. Coating characteristics, such as microstructures and phase analysis, were measured using FESEM/EDS and XRD. Coating density, microhardness, and bond strength were examined by water immersion, Vickers indentation, and ASTM C-633 methods, respectively. A ball-on-disk tribometer was employed to conduct wear examination at various temperatures (25, 300, and 600 °C) and loads (10 and 30 N) against the alumina counter body. The wear rate and friction coefficient of SS316L-30%WC-Co decrease from 25 to 600 °C, while the wear rate of SS316L-30%Cr3C2 increases with temperature up to 300 °C and then decreases at 600 °C. The oxide phase adheres strongly to underlying surfaces forming a protective layer (Cr2O3, NiWO4, Fe2O3, and NiMO4), changing the mode of wear mechanism. At higher temperatures and loads, the coating exhibited oxidation modified adhesive wear, and coatings provide excellent wear resistance along with reduction in friction. This research provides a novel approach for future standardization and evaluation of coatings on metal alloys for industrial applications. © ASM International 2024.