Faculty Publications

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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.
A microstructural study and high-temperature oxidation behaviour of plasma sprayed NiCrAlY based composite coatings
(Elsevier B.V., 2025) Hebbale, A.M.; Ramesh, M.R.; Petr?, J.; Chandramouli, T.V.; Srinath, M.S.; Shetty, R.K.
In this study, the development and performance evaluation of plasma sprayed NiCrAlY based coatings, such as NiCrAlY, NiCrAlY + Al?O? and NiCrAlY + YSZ on T91 steel substrates for high temperature applications is carried out. Microstructural features, phase composition and oxidation resistance under cyclic oxidation at 800 °C of the coatings were characterized. Analysis of the XRD confirmed the formation of protective phases such as Cr?O?, Ni?Al and NiAl, and the improvement observed in the coating's performance was due to the addition of Al?O? and YSZ. Oxidation resistance was improved for the NiCrAlY + Al?O? coating through the formation of a dense Al?O? oxide layer, but the NiCrAlY + YSZ coating was superior in terms of thermal stability and spallation resistance, because YSZ has low thermal conductivity and high thermal shock resistance. Composite coatings showed improved cyclic oxidation behavior and microstructural analysis revealed reduced porosity and enhanced integrity. The results demonstrate that the addition of Al?O? and YSZ in the NiCrAlY coatings leads to capability of tailoring NiCrAlY–based coatings for high temperature industrial applications with improved durability and oxidation protection. © 2025 The Author(s)
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.

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