Mechanical, Anticorrosion, and Tribological Properties of Nanostructured WC-Co/Cr 3 C 2 -NiCr Multilayered Graded Coatin
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, V.S.N. VENKATARAMANA
,
This paper examines the application of multilayered hard coatings on aluminum substrates to improve their mechanical, anticorrosion, and tribological properties. In the present study, graded coatings with alternate layers of chrome carbide–nickel chrome (75:25) and tungsten carbide–cobalt (88:12) are applied on aluminum substrates for improvement in mechanical and tribological properties. High-velocity liquid fuel (HVLF) spray technique is employed to coat the materials on the aluminum substrate. Nanosized Cr3C2-NiCr and WC-Co powders with particle sizes ranging from 300 to 1000 nm are employed for coating on aluminum substrates. The tribological properties are tested on a pin-on-disk tribometer under lubricated conditions. It is found that graded coating with alternate layers of Cr3C2-NiCr and WC-Co have shown good tribological properties. The hardness has improved, with coating strength being in acceptable range for application in automotive engines. The corrosion resistance of multilayered coating is excellent and in line with Cr3C2-NiCr coating. The effects of number of coating layers of graded coating on tribological and mechanical properties are found to be significant. https://doi.org/10.1007/s11661-019-05117-z Ó The Minerals, Metals & Materials Society and ASM International 2019
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INTRODUCTION
FUEL economy improvement is one of the major challenges of the automotive industry. Two major factors impacting the fuel economy are vehicle weight and frictional loss. In engine systems, friction accounts for a loss of over 40 pct of the total vehicle power. In addition to structural components, engine itself contributes significantly to the vehicle weight. The weight of the engine and its substituent components can be reduced dramatically by replacing cast-iron and steel components with aluminum parts. However, compared with conventional cast iron, the surfaces of aluminum cylinder bores have relatively poor friction and wear characteristics. Hard coatings can radically improve the surface wear and hardness performance of the aluminum substrate, even beyond that achieved by other metallurgical processes. Among the thermal spray coatings for wear resistance, the cermet (composite of
V. SRINIVAS, V.S.N. VENKATARAMANA, and KODANDA RAMA RAO CHEBATTINA are with the Department of Mechanical Engineering, GITAM (Deemed to be University), Visakhapatnam 530045, India. Contact e-mail: [email protected] UMACHAITANYA PATHEM is with the Department of Mechanical Engineering, BITS-Visakhapatnam, Visakhapatnam, India. Manuscript submitted September 14, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
ceramic and metallic materials) coatings based on Tungsten carbide with cobalt as binder (WC-Co) and Chrome carbide with Nickle chrome as binder (Cr3C2-NiCr) are the most prevalent and are the widely utilized thermal spray coatings. Several studies have been conducted[1–34] on the improvement of mechanical properties (hardness, microstructure, and coating strength) and tribological properties of metal su
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