Tribological Dependence of the High-Performance Ferrous-Based Coating on Different Coating Counterparts in Engine Oil

ABSTRACT

A ferrous-based coating with significant chromium was fabricated on aluminum alloy substrate using a plasma spray technique. The tribological performance of the as-fabricated ferrous-based coating sliding against different coatings including Cr, CrN, TiN, and diamond-like carbon (DLC) in an engine oil environment were comparatively studied. Results showed that the high hardness of the sprayed ferrous-based coating was achieved due to the dispersion strengthening effect of Cr₇C₃ phase embedded in the austenite matrix. The ferrous-based coating exhibited low friction coefficients when coupled with these four coating counterparts, which could be attributed to the boundary lubricating effect of engine oil. However, both friction and wear of the ferrous-based coating were different when sliding against these different coating counterparts, which might be closely related to the surface roughness, self-lubricating effect, and mechanical properties of the coupled coatings. Ferrous-based coating sliding against CrN and DLC coatings exhibited good tribological performance in engine oil. The best coating counterpart for the ferrous-based coating in an engine was DLC coating.

KEYWORDS:

• Plasma-sprayed ferrous-based coating
• tribological performance
• coating counterpart
• DLC coating
• engine oil

Funding

The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (Grant Nos. 51202261 and 51475449) and the National Basic Research Program of China (973 Program, Grant No. 2013CB632302).