Effect of Cr2O3 on the microstructure and tribological performance of sprayed Fe-based coating on cylinder liner

Improving the vehicle efficiency by weight reduction and friction loss has become the severe challenge to machinery manufacturers. Generally, replacing heavy cast iron engine component by aluminum alloys played a key role in reducing fuel consumption and pollutants emission, but the durability in poor mechanical properties of aluminum alloys restricted its application in severe conditions of engine cylinder. In order to improve the tribological properties of aluminum cylinder liner, Cr2O3-added Fe-based coating was prepared by plasma spraying technology, and the effect of Cr2O3 on the microstructure and tribological performance of sprayed coating was investigated in this study. All the Cr2O3-added coatings improved mechanical properties significantly, such as hardness and wear resistance compared to that of Fe-based alloy. However, appropriate content of Cr2O3 was beneficial to wear resistant but the excessive Cr2O3 deteriorated the wear resistance under dry sliding condition. The degradation was likely generated by the embrittlement of the Cr2O3 reinforcements, weaker interface of Cr2O3/matrix, and the inherent lamellar structure of sprayed coating. As a result, Fe-based coating with 30 wt.% Cr2O3 provided excellent mechanical properties and can be substitute for the application in aluminum alloy cylinder liner.