Wearing behavior of binary Al-Si alloys with cast iron

Abstract

Sliding test of binary Al-Si alloys containing 22.6% of silicon was conducted with a pearlite cast iron ring in the air with no lubricants.The principal results obtained were as follows:(1) The types of wear were reasonably classified into the following four categories by the observation of surface appearance of the sliding rider (alloy). They were cutting surface wear, black surface wear, deposit surface wear, and Fe2O3 inlaid wear.(2) The wear characteristics were varied as follows, depending upon the silicon content.(a) In the case of cutting surface wear, the rates of wear were increased both in the rider and the ring with the increase of silicon content.(b) The cutting surface wear of the hypo-eutectic alloys was governed by adhesion between the rider and the ring. Therefore, the friction coefficient was decreased with the increase of silicon content. Whereas, the primary silicon crystals in the hyper-eutectic Al-Si alloys substantially scratched the cast iron ring and the friction coefficient of these alloys was increased with the increase of silicon content.(c) Al-Si alloys of high silicon content continued to keep the black surface wear at a considerably high sliding speed.(3) The friction coeffcient of the black surface wear was higher than that of the cutting surface wcar. The surface roughness of the cast iron ring was fairly small in the black surface.(4) The alloy containing 1826% of silicon revealed black spotty surface wear at a high sliding speed.