Effect of aluminum content on tribological behavior of a Cu-Fe-C based friction material sliding against FC30 cast iron

An experimental study was made on the effect of aluminum content on the tribological behavior of a Cu-Fe-C based friction material sliding against FC30 cast iron. As a result, the densities of all Cu-Fe-C materials decreased after sintering. In general, when Al content increased, the density decreased. Sintered 65.5 mass%Cu-11.4mass%Fe-6.6mass%C based friction material (A0) had much lower hardness than 57.7mass%Cu-12.6mass%Fe-7.3mass%C and 48.1mass%Cu-14.0mass%Fe-8.0mass%C based friction materials (A10 and A20). During sintering in air, large amounts of oxides formed. The presence of Al caused Cu-Sn to decompose, Al-Cu and Fe-Sn phases to form, Cu to be oxidized, and Fe₂O₃ to be reduced. A10 demonstrated the highest and most stable friction coefficient, as well as the smallest weight loss among three materials. Both film type and particulate type debris morphologies were observed on worn surfaces of Cu-Fe-C specimens. Local delamination of debris film was frequently observed on A0 and A20 surfaces, but seldom observed on A10 surface. Significant amounts of iron transfers from FC30 to A10 and A20 during sliding, but less such transfer occurred in A0.