Comparison of the wear properties of modified ZA-8 alloys and conventional bearing bronze

In this study, an attempt has been made to examine the wear response of some modified Zn–Al based alloys and a conventional bearing bronze (SAE 660) at the sliding speeds of 0.5 ms−1, 1 ms−1, 1.3 ms−1, 1.7 ms−1 and 2 ms−1 using applied load of 30 N and 45 N. The standard ZA-8 alloy and modified with 1% Pb, 1% Sn and 1% Cd alloys have been subjected to a pin-on-disc wear test under dry condition. A conventional bearing bronze has also been subjected to identical tests with a view to assess the working capability of the modified Zn–Al based alloys with respect to existing ones. The results have shown that the ZA-8 alloy and modified with Pb, Sn and Cd alloys revealed higher wear resistance when compared with bearing bronze. In addition, wear resistance of ZA-8 based alloys increased with increasing sliding speed up to 1.7 ms−1 for 30 N and 1.3 ms−1 for 45 N, respectively. But it decreased with increasing sliding speed. The addition of Pb to the ZA-8 alloy increased wear resistance of the alloy for all of the sliding speeds at 30 N and 45 N, while the addition of Cd increased wear resistance of the ZA-8 at 45 N. But Sn alloying element caused worse wear resistance for ZA-8 alloy. On the other hand, the friction coefficients of ZA-8 and modified alloys are higher than that of the bearing bronze. Metallographic studies showed that the addition of Pb, Sn and Cd resulted in modifying on the microstructure of ZA-8 alloy.