Production of ZA27 based composite materials by mechanical alloying method and investigation of their tribological properties

In this study, initially, ZA27 matrix powder was produced from ZA27 alloy which produced via casting by gas atomization method. Then, powders that are 63 μm were obtained by sieving. Nano graphite and alumina powders (100 nm) were used as reinforcing materials. Hybrid nanocomposite powders were produced from mixture of ZA27 matrix powders with the graphite and alumina particles by mechanical alloying method for 8 hour in a planetary type ball mill. ZA27 and hybrid nanocomposite samples have been produced from the milled powders at 350 MPa pressure by hot pressing method after they were sintered for 3 hours at 432 0C. Test period of 30 min, test speed of 100 rev/min and load of 10 N have been chosen as parameters of wear test. While two of these parameters have been kept steady, another one have been changed. It has been determined that hybrid nanocomposites that have content of 1 vol.% graphite and 4 vol.% alumina have good tribological properties. However, it has been understood that hybrid nanocomposites that have 4 vol.% graphite and 4 vol.% alumina content have superior tribological properties under low load, low test speed and long test time conditions. The wear surfaces of unreinforced ZA27 and hybrid nanocomposite samples were investigated in the scanning electron microscope and it has been determined that the main wear mechanism of ZA27 was adhesive type wear and delamination. It has been concluded that the main wear mechanism of hybrid nanocomposites was abrasive type wear with the increasing of alumina content.