Formation and function of protective tribo-oxide layers on TC11 titanium alloy surface

Abstract

Dry sliding wear tests and specially designed double sliding wear tests of TC11 titanium alloys were carried out at sliding velocities of 2.68 m/s and 4 m/s by using a MPX-2000 type pin-on-disc wear tester. The phase, composition and morphology of worn surfaces and tribo-layers were analyzed in detail by X-ray diffractometer, scanning electron microscope and energy dispersive spectrometer. The microhardness distribution from tribo-layers to the matrix was measured by using a digital microhardness tester. The results show that tribo-layers are always found to be formed on the worn surface of TC11 titanium alloy at different sliding rates. The phase, state and property of the tribo-layer vary with the sliding conditions. Tribo-layers can be divided into tribo-oxide layer and no-oxide tribo-layer. Through 4 m/s & 2.68 m/s double sliding wear test, the tribo-oxide layer formed in the dry sliding wear process of TC11 titanium alloy is proved to possess good wear-reducing effect. The wear mechanism of TC11 titanium alloy is delamination wear at 2.68 m/s, and oxidative wear at 4 m/s and 4 m/s & 2.68 m/s.

Keywords

• titanium alloy
• dry sliding
• tribo-layer
• double sliding
• wear mechanism