Investigation of the Friction Properties of TZM Alloy Under Different Loads

Abstract

Titanium-zirconium-molybdenum (TZM) alloy, one of the most widely utilized molybdenum alloys, usually experiences friction during service, which leads to tribological failure. However, its friction performances greatly vary under different loads, and the underlying mechanisms remain unclear. In this study, we developed reciprocating friction tests of TZM alloy in aerobic conditions, and evaluated its tribological properties and mechanism under the normal force ranging from 1 to 10 N. The wear process is primarily affected by oxidation, adhesion, and fatigue wear, and adhesive wear intensifies with increasing load, which mainly results in the gradual decline in coefficient of friction from 1.022 to 0.510, as well as variations of friction performances and wear track morphology, thereby elucidating the wear mechanism. There is a long running-in period at a low load of 1 N, with a significant accumulation of mixed oxides of MoO₃ and Mo₄O₁₁ in the wear tracks, leading to a minimal wear rate of 1.68 × 10^–5 mm³·N⁻¹·m⁻¹ after 9000 cycles. At 2 N and 4 N, these oxides undergo repeated spalling, crushing, and re-forming processes. As the load increases to 7 N and 10 N, the wear rate surges to above 1.31 × 10^–4 mm³·N⁻¹·m⁻¹ due to intensified adhesion and debris discharge.

Graphical Abstract