Investigation of Friction and Wear Properties of Duplex-Annealed Ti-6Al-2Sn-4Zr-2Mo Against Hardened AISI E52100 at Linear Reciprocating Motion

Near-alpha titanium alloys possess enhanced properties such as high specific strength, low density, corrosion resistance and an excellent creep behaviour at high operating temperatures which makes them suitable for a wide range of aerospace application areas. However, titanium and its alloys are known for their poor tribological properties which limit their applicability to structural materials. Due to increasing demands on efficiency and environmental restrictions, the application of Ti-6Al-2Sn-4Zr-2Mo as bearing material should also be considered. Experiments were performed on a linear reciprocating tribometer for a constant sliding distance of 300 m, a fixed stroke of 10 mm, at normal loads between 5 and 20 N varying the frequency between 2 and 4 Hz. For the lubrication tests a biodegradable hydraulic oil based on synthetic esters was applied between the two solid bodies. Mechanical properties of the tribotechnical system were determined by tensile tests, hardness and roughness tests as well as microstructural observations. Under dry condition, the Coefficient of Friction (CoF) decreases with increasing load and increasing frequency, whereas the wear volume increases with increasing load and decreasing frequency. Generally, the CoF significantly decreases by applying a lubricant and tends to increase with increasing load and increasing frequency whereas the wear volume increases at higher loads and frequencies. The protective effect of the lubricant against wear is absent. Either the wear volume shows the same values or possesses higher values compared to dry condition. The occurring wear mechanism was determined using a scanning electron microscope to observe the wear track and conduct an elemental analysis using energy-dispersive X-ray spectroscopy.