Improving the wear performance of TC6 Titanium alloy by ion nitriding treatment

Abstract

TC6 titanium alloy, also known as Ti-6Al-1.5Cr-2.5Mo, is one of the most widely used titanium alloys in the aerospace industry due to its high specific strength, corrosion resistance and excellent mechanical properties. However, its poor wear resistance limits its application in some situations, such as aircraft actuators. To improve its wear resistance, this paper performs ion nitriding treatment on TC6 titanium alloy for aircraft cylinder and studies its wear performance. The ion nitriding test is conducted for 16 h at 820 °C using a bell-type titanium alloy ion nitriding furnace. The nitrided specimen is divided into three parts: nitrided layer, diffusion layer, and substrate layer. The nitrided layer was 4.11 μm thick and consisted of TiN and Ti2N phases. The diffusion layer was 13.69 μm thick and mainly composed of a gap solid solution formed by N element solid dissolved in α-Ti. After nitriding, the surface hardness of the specimen increased to 1105.2 HV, which is 2.37 times higher than that of the matrix. The hardness-affected layer is about 200 μm thick. The wear rate is reduced by 99.78% compared with that of the matrix, indicating that ionic nitriding greatly improves the wear resistance of TC6 titanium alloy. The wear mechanism of the nitriding specimen differs from that of the matrix, mainly due to abrasive wear, while the wear mechanism of the matrix is a combination of adhesive wear and abrasive wear.