Tribological Performances of Molded Micro-Cratered Surface of Superelasticity TiNi Alloy

摘要:

采用模压法在TiNi合金表面获得了微凹坑织构，通过织构几何参数的变化调控材料的摩擦学性能。结果表明，周向和径向间距增大，TiNi合金的摩擦系数和比磨损率均呈现先减小后增大的趋势，而深/径比逐渐增大，使得TiNi合金的摩擦系数和比磨损率呈现先增大后减小的趋势。滑动速度增加，TiNi合金试盘的摩擦系数几乎都呈现先减小后增大的趋势，与Stribeck曲线描述的一致。织构参数微坑深/径比为0.06，径向间距为1.5 mm，周向间距为15°时，表现出较优的摩擦学性能，摩擦系数为0.098，比磨损率为0.87 × 10-5 mm3/(N·m)。由此可见，合适的织构参数和形貌可以降低摩擦系数和减小磨损，因为摩擦过程中微坑会产生动压和捕捉磨屑而减少表面损伤，增强耐磨性。

Abstract:

The micro-crater texture of TiNi alloy was voluminously indented by a mold. Results show that the geometrical parameters of the texture will modify the tribological properties. With increasing of the circumferential pitch and the radial spacing of texture, the friction coefficient and wear rate of TiNi alloy present a decrease at the start, and then an increase after a minimum point. With gradual increasing of the ratio of depth to diameter, the friction coefficient and wear rate of TiNi alloy increase initially and then tend to decrease. When the sliding speed increases, the friction coefficient of TiNi alloy decreases firstly and then increases, following Stribeck curve. With the selected texture parameters such as micro-crater ratio of depth to diameter of 0.06, the radial distance of 1.5 mm, circumferential pitch of 15°, the surface show the best tribological properties of the friction coefficient of 0.098 and wear rate of 0.87× 10-5 mm3/N·m. It is concluded that the texture with appropriate parameters and shapes can reduce the friction coefficient and wear because of micro-hydrodynamic lubrication and the capture of wear debris from micro-crater texture.