利用微米划痕研究TiN涂层的失效机理

利用微米划痕仪和扫描电子显微镜,研究了TiN涂层的失效过程,分析了摩擦系数波动的机理,并评估了涂层的断裂韧性。结果表明:低载荷阶段,TiN涂层发生剪切滑移,划痕轨迹边缘出现了由反向V形裂纹到平行裂纹,再到正向V形裂纹的裂纹形式转变;随着法向载荷的增大,TiN涂层发生阶梯式剥落。摩擦系数的波动主要由于表面形貌和涂层失效的影响,不同的加载方式,摩擦系数有一定差别。采用微米划痕可以较准确地测试TiN涂层的断裂韧性,与压痕断裂法和有限元模拟法的测试结果相吻合。

Study of Failure Mechanism of TiN Coatings by Micro-scratch Testing

The failure process of TiN coating was studied by micro-scratch and scanning electron microscope, the mechanism of friction coefficient fluctuation was analyzed and the fracture toughness of the coating was evaluated. The results show that at low load stage, the TiN coating undergoes shear slip, and the edge of the scratch track appears from the reverse V-shaped crack to the parallel crack, and then to the forward V-shaped crack; as the normal load increases, the TiN coating undergoes stepwise spalling. Fluctuations in the coefficient of friction are mainly due to surface topography and coating failure, different loading methods have different friction coefficients. The fracture toughness of the TiN coating can be tested accurately with micro-scratches, which is consistent with the test results of the indentation fracture method and the finite element simulation method.