中文摘要：

为了揭示Ni-P-Al2O3复合涂层的失效机理，对Ni-P-Al2O3复合涂层进行划痕试验和划痕过程的有限元模拟。划痕试验表明在Ni-P-Al2O3复合涂层的划痕表面上产生了一定间隔距离的横向表面裂纹。划痕过程的有限元模拟揭示在划痕过程的不同阶段涂层表面和界面上应力分布规律，揭示涂层表面裂纹产生的模式和形成的机理。划痕过程分为划针尖端压入涂层表面、在涂层表面上滑动和从涂层表面升高等3个阶段。前两个阶段由于划针尖端对涂层表面的作用，在涂层表面形成划痕沟槽，引起涂层表面产生裂纹。应力分析表明在划痕过程中涂层表面裂纹形成有两种方式。第一种方式是首先在涂层界面产生裂纹，然后裂纹向表面扩展形成表面裂纹；第二种方式是涂层表面直接形成表面裂纹。表面裂纹是最大拉应力引起的，因此，表面裂纹是第一型裂纹。划针尖端从涂层表面升高后在涂层中留下了较大的残余应力，最大残余拉伸应力是出现在接触中心之下的界面上的第一残余主应力。这些结果将为涂层设计和应用提供依据。

英文摘要：

In order to reveal the failure mechanism of coating, both scratch test on Ni-P-A1203 complex coating surface and the simulation of scratch process with finite element method are carried out. Scratch test shows that transverse surface cracks in an interval between two neighboring cracks appear on the scratch groove surface of Ni-P-A1203 complex coating. Finite element simulation of scratch process indicates distributing rules of stress in the coating surface and interface at different stages of scratch process, and reveals coating surface cracks generating mode and forming mechanism. Scratch process is divided into three stages that are stylus tip indenting coating surface, slipping on coating surface and rising from coating surface. In former two stages the scratch groove is formed on the coating surface and the surface cracks are induced by stylus tip acting on coating surface. The stress analysis shows that there are two ways of forming coating surface cracks. One is that coating interface cracks are firstly induced, thus they are propagated to the coating surface, and finally the surface cracks are formed. Other is that cracks are directly formed in the coating surface. Because they are induced by maximum tensile stress, surface cracks are mode I. After stylus tip rising from coating surface, biggish residual stresses remain in the coating. Maximum residual tensile stress is first residual principal stress at the coating interface below the contacting central. Those will supply the basis of coating design and application.