电接触强化对Ni/Cu复合镀层组织与性能的影响

Effect of electrical contact strengthening on microstructure and properties of Ni/Cu composite coatings

利用电刷镀在铸铁表面制备了厚度在1 mm左右的Ni/Cu复合镀层,并对镀层进行了电接触强化试验。利用场发射电镜(FESEM)、维氏硬度计分析了电接触强化对镀层组织性能的影响。试验结果表明,电接触强化改善了镀层表面和内部质量,减少了镀层内部裂纹、孔洞等缺陷。同时,电接触强化使镀层和基体之间产生了部分镶嵌熔融。电接触强化改变了Ni层与Cu层的组织结构,使镀层组织更加致密紧实,Cu层和Ni层之间发生了塑性变形,产生了一定的镶嵌。强化后镀层表面及截面硬度都有所提升。镀层与基体之间形成的硬化层硬度远大于基体硬度,电接触强化提高了镀层与基体之间的结合力。

Ni/Cu composite coating with a thickness of 1 mm was prepared by brush plating on the surface of the cast iron,and the coating was subjected to electrical contact strengthening test.The effect of electrical contact strengthening on the microstructure and property of the coating was analyzed by means of field emission electron microscopy( FESEM) and Vickers hardness tester.The test results show that the electrical contact strengthening improves the surface and internal quality of the coating and reduces defects such as cracks in the coating.At the same time,electrical contact strengthening results in partial mosaic melting between the coating and the substrate.The electrical contact strengthening changes the microstructure of the Ni layer and the Cu layer,making the coating structure denser and tighter,and plastic deformation occurs between the Cu layer and Ni layer,resulting in a certain inlay.After strengthening,the surface and cross-section hardness of the coating are improved.The hardness of the hardened layer formed between the plating layer and the substrate is much greater than that of the substrate,and the electrical contact strengthening improves the bonding strength between the plating layer and the substrate.