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利用电刷镀技术将Ni-P与WC-Al_2O_3纳米粉末共同沉积在40Cr钢基体表面形成纳米颗粒增强的复合镀层。用电接触强化技术对复合镀层进行再处理。利用光学显微镜、扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)和维氏硬度测量分析电接触强化技术对复合镀层的影响。通过镀层的微观金相图片显示,在经过了电接触强化后,复合刷镀层的孔隙和裂纹减少,镀层与基体之间的界面由机械结合转变为冶金结合。XRD结果显示镀层晶粒得到了细化;随着接触电流的加大,复合镀层的硬度也逐步加大。经过20 kA电流的强化,复合镀层的平均硬度由699 HV0.1增加到895 HV0.1,镀层硬度分布更加均匀。
Ni-P and WC-Al_2O_3 nanopowders were co-deposited on the surface of 40Cr steel substrate by brush plating to form nanoparticle-reinforced composite coatings. The electrical contact strengthening technique is used to reprocess the composite coating. The effects of electrical contact strengthening on the composite coating were analyzed by optical microscope, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Vickers hardness measurement. The microscopic metallographic picture of the coating shows that the pores and cracks in the composite brush coating decrease after the electrical contact is strengthened, and the interface between the coating and the substrate changes from mechanical bonding to metallurgical bonding. XRD results showed that the grain size of the coating was refined. With the increase of the contact current, the hardness of the composite coating gradually increased. After 20 kA current enhancement, the average hardness of the composite coating increased from 699 HV0.1 to 895 HV0.1, the coating hardness distribution more evenly.