WC-Al_2O_3纳米颗粒增强Ni-P复合镀层的电接触强化及性能

Electric contact strengthening and properties of Ni-P/WC-Al_2O_3 composite coating by electro brush plating

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 / WC-Al2O3 composite coatings were fabricated on 40 Cr steel substrate surface through electro brush plating and were reinforced by electric contact strengthening（ ECS）. The microstructures and properties of the composite coatings were investigated by optical microscopy,scanning electron microscopy（ SEM）,energy dispersive spectrometry（ EDS）,X-ray diffraction（ XRD） and Vickers hardness tester. The analysis results show that after ECS,the bonding between the composite coating and the 40 Cr steel substrate is changed from mechanical bonding to metallurgical bonding. Furthermore,the grain sizes of the coatings are refined,the pores and cracks in the coatings are reduced. After 20 kA ECS,the average hardness of the coatings are enhanced from 699 to 895 HV0. 1,the hardness distribution of the composite coating becomes more uniform.