电接触强化对Ni-P/Nano-WC复合刷镀层的微观组织及性能的影响  

Effect of Electric Contact Strengthening on Microstructures and Properties of Ni-P/Nano-WC Composite Coating

作　　者：徐梦廓[1] 朱世根[1,2] 丁浩[1,2] 

机构地区：[1]东华大学机械工程学院,上海201620 [2]纺织装备教育部工程研究中心,上海201620

出　　处：《表面技术》2016年第5期187-193,共7页Surface Technology

摘　　要：目的提高Ni-P/nano-WC复合刷镀层的性能。方法利用电刷镀技术将Ni-P与nano-WC粉末共同沉积在40Cr基体表面形成纳米颗粒增强的复合镀层,再利用电接触技术对Ni-P/nano-WC复合镀层进行二次强化。利用光学显微镜、场发射扫描电子显微镜(FESEM)、X射线衍射分析(XRD)、能谱分析(EDS)和显微硬度测量等手段,分析电接触强化处理对Ni-P/nano-WC复合镀层的影响。同时利用滚动摩擦试验分析电接触强化前后复合镀层耐磨性的变化情况。结果电接触强化处理后,Ni-P/nano-WC复合刷镀层的孔隙和裂纹减少,复合镀层与基体之间的界面在高温和高压的作用下发生焊合。XRD分析显示复合镀层的晶粒细化,镀层的晶粒尺寸由35.35 nm下降至26.28 nm。随着接触电流的加大,复合镀层的硬度也在逐步加大。经过20 k A电流的强化,复合镀层平均硬度由637HV0.1增加到885HV0.1,镀层硬度分布更加均匀;4 h的滚动摩损表明,随着接触电流的加大,试样的质量损失逐步减小,经20 k A接触电流强化后的Ni-P/nano-WC复合镀层质量损失为503 mg,比未经电接触强化的Ni-P/nano-WC复合镀层低40%。结论电接触强化技术能有效改善Ni-P/nano-WC复合镀层的微观组织与性能,将镀层界面由机械结合变为冶金结合,同时提高镀层的耐磨性能。Objective To improve the properties of Ni-P/nano-WC composite coatings. Methods Electro brush plating was used for co-deposition of Ni-P and nano-WC powder on 40Cr surface to form nano-particle reinforced composite coating.The coating was secondly reinforced by electric contact strengthening （ECS）. The microstructures and properties of composite coatings were investigated by optical microscopy, field emission scanning electron microscopy （FESEM）, energy dispersive spectrometry （EDS）, X-ray diffraction （XRD） and Vickers hardness analysis. The rolling wear test was used to analyze the wear resistance of strengthened/unstrengthened composite coatings. Results The cracks and pores of composite coatings were re- duced after ECS. Furthermore, the composite coating and the substrate were weld under high temperature and pressure envi- ronment. The XRD analysis presented that the size of gain of composite coating was refined which was reduced from 35.35 nm to 26.28 um. With the increase of contacting electric current, the hardness of composite coating was gradually elevated. The av- erage hardness of coatings was increased from 637HV0.1 to 886HV0.1 through the strengthening of electric current of 20 kA. Hence, the coating hardness distribution was more uniform. After 4-hour rolling wear test, the results showed that with the in- crease of contacting current, the weight losses of samples was gradually reduced. The weight loss of Ni-P/nano-WC composite coatings aider 20 kA ECS was 503 mg which was 40% lower than the unstrengthened composite coatings. Conclusion The ECS can effectively improve the microstructure and properties of Ni-P/nano-WC composite coating, The bonding between the com- posite coating and the 40Cr substrate was changed from mechanical bonding to metallurgical bonding, at the same time, the wear resistance was improved.

关 键 词：Ni-P/nano-WC复合镀层 电接触强化 微观组织 冶金结合 硬度分布 耐磨性 

分 类 号：TQ153.1[化学工程—电化学工业]