微米WC增强Ni60合金高频感应熔覆涂层耐磨性能

采用高频感应熔覆方法在Q235低碳钢基体上制备了不同含量的微米WC增强Ni60A合金复合涂层.用MLS-225型湿砂橡胶轮磨粒磨损试验机评价了涂层的耐磨性能,利用SEM,XRD观察并分析了涂层的显微组织和磨损表面形貌.结果表明,在相同试验条件下,涂层的硬度和耐磨性随WC含量的增加而提高,当WC含量少于30%时,WC分布不均匀,主要集中于涂层的中部,涂层中Cr7C3相以粗大的六方状和长条状存在,不利于涂层耐磨性的提高;当WC含量达到50%时,Ni基合金中加入WC的含量达到了合适比例,耐磨性最佳,相对耐磨性为Ni60A涂层的6.5倍;当WC含量达到60%时,涂层的硬度最高,但出现了较多的孔洞,大量未熔的WC颗粒在磨粒的反复作用下剥落形成了大的剥落坑,导致耐磨性下降.涂层与基体实现了冶金结合,涂层的磨损机制主要为轻微的塑性切削和硬质相的脆性剥落.

Wear resistance properties of micron-WC reinforced Ni60 coating by high frequency induction cladding

The tungsten carbide (WC)reinforced Ni60A alloy composite coatings were prepared on Q235 mild steel by high frequency induction cladding.Abrasive wear resistance was carried out with MLS-225 wet sand rubber wheel tester.The microstructure and wore surface of coatings were studied by scanning electron microscope (SEM)and X-ray diffractometer (XRD)were applied to investigate the phase composition.The results showed that the hardness and abrasive wear resistance of the coating increase with addition of WC content in the same condition.When WC is less than 30% fraction, WC were not distributed uniformly, mainly dispersed in the central of the coating, while Cr₇C₃ was in large elongated, polyhedral shape, which reduce the wear resistance.Coating has the best abrasive wear resistance which is 6.5 times higher than Ni60A coating due to the optimal matching between WC and Ni alloy with 50%WC addition.While the reults with 60%WC showed the highest hardness, porosity and the lower wear resistance.Partial melting of WC particles were peeled out under successive abrasive grains, which created the large cavities and pits in the coating.The composite coating was metallurgical bonded to the substrate.Predominant wear mechanism of the coating was brittle peeling of hard phases and less micro-ploughing.