超细WC颗粒对纳米CeO2增强激光镍基涂层的显微组织和耐磨性影响

Effect of ultra-fine WC particles on microstructural evolution and wear behaviors of Ni-based nano-CeO2 coatings produced by laser

摘要:

CO₂激光器熔覆1wt.%纳米CeO₂和20wt.%WC添加的镍基合金涂层的磨损、显微组织与1wt.%纳米CeO₂添加镍基合金涂层进行对比。上述两种涂层均熔覆在基体30CrMnSiNi2A上并呈优良冶金结合。超细碳化物WC对WC-CeO₂/Ni涂层的显微组织影响由X射线衍射(XRD),扫描电镜(SEM)连同能量色散谱(EDS),电子探针(EPMA)进行分析。添加WC后M₂₃C₆增多,而M₇C₃减少。通过维氏硬度计和磨损测试系统对有WC添加和无添加CeO₂镍基合金涂层进行综合机械性能比。得出结论WC-CeO₂/Ni涂层明显优于CeO₂/Ni涂层。极少数热裂纹出现于WC-CeO₂/Ni涂层,萌生并扩展于熔池凝固过程中,对此做了SEM和EDS分析。裂纹机理可归因为铁稀释和WC添加导致的涂层与基体30CrMnSiNi2A间线膨胀系数间差异。

Abstract:

The wear properties and microstructure of CO₂ laser cladded Ni-based alloy coatings with 1wt.% nano-CeO₂ and 20wt.% WC addition(CeO₂/Ni) was compared with Ni-based coatings with 1wt.% nano-CeO₂ addition(WC-CeO₂/Ni). Both coatings were successfully cladded on 30CrMnSiNi2A steel with good metallurgical bounding to substrate. The influence of ultra-fine carbide WC on the microstructure of WC-CeO₂/Ni alloy composite coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and electron probe micro analysis (EPMA). WC addition increased M₂₃C₆ content, the M₇C₃ decreased. The comparison of comprehensive mechanical properties between coatings with and without fine WC particles were conducted on Vickers hardness and wear-resistance test system. Results indicated that the performance of WC-CeO₂/Ni is better than CeO₂/Ni MMC. Few hot cracks appeared in Ni-based WC-CeO₂ metal matrix composition (MMC) production, which were investigated by SEM and EDS. The crack mechanism can be claimed as Fe dilution and coefficient of thermal expansion for WC-CeO₂/Ni MMC differed from that of base material 30CrMnSiNi2A steel.