低合金钢表面Fe基B4C耐磨涂层组织与性能

目的在低合金结构钢表面制备一层高硬度、高耐磨的铁基陶瓷颗粒增强层,并研究熔覆层的微观结构及性能。方法利用等离子熔敷技术,在16Mn钢基体上熔敷Fe58合金粉与B_4C陶瓷粉的混合粉末。结果在16Mn钢表面成功制备了高硬度、高耐磨的铁基陶瓷颗粒增强层,陶瓷颗粒增强层致密、均匀、无气孔、无裂纹,且与基体结合良好。XRD及SEM结果表明,熔覆层生成了细小、均匀的碳、硼化物增强相,熔覆层与基体的相容性好,界面呈冶金结合,熔覆层的增强相主要有Fe2B、FeB、Cr7BC4、Cr7C3及B_4C相,Fe与B的化合物Fe2B、FeB呈链状沿晶界分布在(Fe,Ni)固溶体上,并与(Fe,Ni)固溶体在晶界形成网状结构。铬的碳、硼化物Cr7BC4和Cr7C3及未完全反应的B_4C陶瓷相,则呈不规则块状和点状在晶内弥散分布。熔覆层断面的显微硬度及表面磨粒磨损测试结果表明,熔覆层断面的显微硬度分布均匀,平均硬度可达11.9GPa,是16Mn钢基体的7.95倍,耐磨粒磨损性能是基体的7倍以上。结论晶内弥散分布的B_4C、Cr7BC4和Cr7C3硬质相与晶界成链状分布的Fe2B、FeB共同作用,使熔覆层的硬度、耐磨性明显提高。

Microstructure and Properties of Fe-based B4C Wear-resistant Coating on 16Mn Steel

The work aims to prepare a hard and wear-resistant Fe-based ceramic particles-strengthened coating on surface of structural low-alloy steels by studying microstructure and properties of the cladding layer. Mixed powder of Fe58 alloy and B4C ceramic was cladded on the substrate 16Mn steel by applying plasma cladding technique. A coating strengthened by wear-resistant and ultrahard Fe-based ceramic particles was fabricated on the surface of 16Mn steel successfully, and microstructure, microhardness and wear resistance of the Fe58-B4C coating were investigated. The coating was dense, uniform, pore-free and crack-free, and was of good coating-substrate adhesion. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to observe coating morphology and phase composition. The results suggested that fine and uniform carbides and borides-reinforced phases, the cladding layer was compatible with the substrate, interface exhibited metallurgical bonding, reinforced phases were mainly Fe2B, FeB, Cr7BC4, Cr7C3 and B4C. In addition, ferroboron compounds (Fe2B and FeB) spread over (Fe,Ni) solid solution phase along grain boundary in chain-like manner, and formed reticular structure together with (Fe,Ni) solid solution on the grain boundary. Chromic carbon, boride Cr7BC4, Cr7C3 and incompletely reacting B4C ceramic phase spread over in the grains in the form of irregular bulk and dot scope. Sectional microhardness and abrasive wear test results of the cladding layer showed that the sectional microhardness spread over uniformly, and average hardness was up to 11.9 GPa, which was over 7.95 times that of 16Mn steel; abrasive wear resistance of the coating was over 7 times that of 16Mn steel. As hard phases Cr7BC4, Cr7C3 and B4C dispersed in the grains jointly work with ferroboron compound (Fe2B and FeB) spreading over grain boundary in chain-like manner, microhardness and wear resistance of the cladding layer are increased dramatically.