激光熔覆原位生成VC-Fe_3C/Fe-Ni复合涂层的组织与性能

Microstructure and properties of in-situ synthesized VC-Fe_3C/Fe-Ni composite coating made by laser cladding

针对超高速电梯安全钳楔块耐高温磨损性差的问题,以FeV粉、石墨粉和Ni粉为原料,在楔块摩擦面进行了激光熔覆原位生成VC-Fe_3C/Fe-Ni复合涂层的实验,分析了不同粉末质量配比、不同工艺参数下熔覆层的组织演变规律,测试了熔覆层的硬度、高温耐磨损性和冲击韧性等力学性能。研究表明:通过原位反应,可获得由VC、Fe-Ni固溶体和Fe_3C组成的复合涂层;VC的含量随石墨含量的增加而增加;在较低的扫描速度下,VC颗粒呈球状或胞状,弥散分布在Fe-Ni固溶体上。当扫描速度较高时,VC呈菊花状、枝晶状和块状,主要分布在晶界上;当FeV粉、石墨粉和Ni粉的质量比是8∶3∶8时,熔覆层搭接时不产生裂纹,复合涂层平均维氏硬度5.9GPa,VC-Fe_3C/Fe-Ni涂层高温磨损量为Ni60激光熔覆层的25%,为45钢的9.7%,VC-Fe_3C/Fe-Ni涂层冲击韧度值比Ni60激光熔覆层提高37.6%。将该工艺应用于电梯安全钳等零件的强化领域,将大大提高电梯零件的耐磨性和使用寿命。

Aiming at the problem of poor high-temperature wear resistance of safety clamp wedge used in ultra-high speed elevator,the experiments of laser cladding to prepare VC-Fe_3C/Fe-Ni composite coating were made.FeV powder,graphite powder and Ni powder were used as cladding material.The evolution rule of microstructure at different mass ratios and process parameters was analyzed.The properties of composite coating such as hardness,high temperature wear resistance and impact toughness were tested.The research results show that the composite coating is made up of VC,Fe-Ni solid solution and Fe_3C by in-situ reaction.The content of VC increases with the adding of graphite content.At low scanning speed,the morphology of VC is presented as ball-like and cellular-like.Most VC particles are equably distributed in Fe-Ni solid solution.At high scanning speed,the morphology of VC is presented as chrysanthemum-like,dendrite-like and bulk-like.Most VC particles are distributed along grain boundary.At the mass ratio of 8∶3∶8 for FeV powder,graphite powder and Ni powder,the overlapping zone has no crack.The average hardness of composite coating is 5.9GPa.The high-temperature wear loss of VC-Fe_3C/Fe-Ni coating is 25%that of Ni60 laser cladding coating and 9.7%that of 45 steel.The impact toughness value of VC-Fe_3C/Fe-Ni coating increases 37.6%than that of Ni60 laser cladding coating.Using this technology to the surface strengthening of elevator parts such as safety clamp wedge,the wear resistance and service life can be greatly improved.