激光熔覆SiC-MoS_2铁基合金覆层的组织与摩擦学性能

Microstructure and Tribological Properties of SiC-MoS_2/Fe-based Coatings by Laser Cladding

采用激光熔覆方法,在45钢基体上制备了以HD钢(4Cr3Mo2VNiNb)成分为主的铁基合金粘结相(简称HD-1)、SiC-MoS2为颗粒相的覆层材料,运用OM、电子探针(BEI、EDS)、XRD、显微硬度及球盘式摩擦磨损试验等方法分析研究了覆层的显微组织结构与力学性能。研究表明,HD-1粉末熔覆层的晶粒细小,显微组织主要由含过饱和碳的α-Fe(Cr、Ni、Mn、Mo等)固溶体及其网状残余奥氏体组成;添加SiC-MoS2颗粒相后,混合覆层组织中残余奥氏体沿晶界呈断续网状分布,还均布着细小的金属硫化物(CrS)颗粒。与HD-1纯粘结相覆层比较,添加颗粒相后覆层的硬度值有不同程度提高,覆层最高硬度值(807HV0.2)较HD-1覆层提高约20%;混合覆层的摩擦系数值明显降低,覆层最低摩擦系数值(0.135)较HD-1覆层降低约39%;混合覆层的最小体积磨损率(0.90×10-3mm-3/m)较HD-1覆层减小了40%。从兼顾覆层的耐磨、减摩和高硬度性能考虑,最优覆层的推荐制备参数为铁基合金HD-1加3%SiC-1.5%MoS2、激光扫描速度16mm/s。

Abstract： The coatings with powders which is mainly composed of HD steel （4Cr3Mo2VNiNb） as Fe-based binding phase （referred to as HD-1） and SiC-MoS2 as reinforcing particle phases were prepared on 45 steel substrate by laser cladding method. The microstructure and mechanical properties of coatings were studied by means of OM, Electron Probe （BEI, EDS）, XRD, microhardness, the ball-on-disk friction and wear tester, etc. Studies show that the grain of HD-1 powder cladding layer is fine and the microstructure is mainly composed of α-Fe （Cr, Ni, Mn, Mo, etc.） solid solution of supersaturated carbon and the net-like residual austenite. While adding SiC-MoS2 particles, there are discontinuous net-like residual austenite along grain boundaries and uniformly distributed with fine metal sulfide （CrS） particles. Furthermore, compared with HD-1 pure binding phase coating, the orthogonal group coatings added with the particle phases have a certain increment of hardness value. The highest hardness value （807HV0.2） is 1.20 times of the pure binding phase coating. The friction coefficient of coatings is obviously decreased and the lowest friction coefficient value （0.135） is 0.61 times of the pure binding phase coating. The smallest volume wear rate of coatings （0.90×10^-3 mm^3/m） is 0.60 times of the pure binding phase coating. By comprehensive analysis, the optimized preparation parameters for laser cladding are recommended as 3%SiC-1.5%MoS2/Fe-based HD-1, laser scanning speed 16 rnm/s.