离焦量对MoS2改性Fe-Cr-Mo-Si合金涂层组织与性能的影响

采用激光熔覆技术在40Cr钢基材上制备了MoS₂改性的Fe-Cr-Mo-Si合金复合涂层,研究了离焦量对复合涂层的宏观形貌、微观组织、显微硬度及耐摩擦磨损性能的影响。结果表明,随着离焦量的增大,复合涂层表面越光滑平整,复合涂层与基材间冶金结合越好;复合涂层上部为细小的等轴晶,中部为树枝晶,底部为垂直熔合线生长的柱状晶及平面晶,等轴晶晶粒尺寸随离焦量增大而减小;随着离焦量的增大,复合涂层硬度值随之增大,离焦量为2 mm时复合涂层上部显微硬度值最高,达696.1 HV0.5,约为基材(230.6 HV0.5)硬度的3倍;在相同磨损工况下,复合涂层平均摩擦因数及磨损量随离焦量增大而减小,在离焦量为2 mm时具有最小磨损量0.010 g,仅为Fe基涂层磨损量的21.7%;复合涂层磨损机制为磨粒磨损和粘着磨损,随着离焦量的增大,复合涂层表面磨损程度越小,耐磨性能越好。

Effect of defocusing amount on microstructure and properties of MoS2 modified Fe-Cr-Mo-Si alloy coating

MoS₂ modified Fe-Cr-Mo-Si alloy coating was prepared on 40Cr steel substrate by laser cladding technology. The effect of defocusing amount on macro morphology, microstructure, microhardness and friction and wear resistance of the composite coating was studied. The results show that with the increase of defocusing amount, the smoother the composite coating surface, the better metallurgical bonding between the composite coating and the substrate. The upper part of the composite coating is fine equiaxed crystal, the middle is dendrite, and the bottom is columnar and plane crystal grown perpendicular to the fusion line. The grain size of equiaxed crystal decreases with the increase of defocusing amount. With the increase of defocusing amount, the hardness value of composite coating increases accordingly, and the highest microhardness value appears in the upper part of the composite coating when the defocusing amount is 2 mm, up to 696.1 HV0.5, about 3 times of that of the substrate (230.6 HV0.5). Under the same wear condition, the average friction coefficient and wear loss of composite coating decrease with the increase of defocusing amount. When the defocusing amount is 2 mm, the minimum wear loss is 0.010 g, which is only 21.7% of that of the Fe based coating. The wear mechanism of composite coating is abrasive wear and adhesion wear. With the increase of defocusing amount, the smaller the wear degree of the composite coating surface, the better the wear resistance.