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采用 5 k W CO2 连续激光在低碳钢表面激光熔覆了钴基合金涂层 (Co6 0 )及添加 2 5 % Cr3C2 (质量分数 )的钴基合金复合涂层 (Cr3C2 / Co) ,对比研究了 Cr3C2 对熔覆涂层的组织、显微硬度及耐腐蚀磨损性能的影响。结果表明 ,在本试验条件下可得到熔覆质量良好的 Co6 0及 Cr3C2 / Co涂层。 Co6 0涂层组织主要由大量初生枝晶γ固溶体及其间的共晶组织γ与 (Cr,Fe) 7C3组成。 Cr3C2 / Co涂层组织主要由未熔 Cr3C2 ,大量杆状和块状的富 Cr碳化物及其间的非常细小的枝晶及其共晶体组成 ,主要组成相为γ- Co,Cr7C3,Cr2 3C6 和未熔 Cr3C2 颗粒。添加的 Cr3C2 改变了Co6 0涂层的凝固特征 ,使 Co6 0涂层的亚共晶结晶方式转变为 Cr3C2 / Co涂层的过共晶结晶方式。未熔 Cr3C2 粒子起到了非自发形核作用 ,在其周围形成了许多富 Cr碳化物 ,并细化了涂层枝晶组织。 Cr3C2 / Co涂层的显微硬度以及在不同腐蚀介质中的耐磨性比 Co6 0涂层都有明显提高。
The Co-based alloy coating (Co6 0) and the Cr3C2 / Co alloyed with 25% Cr3C2 (mass fraction) were laser cladded on the surface of mild steel with a 5 kW CO2 continuous laser. The effect of Cr3C2 on the microstructure, microhardness and corrosion-resistant wear properties of the cladding coatings was investigated. The results show that Co6 0 and Cr3C2 / Co coatings with good quality of cladding can be obtained under the experimental conditions. Co6 0 coating mainly consists of a large number of primary dendrite γ solid solution and the eutectic γ and (Cr, Fe) 7C3 composition. The Cr3C2 / Co coating consists mainly of unmelted Cr3C2, a large amount of rod-shaped and massive Cr-rich carbides, with very fine dendrites and their eutectics, with the major constituent phases of γ-Co, Cr7C3, Cr2 3C6 and Unmelted Cr3C2 particles. The addition of Cr3C2 changed the solidification characteristics of the Co60 coating, which transformed the hypoeutectic crystallization of the Co60 coating into the hypereutectic crystallization of the Cr3C2 / Co coating. Unmelted Cr3C2 particles play a role in non-spontaneous nucleation, in the formation of a lot of its Cr-rich carbide, and refine the dendrite coating. The microhardness of Cr3C2 / Co coatings and their wear resistance in different corrosive media are better than those of Co6O coatings.