为了突破新型动力蠕墨铸铁本体材料不耐磨的技术瓶颈,研究蠕墨铸铁表面激光熔覆合金涂层后的微观组织和力学性能。在RuT300表面激光熔覆含有WC增强相的镍基高温合金,对样品的涂层以及结合区进行组织和成分分析,并对样品的涂层和基体进行硬度测试。涂层中WC颗粒分布不均匀,未全熔的WC颗粒作为非均匀的结晶晶核,外部有花瓣状枝晶沿WC颗粒的边界生长。Ni基WC复合涂层的平均硬度是蠕墨铸铁基体的平均硬度的4.52倍。WC颗粒的密度高于Ni基粉末,且熔池的散热具有非平衡性,使得WC颗粒在涂层中的分布及溶解程度均呈现非均匀性,WC的存在提高涂层硬度,同时为花瓣状枝晶额外提供生长晶核,有助于涂层中的颗粒相与镍基合金溶剂牢固结合,对提高涂层的硬度及耐磨性具有正向作用。

In this study, the microstructure and mechanical properties of the laser cladding alloy coating on the surface of vermicular graphite cast iron are studied to overcome the technical bottleneck associated with the new dynamic vermicular graphite cast iron body materials that do not exhibit wear resistance. Laser cladding of nickel-based superalloy containing tungsten carbide (WC) reinforced phase on the surface of RuT300. Further, the microstructure and composition of the sample coating and the bonding zone are analyzed, the sample coating and substrate are subjected to the hardness test. The WC particles are unevenly distributed in the sample coating, and the uncompletely melted WC particles are considered to be non-uniform crystal nuclei. In addition, petal-like dendrites grow along the boundary of WC particles. The average hardness of the Ni-based WC composite coating is 4.52 times greater than that of the compacted graphite iron matrix. The distribution and solubility of the WC particles in this coating are non-uniform because the density of the WC particles is greater than that of the Ni-based powders and the heat dissipation in the molten pool is unbalanced. The presence of WC particles increases the hardness of the coating. In addition, the petal-like dendrites crystal provides a growth nucleus, which helps the particle phase in the coating to strongly combine with the Ni-based alloy solvent. Furthermore, the hardness and wear resistance of the coating are observed to improve.