原位生成WC/TaC复合激光熔覆层组织研究

In-situ synthesis of WC/TaC reinforced nickel-based composite alloy coating by laser cladding

摘要:

利用激光熔覆技术,将氧化钽和石墨的混合粉末添加到Ni60包WC的镍基合金粉末中,成功制备了TaC/WC复合涂层。使用扫描电镜(SEM)、X射线衍射仪(XRD)等仪器分析了镍基合金复合涂层横断面的显微组织,并对其硬度进行研究分析。结果显示在基体与涂层之间形成了良好的冶金结合,复合涂层不仅含有γ-Ni树枝晶、W₂C、M₇C₃、以及大量的弥散分布的TaC颗粒。复合涂层的硬度可达HV965,是Ni60涂层的1.3倍,主要是因为TaC颗粒的分布促使其内部组织结构改变以及相变引起的硬度上升。

关键词:激光熔覆;镍基合金; 钽; 碳化钽;碳化钨

Abstract:

An in-situ synthesized WC/TaC reinforced nickel-based composite coatings have been fabricated on AISI 1045 mild carbon steel substrate by laser cladding of powder mixture of Ni60/WC with Ta2O5 and graphite. The microstructure and hardness distribution of WC/TaC/Ni60 composite coating are investigated utilizing scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. It is shown that the microstructure of coating has a metallurgical bonding with substrate and is mainly composed of γ-Ni dendrites, W₂C, M₇C₃ carbides, and dispersed TaC particles. The hardness of WC/TaC/Ni60 composite coating has been enhanced to a value similar to that of HV965, which is 1.3 times higher than Ni60 coating. Measurement results demonstrated that these improvements are attributed to the presence of in-situ synthesized TaC particles, microstructure change and phase variations.

Key words:Laser cladding; Nickel-based alloy; Tantalum(Ta); Tantalum carbide(TaC); Tungsten carbide (WC)