等离子束表面冶金制备铁基梯度涂层的研究

Research on the Production of Iron-based Gradient Alloy Coating Using Plasma Jet Surface Metallurgy

利用等离子束表面冶金技术在45号钢基体上制备梯度涂层,探讨了等离子束表面冶金制备铁基梯度涂层的冶金过程,详细分析了等离子束表面冶金熔池的凝固机理、凝固特征对凝固组织的影响。采用金相显微镜、X射线衍射仪、扫描电镜研究了涂层的组织,利用显微硬度计测试了涂层的显微硬度。结果表明,合金涂层组织主要由γ-Fe,M7C3和TiC组成;涂层的显微硬度可达到800HV0.2。从基体到表面,涂层的成分、组织和显微硬度呈现出平缓梯度变化,消除了成分突变和应力集中的影响。因此涂层具有无晶体缺陷,内韧外硬的特性。

Iron-based gradient coating was prepared on the surface of 45 steel using plasma jet surface metallurgy, and the process was discussed. The freezing mechanism, characteristic soliditication feature and influence on microstructure were also analyzed in detail. Morphology and component features were studied by metalloscope,SEM and X-ray diffraction. The micro-hardness was tested by micro-hardness tester. The results showed that the coating was mainly composed of γ-Fe, M7C3 and TiC, and the maximum hardness could reach 800HV0.2. The Composition, structure and hardness of the coating gradually change in gradient from the substrate to the surface, so the influence of abrupt change in the composition and stress concentration are eliminated. Thus it verified that the coating is hard on surface with tough at core and without crystal defect.