基于第一性原理的碳化铬陶瓷颗粒形貌预测及验证分析

Prediction and verification analysis of chromium carbide ceramic particle morphology based on first-principles

  • 摘要: 采用激光熔覆技术制备碳化铬增强Ni60复合涂层,并对其生长形貌与生长机制进行研究和验证。基于第一性原理在Materials Studio(8.0)软件中对碳化铬晶体的生长形貌进行了预测,对Ni基相及Cr3C2陶瓷相的界面结合特性进行了仿真分析,对碳化铬陶瓷相的生长机制进行了研究,并通过熔覆实验对仿真结果进行了验证。实验验证时在Ni60粉末中添加一定含量的C粉及Cr粉,进行球磨作为涂层粉末,采用激光熔覆技术在H13钢表面原位生成碳化铬镍基复合涂层,通过X射线衍射仪(XRD)和扫描电镜(SEM)对涂层的物相和显微组织进行分析,采用维氏硬度计对涂层的显微硬度进行测试。研究结果表明,碳化铬生成相形貌主要为四边形、六边形以及其他不规则形貌,与仿真结果中形貌预测的结果一致。涂层平均显微硬度达到700 HV,是基体硬度的3倍。四边形碳化铬主要为Cr3C2,六边形碳化铬以Cr7C3为主,不规则形碳化铬为Cr7C3和Cr3C2的共晶体。原位生成制备的碳化铬增强相弥散分布在涂层中,使得涂层显微硬度较基体得到显著提升,涂层显微组织细密均匀,与基体形成良好的冶金结合。

     

    Abstract: Chromium carbide reinforced Ni60 composite coating was prepared by laser cladding technology, and its growth morphology and growth mechanism were studied and verified. Based on the first principles, the growth morphology of chromium carbide crystal was predicted in Materials Studio (8.0) software, the interface bonding characteristics of Ni base phase and Cr3C2 ceramic phase were simulated and analyzed, the growth mechanism of chromium carbide ceramic phase was studied, and the simulation results were verified by laser cladding experiment. During the experimental verification, a certain amount of C powder and Cr powder are added to Ni60 powder and ball milled as coating powder.The chromium and Nickel carbide composite coating was in-situ generated on the surface of H13 steel by laser cladding technology. The phase and microstructure of the coating were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microhardness of the coating was tested by Vickers hardness tester. The results show that the morphology of chromium carbide formation phase is mainly quadrilateral, hexagonal and other irregular morphology, which is consistent with the morphology prediction results in the simulation results. The average microhardness of the coating reaches 700 HV, which is three times that of the matrix. Quadrilateral chromium carbide is mainly Cr3C2, hexagonal chromium carbide is mainly Cr7C3, irregular chromium carbide is Cr7C3 and Cr3C2 eutectic. The chromium carbide enhanced phase prepared in situ is dispersed in the coating, which makes the microhardness of the coating significantly improved compared with the matrix, and the microstructure of the coating is fine and uniform, forming a good metallurgical bonding with the matrix.

     

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