梯度硬质合金及耐磨涂层的计算模拟和实验验证

Computer Simulation and Experimental Verification of Gradient Cemented Carbides and Coating

建立了多组元硬质合金W-C-Co-Ti-Cr-Ta-Nb-N体系热力学及动力学基因库。利用所建立的热力学及扩散动力学基因库,模拟了WC-Ti(C,N)-TaC-Co硬质合金梯度层形成过程,计算所得各相体积分数及组元成分与实验结果相吻合。采用SEM和EDS等方法对不同N气氛下梯度烧结所获得的WC-Ti(C,N)-Co梯度硬质合金进行了合金表面组元成分分布测定,并对样品梯度层的形成进行了模拟,模拟能很好地描述实验结果。基于第一原理计算和实验对广泛应用的三元Ti-Al-N耐磨涂层体系的结构、力学、热力学性质和调幅分解曲线,以及调幅分解析出立方二元氮化物的性能进行了研究。计算结果与已有实验值符合较好,可为高性能硬质合金和多元涂层的开发设计提供理论指导。最后提出了硬质合金及耐磨涂层研发的基因框图。

The thermodynamic and kinetic databases for multi-component W-C-Co-Ti-Cr-Ta-Nb-N cemented carbides were established. Based on the established thermodynamic and kinetics databases, the volume fractions of different phases and elemental concentration profiles in the WC-Ti（C,N）-TaC-Co alloy were simulated by means of DICTRA software. The simulated results are in good agreement with the experimental data. SEM and EDS were employed to analysis the microstructure and composition in the gradient zone of the WC-Ti（C,N）-Co cemented carbides sintered under different partial pressures of nitrogen. The gradient zone formation of the WC-Ti （C,N）-Co cemented carbides was simulated by DICTRA, and the simulation results show a good agreement with the experimental results. Based on the first-principles calculations and experiments, the structural, mechanical, thermodynamic properties and spinodal decomposition of Ti-Al- N coating as well as some binary systems involving spinodal decompositions were investigated. The calculations are in good agreement with available experimental data, which can provide a reliable guidance on the design of high performance cemented carbides and coatings. Genome schematic diagram for the development of cemented carbides and coating is finally proposed.