以WC代替Mo_(2)C的涂层金属陶瓷刀片设计研究

Replacing Mo_(2)C Coated Cermet Cutting Tools Design with WC

WC和Mo_(2)C都能改善润湿性,但Mo_(2)C价格较为昂贵,WC较为便宜,因此本研究采用WC替代Mo_(2)C进行金属陶瓷设计。试验结果表明,金属陶瓷基体的硬度会下降,但是下降幅度不大,抗弯强度先变大后变小,在用12wt.%WC替代Mo_(2)C时基体抗弯强度最大,主要原因是晶粒细化提高了基体抗弯强度;当WC替代Mo_(2)C过量时,多余的WC不能与TiC形成固溶体,部分WC以多角状留存于组织,容易引起应力集中,进而导致抗弯强度下降。当WC含量较低时,不能抑制Ti(C,N)晶粒长大,因而晶粒会变得粗大,涂层厚度也变大;当WC含量较高时,能使晶粒细化,涂层厚度变小,涂层和基体会产生部分元素扩散。临界载荷与涂层厚度有关,在WC含量为0~18wt.%时,临界载荷与涂层厚度正相关。涂层厚度与WC的含量以及基体的晶粒尺寸有关,因此临界载荷应与WC的含量以及基体的晶粒尺寸有关。根据试验结论初步分析,在金属陶瓷基体中,用12wt.%的WC替代Mo_(2)C时力学性能最好;在涂层与基体结合试验中,用6wt.%的WC替代Mo_(2)C时基体与涂层的结合情况较好。

Both WC and Mo_(2)C can improve the wettability, but Mo_(2)C is more expensive and WC is cheaper.Therefore, this paper studies the use of WC to replace the Mo_(2)C cermet design.The study shows that with the WC replacing Mo_(2)C,the hardness of the cermet matrix will decrease, but the decrease is not large, the bending strength first become larger and then smaller, the matrix bending strength is greatest when 12 wt.% WC is used instead of Mo_(2)C.The grain refinement is mainly due to the increase of the matrix′s bending strength.When WC substitutes Mo_(2)C excessively, the excess WC cannot form a solid solution with TiC.Some WCs remain in the structure in a polygonal shape, causing stress concentration, which leads to a decrease in bending strength.When the WC content is low, the growth of Ti(C,N) grains cannot be suppressed, so that the crystal grains become coarse and the coating thickness becomes large.When the WC content is high, the grains can be refined and the coating thickness becomes small.The coating and matrix produce some elemental diffusion.The critical load is related to the coating thickness.When the WC content is 0-18 wt.%,the critical load is positively related to the coating thickness.The coating thickness is related to the WC content and the grain size of the matrix, so the critical load should be related to the WC content and the grain size of the matrix.According to the experimental results, the preliminary analysis of the best mechanical properties in the cermet matrix with 12 wt.% WC instead of Mo_(2)C.In the coating-substrate binding experiment, the matrix and coating are better when 6 wt.% of WC is used instead of Mo_(2)C.