渗硼对硬质合金物理力学性能及耐磨性的影响

Effect of Boronizing on Physical and Mechanical Properties and Wear Resistance of Cemented Carbide

采用不同的渗硼工艺制备了渗硼厚度不同的YG11硬质合金试样。利用经典方法测定试样的密度、洛氏硬度、抗弯强度、钴磁及矫顽磁力等性能。通过金相显微镜、场发射电子显微镜观察渗硼试样断面的组织结构,采用X射线衍射仪分析渗硼试样断面的相成分。在自制的专用磨损实验机上对比了各组试样的耐磨性能。结果表明:YG11硬质合金通过气-固相渗硼处理后,断面组织可分为渗硼层、过渡层和基体3个部分。渗硼层出现了新的硬质相W2C、CoW2B2、CoW3B3等,WC晶粒细化,钴相因渗硼得到了强化。合金的耐磨参数比未渗硼时提高了14%～30%。经渗硼后硬质合金抗弯强度下降,但韧性略有提高。

The samples of YG11 cemented carbide with different thickness of boronizing layer were prepared by vari- ous boronizing processes. The properties of the samples, such as density, Rockwell hardness, bending strength, cobalt magnetism and coercive force, were determined by classic methods. The microstructure of the sample ,section was re- searched by metallographic observation, and then the phase composition in the section was determined by X-ray diffrac- tometer. The wear resistance of the sample was compared on the self-made special wear tester. The results show that after gas-solid phase boronizing, the microstructure of the YG11 cemented carbide consists of three parts of boronizing layer, transition layer and matrix. New hard phases appear in the boronizing layer, such as W2C, CoW2B2, CoW3B3, etc. The WC grains are fined and the cobalt phase is strengthened due to the boronizing. The wear resisting coefficient of the cemented carbide is increased by 14%-30% than that of the alloy without boronizing. The toughness of the cemented carbide undergoing boronization has a little increase, meanwhile, the bending strength decreases.