含WB烧结硬质合金的组织结构和性能研究

Effect of Addition of WB on the Microstructure and Properties of Cemented Carbides

将不同含量的WB粉末添加到传统成分的WC-Co粉末中,利用低压烧结技术制备了系列含WB的WC-Co型硬质合金,并对其物相组成、组织结构和力学性能进行了系统表征分析。研究发现,在低压烧结过程中WB与Co发生反应,生成了具有超高硬度的WCoB相,由此降低了粘结相Co对WC晶粒的隔离,增加了WC晶粒间的接触度,引起合金韧性下降。添加WB制备的硬质合金材料其摩擦系数更低,随WB添加量的增加,硬度和耐磨性明显提高,当WB添加量为30%(质量分数)时,制备的硬质合金材料的硬度达到19 000 MPa,其磨损速率仅为传统WC-Co硬质合金1/10。然而,添加WB的WC-Co合金的断裂韧性约为传统WC-Co硬质合金的83%~91%。

Using WB powder and WC-Co powder as raw materials,the cemented carbides with different volume fractions of WB additives were prepared by a hot isostatic pressing（HIP） method.Then,the phase constitution,microstructure and mechanical properties of the prepared cemented carbides have been studied.The results show that the super hard WCoB phase is formed by the reaction of WB and Co.With the decrease of Co phase,less WC grains are separated,and thus the toughness is decreased.With the increase of the WB addition,the prepared cemented carbides have lower friction coefficients and better wear resistance and hardness.When the WB addition is 30 wt%,the hardness of 19 000 MPa can be attained.The abrasion loss of the sample is 1/10 of that of the WC-Co cemented carbide.However,the fracture toughness of the cemented carbide with WB addition is about 83%-91% of that of the conventional WC-Co cemented carbides.