La_(2)O_(3)掺杂量对WC-12Co硬质合金微观结构和硬度的影响

Effects of La_(2)O_(3) Doping Amount on Microstructure and Hardness of WC-12Co Cemented Carbide

本研究采用无压烧结法制备了不同La_(2)O_(3)掺杂量的粗颗粒WC-12Co硬质合金,研究了La_(2)O_(3)掺杂量对WC-12Co硬质合金密度、气孔率、断口形貌、硬度、相组成、摩擦因数等参数的影响。研究结果表明:随着La_(2)O_(3)掺杂量的增加,粘结相Co含量的相对降低导致WC-12Co硬质合金的密度逐渐降低,气孔率升高;La_(2)O_(3)掺杂量低于2.5%时,WC-12Co硬质合金的硬度和耐磨性有所提高,但La_(2)O_(3)掺杂量超过7.5%后,WC-12Co硬质合金的硬度和耐磨性下降;微量La_(2)O_(3)掺杂有利于烧结体颗粒尺寸的降低,随着La_(2)O_(3)掺杂量进一步增加,烧结体颗粒明显增大;因此,La_(2)O_(3)掺杂量低于2.5%有助于提高粗颗粒WC-12Co硬质合金的硬度和耐磨性,大于2.5%时将导致WC-12Co硬质合金性能下降。

In this thesis,coarse particles WC-12Co cemented carbide with different La_(2)O_(3) doping amounts were prepared by pressure-free sintering method.The effects of La_(2)O_(3) doping amount on parameters such as density,porosity,fracture morphology,hardness,phase composition and friction coefficient of WC-12Co cemented carbide were investigated.The results showed that with the increase of La_(2)O_(3) doping amount,the relative decreased of Co content in bonding phase led to the decrease of density and the increase of porosity of WC-12Co cemented carbide.When the doping amount of La_(2)O_(3) is lower than 2.5%,the hardness and wear resistance of WC-12Co cemented carbide are improved,but when the doping amount of La_(2)O_(3) exceeds 7.5%,the hardness and wear resistance of WC-12Co cemented carbide were decreased.The small amount of La_(2)O_(3) doping was conducive to the reduction of particle size for sintered body.With the further increase of La_(2)O_(3) doping,the sintered body particle increased significantly.Therefore,the doping amount of La_(2)O_(3) below 2.5%was helpful to improve the hardness and wear resistance of coarse particle WC-12Co cemented carbide,while the doping amount was beyond 2.5%,it will lead to the degradation of the properties of WC-12Co cemented carbide.