Y_(2)O_(3)改性Co黏结相对WC-10%Co硬质合金组织和性能的影响

Effect of Y_(2)O_(3) Modified Co Binder on the Microstructure and Properties of WC-10%Co Cemented Carbide

采用行星球磨法制备掺杂Y_(2)O_(3)的Co复合粉末,再添加WC粉末制得含Y_(2)O_(3)的WC-Co混合粉末,随后经SPS工序制得WC-Co-Y_(2)O_(3)硬质合金。采用扫描电镜、能谱仪、X射线衍射仪、维氏硬度计和摩擦磨损试验机研究了球磨时间对Co-1%Y_(2)O_(3)复合粉形貌及物相,以及球磨时间、Y_(2)O_(3)含量对WC-Co-Y_(2)O_(3)硬质合金微观组织、物相组成、密度、维氏硬度、断裂韧性和耐磨性能的影响。结果表明:添加Y_(2)O_(3)后球磨,Co衍射峰向较大角度方向偏移;随着球磨时间的延长,Co晶粒被破坏,尺寸变小,导致Co衍射峰强度降低。硬质合金密度、维氏硬度及断裂韧性随着球磨时间的延长而提高,当球磨时间达到36h后,合金硬度趋于稳定,而断裂韧性降低。合金密度、维氏硬度、断裂韧性和耐磨性随着Y_(2)O_(3)含量的增加均出现了先上升后下降的趋势,当Y_(2)O_(3)含量为1%时合金综合性能最佳。分步球磨添加稀土氧化物Y_(2)O_(3)可以强化Co黏结相,抑制WC晶粒长大,增强合金的力学性能。

The Co composite powder doped with Y_(2)O_(3) was prepared by planetary grinding,the WC-Co mixed powder containing Y_(2)O_(3) was prepared by adding WC powder,and then WC-Co-Y_(2)O_(3) cemented car-bide was prepared by SPS.Scanning electron microscope,energy spectrum analyzer,X-ray diffractometer,Vickers hardness tester and friction and wear testing machine were used to investigate the effects of ball milling time on the microstructure and phase composition of Co-1%Y_(2)O_(3) composite powder,and ball mil-ling time and Y_(2)O_(3) content on the microstructure,phase composition,density,Vickers hardness,fracture toughness and wear resistance of WC-Co-Y_(2)O_(3) cemented carbide.The results show that the Co diffraction peak shifts towards a larger angle after adding Y_(2)O_(3) and ball milling.As the ball milling time increases,the Co grains are disrupted and their size becomes smaller,leading to a decrease in the intensity of Co diffraction peak.The density,Vickers hardness and fracture toughness of the cemented carbide increase with the extension of ball milling time.When the ball milling time exceeds 36 h,the hardness of the cemented car-bide tends to stabilize,while the fracture toughness decreases.The density,Vickers hardness,fracture toughness and wear resistance of the cemented carbide first increase and then decrease with the increase of Y_(2)O_(3) content.The best overall performance of the cemented carbide is obtained when the Y_(2)O_(3) content is 1%.The addition of rare earth oxide Y_(2)O_(3) by stepwise ball milling can strengthen the Co binder,inhibit the growth of WC grains,and enhance the mechanical properties of the cemented carbide.