超细WC和细WC/Co添加对WC-10Co硬质合金微观结构与力学性能的影响  

Effects of addition of ultrafine WC and fine WC/Co on microstructure and mechanical properties of WC-10Co cemented carbides

作　　者：于淞百 蒋豪丽 闵凡路[2] 张海龙 王丛旭 姚占虎 张建峰[1] YU Songbai;JIANG Haoli;MIN Fanlu;ZHANG Hailong;WANG Congxu;YAO Zhanhu;ZHANG Jianfeng(College of Mechanics and Materials,Hohai University,Nanjing 211100,China;Key Laboratory of Geomechanics and Embankment Engineering(Ministry of Education),Hohai University,Nanjing 210098,China;Shaanxi Aeronautic Carbide Tool Co.,Ltd.,Hanzhong 724200,Shaanxi,China;CCCC Tunnel Engineering Company Limited,Beijing 100102,China)

机构地区：[1]河海大学力学与材料学院,南京211100 [2]河海大学岩土力学与堤坝工程教育部重点实验室,南京210098 [3]陕西航空硬质合金工具有限责任公司,陕西汉中724200 [4]中交隧道工程局有限公司,北京100102

出　　处：《材料工程》2023年第7期136-145,共10页Journal of Materials Engineering

基　　金：陕西省技术创新引导计划资助项目(2022QFY08-02)。

摘　　要：在粒径为0.5μm的超细碳化钨(WC)粉体表面包覆钴(Co)纳米颗粒获得细WC/Co,将细WC/Co、粗WC和Co粉通过球磨混合均匀,压制成型后在1420℃下真空烧结1 h,得到WC-10Co硬质合金。借助扫描电子显微镜、透射电子显微镜、万能试验机等对比研究细WC/Co和超细WC对WC-10Co硬质合金微观形貌和力学性能的影响。结果表明:相比于超细WC,细WC/Co促进合金的致密化,并形成双晶结构。添加细WC/Co和超细WC制备的硬质合金的平均晶粒度分别为2.18μm和3.57μm。细WC/Co的添加会降低晶粒生长速度并抑制细晶完全溶解,而粗晶通过缺陷辅助生长及溶解-析出生长机制生长为表面阶梯状的缺角三棱柱形;硬质合金的硬度和断裂韧度得到提升,二者分别为1131HV 30和22.1 MPa·m^(1/2),而在1131HV 30同等硬度下,其断裂韧度比线性拟合的断裂韧度高27.7%。机理分析认为,超细WC的添加会导致异常晶粒产生,不利于性能;而细WC/Co的添加能够同时形成双晶结构和均匀的钴相分布结构,降低晶粒缺陷,提升综合力学性能。The ultrafine WC powders with particle size of 0.5μm were coated by nano Co particles for preparation of the fine WC/Co powder.Then it was mixed with the coarse WC and Co powders,following compacted and sintered in vacuum at 1420℃for 1 h for obtaining the WC-10Co cemented carbides.The morphology,the grain structure,hardness,bending strength and fracture toughness of WC-10Co cemented carbides with the fine WC/Co and ultrafine WC for comparison were investigated by scanning electron microscopy,transmission electron microscope,universal testing machine,etc.The results reveal that the addition of the fine WC/Co has greater influence on the densification of WC-10Co cemented carbides than the ultrafine WC,and can form the dual-grained structure with a mean WC grain size of 2.18μm,and the WC-10Co with ultrafine WC has a mean WC grain size of 3.57μm.The WC-10Co with fine WC/Co can reduce grain growth rate and hinder dissolution of the fine grains,resulting in generation of coarse grains with truncated triangular prism and stepped surface by defect-assisted and dissolution-precipitation mechanism.The WC-10Co with fine WC/Co can improve both hardness and fracture toughness,1131HV 30 and 22.1 MPa·m^(1/2),respectively.Furthermore,with the same hardness of 1131HV 30,its fracture toughness is 27.7%higher than linear fitted fracture.The mechanism analysis shows that the addition of ultrafine WC will lead to the formation of abnormal grains,which is not conductive to the performance;while the addition of fine WC/Co simultaneously forms the dual-grained structure and uniform Co distribution structure and reduces the defects in the grains,improves the comprehensive properties.

关 键 词：WC-10CO硬质合金 细WC/Co添加 超细WC添加 微观结构 力学性能 

分 类 号：TF124[冶金工程—粉末冶金]