放电等离子烧结制备超细晶WC-3Co硬质合金的组织和性能  

Microstructure and properties of superfine WC-3Co cemented carbides prepared by spark plasma sintering

作　　者：林小为[1] 肖志瑜[1] 李小峰[1] 朱权利[1] 张文[1] 

机构地区：[1]华南理工大学机械与汽车学院,广州510640

出　　处：《粉末冶金材料科学与工程》2012年第4期462-467,共6页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金资助项目(50874051);广东省产学研项目(0912210500008);教育部新世纪优秀人才资助项目(NCET-05-0739)

摘　　要：采用高能球磨制备纳米WC-3Co粉末,再通过放电等离子烧结(spark plasma sintering,SPS)制备超细晶WC-3Co硬质合金。研究SPS工艺参数对合金致密度、显微组织和力学性能的影响,并对SPS和热压工艺(hotpressing,HP)进行对比。结果表明:SPS可实现WC-3Co粉末的低温快速致密化。升高温度或提高压力都使得合金的致密度提高,同时导致WC晶粒长大。SPS较HP升温速率快且烧结时间更短,合金组织更加均匀,在1 300℃保温5 min、烧结压力为40 MPa的条件下所制备的合金具有最佳综合性能,其平均晶粒度为0.32μm,相对密度、硬度、抗弯强度、断裂韧性分别为99.3%、2257 HV30、1 906 MPa、10.36 MPa.m1/2。而在1 450℃、压力为50 MPa、保压5 min条件下,热压合金的致密度、硬度和断裂韧性分别为99.6%、2 264 HV30和11.01 MPa.m1/2,但抗弯强度只有1 301 MPa,平均晶粒度为0.47μm。WC-Co mixed powders were prepared by high-energy ball milling, and then spark plasma sintering （SPS） process was used to prepare superfine WC-3Co cemented carbides. The effects of process parameters on the density, microstructure and properties of WC-3Co cemented carbides were investigated, and both SPS and hot pressing （HP） molding process were compared. The results show that WC-Co mixed powder compacts sintered by SPS can achieve rapid densification at low temperature. The density of WC-3Co cemented carbides and WC grain size increase with increasing sintering temperature and sintering pressure. Compared with HP, SPS has a faster heating rate and shorter sintering time, and can get more uniform microstructure. The best mechanical properties of WC-3Co cemented carbides with grain size of 0.32 μm are obtained after sintering at 1 300 ℃ for 5 min under 40 MPa. The relative density, hardness, transverse rupture strength （TRS） and fracture toughness （Klc） are 99.3%, 2257 HV30, 1 906 MPa and 10.36 MPa.m1/2, respectively. However, higher density, hardness and fracture toughness but poor TRS are obtained when WC-Co mixed powder compacts are sintered by HP. Its relative density, hardness, TRS and fracture toughness are 99.6%, 2 264 HV30, 1 301 MPa and 11.01 MPa-mu2, respectively, and grain size is 0.47μm.

关 键 词：放电等离子烧结 硬质合金 工艺参数 力学性能 

分 类 号：TG135.5[一般工业技术—材料科学与工程]