摘要
钴池是降低硬质合金抗弯强度的一种缺陷,常以内表面存在一层钴膜的孔洞形式存在,压坯中的粗钴团是形成合金中钴池的主要因素。本文在90%WC＋10%Co（质量分数）混合粉末中掺入粗大钴团（100~400μm）,压制成形后分别在950、1 290、1 310、1 330、1 350和1 410℃烧结,保温时间为5 min。用SEM和金相显微镜研究粗钴团在各温度段的形貌,结果表明：在较低温度（≤1 310℃）烧结后,合金中钴团发生固相烧结,以蜂窝结构存在于孔洞中;继续升高温度,钴部分转变为液相并少量渗入合金组织中,冷却后留下孔,且孔表面有岛状的钴;当烧结温度≥1 410℃时,过量液相铺展在孔内表面,冷却后在合金孔内表面形成一层钴膜。
Cobalt lake,as a defect,can decrease the bending strength of cemented carbide,which usually appears as the formation of pores or voids with a cobalt film in the inner surface.The agglomerate cobalt in the raw materials powders is the primary factor to form cobalt lake in cemented carbides.The 90%WC＋10%Co（mass fraction） spray-material with 0.2% cobalt agglomerate（100~400 μm） is pressed and the samples are sintered at 950,1 290,1 310,1 330,1 350 and 1 410 ℃ separately for 5 min in the present paper.The appearance of cobalt agglomerate at every temperature is observed by SEM and metallography microscope,the results show that cobalt agglomerate is solid phase sintered at low temperature（≤1 310 ℃） and exists in the pores like a honeycomb;with temperature rise,part of the cobalt melt and some of them flow into the alloy,remaining pores after cool down and keeping island cobalt on the pore surface.cobalt islands are formed on the surface of the pores at cooling stage.When the sintering temperature is higher than 1 410 ℃,superfluous cobalt liquid spreads in the pores,and a film of cobalt on the surface of pores is formed after cooling.
出处
《粉末冶金材料科学与工程》
EI
2010年第6期661-666,共6页
Materials Science and Engineering of Powder Metallurgy
基金
国家科技重大专项(20092x04012-032)
关键词
孔洞
钴池
缺陷
烧结
pore
cobalt
defect
sintering
