纳米硬质合金制备技术的研究

Research of Making Technology of Nano-Grained Cemented Carbide

研究了 WC-Co纳米硬质合金的制备技术。采用强化球磨、添加晶粒长大抑制剂和低温加压烧结工艺 ,获得了 WC晶粒度接近 2 0 0 nm的硬质合金。研究了 VC和Cr3 C2 两种抑制剂加入量对合金组织、WC晶粒度和性能的影响以及抑制晶粒长大的机理。研究结果表明 ,添加 VC和 Cr3 C2 晶粒长大抑制剂十分有效的抑制了晶粒的长大 ,合金中的 WC晶粒度随抑制剂加入量的增加而细化。但过多的抑制剂不仅会导致碳化物在 WC/Co晶界上大量析出 ,而且也会增加孔隙度 ,结果增加了合金脆性 ,降低了合金的强度 ,其有害影响 VC比 Cr3 C2 更大。采用加压烧结可消除合金中的孔隙提高合金的强度。

The technology of making WC-Co nano-grained cemented carbide was researched. The cemented carbide with near 200nm WC grains was obtained by strengthened milling, addition of inhibitors of grain growth and low pressure sintering. The effect of inhibitors of VC and Cr 3C 2 on the grain size and properties of nano-grained cemented carbide were investigated. The mechanism of inhibiting grain growth was also discussed. The results showed that the growth of WC grain during the sintering was effectively inhibited by addition of VC and Cr 3C 2. Thegrain size declined with the addition amount of inhibitors. Excess of inhibitor not only resulted in deposit of carbides formed by the inhibitors between the WC/Co boundaries but also pores, consequently increasing the alloys brittleness, in which the bad effect of VC is larger than Cr 3C 2.