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采用纳米碳化钒(V8C7)粉末作为晶粒抑制剂及放电等离子烧结(SPS)方式制备超细WC基硬质合金。X射线衍射结果表明:超细WC基硬质合金主要由WC和Co3C两相组成,随着温度的升高,WC的衍射峰逐渐向小角度偏移。扫描电镜结果表明:SPS和纳米V8C7粉末对超细WC基硬质合金的微观组织具有重要影响。SPS使超细WC基硬质合金在较低温度下(1200℃)实现致密化;纳米V8C7粉末可以有效抑制超细WC基硬质合金中WC的晶粒长大,1200℃时WC的晶粒尺寸约500nm。力学性能结果表明:1200℃时超细WC基硬质合金具有较高的性能(相对密度99.5%,洛氏硬度93.2,断裂韧性12.5MPa·m1/2)。
Ultrafine WC-based cemented carbide was prepared by using nano-vanadium carbide (V8C7) powder as grain inhibitor and spark plasma sintering (SPS). X-ray diffraction results show that the ultrafine WC-based cemented carbide mainly consists of two phases, WC and Co3C. With the increase of temperature, the diffraction peak of WC gradually shifts to a small angle. Scanning electron microscopy results show that SPS and nano-V8C7 powders have an important influence on the microstructure of ultrafine WC-based cemented carbide. SPS ultrafine WC-based cemented carbide at lower temperatures (1200 ℃) to achieve densification; nano-V8C7 powder can effectively inhibit the ultrafine WC-based WC grain growth in WC, 1200 ℃ when the WC grain About 500nm in size. The results of mechanical properties show that ultrafine WC-based cemented carbide has a high performance (relative density 99.5%, Rockwell hardness 93.2, fracture toughness 12.5MPa · m1 / 2) at 1200 ℃.