H_(2)对预烧结后的WC-11.2Co-0.3TaC硬质合金组织及性能的影响

以二次烧结过程中是否通入H2的两组WC-11.2Co-0.3TaC硬质合金为研究对象,采用金相显微镜观察、物理化学性能检测等分析测试方法,研究了H_(2)对预烧结后的合金组织及性能的影响。结果表明:经850℃预烧结后试样的氧含量受放置时间的影响,放置时间越长,试样中的氧含量越高,当放置时间超过12 h后,氧含量基本稳定在0.22%左右。二次烧结过程中H_(2)的介入能较好地保护WC-11.2Co-0.3TaC硬质合金中的碳含量,使其相对磁饱和强度维持在94.9%左右,而较高的碳含量导致出现了较多欠匀的WC晶粒,同时也造成合金密度、硬度、矫顽磁力及抗弯强度下降,相比于未使用H2的二次烧结试样,抗弯强度降低了604 N/mm^(2)。

Sintering of WC-10%Co nano powders containing TaC and VC grain growth inhibitors

WC-10%Co （mass fraction） nanocomposite was synthesized by high energy planetary ball milling at balls to powder mass ratio of 15. For inhibition of growth of WC grains during sintering, TaC and VC were used as inhibitors. Hardness and fracture toughness results reveal that the addition of TaC increases the toughness of hard metal and VC increases the hardness of the sample due to the effective reduction of WC grain size. The effect of co-addition of 0.6% TaC and 0.7% VC on physical and mechanical properties of WC-10%Co sintered sample was investigated. The hardness of the sample is increased to HV30 1 787, which is 24% more than that of the inhibitor-free sample; the fracture toughness achieves 8.7 MPa·m^1/2, 35% higer then that of the inhibitor-free sample; the grain growth is inhibited and grain size achieves 0.38μ m.

Effects of Ta C on microstructure and mechanical properties of coarse grained WC-9Co cemented carbides

Coarse grained WC-9Co cemented carbides with 0-1.0% TaC(mass fraction) were fabricated by HIP-sintering and gas quenching. The effects of TaC on the microstructures and mechanical properties were investigated using scanning electron microscopy(SEM), energy dispersive X-ray analysis(EDS), X-ray diffractometry(XRD) and mechanical properties tests. The results show that the maximum values of hardness and strength are HV 1124 and 2466 MPa respectively when 0.4% TaC is added. When the content of TaC is more than 0.6%, the grain size of WC is no longer affected by the amount of TaC, and(W,Ta)C occurs as well. Moreover, the strength and fracture toughness increase and the(Ta+W) content decreases with the increase of TaC content. The dependence of(Ta+W) content on the mechanical properties indicates that(Ta+W) content in Co should be decreased as low as possible to improve the mechanical properties of coarse grained WC-TaC-9Co cemented carbides with the microstructure of WC+γ two phase regions.

时尚首饰用金属材料的性能对比

以316L不锈钢、TA2工业纯钛、CoCrMo合金、钨钢以及TaC系硬质合金等5种典型的时尚首饰金属材料为研究对象,分别从物理性能、化学性能、力学性能、工艺性能和安全性能等方面进行了试验对比。结果表明,5种材料均属于无色的黑白系,CoCrMo合金的亮度和TaC系硬质合金的色度最高;在人工汗液中均具有优良的耐蚀性能,以TA2的点蚀电位最高,而钨钢最低;在湿法腐蚀研磨中,高硬度材料的磨损率明显低于低硬度材料的,可以更持久地保持首饰的光洁度;316L、TA2、CoCrMo合金可采用多种工艺方法成形,前两者可直接镶嵌饰石,可采用阳极氧化着色,而钨钢以及TaC系硬质合金只适合粉末冶金和线切割成形,不能直接镶嵌饰石。TA2与CoCrMo合金的生物相容性最好。