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采用国产DS6×800T铰链式六面顶压机技术,对纳米结构碳化钽(TaC)粉末样品进行了高温高压烧结,并进行了物理表征。在加载负荷为29.4N时,烧结压力为3GPa,烧结温度分别为1100℃和1300℃时,测试得到纳米结构TaC烧结体的硬度分别为16.5±0.5和17.2±0.4GPa。当我们把烧结压力升高到4GPa,烧结温度仍分别为1100℃和1300℃时,测试得到烧结体的硬度分别为17.0±0.3和19.2±0.6GPa。说明超高压力更有利于使样品致密化,并同时可以降低烧结温度。为了比较,我们将添加了体积比为5%钴(Co)粘结剂的纳米结构TaC粉末烧结体进行了烧结和硬度测试,发现其在烧结压力为3GPa、烧结温度为1100℃时的硬度下降为11.3±0.8GPa。根据断裂韧度与硬度和杨氏模量之间的关系,进一步得到了纳米结构TaC的平均断裂韧度为5.0±0.2 MPa m~(1/2)。通过基于密度泛函理论的第一性原理,模拟计算得到TaC的硬度为20GPa,并与实验值进行了比较。
The domestic DS6 × 800T hinged six-sided top press technology was used to fabricate nanostructured tantalum carbide (TaC) powder samples under high temperature and high pressure. The physical characterization was carried out. When the load was 29.4N, the sintering pressure was 3GPa and the sintering temperature was 1100 ℃ and 1300 ℃ respectively, the hardness of TaC sintered nanostructures was 16.5 ± 0.5 and 17.2 ± 0.4GPa, respectively. When we increase the sintering pressure to 4GPa and the sintering temperature is 1100 ℃ and 1300 ℃ respectively, the hardness of the sintered body is 17.0 ± 0.3 and 19.2 ± 0.6GPa respectively. Description of ultra-high pressure is more conducive to the densification of the sample, and at the same time can reduce the sintering temperature. For the purpose of comparison, we tested the sintering and hardness of the nanostructured TaC powder sintered body with the addition of 5% cobalt (Co) binder, and found that the hardness decreased when the sintering pressure was 3 GPa and the sintering temperature was 1100 ℃ 11.3 ± 0.8GPa. According to the relationship between fracture toughness and hardness and Young’s modulus, the average fracture toughness of TaC nanostructures is further found to be 5.0 ± 0.2 MPa m ~ (1/2). Based on the first principle based on density functional theory, the hardness of TaC was calculated to be 20 GPa, and compared with the experimental data.