Studies of Hardness for the sintered tantalum boride (TaB) at high temperature and high Pressure

Transition metal lanthanum boride (TaB) has potential application value due to its good chemical stability and corrosion resistance, excellent thermal conductivity, electrical conductivity and high hardness. It is suitable for high temperature and wear resistance. It is oxidized and is not easily eroded by hydrochloric acid and aqua regia, but can be slowly decomposed by hot sulfuric acid and hydrofluoric acid. In the past few decades, research on metal TaB has focused on sample synthesis, grain growth and hardness. In 1993, Okada et al. used high-temperature aluminum solution technology to grow TaB single crystals and obtained a hardness of 25.3 GPa. They believed that the hardness of TaB was basically the same as that of Ta5B6 and Ta3B4 single crystals (2330-2530kgf/mm). -2), and there are few reports on the accuracy of TaB hardness measured by other borides, such as CrB and Cr3B4 methods. The hardness of the alloy reacts to the ability of the surface to resist local compression and scoring. In fact, hardness is a comprehensive performance index that characterizes the physical, plastic, toughness and strength of materials. In 2014, we calculated the state equation of TaB, the relationship between elastic modulus and pressure, and the thermodynamic properties of TaB by first-principles calculation. Through calculation, we found that the bulk modulus of TaB at zero pressure is 277GPa (GGA) and 326GPa (LDA). The lattice constants a, b and c vary linearly with pressure and are found to be more easily compressed along the b-axis as the pressure increases, with a compression factor ratio of 5.3%. Through the calculation of the hardness, it is found that the hardness of TaB is as high as 28.6 GPa. It has been reported that Okada et al. [5] obtained a Vickers hardness of about 23.3 GPa for TaB, and Zhao et al. [10] obtained a TaB hardness of 23 GPa. Based on the previous work, this paper uses the DS6×800T hinged six-face press technology to produce high temperature and high pressure sintering of the transition metal TaB powder at a pressure of 4GPa and a temperature of 900 and 1100 °C. After the sintered body was polished, the Vickers hardness of TaB was measured by diamond diamond indentation method, and the relative density of TaB was calculated by Archimedes method. Our research results will help to further understand the mechanical properties of transition metal TaB, as well as the data parameters and scientific basis for TaB applications in industrial and aerospace applications. . Under normal temperature and normal pressure conditions, TaB has a Thalliumiodide-type (Cmcm) with a density of 14.0g/cm3.

Studies of Hardness for the sintered tantalum boride (TaB) at high temperature and high Pressure