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采用置换填充工艺制备了W/ZrC金属陶瓷,研究了其在不同超高温环境中的组成结构演变规律。结果表明:随着热处理温度的升高,材料的质量损失率先增大后减小,在2200℃时有最大值2.05%(质量分数),而孔隙率则不断增大,在2600℃时达到9.29%(体积分数)。在材料表面,残留Cu最先熔化挥发流失,其次残留Zr,在2600℃时部分ZrC也分解流失。在材料内部,1800℃时未反应完的WC相消失,2200℃时残留Zr-Cu合金相和W_2C相消失,2600℃时仅剩下W相和ZrC相。且随着热处理温度的升高,W原子向ZrC基体中的扩散增多,导致ZrC点阵常数逐渐减小,同时W相由颗粒状变成无规则的长条状,其颗粒数量和体积含量明显减少,并形成了大量闭孔。Zr-Cu合金的流失和W原子的扩散是引起W/ZrC金属陶瓷在超高温环境中组织结构变化的重要原因。
The W / ZrC cermets were prepared by the substitution-filling process. The evolution of the composition of the composites was investigated under different ultra-high temperature conditions. The results show that with the increase of heat treatment temperature, the mass loss of the material first increases and then decreases, reaching a maximum value of 2.05% (mass fraction) at 2200 ℃, while the porosity increases continuously, reaching 9.29 at 2600 ℃ %(Volume fraction). On the surface of the material, the residual Cu first melted and volatilized, followed by the residual Zr. At 2600 ℃, some ZrC also decomposed and lost. In the material, the unreacted WC phase disappears at 1800 ℃, the residual Zr-Cu alloy phase and W_2C phase disappear at 2200 ℃, and only W phase and ZrC phase remain at 2600 ℃. With the increase of heat treatment temperature, the diffusion of W atoms into the ZrC matrix increased, which led to the decrease of the lattice constant of ZrC. At the same time, the W phase changed from granular to irregular strip, and its particle number and volume content were obviously Reduce, and the formation of a large number of closed-cell. The loss of Zr-Cu alloy and the diffusion of W atoms are the important reasons for the structural changes of W / ZrC cermets in ultra-high temperature environment.