MoSi_2对注凝成型HfB2超高温陶瓷材料性能的影响

在Ph为10.9,分散剂PMAA-NH4为8vol%,固体含量为40vol%的条件下采用注凝成型技术制备了HfB2-(5%～15wt%)MoSi_2超高温陶瓷坯体,密度达到4.25 g/cm~3以上,在氩气气氛下1950 ℃保温30 min烧成.采用X射线衍射仪、扫描电镜等分析方法研究了添加剂MoSi_2对HfB2超高温陶瓷材料性能的影响、烧结体的物相组成和显微结构.结果表明:添加剂MoSi_2可有效促进HfB2超高温陶瓷材料的致密化,随着MoSi_2加入量的提高,HfB2超高温陶瓷材料的力学性能不断提高,当加入量为15%时,可得到显微硬度为9.8 Gpa,抗弯强度为389.7 Mpa,断裂韧性为3.7 Mpa·m~(1/2)的HfB2超高温陶瓷材料.

Effects of MoSi_2 Additive on the Properties of HfB_2 Ultra High Temperature Ceramics Produced by Gel-gasting

The green bodies of the HfB_2-(5%-15wt%) MoSi_2 ultra high temperature ceramics (UHTCs)system were produced by gel-casting when pH was 10.9, the content of dispersant（PMAA-NH_4）was 8vol% and the solid content of the slurry was 40vol%. the density of the green bodies had achieved above 4.25 g/cm~3 . They were sintered in a high multi-furnace under a flowing argon atmosphere at 1950 ℃ for 30 min. The effects of MoSi_2 additions on the properties of HfB_2 UHTCs were studied. The phase compositions were analyzed with an X-ray diffractometer and the microstructures of the sintered UHTCs were studied by SEM. The results show that the densification and the mechanical properties of the HfB_2 UHTCs added with the increase of MoSi_2 were improved highly. When 15wt% MoSi_2 were added, the hardness of the HfB_2 UHTCs reached 9.8 GPa, the bending strength reached 389.7 MPa and the fracture toughness reached 3.7 MPa·m~(1/2).