凝胶注模制备碳化硼多孔陶瓷

Preparation of Boron Carbide Porous Ceramic by Gel-casting

以琼脂糖大分子为凝胶体系、聚丙烯酸为分散剂,采用凝胶注模工艺制备B4C坯体,经过1 800~2 000℃烧结,制备得到B4C多孔陶瓷。结果表明:pH值为7.5、分散剂含量为0.15%(体积分数)时,陶瓷浆料的稳定性和流动性最佳,制备得到固相含量为45%(体积分数)的低黏度陶瓷浆料。随着烧结温度升高,多孔陶瓷的通孔率下降,1 800℃烧结得到的块体通孔率为100%,气孔呈明显的单峰分布,孔径大小为1μm。多孔陶瓷的抗弯强度在60 MPa左右。Zr金属浸渗B4C多孔陶瓷后得到Zr C/Zr B2复合材料,其微观组织随渗层深度变化出现分层现象。

Boron carbide （B4C） preform was prepared via gel-casting with macromolecule agarose as a gel system and polyacrylic acid as a dispersant. The preform was sintered at 1 800-2 000 ℃ to obtain a porous B4C ceramic. The results show that the maximum solid loading of B4C slurry with a lower viscosity is 45% （in volume fraction） at pH value of 7.5 and dispersant content of 0.15% （in volume fraction）. The open porosity decreases with increasing sintering temperature, and the open porosity is 100% at 1 800 ℃. The pore size distribution of porous ceramics presents a unimodal model with the average pore size of 1 lam. The flexural strength of B4C porous ceramics is 60 MPa, which could be used for the subsequent reactive melt infiltration. The expected ZrC/ZrB2 composite is obtained when Zr infiltrates into the porous B4C ceramic. The microstructure of the composite is layered in the infiltration direction.