Preparation and strengthening mechanisms of in-situ HF catalyzed highly porous mullite with whisker frame structure

HF原位催化高气孔率晶须框架多孔莫来石的制备及强化机制研究

Received: 5 March 2020

Abstract

Using HF as catalyst and based on sol-gel chemical precursor powder molding and sintering process, porous mullite with whisker frame structure was in-situ synthesized in the blank body. Due to the high efficiency catalysis of HF, this structure has both of high porosity and high strength. The effects of HF addition and sintering temperature on the formation of mullite whisker frame, phase transition process, porosity and strength of porous materials were discussed, and the optimal process parameters were determined. The mechanism of strengthening the porous materials was preliminary analyzed, and under the catalysis of HF, the close connection between whisker frame lap joints was formed. When the porosity of mullite is up to 83.22%, the compressive strength of can reach 16.48 MPa.

摘要

利用HF为催化剂，基于溶胶-凝胶化学前驱体粉末模压烧结工艺，使坯体中原位生成晶须框架结构多孔莫来石。由于HF的高效催化，此结构具有高气孔率高强度的特征。讨论了HF添加量和烧结温度对莫来石晶须框架生成、相变过程及对多孔材料气孔率和强度的影响规律，并确定了最佳工艺参数。初步分析经HF催化后，经原位生长得到搭接点间紧密结合的晶须框架结构，进而增强多孔材料强度的机制。该方法制备的晶须框架多孔莫来石气孔率达83.22%时，抗压强度可达16.48 MPa。