Formation, microstructure and properties of aluminum borate ceramics obtained from alumina and boric acid

A series of porous (≈50%) refractory materials from the Al2O3-B2O3 system were developed. The processing strategy resulted in materials with Al18B4O33 as the main crystalline phase. Needle grains with diameters between 0.2 and 1 µm and an aspect ratio over 20:1 were obtained. Thus, based on the information gathered from our research, aluminum borate ceramic materials can be designed for structural, insulating or filtering applications employing only alumina and boric acid as boron oxide source.