Bismuth Oxide Influencing Tungsten Trioxide Ceramic Grain Growth

Bismuth trioxide (Bi₂O₃) is known as yellow powder, it dissolves in water, and it does not dissolve in acid generating bismuth (III) salt. Its melting point is 824 ℃, the boiling point is 1890 ℃. Bismuth trioxide may be obtained from natural bismuth Hua (a mineral), its main source is copper, and bismuth powder can be obtained bismuth trioxide in the air combustion. Bismuth oxide is mainly used in the chemical industry (such as chemical reagents, bismuth salt manufacturing, etc.), glass industry (mainly used for coloring), and the electronics industry (electronic ceramics, etc.). Among them, the electronics industry is the most widely used bismuth oxide industry; it is mainly used in varistors, thermistors, and CRT oxide surge arresters and other fields. In addition, Bi₂O₃ has high refractive index and dielectric constant, significant fluorescence characteristics and inert to water. Therefore, Bi₂O₃ is potential decomposition and degradation of water pollutants visible catalyst.

Bi₂O₃ doping WO₃ceramics, when the doping has smaller number, the presence of single phase is WO₃; when the doping concentration is greater than 0.2mol%, and it will begin to appear as Bi₂WO₆ phase. Bi₂WO₆ phase becomes bigger with the sintering temperature increasing. WO₃ phase will disappear in the solid phase reaction sintering process. Bi₂O₃ can promote the rapid growth of WO₃ ceramic grain, compact structure, porosity reduction, and a high concentration of Bi₂O₃ doped in the grain boundary formation of the second phase Bi₂WO₆ , which increasing the sintering temperature and time, which can promote the growth of WO₃ ceramic grains form more Bi₂WO₆ phase. According to the analysis results, we can get Bi₂O₃ doping can be formed during the sintering process in the reaction; the transfer material ultimately provides the energy for the growth of the ceramic grains.

• < Prev
• Next >