Preparation of fillers based on hydrated aluminium orthophosphate for ers

Abstract

In this paper, aluminum orthophosphates of the monoclinic and orthorhombic structure of AlPO[4]× 2H[2]O (metavariscite and variscite, respectively) and modified H[3]PO[4] of Al[2]O[3]· nP[2]O[5]· xH[2]O, where n = 1.1 −1.2, are obtained by the method of isothermal crystallization of aluminophosphate solutions. It is noted that the monoclinic modification is formed from concentrated solution (380 g P[2]O[5]· l–1), orthorhombic – from a dilute (12 g P[2]O[5]· l–1). According to the results of thermal and infrared spectro-scopic studies it is developed that the energy state of the crystal water molecules in the variscite and metavariscite differs significantly. It is shown that the bond of the crystal water molecules for metavariscite is stronger than for variscite. Fillers for electrorheological suspensions on the basis of the synthesized aluminum orthophosphate are obtained by partial dehydration. The activity of fillers on the base of metavariscite ( τЕ / τЕ =0 = 43−50) is significantly higher than that the base on the variscite ( τЕ / τЕ =0 = 8). It is suggested that the concentration of charge carries depending on the degree of proto-nation of proton containing groups in a layered monoclinic structure of metavariscite and their mobility is higher than the concentration and mobility of the protons in the close-packed structure varistcite. It was shown that the presence of phosphoric acid at the surface of the solid phase has almost no effect on value of the electrorheological activity.