磷酸改性处理后氢氧化铝的热稳定性

Thermal stability of aluminum hydrate modified by phosphoric acid

研究磷酸改善氢氧化铝粉体热稳定性的工艺及修饰处理对粉体形貌与物相的影响,并探讨磷酸提高氢氧化铝热稳定性的机理。结果表明:反应温度的提高、反应时间的延长及磷酸浓度的加大均有利于氢氧化铝热稳定性的提高,当磷酸浓度为10%、反应温度与时间分别取90℃与75 min时,可使氢氧化铝中结晶水的初始失去温度由192℃提高到211℃;磷酸提高氢氧化铝热稳定性的原因可能是磷酸与氢氧化铝反应所生成的耐热铝盐包覆在氢氧化铝颗粒的表面;所研究的修饰工艺没有改变粉体的三水铝石结构,但磷酸处理会使粉体颗粒长大,并且还会有大尺寸团聚粒子的出现。

The modification technology for improving thermal stability of aluminum hydrate powder with phosphoric acid and its effects on morphology and phase of modified powder were investigated, and the improvement mechanism on thermal stability of aluminum hydrate was discussed. The results show that raising reaction temperature, prolonging reaction time and increasing concentration of phosphoric acid are favorable to improve the thermal stability of aluminum hydrate. The initial loss temperature of crystal water in aluminum hydrate rises from 192 ℃ to 211 ℃ at the phosphoric acid concentration of 10%, reaction temperature of 90℃ and reaction time of 75 min. The improvement mechanism of phosphoric acid on thermal stability of aluminum hydrate may be attributed to their interreaction which produces heat resistant aluminum salt film on the aluminum hydrate particle. The modification technology doesn＇t change the trihydrate alumina structure of powder, however, it will make the particles grow up and coarse granule appear.