(中南大学 冶金科学与工程学院，长沙 410083)
摘 要: 研究磷酸改性对氢氧化铝物相、形貌、表面基团及热稳定性的影响，并从动力学与热力学角度分析磷酸改善氢氧化铝热稳定性的机理。采用磷酸改性处理可提高氢氧化铝粉体的热稳定性，其直接的原因是改性后粉体表面形成耐热铝盐包覆层；改性氢氧化铝热稳定性提高的动力学原因是，颗粒受热分解产生的水蒸气在向外扩散时，除需克服分解产物层的扩散阻力外，还要克服其在包覆层中的动力学阻碍；改性氢氧化铝热稳定性提高的热力学原因是，包覆层使氢氧化铝内核表面的水分子浓度提高，使得氢氧化铝分解反应的平衡水蒸气分压增大，从而相应提高分解温度。
关键字: 氢氧化铝；磷酸改性；包覆层；热稳定性；机理
phosphoric acid
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of modification by phosphoric acid on phases, morphologies, surface groups and thermal stability of aluminum hydrate (AH) were investigated, and the mechanism of phosphoric acid improving thermal stability of AH was analyzed from views of kinetics and thermodynamics. The modification by phosphoric acid can improve thermal stability of AH, which attributes to the formation of heat resistant aluminum salt coating on the surface of AH particles caused by the inter-reaction between phosphoric acid and AH particles. The mechanism of improving thermal stability of modified AH is that, according to kinetics of the water vapor produced by decomposing modified AH diffuses, it has to get over not only the diffusion resistance of decomposed product, but also the kinetics resistance of coating layer. According to thermodynamics, AH decomposing the water vapor on the surface of AH kernel increases the equilibrium press of water vapor, thus, the decomposing temperature rises.
Key words: aluminum hydrate; phosphoric acid modification; coating; thermal stability; mechanism
