溶胶凝胶自蔓延燃烧法制备钴蓝颜料

Sol-gel self-propagating combustion synthesis of cobalt blue pigment

采用溶胶凝胶法制备钴蓝前体干凝胶,经自蔓延燃烧及煅烧制备钴蓝颜料,研究了柠檬酸用量、溶胶反应温度、pH值、金属离子浓度、乙二醇等对凝胶的形成、燃烧特性及对制备的钴蓝颜料晶型结构的影响,以及干凝胶热处理方式和煅烧温度对钴蓝颜料晶型的影响。研究表明:柠檬酸用量、溶胶反应温度、乙二醇对制备的钴蓝晶型结构无影响;提高溶胶反应的温度,增加金属离子的浓度(0.01～0.1mol/L),有利于凝胶的较快形成;Co2+、Al3+总浓度低至0.005mol/L,不能形成完好尖晶石结构;适宜的pH值(约6.5)有利于柠檬酸的电离及与金属离子的络合以及干凝胶的自蔓延燃烧;乙二醇的使用可以改善钴蓝颜料的团聚现象;干凝胶自蔓延燃烧不能形成完好的尖晶石结构,燃烧后再煅烧,有助于改善钴蓝颜料的晶体结构及分散性;干凝胶自蔓延燃烧后再煅烧,随着煅烧温度的提高,制备的钴蓝颜料晶型更加完整,颜色更加鲜亮。

Cobalt blue pigment was prepared by self-propagating combustion and calcination from xerogel precursor prepared by sol-gel method.Factors influencing the gel formation and combustion characteristics as well as the crystal structure of prepared cobalt blue were investigated,such as citric acid amount,sol reaction temperature,pH value,concentration of metal ions and ethylene glycol.Effects of thermal treatment methods and calcination temperature of the xerogel on the crystal structure of cobalt blue pigment were also investigated.Results showed that citric acid amount,sol reaction temperature and ethylene glycol have no effects on the crystal structure of cobalt blue pigment.The increasing in sol reaction temperature and concentration of Co2＋ and Al3＋（0.01～0.1mol /L ）was conducive to rapid gel formation.When the total Co2＋ and Al3＋concentration was as low as 0.005 mol / L,the cobalt blue pigment could not be formed with intact spinel structure.Suitable pH value（about 6.5）was favorable to citric acid ionization and complexation with metal ions,as well as the succeeding gel self-propagating combustion.Glycol could improve the agglomeration of cobalt blue pigment.Cobalt blue pigment with intact spinel structure could also not be formed just by gel self-propagating combustion.The crystal structure and dispersion properties of cobalt blue pigment could be improved by the combination of self-propagating combustion and calcination.By calcination after self-propagating combustion,cobalt blue pigment was obtained with more complete crystal structure and with brighter colors with the increasing of calcination temperature.