Laboratory Study Of Aluminium Alkoxide Hydrolysis Preparation Of High Purity Alumina

In this paper, two hydrolysis schemes of high purity alumina precursor were prepared by fractional hydrolysis.the high purity alumina precursor was calcined and the 4N high purity alumina was prepared.The process of hydrolysis of alcohol and aluminum was studied in this paper,the effects of calcination temperature and holding time on the structure, particle size, specific surface area, whiteness and loss rate of water loss of high purity alumina crystal were studied.Experimental results show that:the hydrolyzed products of the hydrolysis time were more uniform, the average size of the product was smaller and the surface area was larger, the hydrolysis of the final product is pseudoboemite,it is one of the many crystalline structures of aluminum hydroxide, after 500~1400 ℃ high temperature calcination, pseudoboehmite has become into high purity alumina powder with different properties, the following results were obtained through the relevant testing methods:(1)The first step and second step hydrolysis time 1h hydrolysis product particle size distribution of 0.3~90 um, average particle size is 11.99 um, specific surface area of 274.731m2/g;The first step and second step hydrolysis time is 2h hydrolysis product particle size distribution is 0.4~40um, average particle size is 10.24 um, specific surface area of 317.623 m2/g.Hydrolysate by phase analysis identified as pseudoboehmite.(2)Phase analysis shows that, the pseudoboehmite after different temperature of calcination, with the increase of temperature, the crystal structure of the sintered product change as follows:Al(OH)3→ε-Al2O3→γ-Al2O3→ζ-Al2O3→α-Al2O3(3) With the calcination temperature rising from 500℃ to 1400℃, the average particle size of powder sintering product and the specific surface area decreases, the whiteness value increases gradually. Insulation 1h firing products of average particle size decreased from 11.26 um to 3.666 um, the specific surface area decreased from 293.637m2/g to 4.62m2/g, the whiteness value increased from 89.8 to 100.8; insulation 4h firing products of average particle size decreased from 10.81 um to 2.666 um, the specific surface area decreased from 294.851m2/g to 3.313m2/g, the whiteness value increased from 83.7 to 99.9.(4)When the calcination temperature is same, the time of the extension is prolonged, and the average granularity of the burned powder and the specific surface area of the burned powder are decreased with the prolonging of the holding time. The dehydration rate of the powder increases with the increase of calcination temperature and the prolonging of holding time.(5) The temperature of calcination was 1200℃ for 1h, the pure alumina purity of the middle part of the powder in the middle of the jade boat is 99.9903%.