A Study On The Preparation Of The High-Purity & Ultra-Fine Mg-Al Spinel Powders

Magnesium aluminium spinel MgAl₂O₄ has good characters such as corrosion resistance,wear resistance, chemical stability, insulating property, the small thermal expansion and thehigh hardness, which make it widely used as the Laser stromal crystal material. Through thestudy of high quality magnesium aluminium spinel, we find the key element is how to productthe high purity MgAl₂O₄ powder. Thought all the product methods have developed goodtechnology by now, people neglect the important of powders' purity not to satisfy thedevelopment of high science and technology. In the paper we find the powders of high purityMgAl₂O₄ which can resolve the problem that magnesium aluminium spinel contenting manyimpurities can not be used in the high technology field.In this paper, solid phase reaction and alkoxide hydrolysis methods are taken to producthigh purity MgAl₂O₄ powder.The method of solid phase reaction takes the preprocessing to Al material to make itchang into accurate contents' Al₂O₃ and AlOOH powders. Then I mixed the powders withMgO and roasted into high purity MgAl₂O₄ powder. In this method, I talked about the facetssuch as material state, the temperature of solid phase reaction, heating preservation time,seeds' adding which are how to effect the reaction. The method of alkoxide hydrolysis takesIodine as Catalyst to product magnalium bimetal isobutanol salt. I take the method ofdecompression distillation to purify the salt to assure the last powders' quality. Then the salttakes the process of hydrolyzing, drying, roasting. In the paper, I talk about the factors such asthe water addition, PH value, the temperature of hydrolyzing, surfactant, the way ofhydrolyzing and so on, which are how to effect the gel particles. I also talk about the effect toMgAl₂O₄ powder particles in the way of drying.Through the method of solid phase reaction, Conclusion of this text are as following:receiving the accurate contents' Al₂O₃ powder under 600℃; receiving the accurate contents'AlOOH powder under 280℃for 48hr; exchanging into MgAl₂O₄ phase under 1400℃; thepowder's qualify is 99.995% in ICP. Taking the method of alkoxide hydrolysis, Conclusionof this text are as following: magnalium bimetal isobutanol salt is purified during 250℃～280℃for 9mmHg. Compared to n-Butyl alkoxide the temperature descends 100℃. under 900℃burning into prutify phase's MgAl₂O₄ powder; The best technology: under roomtemperature 20℃. Solid-alkoxide will hydrolyze directly. The molar ratio of water andalkoxide is 160:1. PH value is under about 1, By joining the starch can modify its appearance.microwave-dryness or freeze-dried. Burned and thermal insulation for 1 hour at 900℃.