The Preparation Of High Property MgAl₂O₄ Spinel Powders

MgAl2O4 spinel has good characters such as corrosion resistance, wear resistance, chemical stability, insulating property, the small thermal expansion and the high hardness, which make it widely used as the Blue-Green-Shiba Laser stromal crystal material. Therefore, to product the high property MgAl2O4 powders is the key element to obtain high quality MgAl2O4 spinel. In this work the preparation of MgAl2O4 spinel has made great advancement, the final powders are ultra-fine, the perfect MgAl2O4 crystal and the good diffusion provide the application in the high technology fields. Due to the fact the method of prepared MgAl2O4 powders is very convenient, and has the lower the prepared temperature, so the great application in industry production is available.In this paper, two preparation methods of high quality MgAl2O4 powders are solid phase reaction and alkoxide hydrolysis. The mineralizers such as NH4F,AlF3,AlCl3 are added in the mixture in order to prepare the high property powders.Through the changes from mineralizers mixed in the AlOOH powders, the function affected the morphology and structure of final powders was studied carefully. In solid-state reaction, the elements like materials, the reaction temperature, holding time and mineralizer are considered to affect the preparation temperature of reaction and morphology. In addition, in alkoxide hydrolysis the factors such as the mount of water, the temperature of hydrolysis, dispersant, surfactant are affecting the particles of colloid, and adding the mineralizer can take changes in the morphology and structure of powders, otherwise hydrothermal technology affecting in the hydrolysis of alkoxide can take influences to the final powders.Through the analysis of TG-DTA, XRD, SEM, the facts indicate the mineralizer can crystal the powders and grow into the bigger spinel crystal. In solid-state reaction, AlOOH can take place of the Al2O3 in order to promote the reaction. The main crystal phase was formed in 1100℃, then the perfect crystal phase appeared in 1400℃. However, the sample contenting the mineralizer can form the perfect crystal phase in 1200℃. The mineralizer mainly contenting the fluoride can crystal the regulation spinel powders. In addition, in alkoxide hydrolysis the mount of water ( 1:200), 65℃,the dispersant isopropanol, a little acetylacetone can prepare the good effect of hydrolysis particles. In 700℃the perfect spinel phase was formed, but the mineralizer can not affect the preparation temperature. In 1200℃the mineralizer can crystal the fine particles. Otherwise the hydrothermal can affect the structure and morphology in final powders.