Study On Prepration Technology And Properties Of Micro-size Alumina Microspheres

The micro-size ceramic sphere is a kind of ceramic product with excellentperformance,and alumina ceramic spheres have been applied in many fieids because of their adventages including high strength,high hardness,wear resistance and corrosion resistance.Therefore,the study on prepration technology and properties of micro-size alumina microspheres is of significance.The alumina green bodies have been prepared by centrifugal spray drying,using alumina powder as starting material.Then the green bodies are sintered to get the micro-size alumina spheres with good morphology,high degree of sphericity and dispersibility.The research contents include the following aspects:The methods of spray drying has been studied.And we also elaborate the principle of spray drying technology and the process of spray and materials' drying.The formation of various defects of green bodies by spray drying is researched.The alumina microspheres have been prepared by centrifugal spray drying.The alumina slurry is prepared by wet ball grinding.We have determined the best solid loading and the most suitable dispersant by orthogonal experiment,then we analyze the influence of the solid loading,dispersant type,percentage composition of dispersant and binder,temperature and grain size of alumina on rheological properties of slurry and characteristics of green body.Part of the operation parameters is changed to adjust the characteristics of green body.The results show that solid loading and dispersant type have crucial effect on the morphology and sphericity of green body.An aqueous slurries with 40%(volume fraction)of alumina with median particle diameter of 3.27?m,0.5%(mass fraction)of dispersant(sodiumlignosulphonate)and 5% of binder can be transformed into green body with good microsphere,reaching a high pellet yield of 92.9%.The green body with best performance is selected to prepare the alumina spheres with high degree of sphericity,high dispersibility,high strength by two-step sintering process.The median particle diameter of microsphere is 46.40?m,and the compressive strength of microspheres sintered at 1400? can reach 105.6MPa.