Study On The Technology And Mechanism Of Alumina Ceramic Prepared From Aluminosilicate Refractory Waste

Ecological Environmental Materials is the materials with excellent performance and enviromental compatibility or improvment. The low recycle ratio of refractory waste leads to the increase of enviroment protection difficulty. China is the largest ceramic production country and large quantity of alumina ceramic balls are used to mill ceramic raw materials annually. The high alumina ceramic ball extremely low profit because of the continuous increasing of alumina raw materials made many factories to stopping produce or bankruptcy. At present, it become urgent to produce high perforamance high alumina ceramic balls in low cost to meet the factory demand.In this paper, aluminosilicate refractory waste with 60%～90% Al₂O₃ was first recycled to prepare high performance industrial ceramic. Ceramic ball was prepared first as an example. The physical and chemical reaction during preparing and the relation between the preparation processes and the products performance, structure and character were studied. High performance alumia ceramic balls with 45%～85% Al₂O₃ were prepared in CaO-MgO-Al₂O₃-SiO₂ quaternary system by using aluminosilicate refractory waste as raw materials and natural mineral as fluent agents, designing the crystal boundary phase and sintering by low temperature and fast sintering technology in air. The relation between ceramic performance, structure and characteristics and process conditions were studied in detail.The ceramic were prepared in the three systems of CaO-MgO-Al₂O₃-SiO₂ (ceramic was name as CMAS), MgO-Al₂O₃-SiO₂(ceramic was name as MAS), CaO-Al₂O₃-SiO₂(ceramic was name as CAS).The sintered temperature of CMAS was the lowest and the sintered temperature range was the widest. The wear resistance of CAS was the highest and MAS was the lowest. The crystal phase of CMAS and CBAS (the ceramic prepared in CaO-BaO-Al₂O₃-SiO₂ system)were the same as mullite, corundum and anorthite. Compared with CMAS, CBAS sintered temperature was lower, glass content was higher resulting in higher density, denser structure and higher wear resistance.Refractory waste particle size decreased with the increase of milling time, leading to lower sintered temperature, particle size and porosity and higher density and wear resistance and the ratio of transcrystal fracture of the as-prepared ceramic ball. The ceramic wear resistance increased with the storage time of the used ceramic blank increasing because of the uniform of the blank property. With the increase of ceramic body forming pressure, the prepared ceramic ball sintered temperature decreased, sinter temperature range and wear resistance increase.In the present dissertation, the high wear resistance of the ceramic with Al₂O₃ lower than 60% and the wear resistance increased with the increase of Al₂O₃ and cordierite were explored. Ceramic crystal phase were the same as the used refractory waste and increased with ceramic Al₂O₃ increasing. The sintered mechanism of the ceramic prepared by the refractory waste was that large particle acted as frame and small particle melt into melt then crystalized from the melt during sintering. The ceramic with corse crystal may have high wear resistance as prepared in suitable conditions. It was found on the ceramic ball milled surface a layer formed by the ceramic crystal with partial broken away indicating that high ratio of transcrystal fracture wear mechanism was occur during milling. The ceramic density and wear resistance increased with the increase of ceramic Al₂O₃ as Al₂O₃ higher than 60%. Ceramic fracture strength, fracture toughness and wear resistance increased with the decrease of crystal size, porosity and pore size. Ceramic sintered temperature decreased, density and wear resistance increased with the increase of the ceramic Fe₂O₃ content, however the ceramic color darkened with the increase of Fe₂O₃ too. The ceramic color also darkened with the increase of ceramic TiO₂, CaO, K₂O, Na₂O.The relations that ceramic wear rate directs proportion to the pressure acted on ceramic ball and the contact points between ceramic balls were explored. A concept simple model of ceramic wear rate and size: w=ar^-1/3/t+b was developed. Compared with the existed models, the developing model is simpler and more rational. The higher the ceramic performance, the accurater results the model report, proving that the higher the ceramic performance, the higher the ceramic reproduction and reliability.A self dispersion technology was developed. The possibility of preparing ceramic by half wet chemical method using self dispersion technology was studied and several results were obtained. First was that ceramic sintered temperature was lower and wear resistance was higher, second was that ceramic sintered temperature decreased and density and wear resistance incereased with the increase of nano AlOOH powder in ceramic body (as AlOOH lower than 3.5%). The secondary crystal phase distributed uniformly in crystal boundary increased the binding strength of crystal boundary, leadding to the increase of transcrystal fracture.Tested in the same conditions, the wear rate of the preapred ceramic ball with 75% Al₂O₃ was 0.0188% and with 85% Al₂O₃, was 0.0124%, while the wear rate of the world best 95 ceramic ball was 0.0523%/h. Furthermore, the ceramic ball prepared in this dissertation exhibits higher ratio of performance to price, raw materials predominance and extensive.