Preparation And Performance Of CaO-Al₂O₃-SiO₂Glass-ceramic Binding Alumina Composites

Alumina-based ceramic materials has good thermal stability, high elastic modulus, lightweight, abundant resources, low prices and many other excellent characteristics, which makesthem widely used at high temperature, high pressure, impact resistance, wear resistance,corrosion resistance, anti-radiation environment. However, Alumina-based ceramic materialsin addition to the brittleness, there are many shortcomings, it required high sinteringtemperature in the sintering process with low degree of densification. With increasingtemperature, the material strength decreases rapidly, creep performance get worse, Fatiguestrength and thermal shock resistance decreased. These shortcomings severely limit theapplication of Alumina as the high performance materials. Low temperature sintering ofalumina-based ceramics is one of the very important research work in ceramic area fordomestic and foreign researchers，introducing a mount of additives to alumina-based ceramiesis very useful method. Cracks and the decline of the overall strength of the material wereappeared frequently during the process of manufacture and application of alumina-basedceramics; crack-induced decreasing of the strength and reliability greatly reduced the practicalapplication of the alumina-based ceramie material.In this paper, the alumina-based ceramies were made by Molding process andCaO-A_l2O₃-SiO₂composite additives was introduced into the alumina-based ceramics assintering agent，then sintered at1350℃respectively in air for2hours.In this experiment, basic CaO-A_l2O₃-SiO₂glass frit was prepared by quenching themelted frit in cold water, and analyzed the properties of frit through DTA, XRD. This kind ofglass-ceramic with wollastonite as its main crystalling phase was prepared by heat treatment,and its thermal expansion coefficient matched alumina ceramies. And the influence of basicfrit component, sintering temperature, dwelling time, basic frit proportion on the apparentporosity of the alumina-based ceramic composites was researched by orthogonal experiment.According to the intuitionistic and variance analysis, basic frit proportion was the main factorthat influenced the apparent porosity of the alumina-based ceramic composites. SEM, XRDand EDS analysis indicated that composites were composed of board-columnar andStrip-shape wollastonite crystalling phase, columnar A_l2O₃crystalling phase and glass phase. The influence regularities and mechanisms of preparation process factors to apparent porosityand phase species of the composites were also studied and analyzed, thus the optimalpreparation process was made sure.Finally, the apparent porosity of optimal sample was13.31%by Archimedes method,bending strength, impact toughness, abrasive resistance and Vickers microhardness of theoptimal samples were tested. Test results as follows: the average value of bending strengthwas215.6MPa, the value of toughness was3.946Mpa·m1/2, the wear rate was2.573×10^－6mm³/N·m, the abrasive resistance and impact toughness was good.