| Since the discovery of alumina and zirconia ceramics has excellent physical and chemical properties, compounding both of them became research priorities.Through the research of ceramics toughening and strengthening mechanism, various of toughening theories has been put forward, such as particle dispersion toughening, phase transformation toughening, microscopic structure of fortitude, the mechanism of layered composite ceramic, fortitude solid solution strengthening, etc.To get better performance of fortitude, no matter which kind of strengthening mechanism higher requirements of the material microstructure is needed, therefore getting high sintering density and without abnormal grow up grains ceramic is particularly important.In addition, ceramic materials performance at normal temperature has been studied more mature.But as refractory material and high temperature ceramic ceaseless research and application, research of ceramic materials properties at high temperature has become very important.This paper aiming at two aspects like the sintering density and high temperature performance of ceramic materials, studied the influence of additives on ceramic materials density and mechanical properties as well as the mechanical performance of Al2O3-ZrO2 ceramics at high temperature systematically, and priority researched following four aspects of content:First, studied the influence of binders on the relative density of Al2O3-ZrO2 composite ceramic materials including the choosing, add ratio and add quantity etc.of binders. At the same time, effect of the add ratio and total add quantity of additives On Al2O3-ZrO2 Ceramics Relative Density and the mechanical proportion was researched.Methyl cellulose (CMC) and polyvinyl alcohol (PVA) obviously affect the relative density of Al2O3-ZrO2 composite ceramic materials.While the quantity ratio of PVA and CMC is 1 to 2.75 the relative density of green body and sintering body reached maxture.Based the best adding ratio, while the quality of adding binders amount to 5% quality score of total quality of powder, the porosity and bibulous rate reduced significantly and the relative density of ceramic materials is the highest. Secondly, based on the study of the above and analysised the function of different additives by synthesis, three suitable sintering additives were choosed to research the influence law of the sintering additives on material densify.Research results show that the addition of SiO2 played unapparent role in causing increases to the density of the materials.with the addition of the relative density increases, the relative density of materials decrease instead.The addition of MgO helped to improve the materials relative density, the peak of material relative density appear in the range of 0.25%-1% as the different content of ZrO2, when MgO addition amount is 0.5%, materials reached maximum bending strength.When the yttrium oxide addition amount is 0.5%, both the relative density and flexural strength achieved maximum.Finally choose optimal proportioning of the three sintering additives, get the best experimental results of sintering additives.Again, study the influence of the above three sintering additives on material flexural strength and fracture toughness.With the addition of SiO2 multiplied, the flexural strength of material reduced steadily and the fracture toughness did not change significantly.When join MgO and yttrium oxide, the flexural strength and the fracture toughness of materials are reached maximum while the addition amount to 0.5%.Finally, the high-temperature thermal shock performance of Al2O3-ZrO2 composite ceramic materials was studied, Discovered that phase change happened within thermal shock process.When the temperature is higher than 1000℃, the mechanical properties of materials appears mutations that the flexural strength have obvious rising phenomenon, this change mains have something to do with martensite transformation and heat on toughening electrolyzing process. |
PDF Full Text Request