Preparation And Properties Of Silica-based Ceramic Core

More and more important roles are ceramic cores playing in the development of air-cooled technology of aero-engine, the properties of which have a direct effect on the manufacturing of hollow turbine blades. However, the production of aero-engines is often hold up due to the poor properties of domestic ceramic cores presently. So a series of influential factors on the properties of ceramic cores were investigated in this paper including the particle size distribution of raw materials, composition of ceramic cores and sintering temperature. Through the investigation, the deficiency of present ceramic cores were overcome such as low flexural strength and great high temperature deformation, and simultaneously the new silica-based ceramic cores with excellent properties were produced, successfully used in practical blades manufacturing. The main conclusions are as follows:(1) The optimal average particle size ranges from 20μm to 30μm for fused silica, and 30μm to 40μm for alumina in this study, and bimodal particle size distribution is better than single-modal distribution for the matrix fused silica. The room temperature flexural strength of ceramic cores is 12MPa, high temperature flexural strength is 26MPa, and deformation at 1250℃ is 17mm, at 1550℃ is 39mm.(2) When little Y2O3 added in the present SA ceramic core, the room temperature flexural strength of ceramic cores is improved by 20%(14.2MPa), high temperature flexural strength improved by 30%(34MPa), deformation at 1550℃ decreased by 50%(23mm), while open porosity keep unchanged(32.5%).(3) The impurities in zircon additive can improve the high temperature flexural strength of ceramic core on small scale, but the properties of ceramic core when zircon added in sintered at 1150℃ is not much better than those of SA ceramic core present.(4) The properties of ceramic core can be improved by increasing sinteringtemperature. When sintering temperature increase to 1180℃, high temperature flexural strength of SA ceramic core is improved by 100%(60.5MPa), deformation at 1250℃ decreased by 50%(8mm). The high temperature flexural strength of SAY and SAZ ceramic core is improved by 40-60%(31.7/35.5MPa), and deformation at 1250℃ is about 0mm.