Study On The Effects Of Y₂O₃and Cristobalite On The Properties Of Silica Oxide Ceramic Cores

Silica-based ceramic cores are widely used in the field of aerospace at present. Ithas high flexural strength at room temperature and high efficient performance ofleaching cores. Meantime, the price of the matrix materials is also the main advantagefor silica-based ceramic cores. However, with the appearance of directional blades andsingle crystal blades, the silica-based ceramic cores’ properties have not met the castingrequirements of new kind of blades. Considering the slight change of the particle size,composition and sintering temperature may lead to significant effects on theperformance, the project study the three factors’influences on ceramic cores’properties.The program prepares the ceramic cores specimens which meet aviation criterionby the hot injection method and also test cores’ properties by conducting some relevantexperiments, such as flexural strength, high temperature deflection at1250℃and1550℃etc. The results show that:With the particle size gradual decreasing, the high temperature deflections ofceramic cores present a decline trend, decreasing to3.16mm. Furthermore, the decreaseof particle size leads to the declining in the open porosity, descending from0.296to0.260. At the meantime, this trend also causes the increase in shrinkages for silica-basedceramic cores.The addition of Y2O3can enhance the flexural strength of the ceramic core and alsomaintain cores’ high temperature performance. At the meantime, it can improve theopen porosity, which is helpful for leaching cores and strengthen technologies.Cristobalite can significantly reduce the ceramic cores’ thermal deformation at hightemperature, with the addition increasing from0%to15%, the high temperaturedeflection at1250℃decreases63.7%from4.14mm to1.50mm. moreover, the additionof cristobalite can decrease the shrinkages for ceramic cores, declining from0.221%to0.021%.When the sintering temperature increases from1150℃to1180℃, the flexuralstrength and high temperature performance can get definite improvement, while it willalso lead to a slight increase in shrinkage and decrease in open porosity. According toproduction process of ceramic cores, ceramic cores need to be strengthened before being utilized. After that, newly developed silica-based ceramic cores are conducted byflexural strength experiment and high temperature deflection at1550℃. The hightemperature deflection is only3.36mm, decreasing74.2%relative to original ceramiccores.