Study On Preparation Process Of Silica-based Ceramic Core

Ceramic cores are mainly used to form the complex inner cavity of hollow turbine blades,which is very important for improving the cooling effect of turbine blades and thrustweight ratio of aircraft engine.Silica-based ceramic core is widely used on hollow turbine blades due to its low thermal expansion and great leachability.Study on the ceramic core has an important reference value for the production of the hollow blade.In this paper,quartz glass powder and corundum powder were used as materials.The influence of sintering parameters,particle size and alumina content on the properties of ceramic core was studied.The flexural strength was measured by three point bending method.The creep deflection was measured at 1550?.The composition,surface morphology and micro-structure of ceramic cores were studied by(XRD)and(SEM).The main results are concluded below:The research of sintering process shows that cracks and other defects will appear on the surface of the sample if the temperature rising with a high speed.Sintering for 2 h at 1250?can help to control the cristobalite content in samples.At the same time,the temperature of 1250? can improve flexural strength to 5.00 MPa and creep deflection to 3.05 mm.The research of raw material's particle size shows that samples come to the most compact when it is composed of 25wt%8.23 ?m and 75wt%32.5?m silica powder.That makes the samples have a more stability on its shape and great cristobalite content.The research of the alumina content in raw materials shows that the addition of little alumina can improve the cristobalite content which up to highest when the alumina content was 12wt%.When alumina content lower than 48wt%,it can promote the sintering effect and creep deflection.When the alumina content beyond 52wt%,the shrinkage start decline.The flexural strength of the core increase first and then decrease with the increase of alumina content.When the alumina content is 12wt%,the cristobalite content is too high to make the flexural strength decrease.The dissolution rate decreased with the increase of alumina content.