| With the rapid development of China’s aerospace industry,developing independent intellectual property rights of the aircraft engine is needed urgent.The ceramic core is the most important part of the production of hollow and complex air-cooled blades,its performance requirements continue improving.The advantages of silicon-based ceramic cores include high mechanical strength,good anti-chilling heat performance,low thermal expansion coefficient,excellent chemical stability and high porosity.But the properties of silicon-based ceramic cores are affected by many factors such as the particle size of matrix material,the type and content of additives,plasticizer content and sintering process.In this paper,the effects of particle size,additive content and sintering process on the mechanical properties,microstructure and phase composition of ceramic core were studied.The main results are concluded below:First,appropriate material particle size ratio can improve the overall performance of ceramic core.By experiment,the shrinkage of the ceramic core is 0.200%.the porosity is 24.58%,the strength is 8.89MPa.the deflection value is 36.6mm,and the comprehensive performance is the best when the ceramic core’s quartz particles of rough:medium:delicate is 3:1:3.The content of the additive has a great influence on the ceramic core performance.When the additive content increases from 5%to 15%,the overall performance of the core has been greatly improved,bending strength of 9.16MPa.When the additive content is increased to 30%,core particles and fracture cracks,core strength and porosity decrease.The strength of the ceramic core increases with the increase of the final temperature and the holding time.then decreases.Its shrinkage increases and porosity decreases.By optimizing,the sintering process,when the final temperature is 1150 ℃and the holding time is 2hours,the ceramic core’s shrinkage is 0.28%.porosity is 27.70%and the flexural strength is 8.28MPa.By increasing the secondary sintering process,the bending strength of the core is increased to 10.97MPa.the sintering shrinkage rate and the porosity change are not obvious.The morphology of the ceramic core is affected by the particle size ratio,the additive content and the sintering process.Reducing the average particle size.increasing the content of additives,increasing the sintering temperature and holding time,that all can make the fracture shape of the core more smoothly.If the additive content is too much,sintering temperature is too large,holding time is too long will lead to core and particle surface cracking,affecting the overall performance.The amount of cristobalite is mainly affected by the additive content and the sintering process.The amount of cristobalite increases with the increase of the content of the additive,the increase of the final combustion temperature and the increase of the holding time.The formation of the cristobalite can reduce the shrinkage and increase the strength,but when the cristobalite content is higher than 20%,the core of the performance indicators are significantly reduced and affect the normal use. |
