Manufacturing of ceramic cores:From hot injection to 3D printing

摘要

With the improvement of aero-engine performance,the preparation of hollow blades of single-crystal superalloys with complex inner cavity cooling structures is becoming increasingly urgent.The ceramic core is the key intermediate part of the preparation and has attracted wide attention.To meet this challenge,new technologies that can make up for the defects of long periods and high costs of fabricating complex structural cores by traditional hot injection technology are needed.Vat photopolymerization 3D printing ceramic technology has been applied to the core field to realize the rapid preparation of complex structural cores.However,the industrial application of this technology still needs further research and improvement.Herein,ceramic cores were prepared using traditional hot injection and vat photopolymerization 3D printing techniques using fused silica,nano-ZrO_(2),and Al_(2)O_(3) powders as starting materials.The 3D printed ceramic core has a typical layered structure with a small pore size and low porosity.Because of the layered structure,the pore area is larger than that of the hot injection ceramic core,the leaching performance has little effect(0.0277 g/min for 3D printing cores,0.298 g/min for hot injection cores).In the X and Y directions,the sintering shrinkage is low(2.7%),but in the Z direction,the shrinkage is large(4.7%).The fracture occurs when the inner layer crack expands and connects with the interlayer crack,forming a stepped fracture in the 3D-printed cores.The bending strength of the 3D printed core at high temperature(1500℃)is 17.3 MPa.These analyses show that the performance of vat photopolymerization 3D-printed ceramic cores can meet the casting requirements of single crystal superalloy blades,which is a potential technology for the preparation of complex structure ceramic cores.The research mode of 3D printing core technology based on the traditional hot injection process provides an effective new idea for promoting the industrial application of 3D printing core technology.