Microstructure refinement-homogenization and flexural strength improvement of Al_(2)O_(3) ceramics fabricated by DLP-stereolithography integrated with chemical precipitation coating process

摘要

In this study,the chemical precipitation coating(CP)process was creatively integrated with DLP-stereolithography based 3D printing for refining and homogenizing the microstructure of 3D printed Al_(2)O_(3) ceramic.Based on this novel approach,Al_(2)O_(3)powder was coated with a homogeneous layer of amorphous Y2O3,with the coated AI2O3 powder found to make the microstructure of 3D printed Al_(2)O_(3) ceramic more uniform and refined,as compared with the conventional mechanical mixing(MM)of Al_(2)O_(3) and Y_(2)O_(3) powders.The grain size of Al_(2)O_(3) in Sample CP is 64.44%and 51.43%lower than those in the monolithic Al_(2)O_(3) ceramic and Sample MM,respectively.Sample CP has the highest flexural strength of 455.37±32.17 MPa,which is 14.85%and 25.45%higher than those of Samples MM and AL,respectively;also Sample CP has the highest Weibull modulus of 16.88 among the three kinds of samples.Moreover,the fine grained Sample CP has a close thermal conductivity to the coarse grained Sample MM because of the changes in morphology of Y_(3)Al_(5)O_(12) phase from semi-connected(Sample MM)to isolated(Sample CP).Finally,specially designed fin-type Al_(2)O_(3) ceramic heat sinks were successfully fabricated via the novel integrated process,which has been proven to be an effective method for fabricating complex-shaped Al_(2)O_(3) ceramic components with enhanced flexural strength and reliability.