Effect Of Layer Thickness On Crack Suppression In Laser Engineered Net Shaping Of Ceramic Structure

Laser engineered net shaping (LENS) has been innovatively applied to direct \nadditive manufacturing of ceramics in recent years. Using this technique, neat ceramic powder \nwithout binders can be completely melted and solidified, obtaining compact and high-purity netshaped \nceramic structures rapidly. However, existing LENS process for fabricating ceramics \nsuffers from cracking defect due to intrinsic brittleness of ceramics and high temperature gradient \nin deposition. Here we reported the effect of layer thickness on cracking in LENS of ceramic \nstructure, which indicates that cracks can be effectively suppressed by reasonably optimizing \nprocess parameters. Pure Al2O3 structures with different layer thickness were fabricated by LENS \nsystem and their microstructure were analyzed to figure out the crack suppressing mechanism of \noptimizing layer thickness. Results indicate that cracks of fabricated specimen decreases obviously \nwith the increase of layer thickness. Reduction of grain boundary defects and increase of \ntransverse grain ratio are the main mechanism of crack suppression.