Effect of layer thickness on crack suppression in laser engineered net shaping of ceramic structure

• Main Authors: Wu, Dongjiang, Yuan, Shijun, Ma, Guangyi, Jia, Zhenyuan, Niu, Fangyong
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Conference or Workshop Item
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Mechanical engineering::Prototyping; Process; Laser Engineered Net Shaping
• Online Access: https://hdl.handle.net/10356/88720; http://hdl.handle.net/10220/45868
• Institution: Nanyang Technological University

Laser engineered net shaping (LENS) has been innovatively applied to direct additive manufacturing of ceramics in recent years. Using this technique, neat ceramic powder without binders can be completely melted and solidified, obtaining compact and high-purity netshaped ceramic structures rapidly. However, existing LENS process for fabricating ceramics suffers from cracking defect due to intrinsic brittleness of ceramics and high temperature gradient in deposition. Here we reported the effect of layer thickness on cracking in LENS of ceramic structure, which indicates that cracks can be effectively suppressed by reasonably optimizing process parameters. Pure Al2O3 structures with different layer thickness were fabricated by LENS system and their microstructure were analyzed to figure out the crack suppressing mechanism of optimizing layer thickness. Results indicate that cracks of fabricated specimen decreases obviously with the increase of layer thickness. Reduction of grain boundary defects and increase of transverse grain ratio are the main mechanism of crack suppression.