LI Zhe 1, 2, ZHOU Boan 3, DUAN Yusen 1, ZHANG Jingxian 1
(1. The State Key Lab of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China; 3. School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China)
Abstract: Low-cost high-performance colored silicon nitride ceramics are important candidate for mobile phone backplanes and smart wearable devices.Tape casting process to fabricate Si3N4 ceramics was examined and optimized. Effects of dispersant content, binder, plasticizer/binder ratio and solid loading on properties of the green sheets were studied. An optimum formulation of casting slurry was proposed, leading to dried green tapes with homogeneous and relatively dense microstructure. Pink Si3N4 ceramics with relative density of 96.08%, flexural strength of (867±18) MPa and fracture toughness of (8.03±0.50) MPa·m1/2 were obtained by using sintered reaction-bonded silicon nitride. In visible light, the f-f transition of the extranuclear electrons of Er 3+ ions in the grain boundary phase is responsible for the color development of the sample. Therefore, it is concluded that low-cost high-performance colored Si3N4 ceramics can be prepared by using tape casting and reaction-bonded silicon nitride technique.
Key words: silicon nitride; tape casting; SRBSN; color