Preparation of Si3N4 ceramics by aqueous gelcasting using non-toxic agar powder as gelling agent without cooling crosslink process
| Autor: | Li-Jin Cheng, An-Nan Chen, Jia-Min Wu, Rong-Zhen Liu, Jian-Ping Lin, Yusheng Shi, Chen-Hui Li, Yi-Xin Ma, Ying Chen |
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| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Aqueous solution Materials science Process Chemistry and Technology 02 engineering and technology 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Dispersant Surfaces Coatings and Films Electronic Optical and Magnetic Materials chemistry.chemical_compound Silicon nitride chemistry Flexural strength visual_art 0103 physical sciences Materials Chemistry Ceramics and Composites visual_art.visual_art_medium Relative density Ceramic Composite material 0210 nano-technology Shrinkage |
| Zdroj: | Ceramics International. 45:20961-20966 |
| ISSN: | 0272-8842 |
| DOI: | 10.1016/j.ceramint.2019.06.211 |
| Popis: | A non-toxic and low-cost gelcasting system was successfully developed using agar as gelling agent to fabricate silicon nitride ceramic green bodies without cooling crosslink process, and silicon nitride ceramic was obtained by pressureless sintering. The effects of agar contents on rheological behavior of silicon nitride suspension, microstructure and mechanical properties of silicon nitride ceramics were investigated. The silicon nitride ceramic suspension with 45 vol% solid loading using 1.2 wt% ammonium polyacrylate (PAA-NH4) as dispersant was successfully prepared for gelcasting. After removing binder at 800 °C for 2 h and pressureless sintering at 1800 °C for 2 h, the silicon nitride ceramics exhibited homogeneous and interlocking microstructure composed of elongated β-Si3N4 phase, which contributes to its mechanical properties. With the increase of agar powder content from 0.25 wt% to 1.5 wt%, the shrinkage and flexural strength of the silicon nitride ceramics increased firstly and then decreased. When the agar powder content was 0.5 wt%, the silicon nitride ceramics had the optimized flexural strength (218 ± 25 MPa) with relative density of 92.85 ± 2.19% and the shrinkage of 16.03 ± 0.15%. Using agar as gelling agent to prepare silicon nitride ceramics by gelcasting is believed to be a novel and low-cost method, which could be used to prepare other high performance ceramics in the future. |
| Databáze: | OpenAIRE |
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