Preparation of Si3N4 ceramics with high strength and high reliability via a processing strategy |
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| Affiliation: | 1. State Key Lab of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, P R China;2. Max-Planck-Institut für Metallforschung and Institut für Nichtmetallische Anorganische Materialien, Universität Stuttgart, Pulvermetallurgisches Laboratorium, Heisenbergstrasse 5, 70569 Stuttgart, Germany;1. School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, 510006, People’s Republic of China;2. School of Physics, Sun Yat-sen University, Guangzhou, 510275, People’s Republic of China;1. Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China;2. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China;2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China |
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| Abstract: | In this study, the preparation of Si3N4 ceramics with high mechanical reliability is investigated. The influences of several processing steps on the bending strength and the Weibull modulus are reported including: (i) coating of the Si3N4 powder with its sintering aids, (ii) oxidation of the coated powder, (iii) cold isostatic pressing, (iv) gelcasting of the green bodies and (v) gas pressure sintering. It was found that all the aforementioned steps contribute to improvements of strength and reliability of Si3N4 ceramics. Via an optimised processing strategy, Si3N4 ceramics with a bending strength and a Weibull modulus as high as 944.7±29.5 MPa and 33.9, respectively, could be prepared. Additionally, it was also found that surface modifications, i.e. coating and oxidation of Si3N4 powder, increased the rheological properties of the powder suspension in aqueous media, which is favourable for in situ colloidal forming such as gelcasting. |
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