Study on Effect of Particle Size and Sintering Time on Texturization Behavior of SiC Ceramics Prepared under 6 T Magnetic Field
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摘要: 具有磁各向异性的陶瓷颗粒在磁场中能够实现定向排列,从而在陶瓷烧结体中形成织构化微观组织,这对于进一步提高陶瓷材料的性能具有重要意义,陶瓷颗粒尺寸和烧结时间均对陶瓷的织构化行为具有影响。基于此,本研究以碳化硅陶瓷为研究对象,在6 T磁场下凝胶注塑成型制备碳化硅陶瓷素坯,并在磁场外1 950 ℃下无压烧结得到织构化碳化硅陶瓷烧结体,分析了碳化硅颗粒尺寸和烧结时间对碳化硅陶瓷素坯和烧结体织构化行为及致密度的影响,研究结果表明:6 T磁场能够实现碳化硅晶粒的c轴沿着磁场方向取向排列。随着大尺寸SiC颗粒比例的增加,碳化硅陶瓷素坯的Lotgering因子从0.84增加到0.92,这主要是因为大尺寸颗粒更容易在磁场中实现取向排列; 1 950 ℃下烧结后,碳化硅陶瓷烧结体形成了具有c轴取向的织构化微观组织。随着大尺寸SiC颗粒比例的增加,碳化硅陶瓷烧结体的Lotgering因子呈现先增大后降低的趋势,最大能达到0.95。但是由于大尺寸颗粒烧结致密化困难,烧结体致密度呈现下降趋势; 烧结时间的适当增加可以促进碳化硅陶瓷烧结体织构化程度的增加,并利于碳化硅陶瓷烧结体的致密化。综上,颗粒尺寸配比和烧结时间的调控和优化对于提高碳化硅陶瓷织构化程度具有重要作用。Abstract: Ceramic particles with magnetic anisotropy can be oriented under the function of magnetic field, and textured microstructure can be formed in the sintered ceramics. The application of this technology is important for further promoting the properties and development of ceramics. The texturization behavior of ceramic is affected by particle size and sintering time. Therefore, in this study, SiC green ceramics are prepared by gel-casting assisted by magnetic alignment technology, and textured SiC sin- tered ceramics are prepared at 1 950 ℃ with no magnetic field or pressure. The effects of SiC particle size and sintering time on the texturization behaviors and densifications of SiC green and sintered ceramics are analyzed. Results showed that c-axis of SiC grains is oriented to align along the magnetic field direction. With the increasing ratio of SiC particles with large size, the Lotgering factor of green ceramics increases from 0.84 to 0.92, which is the result that the SiC particles with big size are easily oriented under same magnetic field intensity. After sintered at 1 950 ℃, textured microstructure is formed in the sintered ceramics with the c-axis of SiC grains oriented. With the increasing ratio of SiC particles with large size, the Lotgering factor of sintered ceramics first increases and then decreases, and the maximum could reach to 0.95. However, owing to the densification difficulty of large particles, the relative density of sintered ceramics shows a decreasing trend. With the suitably increasing of the sintering time, the degree of texture and densification gradually increases. As a result, the optimization of particle size ratio and sintering parameters can play an important role in improving the texturization behavior of ceramics.
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Keywords:
- SiC ceramic /
- magnetic field /
- particle size /
- sintering time /
- texturization
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