Effect of β-Si3N4 Initial Powder Size on Texture Development of Porous Si3N4 Ceramics Prepared by Gel-Casting in a Magnetic Field. Issue 4 (1st October 2016)

• Record Type: Journal Article
• Authors: Yang, Zhigang; Yu, Jianbo; Li, Chuanjun; Zhong, Yunbo; Deng, Kang; Ren, Zhongming; Wang, Qiuliang; Dai, Yinming; Wang, Hui
• Is Part Of: Transactions of the Indian Ceramic Society. Volume 75:Issue 4(2016)
• Page Start: 256
• Page End: 262
• Publication Date: 2016-10-01
• Subjects: Porous -- Texture -- Magnetic field -- Gel casting -- Grain growth; Pottery -- India -- Periodicals; 666.306254
• DOI: 10.1080/0371750X.2016.1202143
• Languages: English
• ISSNs: 0371-750X

Abstract

ABSTRACT: Textured porous Si3 N4 ceramics with fine and coarse β-Si3 N4 powders as the raw materials were prepared by gel casting in a strong magnetic field of 6T and subsequent pressureless sintering. These results showed that highly textured porous Si3N4 ceramics could be obtained by adjusting the ratio between fine and coarse β-Si3 N4 powders in 6T. The Lotgering orientation factor in green bodies showed the value of 0.72∼0.74 with the increase of coarse powder content. The sintering process promoted texture development of the samples by Ostwald ripening owing to the big difference in the β-Si3 N4 initial powder size. After sintering at 1800oC for 2 h, the degree of texture (Lotgering orientation factor) in the sample, prepared with fine and coarse powders at the ratio of 1:1, reached the maximum value (0.91), and it had relatively high density (66.91%) and low apparent porosity (34.51%). The crystallographic texture in porous Si3 N4 ceramics led to the anisotropic bending strength. The method combined with gel casting in a strong magnetic field was beneficial for preparing highly textured porous ceramics with big and complex shape. GRAPHICAL ABSTRACT: