In-situ formation of bulk and porous h-AlN/SiC-based ceramics from geopolymer technique. Issue 18 (15th December 2019)

• Record Type: Journal Article
• Authors: Jia, Dechang; Li, Yihua; He, Peigang; Fu, Shuai; Duan, Xiaoming; Sun, Zhenlin; Cai, Delong; Li, Daxin; Yang, Zhihua; Zhou, Yu
• Is Part Of: Ceramics international. Volume 45:Issue 18(2019)Part A
• Page Start: 24727
• Page End: 24733
• Publication Date: 2019-12-15
• Subjects: Geopolymer-based composites -- High-temperature treatments -- Thermal evolution -- Carbon thermal reaction -- Porous ceramics; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2019.08.212
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: In this paper, bulk and porous AlN/SiC based ceramics were in-situ prepared from graphite/geopolymer composites based on the carbon thermal reduction reaction under high temperatures. Thermal evolution of graphite/geopolymer composites were systematically investigated by XRD, TG/DTA, DIL, SEM, and TEM. The results show that graphite co-exists with amorphous geopolymer below 900 °C, whereas leucite crystallizes from geopolymer matrix and thus results in graphite/leucite composites in the temperature range of 1000 °C–1400 °C. After being treated at 1500 °C, h -AlN emerges due to the carbon thermal reduction reaction. By further increasing the heating temperature to 1700 °C, h -AlN or SiC with flocculent structures dominate the resulting high-temperature products, depending on the sintering atmosphere. It has been proved that h -AlN is the predominant phase of the resulting products after being treated at 1700 °C in N2 atmosphere. Nevertheless, SiC becomes the dominant one in Ar atmosphere, ceteris paribus. Moreover, both h -AlN and SiC ceramics derived by this technique show porous features, with the porosity of 61% and 68% and considerable compressive strength of 0.76 MPa and 0.63 MPa, respectively.