The fabrication of porous mullite ceramics based on the different sizes of aluminum hydroxide

• Published in: International journal of applied ceramic technology Vol. 19; no. 5; pp. 2675 - 2685
• Main Authors: Shan, Qingliang, Ma, Qian, Lian, Jiawei, Yao, Caiyu, Shui, Anze
• Format: Journal Article
• Language: English
• Published: Malden Wiley Subscription Services, Inc 01.09.2022
• Subjects: Activated sintering; Al(OH)3; Aluminum hydroxide; Aluminum oxide; bending strength; Ceramics; Heat treatment; Mullite; Phase transitions; Physical properties; porous ceramics; Sintering; Sintering (powder metallurgy)
• ISSN: 1546-542X; 1744-7402
• DOI: 10.1111/ijac.14085

In this research, for studying the influence of size and heat treatment temperature of initial Al(OH)3 on the physical properties of porous mullite ceramics, porous mullite ceramics were prepared by in situ reaction sintering of amorphous silica and treated Al(OH)3. The transition phases χ‐Al2O3, к‐Al2O3, and stable phase α‐Al2O3 can be obtained in turn when the treatment temperature of raw Al(OH)3 is 500, 1000, and 1500°C, respectively. The coarser the raw Al(OH)3, the higher the strength of porous mullite ceramics. When the sintering temperature is 1500°C, the bending strengths of PS500‐C, PS1000‐C, and PS1500‐C (PSx‐C represents that the specimen was prepared by the coarse grade Al(OH)3, which was previously treated at x°C) are 40.3 ± 2.1, 54.9 ± 5.2, and 64.8 ± 4.8 MPa, respectively. In addition, although the activated Al2O3 can decrease the formation temperature (∼100°C) of porous mullite ceramics, the strength and density of porous mullite ceramics prepared by activated Al2O3 will decrease at the same sintering temperature. It is believed that the increase of defects and pores during the phase transformation should be responsible for this phenomenon.