WANG Zixin ¹, HUA Kaihui ¹, OUYANG Zhen ¹, YAO Liming ², CHEN Weijie ¹, SU Wenzheng ¹
(1. School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China; 2. School of Material Science and Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China)

Abstract:  Mullite whisker-reinforced porous ceramics were in-situ prepared with construction waste as the main raw material, Al₂O₃ as the aluminum source, AlF₃ as the whisker catalyst, B₂O₃ as the sintering aid, and activated carbon and corn starch as the pore former. The effects of the type and content of the pore formers on structure and properties of the porous ceramics, such as open porosity (Hereinafter referred to as porosity), flexural strength and cross-sectional morphology, were studied in detail. The effects of sintering temperature on structure, properties and sound absorption behavior of the porous ceramics were also analyzed. The addition of activated carbon and corn starch as pore-forming agents could increase the porosity of the samples, while the in-situ whiskers enhanced the flexural strength of the ceramics. The porous sound-absorbing ceramics consisting of 41 wt.% construction waste, 45 wt.% alumina, 12 wt.% aluminum fluoride, 2 wt.% boron oxide, 6 wt.% activated carbon and 5 wt.% corn starch exhibited the highest performance, together with porosity of 64.62% and flexural strength of 6.85 MPa. The samples sintered at 1100 °C had the maximum sound absorption coefficient of 0.61 at the sonic frequency of 1250 Hz, while the one sintered at 1200 °C had a sound frequency of 0.42 at the sonic frequency of 1600 Hz. The maximum sound absorption coefficient was 0.42 at 1600 Hz.
Key words:  construction waste; mullite whisker; porous ceramics; pore former; sound absorption