Low-temperature Preparation Of Self-expanding Foamed Ceramic From Ceramic Tile Polishing Waste

As a novel inorganic porous material,foamed ceramic possesses several unique properties,e.g.,lightweight,thermal insulation,water-proof and corrosion resistant,which make it a potential candidate for energy-saving building material and chimney anticorrosion material.However,their industrial applications are limited by their high fabrication costs resulting from the addition of expensive foaming agents and high sintering temperatures(compared to foam glass).In addition,the foaming mechanism of blowing agents still needs to be studied thoroughly.Thus,this paper explores a method for preparing low-temperature self-expanding foamed ceramic from ceramic tile polishing waste(CTPW)and fly ash(FA),and compares the foamed ceramics and traditional walls by using simulation calculation methods.XRD,DTA-TG,TOM-AC,SEM,HSC,Factsage,Energy Plus,and other methods were employed to evaluate the self-expanding foaming mechanism,the influence of CTPW/FA ratio and borax on the structure and performance of the samples,and the energy-saving effects of self-expanding foamed ceramics.The results are as follows.(1)The results of XRD,DTA-TG,and TOM-AC showed that SiC within the CTPW was the self-expanding agent.The Gibbs free energyΔG~θcalculated by HSC suggested that the passive oxidation reaction of SiC leads to the foaming of the samples and that the oxygen transmission rate is the key to controlling the foaming process.(2)Factsage and TOM-AC were used to determine the liquidus temperature,thermal expansion behavior,and viscosity of the samples.Foamed ceramics with different CTPW/FA ratios were prepared at 1175–1275℃.The optimal foamed ceramic obtained by the addition of 75wt%CTPW and 25wt%FA possesses density of 0.66 g/cm~3,compressive strength of8.97 MPa,and porosity of 77.5%.(3)Borax was doped as fluxing agent to reduce the sintering temperatures and its effects on the sintering behavior and thermal expansion of samples were studied.The results shows that borax lowered the sintering temperature and accelerated the passive oxidation of SiC,thus promoting the foaming process.The addition of 18wt%borax reduced the sintering temperature from 1225℃to 925℃.The optimizing performance of foamed ceramic is density,compressive strength,and porosity of 0.55 g/cm~3,7.8 MPa,79.4%,respectively.(4)To evaluate the energy saving effect and application prospect of the optimal sample,the annual/monthly energy consumption of traditional XPS insulation wall material and foamed ceramic material in Moscow,Harbin and other cities were calculated comparatively using Energy Plus software.Compared with that of a traditional wall structure,the annual energy consumption of foamed ceramic walls in Moscow and Harbin was reduced by 6.67%and 8.3%,respectively.The obtained results confirmed that self-expanding foamed ceramic is the potential alternative building material for cold regions.