Lightweight Foamed Ceramics Prepared By Using Polishing Ceramic Tile Waste As Raw Material

Polishing ceramic tile waste is a main kind of ceramic solid waste, which is generatedfrom surface polishing treatment of ceramic tiles. Reusing polishing ceramic tile waste isvery difficult due to its foaming composition. Foamed ceramics with lightweight and heatinsulation are produced by using pure polishing ceramic tile waste as raw material. It can benot only beneficial for saving production cost, but also significant for environmentalprotection and sustainable development of ceramic industry.In this work, the physical and chemical properties of polishing ceramic tile waste areanalyzed, and the optimum formulation for foamed ceramics is explored by orthogonalexperiment method. On this basis, the effects of process parameters on macro andmicroscopic morphology, phase composition, linear expansion rate, relative density, pore sizeand compressive strength are investigated. Moreover, the large sample is produced in factoryand its heat-conducting property is characterized.The XRD patterns indicate that the polishing ceramic tile waste is composed of mulliteand quartz. The polishing ceramic tile waste has an irregular and sharp-edged microstructurewith a size of between0.2and15microns, as shown in SEM images. The DSC-TG resultspresent that there is an endothermic peak at about800°C owing to the oxidation of silicon. Itcan be also seen that the start foaming temperature of foamed ceramics is1130°C observedby the optical thermal instrument.Considering relative density of foamed ceramics fist, the suitable parameters are determinedthrough orthogonal experiment: sintering temperature is1170°C, holding time is20min,heating rate is3°C/min and grinding head addition is2wt%. The larger size foamed ceramicsamples with uniform macrostructures can be made by hand ramming in mold.The changing-single-factor experiment results show that the average pore size and theoverall slump of foamed ceramics will increase significantly with increasing the sinteringtemperature and holding time. There is obvious inverse correlation between compressivestrength and average pore size. The foamed ceramics with2wt%of grinding head additionhas a density of0.28g/cm3when the sintering temperature is1170°C for20min at a heating rate of3°C/min. The main phase of foamed ceramics is quartz, but the content of cordieriteincreases with a higher sintering temperature, longer holding time and more grinding headaddition. Therefore, in order to produce a foamed ceramics with a good uniformity inside, thesuitable parameters are determined as follows: sintering temperature is1160~1220°C,holding time is40~80min, heating rate is0.5~2°C/min, and grinding head addition is2~6wt%.At last, the foamed ceramic samples with a density of0.30g/cm3is produced in thefactory and its heat-conductivity is as low as0.13W/m·K.