Preparation And Properties Of The Foam Ceramics Based On Ceramic Tile Polishing Waste With Additive Method

In recent years,the output of ceramic tile polishing waste increases by years,so the resource utilization of ceramic tile polishing waste has become an urgent problem.In the process of producing ceramic tiles,the ceramic tile polishing waste usually contains about 1⁵wt%silicon carbide?SiC?that derived from polishing tools.The SiC will react with oxygen and release gases such as CO and CO₂,and the generation of gas will hinder the process of firing densification in the production of ceramic tiles.Besides,the utilization rate of the ceramic tile polishing waste is very low under this condition.However,it is possible to use the characteristics to prepare porous foamed ceramics by using ceramic tile polishing waste as raw materials.At present,foam ceramic is one of the most promising building insulation materials for its excellent advantages of chemically stable,low density,long-time stable in physical characteristics and low thermal conductivity.In this study,heat insulation foam ceramics were prepared by ceramic tile polishing waste.Based on the analysis of the physical and chemical properties of ceramic tile polishing waste,the effects of firing temperature,holding time and heating rate on the ceramic tile polishing waste were studied.The results indicated that the ceramic tile polishing waste mainly consisted of quartz phase and amorphous phase,a small amount of SiC and magnesium chloride hydroxide hydrate exist in ceramic tile polishing waste,and the SiC is main foaming substance in the ceramic tile polishing waste.The samples based on the ceramic tile polishing waste had a good pore structure at a firing temperature of 1200°C,a holding time of 30 to 45 min,and a heating rate of 3⁵°C/min.Besides,in order to obtain the foam ceramic with low bulk density,the foaming agent SiC was introduced into the ceramic tile polishing waste.The results showed that after adding SiC,the pore distribution in the foam ceramic were not uniform and the pore sizes in large differences which led to poor performance of the ceramic materials.On this basis,the foam ceramics were prepared by using the ceramic tile polishing waste as main raw material,using the SiC inside the ceramic tile polishing waste as foaming agent,and introducing the ammonium molybdate,sodium phosphate and borax as additives.The introduction of additives could improve the utilization of ceramic tile polishing waste.Furthermore,the effects of the amounts of additions and firing temperature on the phase composition,bulk density,microstructure,pore sizes,thermal conductivity,mechanical properties and thermal conductivity of the foam ceramics were investigated in detail.The results showed that the samples had a better pore structure and lower bulk density via adding additives.The optimum firing temperature of the three additives was 1200°C,and the optimum additive amount were 2 wt%.The sample with adding ammonium molybdate had highest strength,but the sample with adding borax had lowest strength.Among three additives,ammonium molybdate had the best promotion effect on the firing process of foam ceramics.Low-density,high-strength,uniform pore structure,lightweight and thermal insulation foam ceramics were successfully prepared by using ammonium molybdate.The samples that doped with 2 wt%?NH₄?₆Mo₇O₂₄ and fired at 1200oC showed excellent properties:a lowest bulk density?0.362 g/cm³?,smallest thermal conductivity?0.122 W/m·K?,a highest flexural strength?8.16 MPa?.In this study,the uniformity pore structure and aperture of lightweight and thermal insulation foam ceramics innovatively prepared by using the ceramic tile polishing waste as raw material,using SiC inside the ceramic tile polishing waste as a foaming agent,and introducing ammonium molybdate,sodium phosphate,borax as additives.It provides an effective and practical way for the resource utilization of ceramic tile polishing waste,and has important social and economic significance.