| Due to the problems existing in the practical application of wall thermal insulation material and high value-added use of coal gangue, this paper synthesized a eco-friendly type of thermal insulation foam ceramic brick with 90wt% coal gangue content which can theoretically provide heat energy ranging from 1/6 to 1/3 and have high thermal and acoustic insulation, high durability, high strength and low density based on the characteristics of chemical composition of coal gangue by powder compact foaming process. This paper also studied relations between chemical compositions of body, grinding process and firing process and properties of foam ceramic. The chemical composition analysis was conducted by X-ray fluorescence(XRF), the phase analysis by X-ray diffraction(XRD), the particle size analysis by LPS diffraction, the micro-structure analysis by scanning electron microcopy(SEM) and the thermal analysis by TG-DSC. Investigation on the mechanism of foam ceramic and its influencing factors was also conducted.The chemical composition of ceramic body was designed in the first place, and we investigated the relationship between Fe2O3, MgO, Al2O3, foaming agent and the performance of foam ceramic and its mechanism. The results showed that in the condition of high temperature Fe2O3 can decompose and produce oxygen and Fe2+, adjusting the gas-producing rate of foaming agent and decreasing the liquid-producing temperature, therefore, Fe2O3 has the effect of fluxing, widening the sintering temperature range and improving the pore structure, so does MgO. Al2O3 can improve mechanical properties of material by stabilizing foams and increasing the content of solid phase. Foam ceramic with uniform pores can be developed when the ceramic body contains 0.1wt% compound foaming agent. Experiments indicated the appropriate content of compound foaming agent ranged from 0.3wt% to 2.0 wt%, but too much compound foaming agent content can lead to deterioration of pore structure and properties of foam ceramic.The correlation between grinding process and properties of foam ceramic was studied in this paper. And we discussed the effect of grinding additive and grinding time on ceramic body particle size and properties of foam ceramic. The results showed that grinding additive and grinding time can affect the mixing uniformity of raw material, creamic body fineness and particle size distribution, and therefore influence the pore structure and properties of foam ceramic. The foam ceramic developed through technique of wet grinding is similar in pore structure and property with that made by dry grinding technique with 0.035% triethanolamine additive. However, wet grinding process is to be replaced by triethanolaminedry grinding technique because of its complicated process, high energy consumption and long preparation cycle.Finally, the relation between firing process and properties of foam ceramic was investigated. And under the method of single factor variation, effect on foam ceramic properties of sintering temperature and holding time was examined. The results show that sintering temperature and holding time had a notably significant effect on the pore structure and compressive strength of foam ceramic, but had a trivial effect on the water absorption rate. We can get full bubble growth and more uniform pore size distribution and decrease the apparent density and water absorption rate. But too high sintering temperature or too long holding time can destroy the pore structure and produce communication hole and the "cell window", leading to the increase of apparent density and water absorption rate.In addition, this paper represented the correlation between different properties of foam ceramic: properties of foam ceramic were mainly affected by the pore structure and apparent density. |
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