| Summary: | 碩士 === 大同大學 === 材料工程學系(所) === 95 === When rice hull burned under 800℃for 3 hours, it become rice hull ash (RHs) and that contained a lot of silica (cristobalite), inorganic substances, and some metallic compound. We try four types of precursors to synthesize calcium silicate by hydrothermal method, which included: (1). RHs-CaO-H2O system, (2). RHs-Ca(OH)2-H2O system, (3). RHs-CaCO3-H2O system, (4). RHs-Industrial CaO-RHs-H2O system. In this research, we find RHs-CaO-H2O system, when products synthesized in molar ratio Ca/Si=0.55 to get Ca14Si24O58(OH)8-H2O and molar ratio Ca/Si=1 to get Ca6Si6O17(OH)2, compared with JCPDS card #29-0382 Ca14Si24O58(OH)8-H2O(truscottite) and JCPDS card #23-0125 Ca6Si6O17(OH)2(xonotlite). In RHs-Ca(OH)2-H2O system, the product were mainly Ca5(Si6O17)(OH)2(tobermorite). And in RHs-IndustrailCaO- H2O system, the mainly products also were Ca6Si6O17(OH)2(xonotlite). And then truscottite, xonotlite and tobermorite calcined under 1000℃ to get wollastonite(CaSiO3). Finally, it is impossible to synthesize hydrated calcium silicates without additives or mineralizer condition in RHs-CaCO3- H20 system.
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