为了研究一种纯微晶白云石的热分解行为,对分别于700、730、750、1 000、1 200和1 400℃保温3h煅烧后的白云石试样进行了XRD分析、场发射电镜(FESEM)和EDS观察.结果表明:白云石在700℃时部分分解,生成相有方钙石、方镁石、方解石和氢氧化钙；于730℃完全分解,生成相为方钙石、方镁石和方解石；750℃时,方解石分解,最终产物为方钙石、方镁石和少量氢氧化钙；700～1 000℃煅烧后的白云石呈假像结构,由＜70 nm的浑圆粒状团聚体构成；在1 000℃煅烧后的团聚体中可以分辨出方钙石和方镁石微粒的分相形貌,其尺寸为3 ～5 nm；1 200℃煅烧后,白云石假像形貌已完全消失,变为球粒状方镁石和方钙石,其中,方镁石表面光滑,尺寸为0.3～0.4 μm,方钙石表面粗糙,尺寸可达0.5～0.6 μm；1 400℃煅烧后形成的方镁石晶体尺寸为2～5 μm,而方钙石晶体尺寸达十余微米.
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