摘要
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3 h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0.3～0.4μm,方钙石表面粗糙,尺寸可达0.5～0.6μm;1 400℃煅烧后形成的方镁石晶体尺寸为2～5μm,而方钙石晶体尺寸达十余微米。
The dolomite specimens after firing at 700,730,750,1 000,1 200 and 1 400 for 3 h,respectively, were analyzed by XRD,FESEM and EDS in order to research thermal decomposition behavior of the pure microcrystalline dolomite. The results show that：the dolomite decomposes partly at 700 ℃ forming calcia, periclase,calcite and portlandite （ Ca（OH）2 ）, and decomposes completely forming calcia, periclase and calcite at 730℃;at 750 ℃ the calcite decomposes into calcia, periclase and a small amount of portlandite; at 700-1 000℃ the dolomite exhibits a pseudo-morphology structure composed of clusters of round grains smaller than 70 nm;at 1 000 ℃ the morphologies of calcia and periclase microparticles can be distinguished in the clusters and their sizes are about 3-5 nm;the pseudo-morphology of dolomite disappears completely at 1 200 ℃,forming round periclase and calcia grains, and the periclase has smooth surface with size of 0.3-0.4 μm and the calcia has rough surfaces with size of 0.5-0.6 μm ;the size of periclase crystal increases to 2-5 μm and that of calcia crystal is over 10 lam at 1 400 ℃.
出处
《耐火材料》
CAS
北大核心
2013年第1期19-23,共5页
Refractories
关键词
白云石
等温分解
白云石假像
纳米晶体形貌
dolomite isothermal decomposition dolomite pseudo-morphology
morphology of nano-sizedcrystal
