无水硫酸镁对氧化镁水热产物的影响  

Effects of Anhydrous Magnesium Sulfate on Magnesium Oxide Hydrothermal Products

作　　者：白丽梅 孙志雅 祝洪武 马玉新 

机构地区：[1]华北理工大学矿业工程学院,唐山063009

出　　处：《硅酸盐通报》2017年第11期3595-3600,共6页Bulletin of the Chinese Ceramic Society

基　　金：国家自然科学基金(51504078);河北省自然科学基金(E2015209210)

摘　　要：以轻烧菱镁矿获得的氧化镁为原料,在温度为160℃、搅拌速度为400 r/min的条件下反应,研究无水硫酸镁对氧化镁水热产物的影响。当MgO与MgSO_4的摩尔比为10∶1时,反应6 h的水热产物是纯度高、结晶度好的六方片状氢氧化镁;当MgO与MgSO_4的摩尔比为2.5∶1时,前3 h水热产物是六方片状氢氧化镁,随后出现碱式硫酸镁晶须并且其生成量越来越多;当MgO与MgSO_4的摩尔比为10∶7时,前50 min水热产物是六方片状氢氧化镁,然后出现碱式硫酸镁晶须,直至6 h全部生成直径约为300 nm、表面光滑的碱式硫酸镁晶须。在此过程中,小颗粒氢氧化镁出现溶解现象,形成碱式硫酸镁晶核,大颗粒氢氧化镁与溶液中的MgSO_4、H_2O生成大量MgSO_4·5Mg(OH)_2·3H_2O(153型碱式硫酸镁),在其生长方向上生长基元Mg-O_6进入由于螺旋位错形成的二维台阶的凹陷处促使其沿位错方向稳定生长为晶须。无水硫酸镁的浓度越大,生成碱式硫酸镁晶须越多,生成碱式硫酸镁晶须所用时间越短。Active magnesium oxide prepared from low-temperature calcination of magnesite was used as raw material,and in order to study the effects of anhydrous magnesium sulfate on magnesium oxide hydrothermal products,we conducted this experiment under 160 ℃ of hydrothermal synthesis temperature and 400 r/min of stirring speed. When the molar ratio of magnesium oxide and magnesium sulfate is 10∶1,hydrothermal product after six hours was hexagonal flake magnesium hydroxide with high purity and good crystallinity. When the molar ratio of magnesium oxide and magnesium sulfate is 2. 5 ∶ 1,hydrothermal product in the first three hours was hexagonal flake magnesium hydroxide,and with the increase of time,there was more and more basic magnesium sulfate whisker appeared. When the molar ratio of magnesium oxide and magnesium sulfate is 10 ∶ 7,hydrothermal product in the first 50 min was hexagonal flake magnesium hydroxide,then small particles dissolved and formed crystal nucleus of basic magnesium sulfate,while large particles of hexagonal flake magnesium hydroxide formed MgSO_4·5Mg（OH）_2·3H_2O together with MgSO_4 and H_2O. The growth unit Mg-O_6 entered into the sunken of twodimensional steps formed because of screw dislocation in the growth direction,which prompted the stable growth of whisker along the screw dislocation direction. With the increase of anhydrous magnesium sulfateconcentration,there was more and more basic magnesium sulfate whisker in the product,and it would be a short time to form basic magnesium sulfate whisker.

关 键 词：氧化镁 水热 溶解结晶 螺旋位错 

分 类 号：TB321[一般工业技术—材料科学与工程]