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首页> 外文期刊>European Journal of Glass Science and Technology, PartB. Physics and Chemistry of Glasses >MAS-NMR study of the crystallisation process of barium fluorphlogopite glass ceramics
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MAS-NMR study of the crystallisation process of barium fluorphlogopite glass ceramics

机译：钡金云母玻璃陶瓷结晶过程的MAS-NMR研究

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Potassium fluorphlogopite glass ceramics are the basis of machinable ceramics.These materials can be machined to shape using tungsten carbide tooling.The crystallisation behaviour of 8SiO_2.YAl_2O_3.3-75MgO.2(center dot)25MgF_2.BaO glasses with Y varying between 1(center dot)5 and 3(center dot)5 were investigated using differential scanning calorimetry(DSC),x-ray diffraction analysis and ~(27)A I,~(29)Si,~(31)P and ~(19)F magic angle spinning nuclear magnetic resonance(MAS-NMR)spectroscopy.The objective being to develop new machinable glass ceramics based on barium fluorphlogopite,BFP(6SiO_2.Al_2O_3.4MgO.2MgF_2.BaO).In the original glasses the ~(27)Al MAS NMR showed the aluminium to be four-coordinated,Al(IV).The ~(19)F spectra indicated the presence of predominantly F-Mg(n)species.The Si spectra indicated the presence of Q3AI type species.None of the spectra of the glasses changed significantly on varying the alumina content.DSC showed the glasses to exhibit two crystallisation peaks,which decreased in temperature with decreasing alumina content.The first peak(Tpl)corresponded to the formation of BFP.The ~(27)Al spectra changed significantly on crystallisation with Al(V)and Al(VI)being detected.The Al(VI)is thought to be present as crystalline mullite and Al(V)in the residual glass.The ~(29)Si spectra of the glasses heat treated to confirmed the presence of BFP.The ~(19)F spectra exhibited a new sharp peak with a similar chemical shift to the original glasses corresponding to F-Mg(3)species in the BFP.It appears that the structure of the glass is similar to that of the primary crystal phase that forms,BFP.
机译：氟金云母钾玻璃陶瓷是可机加工陶瓷的基础，这些材料可以使用碳化钨工具机加工成型.8SiO_2.YAl_2O_3.3-75MgO.2（中心点）25MgF_2.BaO玻璃的Y值在1（使用差示扫描量热法（DSC），x射线衍射分析以及〜（27）AI，〜（29）Si，〜（31）P和〜（19）F研究了中心点5和3（中心点5）魔角旋转核磁共振（MAS-NMR）光谱学。目的是开发基于钡金云母BFP（6SiO_2.Al_2O_3.4MgO.2MgF_2.BaO）的新型可加工玻璃陶瓷。在原始玻璃中使用〜（27）Al MAS NMR显示铝是四配位的Al（IV）。〜（19）F光谱表明主要存在F-Mg（n）物种，Si光谱表明存在Q3AI型物种。玻璃的光谱随氧化铝含量的变化而显着变化。DSC显示玻璃具有两个结晶峰，温度随铝含量的降低而降低。第一个峰（Tpl）与BFP的形成对应。〜（27）Al光谱在检测到Al（V）和Al（VI）结晶后发生了显着变化。被认为是残留的玻璃中的结晶莫来石和Al（V）的形式。经过热处理的玻璃的〜（29）Si光谱证实了BFP的存在。〜（19）F光谱出现了一个新的尖峰BFP中与F-Mg（3）物种对应的原始玻璃具有相似的化学位移。看来玻璃的结构与形成BFP的初晶相相似。

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