叶蜡石加热相变特征的X射线粉晶衍射分析

X -RAY POWDER DIFFRACTION ANALYSIS ON CHARACTERISTICS OF HEATING PHASE TRANSFORMATION OF PYROPHYLLITE

对叶蜡石经不同温度加热处理产物的物相特征进行了较系统的Ｘ射线粉晶衍射分析，发现叶蜡石的加热相变过程具有明显的阶段性．根据主要物相及其变化和组合特征，从室温到熔点（１７１０℃左右）一般可划分为７个演化阶段，即叶蜡石阶段（室温—５００℃），叶蜡石Ⅰ脱水阶段（５００—８００℃），叶蜡石Ⅱ脱水阶段（８００—９６０℃），偏叶蜡石阶段（９６０—１１５０℃），不定形ＳｉＯ２与莫来石初晶形成阶段（１１５０—１３００℃），方石英与莫来石并存阶段（１３００—１５９０℃），莫来石阶段（１５９０—１７１０℃）．

Based on the X -ray power diffraction analysis for the characteristics of heating phase transformation of pyrophyllite, it is discovered that the phase transformation of pyrophyllite carries out stage by stage during heating . According to the major phases and their assemblage, seven stages can be devided between indoor temperature to melting point (about 1710℃),i. e., the pyrophyllite stage (room temperature—500 ℃), pyrophyllite I dehydration stage (500—800 ℃),pyrophyllite Ⅱ dehydration stage (800—960 ℃),pyrophyllite anhydride stage (960? ? 150 ℃ ),amorphous SiO 2 and mullite crystallite forming stage (1 150—1 300 ℃),coexistence stage of cristobalite and mullite (1 300—1 590 ℃), and mullite stage (1 590—1 710 ℃).