The Phase Analysis of Altered Refractory Fibre Using Phase-Contrast Microscopy and X-Ray Diffractometry

The reproducible identification and quantification of altered ceramic fibres is very important for evaluating and assessing the concentration of hazardous substances in the workplace. The development of a combined method, including phase-contrast microscopy and X-ray diffraction analysis, for the quantitative phase analysis of ceramic fibres and especially for the determination of cristobalite, is reported. The application of phase-contrast microscopy enables cristobalite to be identified optically and its concentration estimated. Changes in texture and surface structure caused by the formation of crystalline phases can also be observed. X-ray diffraction methods permit an exact quantification of cristobalite in altered ceramic fibres. X-ray examination of heat-treated ceramic fibres shows that experimentally- and industrially-altered fibres have distinctive high degrees of cristobalite stacking disorder and the amount of cristobalite can be determined with a profile-fitting program. For the X-ray phase analysis method developed for cristobalite a root mean squared error of 4.4% with a detection limit of 0.3% can be given.