Quantitative Estimation of Crystalline Phases of CordieriteMullite
Based Kiln Furniture by X-ray Diffraction Method |
SUJATA MAZUMDAR, B. MUKHERJEE AND M. K. BASU
Pages : 159-162
DOI : 10.1080/0371750X.1993.10804595 |
Abstract |
Thermal endurance of ceramics as refractory support is
closely related to the crystalline phases present. In the
alumino-silicate refractory family, cordierite-mullite system,
produced by using commercially available raw materials,
offers an attractive proposition up to a temperature
range of l280°C. Cordierite body formed in situ with high
expansion grog as additives contains the following crystalline
phases : (i) cordierite; (ii) mullite; (iii) a -AI20 3; (iv)
cristobalite and (v) quartz. Of these, only the first three
phases are relevant in enhancing the life cycle of kiln furniture
vis-a-vis their thermal endurance. Hence a quantitative
phase analysis is necessary to predict the life of kiln
furniture and improve upon their performance. The
present method of quantitative phase analysis is applicable
where the crystal structure of the component phase whose
proportionate analysis in a phase mixture is required, is
known. Simulated intensity patterns based on the crystallographic
data, viz. space group symmetry, lattice parameters,
positional coordinates of various atoms and their occupancy
factors, crystal density etc, were prepared for each
reflection zone. Relevant computer programmes were developed
at CGCRI. The intensity data collected in different
28 zones were used for finding the volume concentrations of
different phases. The error in quantitative estimation of
phases was nearly 6% when the diffraction data were taken
using monochromatic X-radiation. The chemical analysis
corroborates this result. The materials contained a certain
amount of glassy phase. Assuming that the glassy phase was
composed mainly of silica glass along with other impurities,
the result showed that only 85% of the total phase was
crystalline and the remaining part was amorphous. |
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