Phase analysis program for magnesia refractories
- CSIRO, Port Melbourne (Australia). Div. of Mineral Products
Dead-burned magnesia is one of the major raw materials used in the manufacture of refractories that does not melt below 2,500 C. The MgO content, in itself, is not the only factor that is industrially important. Impurity levels are equally important and can affect the slag resistance and high-melting-point properties of the product caused by the formation of low-melting phases, such as monticellite (CMS, CaMgSiO{sub 4} or CaO{center_dot}MgO{center_dot}SiO{sub 2}), merwinite (C{sub 3}MS{sub 2}, Ca{sub 3}Mg(SiO{sub 4}){sub 2} or 3CaO{center_dot}MgO{center_dot}SiO{sub 2}) and bredigite (C{sub 7}MS{sub 4}, Ca{sub 7}Mg(SiO{sub 4}){sub 4} or CaO{center_dot}MgO{center_dot}4SiO{sub 2}). The presence and proportion of these phases are critical, but chemical analysis cannot presently yield such information. CSIRO Division of Mineral Products researchers use the Rietveld method of phase analysis to determine the abundance of individual phase components of various materials, including magnesia refractories. However, for magnesia refractories, the accuracy of the Rietveld results has not yet been tested against an alternative method. The determination of phase abundance by point-counting techniques is a difficult, if not impossible, task. A procedure for calculating the phase compositions from chemical data--such as the Bogue method used in the cement industry--has not been developed yet. This article describes such a method that is called MAGNORM. MAGNORM calculates normative phase compositions of magnesia refractories from their bulk chemical analyses. Its advantages are the speed that results can be produced from predetermined chemical analysis, the low cost to produce them and consistency. The same rules and assumptions apply to all calculations, allowing more meaningful comparison between samples.
- OSTI ID:
- 27961
- Journal Information:
- American Ceramic Society Bulletin, Vol. 74, Issue 2; Other Information: PBD: Feb 1995
- Country of Publication:
- United States
- Language:
- English
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