Abstract
The relation between the atomic structure and the macroscopic properties and behaviors of a material constitute one of the objectives of the materials science, particularly in the design and development of ceramic materials.Crystalline and non crystalline phases together with pores, grain boundaries, etc. affect mechanical and fracture properties as well as chemical resistance and electric properties. These aspects will be bonded to the raw materials chosen and the whole processing route.In glass industry, although there are other electrofused refractories such as the alumina ones used in the feeding of the fusion kilns, probably the most used refractories in contact with the melted glass are electrofused materials that belong to the Al2O3-SiO2-ZrO2 system commonly named AZS.Exceptionally for refractory materials the amount of the glassy phase in a AZS material is important and appreciable; and makes them particularly adequate for containing fussed glass. The glass proportion will define much of their properties and behaviors.In the present work the results of the non crystalline phase quantification of two samples of commercial AZS materials are presented and compared. These were obtained by three different methods using in the X ray powder diffraction (XRD) techniques. The first method consists in the linear interpolation of the base lines of the diffractograms compared to the amorphous silica and the fully crystalline quartz. The other two methods are based in the application of the Rietveld method. One is the internal standard method with quartz as fully crystalline standard and the other one consist in the inclusion of the glassy phase to the refinement with a structural model that can be understood as the widening of the peaks consequence of an extreme decrease in the crystallite size of a quartz phase.The three methods showed equivalent results (with differences less than 3%) for the two samples and demonstrated that are adequate for the quantification of the non crystalline phase in this kind of materials.
Highlights
There are other electrofused refractories such as the alumina ones used in the feeding of the fusion kilns, probably the most used refractories in contact with the melted glass are electrofused materials that belong to the Al2O3-SiO2-ZrO2 system commonly named AZS
In the present work the results of the non crystalline phase quantification of two samples of commercial AZS materials are presented and compared. These were obtained by three different methods using in the X ray powder diffraction (XRD) techniques
This equation commonly utilized for determining crystallinity in vitro-ceramic materials in a wide range of proportions [8,9], it could be valid to assume that the amorphous or non crystalline (NCO%) proportion can be obtained from the following equation defining NCOh% as a complement of the crystallinity (NC% + C% = 100)
Summary
There are other electrofused refractories such as the alumina ones used in the feeding of the fusion kilns, probably the most used refractories in contact with the melted glass are electrofused materials that belong to the Al2O3-SiO2-ZrO2 system commonly named AZS. Where Ig, I m y Ic are the diffractogram intensities at 2θ = 22.5°C corresponding to a sample 100% glass (amorphous silica), the partially crystalline phase (problem sample) and the 100% crystalline standard (quartz) respectively This equation commonly utilized for determining crystallinity in vitro-ceramic materials in a wide range of proportions [8,9], it could be valid to assume that the amorphous or non crystalline (NCO%) proportion can be obtained from the following equation defining NCOh% as a complement of the crystallinity (NC% + C% = 100). In the Rietveld analysis, the crystalline structure of each phase in the sample should be known This method does not allow including the amorphous or non-crystalline phases. In the present work the results of the non crystalline phase quantification of two samples of commercial AZS materials are presented and compared These were obtained by three different methods based in the X ray powder diffraction (XRD). The Le Bail model based method was applied with the amorphous phase incorporated as a nanocrystalline material with a ß-Carnegieite structure
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