Determination of components in alumina - chrome refractories by X-ray fluorescence spectrometry using glass beads

The chemical components in alumina-chrome (AC) refractories were determined by X-ray fluorescence spectrometry (XRF) using glass beads (GB). AC refrac tories which contain much Cr2O3 can not be fused with only Li2B4O7 Thus, Li NO3 must be added as an oxidizing agent. The fusing conditions for the GB w ere chosen as follows: sample (0.2000 g)-Li2B4O7 (3.0000 g) LiNO3 (3.000 g) , 1250 degreesC-10 min. Complete fusion of the Cr-containing sample was sus pected to have been proceeded by the formation of Cr-4(2-), caused by the o xidation of Cr(III), converting it to Cr(VI). This possibility was investig ated by the CrK-edge X-ray absorption near-edge structure (XANES) spectra. According to preliminary results of Cr(VI) by XANES, the Cr(VI) content in a GB prepared with only Li2B4O7 was merely 7% against the total Cr, but in the GB with Li2B4O7 and LiNO3 it was 39%. Moreover, the Cr(VI) content in t he GB with Na2B4O7 and NaNO3, which could be easily fused, but could not be used for actual analysis, because of the contain Na2O content, was 95%. Th e GBs used for the calibration curve were prepared by accurately weighing a lumina system reference materials and reagent Cr2O3 On a micro-balance of 1 mug accuracy limit and fusing them with Li2B4O7 and LiNO3. As a result, th e accuracies (SD) of the calibration curves prepared with these GBs were ve ry satisfactory for Al2O3: 0.21 mass%, Cr2O3: 0.07 mass %, SiO2: 0.027 mass % and so on.