DETERMINATION OF IMPURITIES IN TITANIUM DIBORIDE BY ACID DECOMPOSITION ICP-AES

In order to determine impurities in titanium diboride by ICP-AES, a sample dissolution procedure using acids was examined. A 0.25 g titanium diboride powder sample was taken in a 100 ml quartz beaker and 10 ml of sulfuric acid (1 + 1) was added. After covering with a quartz watch-glass, 2 ml of a mixture of nitric acid and hydrogen peroxide solution was added dropwise, and the beaker was left to stand with only occasional swirling at room temperature. After the reaction was completed, the mixture was boiled for several minutes on a sand bath, and further heated until sulfur trioxide fumes appeared after removing the watch-glass. After cooling, 20 to 30 ml of distilled water was added, and the mixture was filtered. The small amount of residue on the filter-paper was ashed in a platinum crucible, and transferred into a Teflon pressure vessel with 3 ml of sulfuric acid (1 + 1), 1 ml of nitric acid and 2 ml of hydrofluoric acid (1 + 9). The capped vessel was kept at 180 degrees C for 16 h in a drying oven to dissolve the ashed residue. The filtrate and the residue solution were collected in a 100 ml calibrated flask and diluted to the mark with distilled water, followed by ICP-AES measurement. For most elements, the values obtained by the proposed method were in good agreement with those obtained by the fusion method with sodium carbonate.