DETERMINATION OF TRACE IMPURITIES IN SINTERED ALUMINUM NITRIDE AND BORON-NITRIDE BY PRESSURE ACID DECOMPOSITION ICP-AES

Several decomposition methods were examined to determine impurities in sintered aluminium nitride and boron nitride samples. The pulverized samples were severely contaminated. A lump (about 0.3 g) of sintered aluminum nitride sample was decomposed with 15 ml of hydrochloric acid at 200 degrees C, or 10 mi of sulfuric acid (1+2) at 230 degrees C in a Teflon pressure vessel. Similarly sintered boron nitride samples were decomposed with a mixture of 7.5 mi of hydrofluoric acid and 2.5 mi of hydrochloric acid at 200 degrees C. Several commercial samples were decomposed by the proposed methods, and impurities were determined by ICP-AES.