EVOLUTION OF CARBON DURING BURNOUT AND SINTERING OF TAPE-CAST ALUMINUM NITRIDE

The surface nature and the composition of AlN powder, as-received and exposed to binder burnout, were studied using XPS and TEM. The surface of as-received AlN powder was covered by a thin layer of aluminum oxy nitride and oxide mixture. A small portion of residual carbon from bin der burnout was bound to oxygen atoms on the AlN powder surface, and t he majority of the carbon was amorphous graphitoid carbon which covere d the AlN powder surface uniformly. AlN samples were made using tape c asting and pressureless sintering. Surface-carbon-to-oxygen ratio of A IN powder after binder burnout was evaluated using XPS. The surface C/ O atomic ratios were observed to correlate with the sintering behavior , the composition of the second phase, the second phases distribution, and grain-boundary composition, as well as thermal conductivity of Al N samples.