THERMOGRAVIMETRIC STUDY OF YTTRIUM ISOPROPOXIDE AND DISPERSANT BURNOUT IN ALUMINUM NITRIDE CERAMIC PROCESSING

Yttrium isopropoxide, an yttrium oxide precursor, is sometimes used as a sintering aid for producing aluminum nitride ceramics. In the prese nt work, this sintering aid was used with isopropanol as the solvent a nd polyethyleneimine as the dispersing agent. After initial ball milli ng and drying steps, the burnout behaviour of samples taken from isost atically pressed pellets was studied by thermal analysis in nitrogen a nd air. In addition to the milled and pressed pellets, each component was also analyzed separately. Complete conversion to yttrium oxide, wi th no residual carbon, would be a desirable property of this system. H owever, during the preparation of the aluminum nitride pellet, there w as only partial yttrium isopropoxide decomposition. The nitrogen burno ut residue contained carbon formed from the yttrium isopropoxide and d ispersant overlapping thermal decomposition, mostly from an intermedia ry decomposition stage of the former that occurs between 300 and 550-d egrees-C. The residual carbon content and the previous yttrium isoprop oxide decomposition were estimated by thermogravimetry.