Decomposition of solid alumina in the presence of carbon in vacuum

Abstract

The decomposition of solid Al2O3 in the presence of C was researched at 1873 K–2073 K in vacuum, using α-Al2O3 powders as the raw materials and the graphite crucible as C source. There was no direct contact between the Al2O3 and the C. The results showed that the Al2O3 decomposed into gaseous species, and the C making up the graphite crucible was reacted to form CO. The coupled reaction was proposed: Al2O3 decomposed into gaseous Al-containing species (mainly Al and Al2O) and O2, and then C reacted with O2 to form CO to maintain low O2 partial pressure, making the decomposition of solid Al2O3 in vacuum possible. With a decrease in temperature, the gaseous products Al, Al2O and CO formed the condensates containing a lot of fibrous materials. The condensates mainly consisted of Al4O4C, Al4C3, Al2O3 and Al, and the content of Al4O4C was the highest.