Conversion of a precursor derived from cage-type and cyclic molecular building blocks into Al-Si-N-C ceramic composites

A precursor derived from (HAlNⁱPr)_m and [MeSi(H)NH]_n, which mainly consisted of cage-type compounds and cyclic compounds, respectively, was converted into Al-Si-N-C ceramic composites via pyrolysis. A dehydrocoupling reaction between AlH groups and NH groups occurred at low temperatures (≤ ∼ 250°C), which mainly accounts for its high ceramic yield (69% up to 900°C). At high temperatures (≥ ∼ 250°C), the organic groups were decomposed. The product pyrolyzed at 1350° and 1500°C under Ar contained a 2H wurtzite-type compound and a β-Si₃N₄-type compound, while β-SiC was clearly detected in addition to these compounds in the product pyrolyzed at 1600°C under Ar. On the other hand, the product pyrolyzed at 800°C under NH₃ and subsequently at 1350°C under N₂ consisted of AlN and β-Sialon.