Novel mullite synthesis based on alumina nanoparticles and a preceramic polymer

Heating in air of a selected mixture of a silicone resin and alumina nanoparticles in the temperature range 1200 degrees-1500 degrees C yielded dense, crack-free mullite samples. Al2O3, due to its nanometric size, proved to be very reactive toward silica, deriving from the ceramization of the preceramic polymer, leading to the formation of a large volume fraction of mullite crystals even at low firing temperatures (1250 degrees C). Because of the homogeneity of the distribution of alumina nanoparticles in the starting system, the ceramized samples exhibited a very fine microstructure consisting of crystals with an average dimension in the range of 50-300 nm.