Abstract
Sintered glass-ceramics based on cordierite modified glass with partial substitution of aluminum by boron [(Mg2Al4-xBxSi5O18 (x = 1 and 3)] were prepared mainly from natural raw materials. Mono-mineralic cordierite was formed at all the sintering temperatures. The results of infrared spectra confirmed the cordierite presence. The microcrystalline structure shows scattered hexagonal cordierite crystals, either at the micro- or nano-scale, in a glassy groundmass. The microanalysis of the hexagonal crystals indicated the incorporation of some elements in the cordierite structure. The density of the sintered samples was 2.0857 and 1.4857 g/cm (3) and the coefficient of thermal expansion, from room temperature up to 500 C-ay, was in the range from 10.46 and 25.60 x 10(-7) (ay) C (-1). The microhardness value was 5.64 GPa and 5.90 GPa.