Materials Science Forum, Vol.455-456, 230-234, 2004
Porosity assessment of beta-spodumene/glass matrix composites by Small Angle Neutron Scattering
Small Angle Neutron Scattering (SANS) is used to study the microstructure of beta-spodumene/glass matrix composites prepared by sintering of soda-lime glass powder and sol-gel prepared beta-spodumene (LiAlSi2O6) up to 25wt.%. The glass matrix reinforcement with beta-spodumene results in fracture toughness, hardness and thermal shock resistance increasing. SANS allows distinguishing micro-pores inside beta-spodumene agglomerates and large sized pores in the glass matrix that result from incomplete densification during the sintering cycle. It is proved that composites with dispersed phase contents below 15 wt.% are homogeneous, whereas for larger contents, such beta-spodumene particle aggregates are observed inside the glass. Also, for high beta-spodumene contents, e.g. 25wt.%, the crystallisation of anorthoclase in the glass matrix occurs in parallel with the sintering process. Comparison of porosity and total surface area results obtained by SANS proves that the dimensional changes related to such phase transformation result in surplus macro-porosity and cracking, while micro-porosity does not develop.