Optimization of milling condition in a planetary mill and effect of particle size distribution on sintering of a Li2O.Al2O3.SiO2 (LAS) glass

摘要

The optimization of the milling conditions is important for the sintering of glasses, since it allows the obtaining of powders in short intervals of time, with less tendency to the superficial crystallization and consequent greater sinterability. In this work, the high-energy milling conditions were investigated to obtain vitreous powders with an average particle size under 5 μm, using a planetary mill. The diameter of the milling media was varied in order to obtain fine particles in the shortest possible time, also the dry and wet milling were compared. The sintering of a glass from the Li2O.Al2O3.SiO2 (LAS) system was performed, using the powders obtained under the optimum milling conditions. This glass was used due its high surface crystallization tendency. The milling time of 60 min and 90 min showed an average particle size of about 5 μm and 3 μm, respectively. The obtained glass-ceramics showed pore fraction below 5%. Milling with longer times ( 200 minutes) led to very low average particle size (0.70-0.80 μm), however these powders did not presented high densification. Wet milling using isopropyl alcohol was extremely damaging for LAS sintering, leading to a glass-ceramic with a pore fraction of 20 ?± 1%. We demonstrated that to favor the sintering of vitreous powders, which have a high tendency to surface crystallization, it is recommended to use dry high-energy milling and milling times up to 90 minutes.