Mechanochemical Activation of Mixtures for Low-Melting Glasses Production

Mechanochemical activation in high-energy devices (micronizers) as a way of giving mechanical energy to solid-state materials has become very popular. During the mechanochemical activation various structural changes of material and at the same time changes of its properties (chemical, electrical, thermal, mechanical etc.), as well as reactivity increase are taking place. Whereas numerous chemical reactions are happening during the glass production, investigating of the influence of previous mechanochemical treatment on those reactions and on the glass production at once is very attractive. Because of the great interest for low-melting glasses, PbO-B2O3-SiO2 system, with following chemical composition: 40 mol% (69,4 wt%) of PbO, 34 % (18,4 wt%) of B2O3 and 26 mol % (12,2 wt%) of SiO2 was chosen for investigation in this research. In the experimental work, minium (Pb3O4), boric acid (H3BO3) and quartz sand (SiO2) were used as raw materials for preparation of glass mixtures. Five glass mixtures were prepared. Mechanochemical activation was a realized in high-energy vibro mill with rings. Following times of mechanical activation were used: 7 min., 14 min., 28 min., and 49 min. The referent, non-activated glass mixture and four mechanochemically activated glass mixtures were subjected to differential thermal analysis (DTA). Applied method for the quantification of mechanochemical activation results showed that the effects of mechanochemical activation on the properties of glass mixtures for obtaining low-melting glasses were considerable. Mechanochemical activation had a significant influence on temperature changes in the investigated system, during heating. Differential thermal analysis showed the existence of qualitative changes in thermal properties of prepared glass mixtures depending on the time period.