Crystallization pathways in glass-ceramics by sintering cathode ray tube (CRT) glass with kaolin-based precursors

The crystallization mechanisms for the formation of glass-ceramics by sintering CRT glass with kaolin-based precursors were investigated by quantitatively determining the crystalline and amorphous phases in the products. Amorphization of sintered products was observed in CRT/kaolinite and CRT/mullite glass-ceramics systems at 700-900 °C. With the increase of temperature, the crystallochemical formation of lead feldspar and orthoclase was detected. Orthoclase was found to be the major crystalline phase in both CRT/kaolinite and CRT/mullite systems at 1000-1100 °C. When the temperature increased to 1000-1100 °C, lead feldspar was formed as the only crystalline phase to host Pb. The leaching tests suggested that the glass-ceramic product sintered by CRT/kaolin-based precursors has stronger resistance against acid attack because of the incorporation of lead into lead feldspar crystal protected by glass matrix. The incorporation of CRT glass into glass-ceramics provides a promising strategy for reducing the environmental hazard of CRT glass.