Preparation of foamed glasses from CRT TV glass by means of hydrothermal hot-pressing technique

The feasibility to prepare foamed glass specimens by using waste TV monitor (panel) glass as starting material under hydrothermal hot-pressing (HHP) conditions, followed by a conventional heating of the compact, was investigated. Hydrothermally hot pressed glass compacts were preliminarily prepared at a constant temperature of 200 °C, with a loading pressure of 20 MPa and two different water contents (5 and 10 wt%), for reaction intervals between 0.5 and 2 h, employing a glass particle size <38 μm. After the powder densification stage, firing of the compacted disk glass was conducted over a temperature range of 650–850 °C for 1 h. Microstructural observations conducted by SEM showed the formation of a new glass phase which incorporates water, this phase was formed during the glass densification stage at 200 °C for 2 h, with a water content of 10 wt%. The lowest apparent density achieved on these glass compacts heated at 700 °C for 1 h was 0.36 g/cm3. This value is similar to that of other foamed glasses that have close cell network and low thermal conductivity (0.0021 W/cm/°C).