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The effect of hydrothermal hot-pressing parameters on the fabrication of porous ceramics using waste glass

2004; IOP Publishing; Volume: 16; Issue: 14 Linguagem: Inglês

10.1088/0953-8984/16/14/049

1361-648X

Z. Matamoros-Veloza, Kazumichi Yanagisawa, J.C. Rendón-Ángeles, Shuji Oishi,

Nuclear materials and radiation effects

The effect of varying hydrothermal hot-pressing (HHP) parameters on the expansion of waste glass powder was investigated by conventional heat treatment. Glass ceramic porous materials were prepared by hydrothermal hot pressing under standard conditions at 200 °C, for 2 h at a constant uniaxial pressure of 20 MPa, while varying experimental variables such as glass particle size, water content, reaction interval, temperature and heating rate. SEM investigation showed the presence of a new glass phase, which incorporated water in its structure. The degree of reactivity attainable between glass particles and water seems to control the expansion process during heating of HHP glass compacts. It was found that the expansion process is independent of experimental parameters such as reaction time, temperature and heating rate, but does depend on the particle size and water content. During the heat treatment, the glass foaming process was preceded by decomposition of the new glass phase in the HHP compacts. A minimum apparent density of 0.40 g cm−3 was obtained on specimens prepared with low water content (5 wt%) and medium particle size (39–45 µm). X-ray diffraction patterns of the expanded glasses revealed the formation of SiO2 (α-cristobalite and quartz) and CaSiO3 (wollastonite).