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The magnesia-phosphate reaction was used to develop a cold-setting refractory castable. A cement paste based on alumina, silica fume, magnesia and ammonium dihydrogen phosphate (NH4H2PO4) was designed to form cordierite during heating. This paste plus cordierite-mullite aggregates (scrap refractory material) was cast in steel molds. The coldsetting concrete obtained was thermally treated and the phases evolution was observed. Struvite (NH4MgPO4·6H2O) was detected at room temperature by XRD. At 1350 °C the main crystalline phases were cordierite and mullite. The cold flexural strength at different temperatures, the modulus of rupture at 1200 °C and the thermal shock resistance were measured. Physical properties as density, porosity and thermal expansion of the castable at 1350°C were also analyzed.
Plaster samples containing different amounts of portlandite and sepiolite were prepared, in order to analyze the vapor absorption/desorption characteristics. The comparison among the samples has shown that the materials containing higher amounts of sepiolite exhibit higher levels of absorbed vapor. The vapor adsorption/desorption sites seem to be rather meso- and micro-pores, than macro pores. The carbonation treatment appears to have a significant influence on the amount of absorbed vapor, and a negligible effect on the vapor adsorption/desorption feature.
The possibility to recycle waste materials in ceramic products, nowadays a topic research, is advantageous both for the environmental safety and for the ceramic industry. This paper reviews several studies, regarding the production of heavy clay products, ceramic tiles, sanitaryware, tableware and earthware that, in their industrial production, used different urban and industrial wastes, such as fuel, fly ash, fluxing wastes, mining and metallurgical industry wastes, granite sludges, frits, packaging glass and asbestos thermally treated. Several waste materials favoured the energy saving and the final products showed to have better mechanical characteristics.
The aim of the described procedure was to improve the reconstructive technique of a cranial lacunae in term of prosthesis functional properties, simplifying of the surgical procedure and aesthetics result; the proposed technique is the custom made device application. The selected material proposed in the procedure for morphology and the chemical composition close to that of natural bone, was hydroxyapatite. The case proposed shows the treatment of bone lesion due to infiltration neoplasma. CAT check, after 6 months, underlined a possible osteoblastic colonization of the prosthesis implanted.
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