Foaming Ability of Zeolitic Rocks as a Function of Their Composition
Статья (Full article),
Journal of Ceramic Processing Research
||Cationes, Composition, Foaming, IR-spectroscopy, Melt viscosity, Natural zeolites, Sintering
Institute of Mineralogy and Petrography, 630090, Acad. Koptyug Prosp., 3, Novosibirsk, Russia
Institute of Catalysis, 630090, Lavrentyev Prosp., 5, Novosibirsk, Russia
Samples of natural zeolites of different structural type, genesis, and cation composition (Ca and Mg- or Na and K-rich zeolites) were tested for their foaming ability at 1200°C. The degree of foaming was estimated by the density of solid foamed material obtained after calcination. Thermally-induced foaming ability of natural zeolites was shown to be a function of the chemical composition. Only Ca and Mg-rich zeolites foam at 1200°C calcination. The FTIR method showed that upon dehydration of the Ca and Mg-rich zeolites original water molecules transform into thermostable framework OH groups that became the source of high-temperature water vapor for foaming zeolite. Foamed material is formed if the temperature of OH group recombination into H2O coincides with that of sintering, and the viscosity of the melt at 1200°C is sufficient to enclose the H2O vapor within the pores. Both the sintering and viscosity of the melt are functions of the chemical composition of a zeolitic rock.