Modification of Porous Cordierite Ceramic

Abstract

Highly porous cordierite ceramic by using of talcum, kaolinite and γ-alumina was obtained by method of slip casting of concentrated suspension. Additives of amorphous silica and non-stabilized zirconia in the amount of 5 wt% were used. Sintering temperature of dried samples was in range of 1250 – 1450°C. All the samples contain crystalline phases of cordierite, mullite and corundum but, depending on the additives, as a result of sintering in addition forms spinel, cristobalite or zircon (ZrSiO4). Porosity of obtained materials changes in large scale from 42 to 59 per cent; it is influenced by both sintering temperature and composition. Compressive strength increases with the addition of zirconia. In comparison, compressive strength of samples without additives or with silica additive does not exceed 3.5 MPa. The increase of coefficient of thermal expansion depends both on the composition and sintering temperature. ZrO2 additive increases the coefficient of thermal expansion considerably.

Augsti poraina oksīdu keramika

“…Amorfā SiO2 piedevas gadījumā temperatūrās virs 1300 °C parādās kristobalīts. Savukārt paraugos, kur izejvielu maisījumam pievienots ZrO2, temperatūrās virs 1250 °C veidojas ZrSiO4[15].Par materiāla poru struktūru un tās atšķirībām liecina dzīvsudraba porozimetrija 16…”

Sorption Roperties of Latvian Clays and Environmental Protection Survey

“…Determination of cation exchange capacity must be specially accentuated. This characteristic is significant in analyzing different unacceptable (toxic, radioactive) adulterant migration in over ground and ground-waters in normal or catastrophe created situations, it will open up the new opportunities for scientific motivated usage of sorbents for waste water treatment [26] and other. Capacity amount of clay ion exchange plays a great role in various processes, however, for Latvia the most important are those related to soil fertility and environment pollution problems.…”

“…It adsorbs weakly on the samples, whose surface is partially covered with rapeseed oil coking products [27]. In scientific work [26], opportunities of using natural and thermally treated clay samples (from 200 to 800 0 C) from Suntaţi, Laţa, Veldze and Kuprava deposits for cleaning wastewater are researched. The highest adsorption ability is characteristic for clays from Kuprava deposit, and it's explained by its mineralogical properties and small amount of additions.…”

“…It's said that the active component in the clay composition is hydro muscovite. Chrystallic chemical structure of clays decomposes in -500-600 0 C temperature [26], and its destruction is accompanied by reducing adsorption ability. Clays from Veldze deposit, both natural and at 600 0 C thermally treated, show good sorption abilities by cleaning wastewaters at "Reagents" and "Grindeks" companies.…”