Abstract
A novel and aqueous gel-casting process has been successfully developed to fabricate porous MgAl2O4 ceramics by using hydratable alumina and MgO powders as raw materials and deionized water as hydration agent. The effects of different amounts of deionized water on the hydration properties, apparent porosity, bulk density, microstructure, pore size distribution and compressive strength of the samples were investigated. The results indicated that the porosity and the microstructure of porous MgAl2O4 ceramics were governed by the amounts of deionized water added. The porous structure was formed by the liberation of physisorbed water and the decomposition of hydration products such as bayerite, brucite and boehmite. After determining the addition amounts of deionized water, the fabricated porous MgAl2O4 ceramics had a high apparent porosity (52.5–65.8%), a small average pore size structure (around 1–3 μm) and a relatively high compressive strength (12–28 MPa). The novel aqueous gel-casting process with easy access is expected to be a promising candidate for the preparation of Al2O3-based porous ceramics.
Highlights
Porous MgAl2 O4 spinel ceramics have attracted a growing interest due to their high melting point (2135 ◦ C), good thermal shock resistance, excellent chemical inertness, and their low thermal conductivity and thermal expansion coefficient; they are widely used for various applications such as gas filters, thermal insulation materials, waste water filters, catalyst supports and separation membranes [1,2,3,4,5]
The results of this research have been extremely valuable for the development of the gel-casting process, aside from a few small disadvantages
Thereby, in combination with the gel-casting process, when introducing ρ-Al2 O3 as the gelling source, it is expected that a novel method for fabricating porous ceramics will result
Summary
Porous MgAl2 O4 spinel ceramics have attracted a growing interest due to their high melting point (2135 ◦ C), good thermal shock resistance, excellent chemical inertness, and their low thermal conductivity and thermal expansion coefficient; they are widely used for various applications such as gas filters, thermal insulation materials, waste water filters, catalyst supports and separation membranes [1,2,3,4,5]. The results of this research have been extremely valuable for the development of the gel-casting process, aside from a few small disadvantages These gelling agents are organic compounds, which will release CO2 or hydrocarbon. Thereby, in combination with the gel-casting process, when introducing ρ-Al2 O3 as the gelling source, it is expected that a novel method for fabricating porous ceramics will result This is because the hydration of ρ-Al2 O3 can form gels to bind the green body, and small amounts of water can be enclosed in the green body by the interlocking gels. An aqueous gel-casting process has been successfully developed for fabricating porous MgAl2 O4 ceramic by utilizing ρ-Al2 O3 and MgO powders as raw materials and deionized water as a hydration agent. MgAl2 O4 ceramic, in terms of hydration properties, phase composition, porosity, microstructure, pores size and compressive strength, have been investigated and discussed in detail
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