Fabrication of Al2O3-Bonded Fibrous Ceramics by An Aqueous Gel-Casting Process

Abstract

The traditional gel-casting method mostly uses organic compounds, which are complex process, expensive and pollute the environment. In order to overcome the disadvantage of the traditional gel-casting method, an environment friendly aqueous gel-casting process is introduced in this paper. Al2O3-bonded fibrous ceramics with high porosity and low thermal conductivity have been prepared by a novel hydrated alumina gel-casting process using the ρ-Al2O3and mullite fibers or YSZ fibers as raw materials and the deionized water as hydration agent. A bird-nest-patterned three-dimensional reticular skeleton structure was established by the fibers to ensure a certain mechanical strength. The effects of the amount of mullite fibers andYSZ fibers on the properties of porous ceramic, such as phase composition, microstructure, sintering behavior and relative properties were investigated. Results showed that the as-prepared Al2O3-bonded fibrous mullite ceramics have high porosity of 66.9%∼78.6%, low thermal conductivity of 0.236∼0.479 W/m·K, and relatively high compressive strength of 0.80∼2.78 MPa. The as-fabricated fibrous YSZ ceramics had a high porosity (71.1%∼72.7%), a low thermal conductivity (0.209∼0.503 W/m·K) and a relatively high compressive strength (3.45∼4.24 MPa). Comparing to the as-fabricated fibrous mullite ceramics, the compressive strength of as-fabricated fibrous YSZ ceramics is promoted obviously.