Preparation and characterization of porous alumina ceramics using sunflower seed shells as fugitive material

Abstract

Porous alumina ceramics were prepared through the space holder technique, using ground sunflower seed shells as a fugitive material and uniaxial pressing for forming the green ceramics. Influences of the sunflower seed shell content on the shrinkage of the green bodies and porosity of sintered products were evaluated. The prepared ceramics were characterized for mechanical properties using the Brazilian disk test, and the porosity effect on the measured strength was determined. The microstructure was characterized by SEM. The sunflower seed shell content was varied from 0 to 60 wt%. Porosities within 29.9-71.0 vol% were achieved, and the strength of the obtained alumina ceramics decreased accordingly from 59.7 to 4.0 MPa. Additional samples, prepared with different compaction pressure, were characterized for electrical properties and showed high electrical insulation capability, which increased with porosity. Mechanical and electrical data were discussed based on theoretical models, namely the Gibson-Ashby model and/or the minimum solid area model.

Evaluating the properties of cellular ceramics prepared with a granite dust and plantain (Musa paradisiaca) peel powder for external wall thermal insulation of buildings

“…Andreola et al [13] experimented three different manufacturing techniques of porous ceramics and concluded that one technique can be preferable as compared to the others depending on the specific use. The pore-former technique is based on the mixing of the ceramic powder, or its precursors, with a fugitive material that acts as a poreforming agent, followed by the formation of a green body, extraction of the pore-former, and sintering of the ceramic phase [14]. The burning out of pore-former's technique is widely used given its easy usability for achieving optimum results [15].…”