Effect of Simultaneous Addition of Albumin and Yolk on the Porosity and Strength of Alumina Prepared by Gel Casting

Abstract

Porous ceramics are a new class of advanced ceramics which are being widely used in many interesting applications such as molten metal filtration. catalyst carrier, support for fuel cells, thermal insulation, bioreactors as well as scaffolds for biomaterials. In this project, porous Alumina samples are prepared using 25vol.% solid loading, guar gum as binder and different percentages of albumin (i.e. 5. 10. 15 and 20) which acts as both binder and foaming agent through gel casting technique. Foam Drainage rate has been measured for different wt.% of guar gum (0.1- 0.5wt.%) and it has been observed that 0.5wt% guar gum gave minimum drainage rate (6.94µL/sec). The rheology study showed that the viscosity of the slurry containing alumina, albumin, yolk and guar gum increased as the temperature increased from 60OC to 65OC. This increase in viscosity is due to the de-naturization of albumin at that particular temperature. The samples which are prepared are dried in hot air oven at 70OC for 24 hours and are sintered at three different temperatures i.e. 1450OC, 1550OC and 1600OC. Physical properties like Apparent Porosity, Bulk Density, Closed Porosity, Total Porosity, microstructure and flexural strength are measured. It was observed that the samples with 5wt.% albumin resulted in high porosity (83.17%) but low strength (0.67MPa) when sintered at 1450oC. The strength increased to 2.35MPa when sintered at 1600oC. The effect of simultaneous addition of albumin as well as egg yolk (1-4wt.%) on the porosity and strength on the alumina samples is also studied. The addition of yolk decreased the porosity of the samples but increased the strength. The flexural strength analysis showed that samples with 3 wt.% yolk had high strength (12.22MPa) when sintered at 1600OC.