3D Interconnetive Porous Silica Ceramics Prepared by Gel Casting with Egg White Protein as a Foaming Agent

Highly porous silica ceramics were produced by gel casting with egg white protein (EWP) as a foaming agent and evaluated by measuring the porosity, mechanical strength and microstructure. After drying, the green bodies were debindered and sintered at 1300 degrees C for 4 h. The influences of the EWP content on the open porosity as well as the strength were investigated. The porosity of the obtained porous silica ceramics was within 70.2%-86.1%, and the bending strength decreased from 6.81 MPa to 5.48 MPa. It was found that the strength dependence of the porosity was well described by a modified exponential relation of the form sigma=sigma(0) exp(-BP), where P is the porosity and B is a constant (B = 1.37 was obtained by fitting the experimental data). This finding is in agreement with other literature data and seems to indicate a common feature of all porous ceramics.