Mechanical properties of carbon fiber-reinforced Al2O3 porous ceramics

This study reports the improvement of the mechanical properties of Al2O3 porous ceramics from particle-stabilized colloidal suspension with the addition of carbon fiber through direct foaming. The initial colloidal suspension of Al2O3 was partially hydrophobized by a surfactant, propyl gallate (2 wt%), to stabilize the wet foam used with the addition of carbon fiber from 2 to 8 wt% as reinforcement. The influence of carbon fiber on the air content, bubble size, pore size, and pore distribution were discussed in terms of the wet foam stability and the physical properties of the porous ceramics. The mechanical properties of the sintered porous samples were investigated by the Hertzian indentation test. The results show that the wet foam stability of more than 90% corresponds to the compressive load bearing capacity of 110 N using tungsten carbide ball with a radius of r = 7.93 mm and the elastic modulus of 114.3 MPa in the sintered sample with 2 wt% of carbon content.