Preparation of macroporous alumina ceramics using wheat particles as gelling and pore forming agent

The present work reports a simple process for preparation of macroporous alumina ceramics from aqueous powder slurries using wheat particles as gelling and pore forming agent. Wheat particles incorporated in aqueous alumina slurries rapidly absorb water on heating and transform it into a strong gel. The gelled bodies did not undergo crack and warpage during drying. The dried green bodies showed diametrical compressive strength in the range 0.41–0.59 MPa and are amenable to machining operations such as milling, drilling and lathing. Pyrolytic removal of the pore former followed by sintering at 1600 °C produced alumina bodies with porosity 67–76.7% and diametrical compressive strength 2.01–5.9 MPa. Isotropic shrinkage was observed during sintering. Microstructure showed both large (200–800 μm) and small (less than 20 μm) pores. Small pores were uniformly distributed in the struts and walls of the large pores.