November 1998

Ceramics Shape Up

By Technology Review

For a parent, a child's lopsided art-class ashtray holds a certain charm. But to the manufacturers of ceramic parts for such devices as medical implants and cell phones, lopsidedness means failure. Researchers at Ohio State University have come up with a new recipe for ceramics that can avoid a major cause of malformation.

In conventional ceramics production, organic material is often added to the mix to make shaping easier. But firing the pieces burns off the organics, leaving behind pores. These must be filled in a second firing that can induce nonuniform shrinkage of the part, causing cracks or deformations.

To sidestep the need for the second firing, Ohio State ceramist Kenneth Sandhage adds powdered or molten metal to the ceramic precursor mix. Instead of burning off, the metal reacts with oxygen. The oxides anneal to form a solid ceramic part, without shrinking. Sandhage is seeking licensees for the patented process.