Toughening Methods 1

Several methods are used to improve fracture toughness, which in turn leads to higher fracture strengths and higher service stresses. One traditional method for improving toughness is to surround the brittle ceramic particles with a softer, tougher matrix material. This is done in producting cermet cutting tools and abrasives, which are really composite materials. As an example, very hard tungsten carbide ( WC ) particles are embedded in a matrix cobalt metal.

The composite part retains the high hardness and cutting ability of WC, but the softer, more ductile cobalt deforms and absorbs energy.
Other cermets, such as TiC particles in a nickel matrix or TiB in a cobalt matrix, provide good high-temperature strength and corrosion resistance for applications such as rocket motors, and UO2 in an aluminum matrix serves as a nuclear fuel.
Another approach is to create ceramic matrix composites ( CMCs ) by introducing ceramic fibers or agglomerates into the ceramic matrix. When a crack tries to propagate in the matrix, it encounters the interface between the matrix and the ceramic fiber; the interface helps block the propagation of the crack.