By T.E. Mallouk, et al . The subject invention describes a new quaternary alloy electrocatalyst that has substantially higher activity in PEM fuel cells than Pt-Ru. The brittle fracture behavior of glasses and ceramics makes the strength of these materials strongly dependent on the size and location of stress concentrating flaws. Surface flaws formed during contact damage reduce strength resulting in the failure of glasses and ceramics usually in an unstable and catastrophic way. This invention uses residual compressive stresses to induce crack stabilization - a novel alternative means of enhancing mechanical reliability.
Treated materials undergo multiple cracking.
A crack forms in the surface, but then arrests. This is followed by the formation of other cracks.