Previous work has shown that layers within ceramic laminates containing biaxial compressive stresses also contain tensile stresses where the layer intercepts the surface. It was shown that when the thickness of the layer exceeds a critical value, the tensile stresses at & near the surface can produce a centerline crack extending along the surface to a depth corresponding to the thickness of the compressive layer. This work explores the concept of preventing the occurrence of surface cracks with a thin layer of material that places the entire external surface in compression. A recent finite element analysis showed that when external surface layer material was identical to the compressive layers, the tensile stresses at the surface could be reduced to zero when the thickness of the surface layer was 0.6 of the thickness of the compressive layer.
