GRADED CERAMICS FOR IMPROVED CONTACT-DAMAGE RESISTANCE: A REVIEW
Abstract
The concept of elastic-modulus-graded ceramics for improved resistance to quasi-static contact damage (Hertzian-indentation), sliding-contact damage, and wear is reviewed. In these graded materials, the in-plane elastic modulus (E) is low at the contact surface and high in the interior (substrate) with a continuous, or step-wise continuous, E-gradation in-between. Processing strategies for fabricating such E-graded ceramic composites in the Al2O3-glass, the Si3N4-glass, and the Si3N4-SiC systems are described. The Hertzian indentation (quasi-static and sliding) behavior of these composites, along with some results from wear tests, are reviewed. Computational modeling (finite-element analysis or FEA) results are also reviewed, and are used to discuss the role of E-gradients in imparting contact-damage resistance to these materials. The use of calibrated FEA models as predictive tools for the design of next-generation graded materials is also discussed.
