Rational durability design of heterogeneous functional materials: Some first principles

Abstract

The present paper proposes a rational approach to the design of constituents, their morphology, and their multiscale arrangement in heterogeneous functional material systems to control the evolution of their properties, morphology, and performance as they interact over specified histories of applied mechanical, electrical, chemical, and thermal fields. The principal thrust of the paper is the postulate of a “first law” for such an approach, which states that “only 100 percent efficient systems are 100 percent durable; the durability is controlled by non-conservative changes in the material state, which are uniquely reflected in changes in the material compliance to applied fields.” The application of the “first law of rational durability design” is discussed for mechanical and electrical applied fields acting upon primarily two-phase heterogeneous material systems. A rational design analysis is demonstrated, and the results are compared with experimental data for fiber-reinforced control materials. The application of the concepts to heterogeneous functional materials (HeteroFoaM) used in fuel cells, batteries, membranes, and electrolyzers is also discussed.