Effect of metal-layer structure on the mechanical properties of multilayer metal–ceramic composites. II. Heat resistance

Abstract

The effect of the metal-layer structure and of the interface between the ceramic and metal components on the heat resistance of multilayer ceramic-metal composites is examined. The use of metal fabric layers substantially enhances the heat resistance of composites. The adverse effect of the residual porosity and, sometimes, poor adhesion between the ceramic and metal phases on heat resistance decreases owing to the skeleton structure of metal layers. The skeleton structure of metal layers promotes crack branching and retards the formation of the main crack.Heat resistance is an important characteristic of many types of ceramics, which is the capability of a material to withstand, without failure, thermal stresses caused by temperature change during heating or cooling. Metal-based ceramic materials often exhibit low thermal expansion coefficient, low heat conductivity, high elastic modulus, ultimate strength over a wide range, and low plasticity; hence, they have low heat resistance.One of the ways to improve the heat resistance of ceramics is to produce composite materials by introducing metal fibers into the ceramic base. Heat resistance is also enhanced because mechanical stresses are better distributed and hardening fibers restrain cracking of the ceramic matrix [1]. Layered metal ceramic composites, in which metal fabric and ceramic layers alternate, may serve as an example [2].It was previously shown that such multilayer composites exhibited high fracture toughness though the samples had significant (to 24-25%) residual porosity [3]. Fracture toughness grows substantially especially when mesh layers are made of metal fabric. When such samples are pressed, ceramic powder fills the fabric cells and the resulting metal ceramic layer has a skeleton-like structure. Such a developed skeleton structure of layered composites weakens the adverse effect of residual porosity on the mechanical properties. This paper examines how the structure of metal layers and the interface between ceramic and metal layers influence the heat resistance of layered metal ceramic composites.