Environment induced crack growth of ceramics and glasses

Abstract

This paper reviews the behavior of glasses in water and water vapor, and ceramics and ceramic composites in high temperature gas environments. The exposure of glass and ceramics to water can produce subcritical crack growth, which can result in the development of a critical-sized flaw and catastrophic failure. Fiber optics, bone implants, dental porcelain, and glass fiber reinforced composite materials are examples where the stress corrosion of glass and ceramic materials is technologically significant. Failures of fiberglass-reinforced plastics (RMP) are reported in applications in which the material is stressed and in contact with an aqueous environment. Ceramic matrix composites (CMCs) are developed to take advantage of the high-temperature properties of ceramics while overcoming the low fracture toughness of monolithic ceramics. Toughening mechanisms, such as matrix cracking, crack deflection, interface debonding, crack-wake bridging, and fiber pullout, are incorporated in CMCs to reduce the tendency for catastrophic failure found in monolithic ceramics. Ceramics reinforced with particulate, whiskers, and continuous fibers exhibit varying aspects of the toughening mechanisms; however, reinforcement with continuous fibers offers the greatest improvements in toughness. Composites with carbide, oxide, glass, and carbon matrices are utilized in the development of CMCs.