10 - Alumina ceramics

Abstract

Publisher Summary Aluminum oxide (Al2O3), more commonly known as alumina, is the most widely used oxide ceramic material. As a raw material, Al2O3 powder is produced in large quantities from the mineral bauxite, by the Bayer process. Its applications are widespread in engineering and biomedical applications. Some common examples include spark plugs, tap washers, pump seals, electronic substrates, grinding media, abrasion-resistant tiles, cutting tools, bioceramics, orthopedic and dental applications, body armor, laboratory ware, and wear parts for the textile and paper industries. High-purity alumina is normally classified as that with a purity of 99.99% and has been developed as an alternative to surgical metal alloys for orthopedic and dental applications such as total hip replacement. Due to its high hardness, low friction, and excellent wear and corrosion resistance, alumina is suitable for use as articulating surfaces in orthopedic applications. To achieve the long-term stability of alumina in orthopedic applications, the material must be free of porosity and its microstructure must be fine and homogeneous. Medical-grade alumina has a very low concentration of sintering additives, very small grain size, and a narrow grain-size distribution. Such a microstructure is capable of inhibiting static fatigue and slow crack growth while the ceramic is under load. Recently, alumina matrix composites were selected as the best new family of ceramics to provide the foundation for an expanded use of ceramics in orthopedics. This chapter provides an insight into the physical properties and microstructure of alumina ceramics and their mechanical and tribological properties, new generation and currently used medical grade alumina bioceramics, current status of major implant production companies and the current research, development, and applications of alumina ceramics and its composites in the biomedical field.