Surface and Colloid Chemistry in Ceramics

By using techniques from colloid chemistry, defects can be removed and the strength of ceramic materials increased considerably. Synthesis of ceramic powder is yet another area of application of surface chemistry. In a ceramic material, the links are represented by defects such as cracks, inclusions, and pores, all of which give rise to stress concentrations and a consequent risk of brittle failure. The strength of a brittle material can be deduced from the fracture toughness and the size of a critical defect. For a single phase ceramic, the chosen phase and grain size determine the fracture toughness. However, many single phase ceramics have a grain boundary interphase of special composition. Many ceramics are used in applications where electric, piezoelectric, magnetic, and optical properties are the main reason for using the material. These types of ceramics are sometimes called functional ceramics. The main properties of functional ceramics are not controlled by single defects but rather by the average microstructure.