TRADITIONAL CERAMICS

ceramic materials that are derived from common, naturally occurring raw materials such as clay minerals and quartz sand. Through industrial processes that have been practiced in some form for centuries, these materials are made into such familiar products as china tableware, clay brick and tile, industrial abrasives and refractory linings, and portland cement. This article describes the basic characteristics of the raw materials commonly used in traditional ceramics, and it surveys the general processes that are followed in the fabrication of most traditional ceramic objects. From this survey the reader can proceed to more detailed articles on the individual types of ceramic products, links to which are provided at the end of this article. Traditional ceramic objects are almost as old as the human race. Naturally occurring abrasives were undoubtedly used to sharpen primitive wood and stone tools, and fragments of useful clay vessels have been found dating from the Neolithic Period, some 10,000 years ago. Not long after the first crude clay vessels were made, people learned how to make them stronger, harder, and less permeable to fluids by burning. These advances were followed by structural clay products, including brick and tile. Clay-based bricks, strengthened and toughened with fibres such as straw, were among the earliest composite materials. Artistic uses of pottery also achieved a high degree of sophistication, especially in China, the Middle East, and the Americas. With the advent of the Metal Age some 5,000 years ago, early smiths capitalized on the refractory nature of common quartz sand to make molds for the casting of metalsa practice still employed in modern foundries. The Greeks and Romans developed lime-mortar cements, and the Romans in particular used the material to construct remarkable civil engineering works, some of which remain standing to this day. The Industrial Revolution of the 18th and 19th centuries saw rapid improvements in the processing of ceramics, and the 20th century saw a growth in the scientific understanding of these materials. Even in the age of modern advanced ceramics, traditional ceramic products, made in large quantities by efficient, inexpensive manufacturing methods, still make up the bulk of ceramics sales worldwide. The scale of plant operations can rival those found in the metallurgical and petrochemical industries. Additional reading A good introduction to ceramics is provided by David W. Richerson, Modern Ceramic Engineering: Properties, Processing, and Use in Design, 2nd ed., rev. and expanded (1992). The processing of traditional ceramics is described in F.H. Norton, Elements of Ceramics, 2nd ed. (1974); James S. Reed, Introduction to the Principles of Ceramic Processing (1988); George Y. Onoda, Jr., and Larry L. Hench, Ceramic Processing Before Firing (1978); and four sections of Theodore J. Reinhart (ed.), Engineered Materials Handbook, vol. 4, Ceramics and Glasses, ed. by Samuel J. Schneider (1991): Ceramic Powders and Processing, pp. 41122; Forming and Predensification, and Nontraditional Densification Processes, pp. 123241; Firing/Sintering: Densification, pp. 242312; and Final Shaping and Surface Finishing, pp. 313376. Thomas O. Mason