Ceramics

The main constituents of clay are hydrous aluminum silicate compounds such as kaolinite and montmorillonnite. These are created by the mineral re-formation during the erosion of rocks containing feldspars (e.g. granite, porphyry). Added to this are impurities in the form of quartz, calcite, mica and iron oxide from the original rock, plus organic residues. the two-dimensional crystals of the clay minerals exhibit a foliar structure, which owing to its large surface area is capable of storing capillary water and swelling. Hence, the clay minerals bond the aggregation and make the mass plastically mouldable.

The inherent color of a ceramic material depends on the metal oxides of the constituent clay and the oxygen supply during firing. Iron oxide gives the body (i.e. the clay product without the glaze) the well-known red color, at higher temperatures a blue-green color. Manganese in the clay leads to a body with a brown color, graphite a grey body, and lime a yellow body. Pure clay (kaolin) is white.

source: Engineering Materials and Index,....,....

Internal Structure


Real ceramic microstructure


SEM micrograph of the ceramic microstructure. Image courtesy of Kenneth A. Snyder



Atomic and Molecular Structure



Silicate Ceramic




Nitride Ceramic


Ferro-electric Ceramic


Link:

NDT Resources Center

Digital Library of Ceramic Microstructures

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