Ceramics. Products Typology

Ceramic materials are particularly diverse, as highlighted in the overview article Ceramics. Characteristics and technologies [N4811] . This is due, on the one hand, to the multiplicity of compounds and, on the other, to the large number of possible uses for these materials.

Concerning the multiplicity of ceramic compounds, suffice it to recall that a ceramic material is made up of an assembly of metallic atoms (there are around 80) with certain non-metals or metalloids: oxygen, carbon, nitrogen, boron and silicon. (To these must be added a number of covalent compounds of boron and silicon with nitrogen and carbon, which have special properties: Si ₃ N ₄ , SiC, BN, B ₄ C and B ₄ C ₃ .) That makes thousands of possible ceramic compounds when you consider combinations of 2, 3 or 4 different kinds of atoms, or even more, not to mention combinations of materials containing ceramics (composite materials).

The range of possible uses for these materials reflects the diversity of their properties. Generally speaking, ceramics are hard, brittle materials with high melting temperatures, fairly light, good electrical insulators and poor thermal conductors. However, there are also ceramics or ceramic composites that escape these compartmentalizations: for example, pure AlN aluminum nitride is almost as good a thermal conductor as copper, and ceramic springs can be manufactured despite the high rigidity displayed by these materials. All this means that ceramics can be found in thousands of different products, for a wide variety of applications, and that it is absolutely essential to classify them in order to make sense of them all.

For this purpose, several typologies are usually proposed. One is based on product composition. Ceramics can be divided into oxides, carbides, nitrides, borides, silicides, silicates and composites. Another common classification is based on the uses to which these materials are put, and this is the one adopted here, considering that engineers most often orient their work according to the purpose of the parts or equipment they manufacture: the use of the products and their properties of use are therefore their primary concerns. The typology of ceramic materials presented in the following pages is therefore based on their use and, for the sake of consistency with article [N4811] , the order chosen is that given in table 3 (§ 1.4) of the said...