Hard or refractory ceramic
Technical ceramics is a branch of ceramics intended for its industrial applications, as opposed to artisanal (pottery) or artistic (artistic ceramics) or porcelain creations. The objective of this industry is the creation and optimization of ceramics with specific physical properties: mechanical, electrical, magnetic, optical, piezoelectric, ferroelectric, superconducting.
Technical ceramics fall into three different categories:
- oxides: aluminum oxide, zirconium oxide;
- non-oxides: carbides, borides, nitrides, ceramics composed of silicon and atoms such as tungsten, magnesium, platinum, or even titanium;
- composite ceramics: combination of oxides and non-oxides.
Ceramics are distinguished from all other materials by their particular qualities:
- heat resistance (refractory materials),
- hardness and wear resistance,
- insulating, magnetic and piezoelectric properties.
The hardness of ceramics is highly sought after, because it allows to obtain coatings and materials that are very resistant to wear. The low density of ceramics also makes it possible to prefer them to metals, which are much heavier, when weight is a determining criterion. These characteristics, combined with good heat resistance, make ceramics good materials for all applications where repeated friction gives off heat: cutting objects, rotary joints, drilling and excavating tools, spinning nozzles. There have even been attempts to make ceramic automotive engines lighter and more efficient than conventional engines. Even if the idea is now abandoned, ceramics nevertheless enter into the composition of many engine parts: rotors, combustion chambers, cylinder heads, valves, etc ... The strength and resistance to wear of ceramics is also one of the reasons for their use in medicine, where they enter into the composition of particularly durable prostheses (teeth, femur, knee).