Highly refractory composite material made of a ceramic (highly refractory oxide) and a metallic component. They are characterized by particularly great hardness and wear resistance.
Cermets are produced by soaking the ceramic material in liquid metal or by sintering the two component with the metal being in a solid state for this process. Sintering is performed similar to homogenous powders with the only difference that the metal undergoes greater compaction than the ceramic material at equal pressure. The greatly differing density of metal and ceramic sintering components easily cause disintegration so that stabilizing additives are required.
The most frequent phases of cermets are aluminum oxide (Al2O3) and zircon oxide (ZrO2). The metal phases used for cerments mainly are niobium, molybdenum, titanium, cobalt, zircon, and chromium (see Cargonitride).
Any composition ratio between almost pure metal to almost 100% ceramics is referred to as cermet. This results in the differentiation between infracermets (metal phase 85 vol.-%) and ultracermets (ceramic phase 85 vol.-%). The principal fields of application range from implementation as high-temperature heating elements to protective tubes for thermoelectric couples, turbine materials, corrosion-resistant friction bearings, through to cutting materials for metal-processing industries.