Technical or advanced ceramics are a new, emerging, and growing family of ceramics that have usually been called nontraditional ceramics.
Advanced ceramics such as piezoelectric and semiconductor materials exhibit several enhanced and important functional properties as compared to traditional ceramics. They can be tailored with functional properties for mechanical, electrical, electronic, biomedical, optical, and magnetic applications, among others. Technical ceramic materials can be categorized into four groups based on their composition: glass ceramics, such as lithium aluminosilicate; oxides, such as alumina, zirconia, and mullite; nitrides, such as silicon nitride; and carbides, such as silicon carbide. In general, advanced ceramics comes in three forms, ceramic composites, bulk ceramics, ceramic coating.
Definition according to ISO 3252: Sintering is a "thermal treatment of a powder or compact at a temperature below the melting point of the main constituent, for the purpose of increasing its strength by bonding together of the particles."
Sintering processes for ceramics are commonly divided into several categories, these include solid-state sintering (e.g. Al2O3 - with MgO additive), liquid-phase sintering (e.g. MgO with a silicate glass), pressure sintering (e.g. Si3N4 with Al2O3 and Y2O3 additives under nitrogen gas pressure or under an externally applied pressure), viscous sintering (e.g. SiO2 gel), and vitrification (e.g. Porcelain).
Depending on material and to be sintered and processes different atmospheres and atmosphere compositions are used.
The exact and consistent composition of the protective gas is vital for the quality of ceramic surfaces. Any unwanted chemical reactions with the metal must be reliably prevented. The solution is the Neutrotherm process, which is based on a neutral gas mixture containing less than 5 % hydrogen.
With minimal investment in hardware, the process provides excellent protection against oxidation of the metal, ensuring the surface remains clean.
Messer process = "Neutrotherm"