Ceramics are defined as inorganic, non-metallic materials. Ceramics are hard materials that are resistant to high temperatures and are not deformed plastically, as well as having good resistance to corrosion and low electrical conductivity. Ceramics are manufactured by compacting powder to a body which is then sintered at high temperatures. The geometry, production volume and characteristic requirements for the component govern the choice of manufacturing process.
A common shaping process in the ceramics industry. Works well for complex geometries, produces material with good homogeneity and the mould material used, plaster, is cheap. Pressure moulding is now used to speed up the process. Porous polymer moulds have replaced plaster moulds and by applying an external pressure, you get a significantly quicker casting process.
Tape casting is used for the manufacture of thin sheets, for, e.g. membranes or sensors. The equipment at Swerea IVF has a stationary casting station and is used to create tapes with a thickness of between 4 and 400 µm. Thicker material or composite material can be created by laminating several sheets together.
Colloidal shaping processes which build on the principle of transforming a powder suspension directly into a fixed body without powder compacting. Several alternative techniques are available. Works well for manufacturing individual items or short series of components with complicated geometries.
Powder pressing is a common industrial shaping process for manufacturing simple geometric shapes in large series. The combination of cold isotatic pressing (CIP) and machining before sintering is used industrially for the manufacture of dental crowns and other dental products. The process also works extremely well for manufacturing prototypes.
Optimal process for manufacturing large series of relatively small components. By mixing ceramic powder and suitable binder systems it is possible to injection mould ceramic components. The polymer binder is burned off in a separate burn off stage before sintering.
Free form fabrication (FFF) or rapid prototyping
Techniques which allow tailoring of component and material structures as the component is built up layer by layer. One variation is indirect free forming where you first build a polymer mould. The mould is then used to manufacture the desired components, e.g. by using suitable direct consolidation processes.
Burn-off and sintering
In certain moulding processes a relatively large amount of temporary organic binder is used, which needs to be burnt out in a separate step. Sintering is then carried out in air. We have furnaces for sintering in air up to 1800°C, or inert graphite furnaces with a maximum temperature of 2300°C.