Share this page by mail Why can alumina silicate be a cost-effective alternative to sintered ceramics?
Alumina silicate is a natural ceramic derived from pyrophyllite rock which can be heat-treated to improve its mechanical properties and temperature resistance. Without temperature treatment, alumina silicate, with a density of 2.9 g/cm3 and a thermal conductivity of approximately 1.5 W/(m.K), can withstand a continuous exposure to temperatures up to 700°C. After an appropriate heat treatment, the maximum working temperature of alumina silicate is 1,300°C, giving it a compression resistance of approximately 487 MPa and a flexural strength of approximately 50 MPa. Its thermal conductivity also shows a light increase, reaching 2.67 W/(m.K).
Final Advanced Materials recommends alumina silicate for brazing or welding applications, but also for electrical and thermal insulation applications at temperatures of over 1,000°C.
Macor is a machinable vitroceramic with a density of 2.52 g/cm3 and capable of resisting temperatures up to 1,000°C for a short term. Macor stands out for its excellent machinability when dry, and by its low thermal conductivity (1.46 W/(m·K)), making it an effective insulator for high temperatures, and an excellent electrical insulator.
Shapal Hi-M Soft has a high thermal conductivity (92 W/(m·K)) and good mechanical properties. Shapal Hi-M Soft is slightly more difficult to machine than Macor but is excellent for heat dissipation.
Final Advanced Materials recommends Macor for prototyping or complex parts with a maximum continuous temperature of 800°C and a short-term temperature of 1,000°C, and Shapal Hi-M Soft for challenging thermal applications.
Hexagonal boron nitride (h-BN) has a hexagonal crystalline structure, meaning that it is easy to transform using dry machining with carbide tools on a standard CNC machine. Its thermal conductivity is high (20–120 W/(m·K)), and it can withstand temperatures as high as 850-900°C in air. Final Advanced Materials recommends h-BN for high-temperature electrical insulators, or for applications in contact with molten metals or scoria (crucibles, casting support).
Among machinable ceramics, Macor stands out for its high dielectric strength of 45 kV/mm, resistivity of 1015 Ω.m and dielectric constant of 6.01 (at 20°C and 1 MHz). Macor remains stable up to 1,000°C, making it the ideal solution for high-temperature insulators and electronic substrates. For applications where the top priority is high-temperature electrical insulation, Final Advanced Materials therefore recommends Macor for its dielectric stability and its low dielectric loss.
96% machinable alumina's density is of 3.0 g/cm³, with a porosity of 10% and a thermal conductivity of approximately 4.6 W/(m.K). Its maximum short-term working temperature is of approximately 1,650°C. It also has a good chemical stability and thermal shock resistance. Final Advanced Materials recommends machinable alumina for high-temperature applications requiring thermal or electrical insulation at temperatures of over 1,300°C.