3M Nextel™ 440 Industrial Ceramic Fiber

Chemical composition above is wt%. Crystal phases are gamma alumina + mullite + amorphous SiO2. Filament diameter is 10-12 µm.3M Nextel fibers 312, 440, and 550 are designed for non-structural applications where their primary purpose is to act as a flame barrier. 3M Nextel Ceramic Fiber 440 is made from Al2O3, SiO2, and B2O3. Because B2O3 is present, this composition has both crystalline and glassy phases. The glassy phase helps the fiber retain strength after exposure to high temperatures because it slows the growth of crystalline phases that weaken the fiber. However, when the fiber is stressed at high temperature, the glassy phase weakens the fiber due to viscous flow much like a glass fiber.Information provided by 3M Ceramic Textile and Composites.