Fabrication of large diameter SiC monofilaments by polymer route

摘要

We demonstrate the possibility to fabricate SiC monofilaments with large diameters of 100 μm by a polymer route using a dry-spinning process. The properties of the spinning solution and the parameters of the spinning process were optimized to achieve a circular cross section of the spun filaments despite their large diameter. The evolution of the diameter and the mechanical properties of the filaments with pyrolysis temperature were studied. Filament shrinkage started above 400 ℃. A radial shrinkage of about 25% was measured for pyrolysis temperatures of 1200 ℃. The mechanical properties significantly start to increase at pyrolysis temperatures above 600 ℃. At a diameter of 100 μm the filaments show a tensile strength of 620 MPa and a tensile modulus of 138 GPa after pyrolysis at 1200 ℃. A decrease in the filament diameter leads to an improvement of the mechanical properties. We demonstrate the fabrication of these SiC monofilaments on spools.