BN-Based Fiber Coatings by Wet-Chemical Coating

• Published in: Key engineering materials 2019-06, Vol.809, p.421-426
• Main Authors: Maier, Jonathan, Nöth, Andreas, Schönfeld, Katrin
• Format: Article
• Language: English
• Subjects: Bundles; Bundling; Coated fibers; Continuous fibers; Dip coatings; Fiber coatings; Fiber pullout; Heat treatment; Immersion coating; Infiltration; Organic chemistry; Polymer matrix composites; Pyrolysis; Reduction; Silicon carbide; Silicon nitride; Tensile stress; Tensile tests
• ISSN: 1013-9826; 1662-9795; 1662-9795
• DOI: 10.4028/www.scientific.net/KEM.809.421

Fiber coatings for BN/SiC-and BN/Si3N4-bilayer systems were developed for the use in SiC/SiC composites. All coatings were produced with high process velocities of 500 m/h by a continuous roll-to-roll dip-coating process. The fiber surface was fully covered with a homogeneous coating and without fiber bridging. Tensile tests of fiber bundles were used to examine potential degradation of the fiber properties due to the application of the coatings. The coated fiber bundles showed a reduction of the maximum tensile load to 90.0 % for the BN/Si3N4 and to 86.7 % for the BN/SiC coating in comparison to the fiber bundle in the as-received state. A thermal treatment of the coated fiber bundles up to 1650 °C led to no reduction of their maximum tensile load. SiC/SiC composites were fabricated by polymer infiltration and pyrolysis. The flexural strength and strain of composites with BN/SiC fiber coating were improved to 467 MPa and 0.42 % in comparison to the composites without fiber coating. The composites with BN/SiC coating showed toughened fracture behavior with fiber pull-out effects.