Development and Evaluation of Carbon-Carbon Threaded Fasteners for High Temperature Applications

Abstract

Carbon-Carbon (C-C) threaded fasteners have been developed for joining C-C composites experiencing temperature above 1500 °C. The fasteners were fabricated from spun yarn graphitized carbon fabric through resin route and from needle punched carbon felt through pitch route techniques. The preforms were processed with multiple cycles of impregnation, carbonisation, and graphitisation up to densities of 1.78 gcm -3 and 1.90 gcm -3. Densification process cycles were repeated to obtain composites with reduced porosity and improved thermo-mechanical properties. Material evaluation of C-C fasteners is discussed and compared with existing graphite fasteners used in industrial and aerospace sectors. Scanning electron microscopy was also carried out to study microstructure of fractured specimens.

Studies on Fibre Orientation of Carbon Fibre Preforms for Fabrication of C/SiC Fasteners

“…Mei et al (2010) reported carbon fiber cloth reinforced 2D C/SiC bolts with the tensile strength of 210-230 MPa by CVI process. Kushwaha et al (2012) fabricated carbon-carbon (C/C) threaded fasteners from spun yarn graphitized (SYG) carbon fabric through resin route and from needle-punched (NP) carbon felt through pitch route techniques with tensile strengths of 102 MPa and 103 MPa, respectively.…”

“…Researchers worldwide have studied one or the other preforms mostly using PIP, LSI and CVI + PIP process for making composite fasteners (Verrilli et al 2002;Böhrk et al 2010;Wan 2005;Zhang et al 2011;Mei et al 2010;Kushwaha et al 2012), but to the best of our knowledge, a comparison amongst different possible orientations of continuous fibre preform architectures for realizing nearnet-shaped composite fasteners using CVI process is not reported. There are different methodologies available for fabrication of continuous fibre preforms such as alternate stacking of carbon fabric plies in the order of 0°/90°/ ± 45° followed by stitching (termed as 2D stitched preform), weaving of carbon fibres along mutually orthogonal directions (3D woven preform) and NOOBing (Non-interlacing, Orienting Orthogonally and Binding) technique described by Khokar (2002) as a non-woven three-dimensional fabric-forming process which could be utilized for fabrication of near-net-shaped composite fasteners (4D/5D NOO-BED preform).…”