The objective of the EY Technologies proposal is to develop a graphite fiber interface on the surface of a 2D graphite unidirectional tape to enhance the thermally conductive and structural properties on all axis of a composite, with emphasis in enhancing the Z-axis. Currently, industry has not been able to make 2D laminate composite from unidirectional materials that simultaneously meet thermally conductive and structural criteria on all axis, especially Z-axis, thus limiting the usefulness of composite materials to reduce weight in aircraft, directed energy systems and satellites. The present 2D structures can allow 120+W/mK on the x and y axis, while the proposed work will provide such thermal properties and improved structural properties in the Z direction also. The proposed method will provide for a continuous process to implant and orient short fibers (length= 0.5-1.0 mm) cut from graphite filaments into the 2D unidirectional reinforcement in-line with the prepreg process. The z-direction fiber can provide a continuous conductive path from layer to layer within the matrix, as a superior means to improving desired thermal and electrical criteria. Not only will the Z-axis laminar composite technology improve thermal and electrical performance, but will also improve fracture toughness quality as well. Flocking technique uses an electric field to propel short fibers onto an adhesive coated textile substrate where the fibers remain oriented in the Z direction. EYT proposes to adapt the process for incorporating flock fibers from graphite filaments in real time with the uni-tape resin impregnation process. This process approach will allow the Z-direction flock (graphite) fibers to provide a continuous conductive path from layer to layer in multi laminate composites, a far superior means to improving desired thermal and electrical criteria. Additionally, the Z-axis laminar composite technology will improve fracture toughness quality as well.
Benefit: Positive results from this work will provide a platform of revolutionary technologies to enhance high performance composites with designed Z-axis reinforcement and enhanced properties such as thermal and electrical conductivity. There is seemingly unlimited fiber opportunities including organic, inorganic and even metallic that can be cut and flocked into composites performs, 2D and 3D, including 3D woven and braided and reinforcing fiber bundles and/or tows. The process to impinge and orient cut fiber for Z axis enhancement will be adaptable to individual cut pieces, continuous prepreg fabrics and even for in-line filament winding either onto the tow or directly on the rotating mandrel. The capital costs to adapt to traditional composite processing equipment are economical, readily available and required engineering of equipment and installation relatively simple.
Keywords: Thermally Conductive, Structural, 2d Laminate, Cut Graphite Fiber, Laminar Composite, Z-Axis Reinforcement, Prepreg Process, Interface.
