Integral Metal Foil Layer
Publication Date: 2017-Jul-25
The IP.com Prior Art Database
INTEGRAL METAL FOIL LAYER
• For certain aircraft applications, it is common for composite components to be manufactured with a surface layer comprising of an electrically conductive metal foil (eg: for lightning strike protection purposes)
− However, the foil products often comprise of a low areal weight and can be both difficult to manipulate into the cure tool, and secure in position at the tool surface. In particular, the unsupported foils can be
highly prone to distortion during handling.
− This can be a particular problem for resin infusion processes involving dry fabrics (ie: which often do not benefit from any tack to assist in securing the foil position).
• A photograph of a typical dry copper foil is attached below:
For processes involving prepreg materials
• The metal foil is typically applied in combination with a thermoset resin film product or supplied pre- impregnated with a thermoset resin
• In this format, the metal foil benefits from ‘tack’ (ie: stickiness from the resin) to enable the foil to be affixed to the tool surface during the composite component lay-up process
• Some commercially available pre-impregnated foil products also include an integral surface veil to promote the formation of a resin-rich surface, which can be beneficial to prevent exposure of the metal foil during
subsequent paint preparation activities
• The product is also be supplied with a removable backing film which serves to support the film handling and can prevent distortion
For liquid resin infusion processes
• The resin is applied after the fabric lay-up process
• Therefore, the metal foil must be either applied dry (ie: which would be extremely difficult), or another means must be used to introduce a conductive layer at the component surface.
• Possible alternative proposed solutions have included the following (but all suffer cost/weight penalties):
− Apply a metallised coating to the mould tool (eg: metal powder spray process)
− Apply a metallised coating to the fibres within the reinforcing fabric
− Co-weave metal fibres alongside reinforcing fibres within a woven fabric for...