Lightning-Protective Coatings for Aircraft Engine Nacelles Made of Polymer Composite Materials. Part 2. Advanced Detonation Technology for Applying a Lightning-Protective Coating

Abstract

The present paper contains results of trying the detonation technology of applying a lightning-protective coating and the results of testing the lightning resistance of samples of structurally similar elements of a nacelle made of polymer composite materials and coated using this technology. A lightning-protective coating was sprayed on samples of structurally similar elements of a nacelle made of carbon fiber prepreg VKU-25. The coating was applied using the CCDS2000 detonation computerized complex developed by the Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences. Copper, bronze and aluminum were used as materials for the lightning-protective coating. The thickness of the applied metallized layer was varied from 10 to 20 microns, this providing an extremely low specific gravity of lightning protection at the level of 0.087–0.178 kg/m2 for copper and bronze; 0.027–0.054 kg/m2 for aluminum. Samples with and without lightning-protective coating were tested with a simulated lightning discharge according to the requirements of aviation standards AP-25, including components related to lightning-hazardous zones 1A, 2A, 1B. The combi-nations of components complied with the qualification requirements of KT-160G. According to the results of tests on the lightning resistance of samples made of the VKU-25 carbon fiber prepreg, the functional operability of the detonation technology for any lightning-hazardous zone of the nacelle according to AP-25 has been demonstrated. No through destruction of carbon fiber was found in samples with detonation spraying. Samples without lightning-protective coating turned out to be non-resistant to the lightning current exposure. The tried detonation technology has the technical potential to reduce (up to 3 times) the specific gravity of the conduc-tive layer of the lightning-protective coating used in the engine polymer nacelles of commercially operated aircraft engines.