CERAMIC-PLASTIC COMPOSITES FOR RAIN EROSION RESISTANT RADOMES.
NAVAL ORDNANCE LAB WHITE OAK MD
Pagination or Media Count:
Various ceramic materials in thin sheet form for use in covering critical areas of glass fiber reinforced plastic radomes were evaluated in rain erosion resistance. Of the ceramic materials tested, dense, high purity alumina coatings were the most resistant. However, as the alumina density increases and porosity decreases, the bond to the reinforced laminate becomes weaker. Advantage can be taken of the natural gradient in porosity of flame sprayed Rokide A alumina sheet by removing the coating from the metal substrate upon which it is formed and bonding the more porous face against the reinforced plastic laminate either as-sprayed or after firing. Rain erosion resistance appeared to increase also when the Rokide A surface, exposed to rain erosion, was impregnated with Epon 1031 epoxy resin and polished smooth. Matching of the thermal expansion of the laminate and the alumina coating is very important. In general, the better alumina coatings were about two and one-half times more rain erosion resistant than the standard neoprene coating. Pyrolytic boron nitride and glass bonded refractory oxides, such as zirconia or alumina, eroded rapidly and did not show up as well as neoprene. Author
- Coatings, Colorants and Finishes