Graded-Composition Refractory Coatings for Protection of Cu-Rails for Electromagnetic Launchers

The Navy is developing an electromagnetic (EM) launcher for long-range naval surface-fire-support. Severe operating conditions of the EM system place stringent requirements for materials, including high current and magnetic fields, high temperatures, contact with liquid metals, high stress/gouging from balloting contacts and high-speed-sliding electrical-contact with an Al armature. Engineered Coatings Inc., Southwest Research Institute, and the Institute for Advanced Technology, University of Texas, will demonstrate thick Plasma-Enhanced Physical Vapor Deposited coatings to protect copper rails with: 1) graded composition Cu-refractory metal (e.g., Ta, W or Cr) coatings; 2) solid-lubricating nanomultilayer nitride coatings (e.g., TiAlCrN / TiN bilayers); and 3) nanostructured (nm crystal size) nitride coatings. Basic coating properties; electrical resistivity/conductivity, indent-adhesion/toughness, hardness after thermal exposure, oxidation resistance, and sub-scale rail gun experiments, will be determined for these coating groups. A down-selected coating will have additional rail-gun tests in the Phase I option to assess coating reliability and reproducibility.