ULTRAHARD COATINGS ON METALS

Arc heater segments fabricated from oxygen free high conductivity copper (OFHC) need an effective means of dissipating high heat flux loads from the inner bore while maintaining electrically non-conducting surfaces. Smooth, ultrahard coatings that have good thermal conductivity and little or no electrical conductivity can protect these surfaces by preventing arc erosion. In this Phase I effort, Materials Modification Inc., (MMI) proposes several different approaches to address this requirement using cubic boron nitride and aluminum nitride coatings over OFHC surfaces. The coatings will be also exposed to elevated temperatures to ascertain their oxidation resistance and characterized extensively using standard optical, SEM/EDAX hardness techniques. After preliminary screening in Phase I, we will proceed in Phase II to deposit coating on arc heater segments for actual testing in an operating system at AEDC.