Development of Oxidation Barrier Coatings for Heat Exchanger Panels for NASP Scramjets

Development of the National Aerospace Plane (NASP) has exposed a serious need for materials and coatings that can survive very severe thermal environments. The heat exchanger panels for the proposed scramjet power system must withstand temperatures in excess of 2300 degrees F for significant periods of time. The panel substrate material has been proposed to be Mo-47% Re alloy, which has the required thermal capability, except for the fact that it rapidly oxidizes at this temperature. It has also been determined that a platinum, or possibly a platinum sandwiched rhodium, coating will afford the most reliable oxidation protection for the system. This proposal addresses problems encountered to date in applying such coatings to the refractory substrate. Bonding and coating porosity have been major drawbacks. The proposed work package will develop solutions to these problems by providing new processes for better preparation of the substrate for application of high density platinum (or platinum-rhodium) coatings of high bond integrity and excellent oxygen corrosion performance.