DYNAMIC OXIDATION PERFORMANCE OF NARLOY-Z WITH CU-30 VOLUME PERCENT CR COATING

The copper alloy NARloy-Z (Cu-3Ag-0.5Zr wt%) has good potential for hi gh heat flux structural applications in hypersonic vehicles because of its high thermal conductivity and high temperature strength. However, it is subject to severe oxidation at temperatures where it might be u sed. ci Cu-30 vol% Cr protective coating produced by low-temperature a re vapor deposition was evaluated under dynamic oxidation in an electr ic are-heated wind tunnel. The emittance of the coating is greater tha n the emittance of the alloy, and the recombination efficiency of the coating is typical of values encountered with metal alloys and metalli c oxides. The coating protects the alloy under dynamic oxidation condi tions, with specimens gaining less than 1 mg/cm(2) over a 10-h exposur e period. Protection of the alloy from oxidation results from a contin uous layer of Cr2O3 that it is partially shielded from the hostile dyn amic oxidation/atomic oxygen environment by a layer of CuO.