High-Temperature Oxidation of the Copper-Nickel Alloys Synthesized by Spark Plasma Sintering

The article presents data on heat resistance high-temperature tests of powder materials based on copper-nickel. The features of oxidation of samples of copper-nickel alloys with various alloying elements have been studied. Compaction of samples of copper-nickel alloys was performed by spark plasma sintering (SPS). The dependence of the growth rate of the oxide film on the temperature of high-temperature oxidation was established, and the effect of alloying elements in the composition of the samples on their heat resistance was considered. On the basis of the results of studies, the dependence of the oxide film growth rate on high-temperature oxidation and the influence of alloying elements in the composition of sintered copper-nickel alloys on their heat resistance was considered. It was determined that, for all the considered compositions of copper-nickel alloys synthesized by spark plasma sintering, the temperature of 1000 degrees C of 20-h test for heat resistance is not the limiting one, since the samples retain their integrity. It is shown that simultaneous alloying of copper-nickel alloys with aluminum and chromium provides the highest heat resistance. The rate of growth of scale for composition Cu-Ni-Cr-Al is 1.49 x 10(-3) g/cm(3), which is lower than the oxidation rate of pure nickel of 3.78 x 10(-3) g/cm(3) at 1000 degrees C. These two samples demonstrate the lowest weight gain after testing at 1000 degrees C; for compositions Cu-Ni-Al, Cu-Ni-Cr-Si, and 50 wt % Cu-50 wt % Ni, the oxidation rate increases by two orders of magnitude; for compositions Cu-Ni-Si and Ni, it increases by three orders of magnitude.