Oxygen Catalytic Recombination on Copper Oxide in Tertiary Gas Mixtures

Abstract

This paper presents experimental and theoretical results on catalytic phenomenon occurring in a test gas consisting of a mixture of 21% oxygen and 79% argon. The heat-transfer rates at the stagnation point of a blunt body are measured in a shock tube using a thin-film gauge. The surface of the test model was coated with silicon dioxide, copper oxide, or copper. The copper-coated model showed a heat-transfer-rate-value 45% higher than that to a silicon-dioxide-coated model and 28% higher than that to a copper-oxide-coated model. The model surface was examined under a scanning electron microscope before and after the tests to confirm that the surface structure remained intact. The heat-transfer-rate formula obtained from the present analysis extends the theory of Goulard for a binary-gas mixture to a tertiary mixture. When the surface has low catalytic efficiency the tertiary formula gives nearly the same heat-transfer rate as Goulard's formula, but when catalytic efficiency is high some differences are seen. Using this theoretical result, the experimental data are analysed. Catalytic efficiency of copper oxide is deduced to be 0.0026 to 0.0032, whereas copper has an efficiency of 0.016.