| Popis: |
Stable adherent high‐emissivity tungsten carbide/carbon coatings have been deposited onto iridium and carbon/carbon substrates by reactively sputtering a cemented tungsten carbide target in an acetylene–argon atmosphere. The thin, light‐weight, high‐emissivity coatings have potential for improving the heat transfer characteristics and reducing the weight of satellite thermoelectric generators. The tungsten carbide/carbon coating emissivity increased from 0.35–0.91 as the acetylene partial pressure during deposition increased from 0–0.133 Pa. Auger electron spectroscopy, x‐ray diffraction, and electron microprobe analysis of the coatings revealed that the film structure and composition changed from β‐WC1‐x to an amorphous carbon‐rich material as the acetylene partial pressure exceeded 0.034 Pa. One‐micron‐thick tungsten carbide/carbon films on iridium withstood vacuum anneals at 1775 K for 19 h without significant degradation in the coating durability or emissivity. |
