AlPO4–C coating deposited by sol–gel technique on Ni base superalloy substrate Nimonic-75 has been examined for high emissivity applications. The coating showed a spectral (2–25 μm wavelength) emissivity in the range of 0·8–0·91, and the emissivity increased with coating thickness. The coating exhibited a reasonably good adhesion with the substrate, as determined from nanoscratch test. The above coating also had a good oxidation resistance in air at 800 and 900°C under cyclic heating and cooling conditions.
LaubB, VenkatapathyE: ‘Thermal protection system technology and facility needs for demanding future planetary missions’, Proc. Int. Workshop on ‘Planetary probe atmospheric entry and descent trajectory analysis and science’, Lisbon, Portugal, October 2003, ESA Publications Division, 239–247.
