Preparation of Chameleon Coatings for Space and Ambient Environments (Preprint)
NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF PHYSICS
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Tribological coatings of yttria stabilized zirconia YSZ, gold, diamond like carbon DLC and MoS2 were synthesized using magnetron assisted pulsed laser deposition MSPLD. The coatings were synthesized in four-component and three-component combinations that included YSZAuDLCMoS2, YSZAuMoS2, and YSZAuDLC. A range of coating compositions was studied to explore coating optimization for low friction in varying environments dry, humid and high temperature. For four-component YSZAuDLCMoS2 coatings, the optimal compositions for friction adaptation between dry nitrogen and humid air included relatively high concentrations of the soft phase, Au 20 at. , and low amounts of the hard phases, DLC and YSZ. Ex situ Raman spectroscopy analysis indicates that friction adaptation involves a combination of both lubricating species, MoS2 and carbon where transitions of DLC to graphitic-carbon and amorphous MoS2 to its hexagonal phase occurs after cycling between both room temperature humid air and dry nitrogen. In large carbon concentrations 30 at. , the DLC component was found to be detrimental for friction in dry nitrogen and humid air, but promoted a longer coating wear life at 500 deg C. The three-component coating of YSZAuMoS2 performed well in both dry nitrogen and humid air, suggesting a synergism between Au and MoS2, where carbon was not necessary for lubrication in humid air.
- Atmospheric Physics
- Coatings, Colorants and Finishes