Determination of Optical Properties in Germanium Carbon Coatings Deposited by Plasma Enhanced Chemical Vapor Deposition

In this research, Germanium-carbon coatings were deposited on ZnS substrates by plasma enhanced chemical vapor deposition (PECVD) using GeH4 and CH4 precursors. Optical parameters of the Ge1-xCx coating such as refractive index, Absorption coefficient, extinction coefficient and band gap were measured by the Swanepoel method based on the transmittance spectrum. The results showed that the refractive index of the Ge1−xCx coatings at the band of 2 to 2.2 µm decreased from 3.767 to 3.715 and the optical gap increased from 0.66 to 0.72 eV as CH4:GeH4 increases from 10:1 to 20:1

COMPARISON OF THERMAL SHOCK BEHAVIOR OF 7YSZ, 15YSZ AND SYSZ THERMAL BARRIER COATINGS PRODUCED BY APS METHOD

Nanostructured scandia, yttria doped zirconia (SYSZ), 7wt. % yttria stabilized zirconia (7YSZ) and 15YSZ thermal barrier coatings (TBCs) were produced by plasma spraying on nickel-based superalloy substrates with NiCrAlY as the bond coat. The thermal shock behavior of the three as-sprayed TBCs at 1000 °C was investigated. The results indicated that the thermal cycling lifetime of SYSZ and 7YSZ TBCs was longer than the 15YSZ TBCs due to the lower thermal mismatch stress between the ceramic layer and the metallic layer at high temperature and higher amount of tetragonal phase