Experimental analysis of thermal and thermo-physical behavior of 7Y-PSZ as thermal barrier coating overA336 alloy substrate

Author(s): A.K.Saini

The worldwide research in the field of thermal barrier coatings has suggested zirconia (ZrO2) as a highly suitable material for high temperature engineering applications. In the present investigation, oxy-acetylene flame heating tests were conducted over plasma sprayed yttria partially stabilized zirconia (7Y-PSZ), coated over an aluminium alloy substrate of grade A336 using an intermediate bond coat of NiCrAlY and it was found that the coating was highly effective in lowering the temperatures within the substrate. A coating of thickness of 150 microns caused a drop of 4.48% in the maximum temperature set up within the substrate while the coating of 300 microns thickness resulted into a temperature decrease of 8.11% at the same surface. Similarly, top surface temperature was found to improve by 21.12% and 35.24% for 150 microns and 300 microns thick coatings, respectively. Further, the special techniques of X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to visualize the effects of high temperature atmosphere on the coating material and the results showed that the thicker coating was more prone to degradation as compared to the thinner one.

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