Abstract
It is very important to clarify the characteristic deformation behaviors of thermal barrier coatings. Monotonic and cyclic deformation behaviors of thermal barrier coatings under uniaxial compressive loading were examined. Specimens of plasma-sprayed ZrO2-8%Y2O3 and CoNiCrAlY were fabricated to test the coating materials independent of the substrates. The specimen was fabricated by dissolving out the substrate only at the region of gauge length. Thicknesses of the coatings were 300 μm. The stress-strain response was measured using the laser speckle strain / displacement gauge (SSDG). ZrO2-8%Y2O3 coating showed the nonlinear stress-strain response with a considerably lower elastic modulus which value was about 10% of sintering ceramics. The coating was found to leave permanent strain by compressive loading: the compliance of the coating decreased by compressive loading. The compliance was also found to decrease furthermore by undergoing cyclic compressive load. On the contrary, CoNiCrAlY coating deposited by low pressure plasma spraying was found to show the stress-strain response with insignificant nonlinearity. The compliance of the stress-strain curve didn’t also decrease with increasing the number of compressive stress cycles. It was found that coating with many defects and pores showed stress-strain response with large nonlinearity.
