Monotonic and cyclic deformation behavior of plasma-sprayed coatings under uni-axial compressive loading

摘要

Monotonic and cyclic deformation behavior of thermal barrier coatings under uni-axial compressive loading was examined. Specimens of plasma-sprayed ZrO_2-8 percent Y_2O_3, Al_2O_3, CoNiCrAlY and NiCr were fabricated to test the coating materials independent of the substrates. Stress-strain response was measured using the laser speckle strain-displacement gauge (SSDG). The coatings showed nonlinear stress-strain responses with considerably low elastic moduli compared with those of the bulk materials. The nonlinearity of the stress-strain response was insignificant if the coating contained few microscopic defects and pores. In case of the coating with many defects and pores, the compliance was found to decrease after the coating underwent compressive stress and the compliance was also found to decrease with increasing the number of compressive stress cycles.