Plasma-sprayed ceramic thermal barrier coatings for turbine vane platforms

Abstract

Increased resistance of plasma-sprayed ceramic coatings to cyclic thermal exposure can be achieved by increasing the strain tolerance of the ceramic and by controlling harmful residual stresses. Strain tolerance can be increased by controlling internal structure to minimize harmful flaws and to add favorable discontinuities. Structures with controlled porosity, internal microcracking and segmentation were shown to give good resitance to thermal cycling. Plasma spraying on low temperature substrates was shown to increase spalling life in a cyclic thermal test by reducing damaging compressive stresses.