Abstract

A P.S.Z. coating elaborated by r.f. plasma spraying was studied and compared to industrial arc plasma-sprayed P.S.Z. coatings to evaluate the quality of the corresponding thermal barrier coating system for gas turbine applications. One commercial ZrO2 - 8% Y2O3 powder was sprayed with two industrial d.c. torches (7MB and F4) and one r.f. plasma torch (Tekna PL50). Physical properties such as density, porosity and thermal diffusivity were measured on the three types of P.S.Z. coating. The microstructure and quantitative phase analysis were respectively investigated by S.E.M. and X-Ray diffraction. The burner rig tests on the T.B.C. systems showed that the thermal shocks resistance on the r.f. coating was at least the same as the others. Induction plasma spraying gave a high deposit efficiency (around 80%) and a P.S.Z. coating with very interesting thermal properties. All these facts demonstrate that r.f plasma spraying can be a competitive process to produce high quality thermal barrier coatings.

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