Thermal barrier coatings with Al2O3–Pt composite bond-coat and La2Zr2O7–Pt top-coat prepared by cathode plasma electrolytic deposition

Abstract

Abstract Thermal barrier coatings (TBCs) with Al2O3–Pt composite bond-coat and La2Zr2O7–Pt top-coat were prepared by cathode plasma electrolytic deposition (CPED). The Al2O3–Pt composite bond-coats about 6–8 μm thick have rough and porous surfaces, and show a good adhesion with the substrate. The La2Zr2O7–Pt top-coats with a thickness of 120 μm possess a crack-free surface and are composed of pyrochlore La2Zr2O7. Owing to the chemical interaction between the La2Zr2O7 and molten mixture of Na2SO4 + V2O5, such TBCs do not possess a good hot corrosion resistance. However, it is demonstrated, from the cyclic oxidation test, thermal insulation capability test and mechanical properties test, that such TBCs possess not only excellent resistance to oxidation and spallation, but also quite well thermal insulation. These beneficial effects can be attributed to that: such TBCs can prevent high-temperature oxidation owing to the low oxygen diffusion rate of Al2O3 and La2Zr2O7, provide well thermal insulation owing to the low thermal conductivity of La2Zr2O7–Pt top-coat, and possess good mechanical properties owing to the toughening effect of Pt particles.