Study on microstructure and thermal shock resistance of plasma sprayed Cr2O3/8YSZ composite coating

In order to explore the high temperature performance of Cr2O3/8YSZ composite coating, four kinds of Cr2O3/8YSZ composite coatings were prepared on the surface of Q235 steel by using the plasma spraying technology (the content of 8YSZ is 50%, 30%, 20% and 0%, respectively). The morphology of the coating was characterized through thermal field emission scanning electron microscopy, and the distribution of elements in the section of the coating was scanned by using EDS line. The phase composition of the composite coating was analyzed by using X-ray diffractometer, and the surface roughness of the composite coating was measured by using surface profilometer. The microhardness of the coating was measured by using automatic micro-Vickers hardness tester, and the scratch resistance of the coating was compared by using scratch tester. The thermal shock resistance of the coating was tested in Gleeble-3800 thermal physical simulator, and the cross section morphology after thermal shock was observed and analyzed. The results show that when the ratio of Cr2O3 to 8YSZ is 7∶3, the sample coating has good thermal shock resistance due to the deflection effect of 8YSZ on the vertical cracks and the thermal stress release effect of the pores and cracks in the coating.