SELECTED PROPERTIES OF THERMALLY SPRAYED OXIDE CERAMIC COATINGS

The article presents the results of the study on exploitation properties of flame sprayed ceramic coatings produced by oxide ceramic material in the form of powder on the aluminum oxide Al2O3 matrix with 3% titanium oxide TiO2 addition and also on the zirconium oxide (ZrO2) matrix with 30% calcium oxide (CaO) on the substrate of unalloyed structural steel of S235JR grade. As a primer powder, metallic powder on the base of Ni-Al-Mo has been applied. Plates with dimensions of 5x200x300 mm and also front surfaces of square 40x50 mm cylinders have been flame sprayed. Spraying of primer coating has been done using RotoTec 80 torch and external specific coating has been done with CastoDyn DS 8000 torch. Investigations of coating properties are based on metallography tests, phase composition research, measurement of microhardness, coating adhesion to the ground research (acc. to EN 582: 1996 standard), abrasive wear resistance (acc. to ASTM G65 standard) and erosion wear resistance (acc. to ASTM G76-95 standard) and thermal stroke study. Performed tests have shown that the flame spraying with 97% Al2O3 powder containing 3% TiO2 and also by the powder based on zirconium oxide (ZrO2) containing 30% calcium oxide (CaO) performed in a wide range of technological parameters allow to obtain high quality ceramic coatings with thickness up to ca. 500 mu m on a steel substrate. The primer coating sprayed with the Ni-Al-Mo powder to the steel substrate and external coatings sprayed has the of mechanical bonding character. The coatings are characterized by high adhesion to the substrate and also high erosion and abrasive wear resistance and the resistance for cyclic thermal stroke.