HIGH-TEMPERATURE ZrB2-BASED COATINGS ON METALLIC ALLOYS PRODUCED BY HIGH-VELOCITY AIR-FUEL THERMAL SPRAYING

摘要

The composition and structure of ZrB2-based coatings with MoSi2, SiC, and AlN additions on metallic alloys produced by high-velocity air-fuel thermal spraying are studied. The use of composite powders with a low content of the NiCr binder (<= 10 wt.%) is shown to be beneficial due to intensive adhesive interaction of the components. The phase transformations induced by high-temperature thermodynamically nonequilibrium processes, including oxygen-assisted ones, occur when the coatings are being formed. The coatings with a hardness of similar to 15 GPa and a porosity of <= 4% are characterized by a granular structure without cracks and have a 50-120 mu m thick ceramic layer and an interfacial layer of uniform width (similar to 10 mu m) at the boundary between the NiCr alloy and stainless steel.