Zr–O–B ceramics/Ni–20%Cr alloy graded coating produced by electrothermal explosion spraying

Zr–O–B ceramic coatings were produced by electrothermal explosion spraying using a mixture of Zr and B2O3 powders. Coatings reactively sprayed consisted mainly of ZrO2, ZrB2, and a zirconium compound. Energy-controlled multiple sprays against the same substrate brought the hetero-structure composed of a top Zr–O–B ceramic layer and a graded layer whose composition continuously changed from the ceramics to an undercoat of Ni–20%Cr. Hardness of the ceramic layer was close to that of sintered ZrB2.