The effect of ion implantation on the oxidation resistance of vacuum plasma sprayed CoNiCrAlY coatings

摘要

CoNiCrAlY coatings prepared by vacuum plasma spraying (VPS) were implanted with Nb and Al ions at a fluence of 10~(17) atoms/cm~2. The effects of ion implantation on the oxidation resistance of CoNiCrAlY coatings were investigated. The thermally grown oxide (TGO) formed on each specimen was characterized by XRD, SEM and EDS, respectively. The results showed that the oxidation process of CoNiCrAlY coatings could be divided into four stages and the key to obtaining good oxidation resistance was to remain high enough amount of Al and promote the lateral growth of TGO. The implantation of Nb resulted in the formation of continuous and dense Al_2O_3 scale to improve the oxidation resistance. The Al implanted coating could form Al_2O_3 scale at the initial stage, however, the scale was soon broken and TGO transformed to non-protective spinel.