Bond coatings, CoNiCrAlY, are prepared on Inconel 738 substrate by vacuum plasma spray (VPS). Mechanical properties of VPSed CoNiCrAlY coatings are investigated via Taguchi method and L18(21×37)orthogonal arrays to determine the optimal setting and the relationship of experimental variables. Seven parameters were considered as follows: (A) arc current; (B) primary gas flow rate; (C) secondary gas flow rate; (D) stand-off distance; (E) working pressure; (F) carrier gas flow rate (Ar); and (G) powder feeding rate.The effect of carrier gas flow rate on the porosity is determined to be the highest among the parameters investigated. Higher microhardness values are observed for the VPSed coatings as compared to the coatings prepared by conventional high velocity oxygen fuel probably due to low amount of the porosity.

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