Influence of a Nb interlayer on the oxidation behavior of a Cr coating deposited on Inconel 718 alloy substrate
Annotatsiya
In order to improve the high-temperature oxidation resistance of Inconel 718 alloy, a Nb/Cr composite coating was manufactured using double glow plasma surface alloying (DGPSA). The addition of the Nb interlayer did not alter the phase composition of the Cr coating, which retained its bcc-Cr structure. However, it induced a shift in the preferred orientation of the Cr coating from (200) to (110). After 100-h cyclic oxidation at 800 °C and 900 °C, compared to the single Cr coating, the Nb/Cr composite coating formed a denser surface oxide layer with a reduced thickness. The total weight gain per unit area of the Inconel 718/Cr coated sample after oxidation for 100 h at 800 °C and 900 °C was 0.4707 mg/cm 2 and 0.6452 mg/cm 2 respectively; the Nb/Cr composite layer sample had weight gains of 0.2083 mg/cm 2 and 0.3700 mg/cm 2 after oxidation for 100 h at 800 °C and 900 °C respectively. When the temperature increases from 800 °C to 900 °C, Nb diffuses toward the Cr coating during the oxidation process, resulting in oxidative segregation. Meanwhile, Nb exerts a solute drag effect to inhibit the further supply of Cr to the surface layer, which induces a reduction in the size of oxide particles in the surface layer. Consequently, the material exhibits superior oxidation resistance.
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