The Research On High Temperature Oxidation And Hot Corrosion Of Ni-based Superalloy Containing Rhenium

In order to meet the fire-end components of ship gun ocean climate conditions ofwork, a nickel-based superalloy containing rhenium was developed. High temperatureoxidation and hot corrosion experiments were conducted in different conditions for thenickel-based superalloy.By means of TGA, XRD and SEM/EDX, the mechanism of theoxidation and hot corrosion mechanism of the alloy were researched for providing atheoretical basis for the application of the superalloy in the naval artillery.Respectively, the oxidation kinetic curves of isothermal oxidation for thenickel-based superalloy at900℃and1000℃for300h are subject to oxidation initialoxidation rate is rapid, with the oxidation time, the increasing of oxidation weightoverall tends to be smooth, but the oxidation kinetics curve for superalloy later has awavy change and obviously for the higher oxidation temperature. The initial oxide onthe superalloy surface in high temperature for900℃and950℃were consisted of NiO,and Ni2Cr2O4and Ni2CoO4; later the oxide mainly were consistent of Ni2Cr2O4andNi2CoO4, also formed a large number of Al2O3and a small amount of CrTaO4. Thenickel-based superalloy at900℃and1000℃appeared both oxidation and nitridationphenomenon, and the inner oxide and nitride showed a significant level of distribution.The internal oxidation was in the medial border of superalloy and oxide film whichcontained the oxide for the block element Al. In addition, the needle nitride AlN wasformed beneath the oxide.The nickel-based superalloy beneath75%Na2SO4+25%K2SO4mixture saltdeposit at900℃and950℃corrosion kinetic curves of100h obeyed linear law, but thecorrosion kinetic curves of900℃was found obvious turning for slope decreasing for thecorrosion mechanism of900temperature changes. The nickel-based superalloy surfacecorroded for900℃mainly formed NiCr2O4、AlTaO4and CrTaO4, as well as a largenumber of Al2O3and a small amount of sulfide Ni3S2and Cr3S4; the nickel-basedsuperalloy corroded for950℃mainly formed NiO and Al2O3,as well as a amount ofoxide and sulfide, Ni3S2and Cr3S4.The nickel-based superalloy at900℃and950℃oxidation100h appeared internal oxidation significantly, especially corroded for950℃ near the substrate appeared sulfide punctate, consisting of main components of sulfideelement Cr.