Research On Aluminum-Silicon And Graphene Coating Of GH4413 Alloy For Power Turbine Blades

As a hot end component,turbine blades need to meet the most severe conditions in the service of aircraft engines and industrial gas turbines,and ship gas turbines must not only bear high temperature and complex stress conditions in the marine environment,but also need to withstand the severe test of oxidation and corrosive atmosphere.GH4413 alloy is a precipitation-strengthened nickel-based deformed superalloy with excellent comprehensive mechanical properties and corrosion resistance,and is used for 5 and 6 stage turbine blades of marine gas turbines.In order to better meet the service conditions,this paper studies the Al-Si coating and graphene-modified SiO₂ coating on the surface of GH4413 alloy,which play a good protective role on the blade surface.The thermal corrosion resistance of GH4413 alloy after Al-Si and graphene coating and the influence of mechanical properties such as tensile,durable and fatigue.The combination of coating process and alloy heat treatment system can improve the corrosion resistance of the alloy without damaging the mechanical properties of the alloy,and provide theoretical and experimental data support for prolonging the service life of power turbine blades and reducing the cost of blades.Combined with the morphology,composition and cross-sectional morphology of the oxide film after thermal corrosion,the thermal corrosion resistance of the two coatings was comprehensively judged.The results show that the weight loss of the uncoated alloy is obvious at a temperature greater than 600℃,and after 100h corrosion,Al-Si coating and graphene modified SiO₂ The coating still completely covers the alloy surface and has good corrosion resistance.The corrosion results of graphene-modified SiO₂ coating were slightly better than that of Al-Si coating,and the sample only formed Al₂O₃ at the interface between the coating and the alloy.No other corrosion products were found,SiO₂ was very stable under corrosive salts and had good corrosion resistance and peeling resistance,and the addition of graphene could inhibit the formation of harmful phases,which was beneficial to the thermal corrosion resistance of the coating.The thermal oxidation behavior of nickel-based GH4413 alloy at 600℃,660℃and 700℃ after graphene modified silica coating were studied.The resistance of thermal oxidation of graphene-modified silica coating was judged.The results show that after oxidation at 600～700℃ to 1000h,the dense Al₂O₃ and Ti O₂ layer and a small amount of Cr₂O₃ appear at the interface between the coating and the matrix without loose harmful oxidation product.The addition of graphene reduces the chemical activity of the silica coating,and the coating is denser.The samples were coated with uncoated GH4413 alloy,Al-Si coating and graphene-modified SiO₂ at 660℃ and 850℃ Lower stretch experiment,and were subjected to durable test at 850℃/265MPa,and the high temperature rotational bending fatigue performance after Al-Si coating and graphene modified SiO₂coating.The results show that the tensile properties of two Al-Si coating systems are lower than those of uncoated alloys,The tensile properties of graphene-modified SiO₂-coated specimens were comparable to those of uncoated alloys.The long-lasting life of Al-Si coated specimens is smaller than that of uncoated specimens,and the test results showed that the reduction of the effective bearing area of GH4413 durable specimens after Al-Si coating was the main reason for the long life.The long-lasting life of the graphene-modified SiO₂-coated GH4413 alloy is comparable to that of the uncoated alloy,so the alloy parts of the same size are coated,graphene The durable performance of modified SiO₂ coating under the same conditions is better than that of Al-Si coating.The rotational bending fatigue cycle of GH4413 alloy after graphene modified SiO₂coating was higher than that of uncoated alloy,and the fatigue properties of the alloy were not affected after thermal corrosion by salting.After comprehensive analysis of the above experimental results,the graphene-modified SiO₂ coating has better comprehensive performance and is of great engineering significance for extending the service life of Marine gas turbine blades.