High Temperature Oxidation Resistance Of Nickel-based Alloys And Protective Coating

Nickel-based alloys have excellent resistance to oxidation and mechanical properties at high temperatures,are widely used in aircraft engine turbine blades and other parts of the hot end,in order to meet the development needs of modern aviation engines,its turbine blades in protective coating to be applied before serving layer to improve the high temperature oxidation resistance.In this paper,a nickel-based alloy and by multi-arc ion plating of Ni11Co26Cr6Al0.5Y protective coating high temperature oxidation experiments were carried out by X-ray diffraction,scanning electron microscopy techniques to study the nickel-based alloys and protective coating high temperature oxidation behavior layer,and a high temperature oxidation mechanism analysis.Alloy at 900℃ and 1000℃ oxidation kinetics 300 h wavy change,have to follow the high temperature oxidation of the alloy in the initial rate of weight gain rapidly with increasing oxidation time,decreased rate of weight gain,weight gain curve gradually getting in the flat,but the alloy weight gain overall upward trend.Alloy 900℃ high temperature oxidation over time,the surface oxide film mainly composed of Al element,mixed oxides and composite oxides of Cr and Ti elements,and only a few close to the oxide film generated at the oxide inside the alloy.When the alloy at 1000℃ high temperature oxidation,oxide film can be divided into three layers,the outer layer of the oxide film which is mainly composed of Ni oxide interlayer oxide film mainly composed of oxides of Cr and Al elements,most within the lower oxide film mainly as oxide Al element inside its alloy substrate oxidation is not now clear,indicating that the oxide film produced better protective properties of the alloy matrix.Ni11Co26Cr6Al0.5Y coating at 1000℃ and 1100℃ oxidation kinetics of 300 h are manifested as early oxidation,alloy faster rate of weight gain with increasing oxidation time,gradually slowing the rate of weight gain,followed by oxidation kinetics leveling off,in line with an approximate parabolic law.Ni11Co26Cr6Al0.5Y coating after oxidation at 1000℃,the surface oxide film is mainly composed of loose texture metastable phase θ-Al2O3.Ni11Co26Cr6Al0.5Y coating after oxidation at 1100℃,the surface oxide film is mainly composed of dense texture of the steady-state phase α-Al2O3,and the cracks in varying degrees.Coating alloy samples surface after the high temperature oxidation were now clear off phenomenon.Ni11Co26Cr6Al0.5Y coating high temperature oxidation process,in which the Co,Cr acts as a third element to promote a better oxidation of Al element to generate high temperature oxidation resistance of Al2O3.Where in Y is an active element,to improve the adhesion of the surface oxide film.