In order to improve the hot corrosion resistance of DZ125 alloy,Ce-Y modified aluminum coatings were prepared on DZ125 alloy by pack cementation process at 950°C for 2 h.The microstructure,phase constitution and ...In order to improve the hot corrosion resistance of DZ125 alloy,Ce-Y modified aluminum coatings were prepared on DZ125 alloy by pack cementation process at 950°C for 2 h.The microstructure,phase constitution and formation mechanism of the coatings were investigated.The hot corrosion behaviors of DZ125 alloy and the coatings in molten salt environment of 25%K2SO4+75%Na2SO4(mass fraction)at 900°C were studied.Results show that the obtained Al-Ce-Y coatings were mainly composed of Al3Ni2,Al3Ni and Cr7Ni3,with a thickness of about 120μm.After hot corrosion test,DZ125 alloy suffered catastrophic hot corrosion and serious internal oxidation and internal sulfidation arose.Two layers of corrosion products formed on surfaces of DZ125 alloy,including the outer layer consisting of Cr2O3 and NiCr2O4,and the inner layer of Al2O3,Ni3S2 and Ni-base solid solution.After being coated with Al-Ce-Y coating,the hot corrosion resistance of DZ125 alloy is improved notably,due to the formation of a dense scale mainly consisting of Al-rich Al2O3 in the coating layer.展开更多
Y-modified Cr-Al coatings were co-deposited on DZ125 alloy by a pack cementation process,and the microstructures,constituent phases,and formation mechanisms of the obtained coatings were studied.The oxidation resistan...Y-modified Cr-Al coatings were co-deposited on DZ125 alloy by a pack cementation process,and the microstructures,constituent phases,and formation mechanisms of the obtained coatings were studied.The oxidation resistance of the coatings was also investigated.The experimental results show that the coating prepared by co-depositing Cr-Al-Y at 1050℃for 2 h has a multi-layered structure with an outer layer composed of Cr and Ni_(3)Cr_(2),a middle layer composed of Ni_(3)Cr_(2) and Al_(13)Co_(4),and an inner layer composed of Ni_(3)Al.The co-deposited Y is mainly present in the outer and middle layers of the coating.The coating formation process follows a sequential deposition mechanism in which Al is deposited during the initial stage,followed by Cr deposition.After oxidation at 1100℃for 100 h,a dense Cr_(2)O_(3)·Al_(2)O_(3) scale forms on the obtained coating,which effectively protects the DZ125 alloy from oxidation by preventing the inward diffusion of oxygen.展开更多
The key in antioxidant capacity of aero-engine hot components is the protective oxide scales.Many factors can affect the performance of oxide scales.The effect of tensile stress on high-temperature oxidation behavior ...The key in antioxidant capacity of aero-engine hot components is the protective oxide scales.Many factors can affect the performance of oxide scales.The effect of tensile stress on high-temperature oxidation behavior of directionally solidified DZ125 Ni-based superalloy was investigated by thermogravimetric analysis(TGA).Tensile samples were subjected to stress of 100 MPa,and the oxidation behavior was studied at 980℃in air.The surface and cross-sectional morphologies of the oxidized coating were analyzed by scanning electron microscope(SEM).The influence of tensile stress on the oxidation behavior of directionally solidified DZ125 Ni-based superalloy at high temperature was discussed.Results show that an applied tensile stress generally leads to larger Cr/Ni mass ratio in the oxide scales,greater overall chromium depletion values directly under the oxide scales,lower specific weight gain values and thinner oxide scales.These factors are attributed to the formation of fast diffusion paths for Cr atoms to diffuse to the surface under tensile stress,thus causing a reduction in the duration of the less protective transient oxidation period and promoting a faster formation of the protective Cr_(2)O_(3)layer.展开更多
基金Project(51961003)supported by the National Natural Science Foundation of ChinaProject(NGY2018-148)supported by the Science and Technology Research of Ningxia Colleges,ChinaProject(NZ16083)supported by Key Program of Natural Science Foundation of Ningxia,China
文摘In order to improve the hot corrosion resistance of DZ125 alloy,Ce-Y modified aluminum coatings were prepared on DZ125 alloy by pack cementation process at 950°C for 2 h.The microstructure,phase constitution and formation mechanism of the coatings were investigated.The hot corrosion behaviors of DZ125 alloy and the coatings in molten salt environment of 25%K2SO4+75%Na2SO4(mass fraction)at 900°C were studied.Results show that the obtained Al-Ce-Y coatings were mainly composed of Al3Ni2,Al3Ni and Cr7Ni3,with a thickness of about 120μm.After hot corrosion test,DZ125 alloy suffered catastrophic hot corrosion and serious internal oxidation and internal sulfidation arose.Two layers of corrosion products formed on surfaces of DZ125 alloy,including the outer layer consisting of Cr2O3 and NiCr2O4,and the inner layer of Al2O3,Ni3S2 and Ni-base solid solution.After being coated with Al-Ce-Y coating,the hot corrosion resistance of DZ125 alloy is improved notably,due to the formation of a dense scale mainly consisting of Al-rich Al2O3 in the coating layer.
基金Funded by the Basic Scientific Research of the North Minzu University(FWNX42)the Natural Science Foundation of Ningxia(2020AAC02025)+1 种基金the National Natural Science Foundation of China(51961003 and 52161009)the Ningxia Youth Talents Supporting Program(TJGC2019040)。
文摘Y-modified Cr-Al coatings were co-deposited on DZ125 alloy by a pack cementation process,and the microstructures,constituent phases,and formation mechanisms of the obtained coatings were studied.The oxidation resistance of the coatings was also investigated.The experimental results show that the coating prepared by co-depositing Cr-Al-Y at 1050℃for 2 h has a multi-layered structure with an outer layer composed of Cr and Ni_(3)Cr_(2),a middle layer composed of Ni_(3)Cr_(2) and Al_(13)Co_(4),and an inner layer composed of Ni_(3)Al.The co-deposited Y is mainly present in the outer and middle layers of the coating.The coating formation process follows a sequential deposition mechanism in which Al is deposited during the initial stage,followed by Cr deposition.After oxidation at 1100℃for 100 h,a dense Cr_(2)O_(3)·Al_(2)O_(3) scale forms on the obtained coating,which effectively protects the DZ125 alloy from oxidation by preventing the inward diffusion of oxygen.
基金financially supported by the National Natural Science Foundation of China (No.51571010)the National Basic Research Program of China (No.2015CB057400)
文摘The key in antioxidant capacity of aero-engine hot components is the protective oxide scales.Many factors can affect the performance of oxide scales.The effect of tensile stress on high-temperature oxidation behavior of directionally solidified DZ125 Ni-based superalloy was investigated by thermogravimetric analysis(TGA).Tensile samples were subjected to stress of 100 MPa,and the oxidation behavior was studied at 980℃in air.The surface and cross-sectional morphologies of the oxidized coating were analyzed by scanning electron microscope(SEM).The influence of tensile stress on the oxidation behavior of directionally solidified DZ125 Ni-based superalloy at high temperature was discussed.Results show that an applied tensile stress generally leads to larger Cr/Ni mass ratio in the oxide scales,greater overall chromium depletion values directly under the oxide scales,lower specific weight gain values and thinner oxide scales.These factors are attributed to the formation of fast diffusion paths for Cr atoms to diffuse to the surface under tensile stress,thus causing a reduction in the duration of the less protective transient oxidation period and promoting a faster formation of the protective Cr_(2)O_(3)layer.
