The influence of applied temperatures on the creep rupture life of the third-generation low-cost single crystal(SX)superalloy with Pt-Al coating was evaluated.The creep damage was observed under the conditions of 1100...The influence of applied temperatures on the creep rupture life of the third-generation low-cost single crystal(SX)superalloy with Pt-Al coating was evaluated.The creep damage was observed under the conditions of 1100℃/137 MPa,1120℃/137 MPa,and 1140℃/137 MPa.Results show that the properties of bare superalloy outperform those of coated superalloy under all test conditions.The most significant reduction in creep life reaches 50%when the test condition is 1100℃/137 MPa.At higher temperatures(1120 and 1140℃),the crack propagation rate in Pt-Al coatings to SX superalloy substrate decreases,thereby reducing the degradation degree of mechanical properties.Instead of the penetration into SX substrate,tip oxidation and Al diffusion of the coating cracks cause the formation of oxides,therefore leading to the slow degradation in microstructures of the substrate beneath the coating.At 1100℃,however,the microstructure of coating/SX superalloy substrate degrades due to the Al internal diffusion.This diffusion mechanism promotes the formation of harmful topologically close packed phases around 1100℃.At 1120 and 1140℃,the dislocation of SX superalloy substrate beneath the coating is relatively unchanged,compared to that in the inner superalloy.In contrast,the dislocation network of the substrate beneath the coating becomes sparse,and the number of superdislocations cutting intoγ′phases increases at 1100℃.展开更多
利用SEM和TEM对比研究了无涂层和Pt-Al涂层试样在760和980℃的拉伸性能。研究结果表明:在2个温度下,Pt-Al涂层试样的屈服强度均低于无涂层试样。由于Pt-Al涂层存在韧脆转变温度(ductile to brittle transition temperature,DBTT),因此...利用SEM和TEM对比研究了无涂层和Pt-Al涂层试样在760和980℃的拉伸性能。研究结果表明:在2个温度下,Pt-Al涂层试样的屈服强度均低于无涂层试样。由于Pt-Al涂层存在韧脆转变温度(ductile to brittle transition temperature,DBTT),因此在不同温度下涂层表现出不同的变形机制和裂纹萌生方式。在高温下由于β向γ′转变有利于位错产生滑移,从而导致Pt-Al涂层的塑性变形。Pt-Al涂层在DBTT以上拉伸强度的提高是由于Pt在β-NiAl相中起到固溶强化效应。展开更多
The prediction of fatigue life of metallic alloys is justly accepted as one of the most important phenomena in the field of metallurgical and mechanical engineering.At elevated temperatures,oxidation of the surfaces h...The prediction of fatigue life of metallic alloys is justly accepted as one of the most important phenomena in the field of metallurgical and mechanical engineering.At elevated temperatures,oxidation of the surfaces has an effective role in the fatigue strength and ductility of the alloys.In the present work,the effect of prior cyclic oxidation on the high temperature low cycle fatigue(HTLCF)properties of nickel-based superalloy Rene®80 has been assessed in the uncoated state and in the Pt-aluminide(Pt-Al)coated condition at 930℃.To apply cyclic oxidation,simulation of engine thermal exposure was carried out by exposing coated and uncoated fatigue specimens in the burner rig(120 cycles at 1100℃).The cyclic oxidation procedure led to a changing in the coating microstructure from the dual-phase(ξ-PtAl_(2)+β-(Ni,Pt)Al)to single phase(β-(Ni,Pt)Al).Results of HTLCF tests showed an improvement in the HTLCF life around 11.5%in the unexposed coated specimen(pre-cyclic oxidation)as compared to unexposed bare specimen,while this rise for exposed coated specimen(post-cyclic oxidation)was only 5%.Although a mixed mode fracture morphology(ductile and brittle)was observed on the fracture surfaces of failed specimens,the wider regions of brittle fracture belonged to exposed coated/uncoated ones.展开更多
The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）o...The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.展开更多
基金National Key Research and Development Program of China(2017YFA0700704)China Postdoctoral Science Foundation(2023M733570)+1 种基金Excellent Youth Foundation of Liaoning Province(2021-YQ-02)Science Center for Gas Turbine Project(P2021-A-Ⅳ-002-002)。
文摘The influence of applied temperatures on the creep rupture life of the third-generation low-cost single crystal(SX)superalloy with Pt-Al coating was evaluated.The creep damage was observed under the conditions of 1100℃/137 MPa,1120℃/137 MPa,and 1140℃/137 MPa.Results show that the properties of bare superalloy outperform those of coated superalloy under all test conditions.The most significant reduction in creep life reaches 50%when the test condition is 1100℃/137 MPa.At higher temperatures(1120 and 1140℃),the crack propagation rate in Pt-Al coatings to SX superalloy substrate decreases,thereby reducing the degradation degree of mechanical properties.Instead of the penetration into SX substrate,tip oxidation and Al diffusion of the coating cracks cause the formation of oxides,therefore leading to the slow degradation in microstructures of the substrate beneath the coating.At 1100℃,however,the microstructure of coating/SX superalloy substrate degrades due to the Al internal diffusion.This diffusion mechanism promotes the formation of harmful topologically close packed phases around 1100℃.At 1120 and 1140℃,the dislocation of SX superalloy substrate beneath the coating is relatively unchanged,compared to that in the inner superalloy.In contrast,the dislocation network of the substrate beneath the coating becomes sparse,and the number of superdislocations cutting intoγ′phases increases at 1100℃.
文摘利用SEM和TEM对比研究了无涂层和Pt-Al涂层试样在760和980℃的拉伸性能。研究结果表明:在2个温度下,Pt-Al涂层试样的屈服强度均低于无涂层试样。由于Pt-Al涂层存在韧脆转变温度(ductile to brittle transition temperature,DBTT),因此在不同温度下涂层表现出不同的变形机制和裂纹萌生方式。在高温下由于β向γ′转变有利于位错产生滑移,从而导致Pt-Al涂层的塑性变形。Pt-Al涂层在DBTT以上拉伸强度的提高是由于Pt在β-NiAl相中起到固溶强化效应。
文摘The prediction of fatigue life of metallic alloys is justly accepted as one of the most important phenomena in the field of metallurgical and mechanical engineering.At elevated temperatures,oxidation of the surfaces has an effective role in the fatigue strength and ductility of the alloys.In the present work,the effect of prior cyclic oxidation on the high temperature low cycle fatigue(HTLCF)properties of nickel-based superalloy Rene®80 has been assessed in the uncoated state and in the Pt-aluminide(Pt-Al)coated condition at 930℃.To apply cyclic oxidation,simulation of engine thermal exposure was carried out by exposing coated and uncoated fatigue specimens in the burner rig(120 cycles at 1100℃).The cyclic oxidation procedure led to a changing in the coating microstructure from the dual-phase(ξ-PtAl_(2)+β-(Ni,Pt)Al)to single phase(β-(Ni,Pt)Al).Results of HTLCF tests showed an improvement in the HTLCF life around 11.5%in the unexposed coated specimen(pre-cyclic oxidation)as compared to unexposed bare specimen,while this rise for exposed coated specimen(post-cyclic oxidation)was only 5%.Although a mixed mode fracture morphology(ductile and brittle)was observed on the fracture surfaces of failed specimens,the wider regions of brittle fracture belonged to exposed coated/uncoated ones.
文摘The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.
