Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from l...Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from liquid splats, nano-sized clusters, and the vapor phase forming different structured coatings, which shows obvious advantages in contrast to conventional technologies like atmospheric plasma spray(APS) and electron beam-physical vapor deposition(EBPVD). In addition, it can be used to produce thin, dense, and porous ceramic coatings for special applications because of its special characteristics, such as high power, very low pressure, etc. These provide new opportunities to obtain different advanced microstructures, thus to meet the growing requirements of modern functional coatings. In this work, focusing on exploiting the potential of gas-phase deposition from PS-PVD, a series of 7 YSZ coating experiments with various process conditions was performed in order to better understand the deposition process in PS-PVD, where coatings were deposited on different substrates including graphite and zirconia. Meanwhile, various substrate temperatures were investigated for the same substrate. As a result, a deposition mechanism of heterogeneous nucleation has been presented showing that surface energy is an important influencing factor for coating structures. Besides, undercooling of the interface between substrate and vapor phase plays an important role in coating structures.展开更多
Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder...Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder bed fusion(LPBF).The effect of laser process parameters on interfacial defects was evaluated by X-ray tomography,which indicates a low porosity level of 0.042%therein.Gradient/fine dendritic grains in the interface are incited by high cooling rates,which facilitates interface strengthening.Multiple mechanical tests evaluate the bonding reliability of interface;and the fatigue tests further substantiate the ultrahigh bonding strength in FGMs,which is superior to traditional manufacturing methods.Mechanisms of the high interfacial bond strength were also discussed.展开更多
Plasma spray-physical vapor deposition(i.e.,PS-PVD)is a promising method for obtaining advanced environmental barrier coatings(EBCs).The EBCs must meet some requirements in the application,in which the thermal cycle p...Plasma spray-physical vapor deposition(i.e.,PS-PVD)is a promising method for obtaining advanced environmental barrier coatings(EBCs).The EBCs must meet some requirements in the application,in which the thermal cycle performance affects the service lifetime.The preparation of artificial vertical cracks in Yb_(2)SiO_(5) coatings is an effective approach for meeting the requirements above because vertical cracks provide a strain tolerance.To clarify the formation mechanism of vertical cracks during the PSPVD,the effects of coating thickness and substrate temperature on the formation of vertical cracks were investigated.In addition,the interactions of spray powder and plasma flame during coating deposition were also characterized by optical spectroscopy.It is indicated that vertical cracks are formed due to a thermal expansion mismatch between Yb_(2)SiO_(5) and mullite coating,transient cooling after deposition and the nucleation of evaporated Yb_(2)SiO_(5) as well.展开更多
To increase the performance and efficiency of thermal barrier coating (TBC), it is important to improve the thermal insulation property. In this work, a columnar AI film was deposited at the top of 7 wt% yttria- sta...To increase the performance and efficiency of thermal barrier coating (TBC), it is important to improve the thermal insulation property. In this work, a columnar AI film was deposited at the top of 7 wt% yttria- stabilized zirconia (7YSZ) TBC by magnetron sputtering. A vacuum heat treatment was then carried out to improve the insulation property of Al-deposited TBC. Reaction mechanism of AI-ZrO2 system in AIdeposited TBC was studied by differential thermal analysis (DTA). The phase structures of the assprayed TBC, the Al-deposited and vacuum-treated TBC were characterized. The microstructure evolution of M-deposited TBC was illustrated after vacuum heat treatment. And the insulation property of the assprayed TBC and treated TBC was compared. The results show that a multi-scaled layer, consisting of micron/ nano structured α-Al2O3 and AI3Zr grain was in situ synthesized at the top of 7YSZ coating via vacuum heat treatment. The TBC with the multi-scaled overlay has better insulation property than the asspraved TBC.展开更多
Yttria-stabilized-zirconia (YSZ) hollow spheres are widely utilized for their novel physical and chemical properties. However, developing a simple and low-cost method for preparing such hollow spheres still remains ...Yttria-stabilized-zirconia (YSZ) hollow spheres are widely utilized for their novel physical and chemical properties. However, developing a simple and low-cost method for preparing such hollow spheres still remains a great challenge. In this paper, an atmospheric plasma spray (APS) method is introduced, and the formation mechanism of hollow 7YSZ (ZrO2-7wt%Y2O3) spheres is presented. The hollow sphere morphology was observed by scanning electron microscopy (SEM) when agglomerated and sintered 7YSZ powders were used. Additionally, additive composition changes, phase transformations, and the thermal behavior of 7YSZ powders were analyzed by energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), thermogravimetric analysis (TG) and differential scanning calorimeter analysis (DSC). Furthermore, the phase transformations of agglomerated and sintered 7YSZ powders, 7YSZ hollow spheres that annealed at various temperatures for different times are analyzed.展开更多
Plasma spray-physical vapor deposition(PS-PVD)as a novel process was used to prepare feather-like columnar thermal barrier coatings(TBCs).This special microstructure shows good strain tolerance and non-line-of-sight(N...Plasma spray-physical vapor deposition(PS-PVD)as a novel process was used to prepare feather-like columnar thermal barrier coatings(TBCs).This special microstructure shows good strain tolerance and non-line-of-sight(NLOS)deposition,giving great potential application in aero-engine.However,due to serious service environment of aero-engine,particle erosion performance is a weakness for PS-PVD 7YSZ TBCs.As a solution,an Al-modification approach was proposed in this investigation.Through in-situ reaction of Al and ZrO2,anα-Al2O3 overlay can be formed on the surface of 7YSZ columnar coating.The results demonstrate that this approach can improve particle erosion resistance since hardness improvement of Al-modified TBCs.Meanwhile,as another important performance of thermal cycle,it has a better optimization with 350-cycle water-quenching,compared with the as-sprayed TBCs.展开更多
基金financial supports from National Key Research Program (2017YFB0306100)Guangdong Academy of Sciences (No. 2017GDASCX-0843)+3 种基金Guangdong Technical Research Program (Nos. 201707010385, 2014B070706026, 2013B061800053)Guangdong Natural Science Foundation (No. 2016A030312015)National Natural Science Foundation of China (No. 51501044)Guangzhou Technical Research Program (No. 201707010385)
文摘Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from liquid splats, nano-sized clusters, and the vapor phase forming different structured coatings, which shows obvious advantages in contrast to conventional technologies like atmospheric plasma spray(APS) and electron beam-physical vapor deposition(EBPVD). In addition, it can be used to produce thin, dense, and porous ceramic coatings for special applications because of its special characteristics, such as high power, very low pressure, etc. These provide new opportunities to obtain different advanced microstructures, thus to meet the growing requirements of modern functional coatings. In this work, focusing on exploiting the potential of gas-phase deposition from PS-PVD, a series of 7 YSZ coating experiments with various process conditions was performed in order to better understand the deposition process in PS-PVD, where coatings were deposited on different substrates including graphite and zirconia. Meanwhile, various substrate temperatures were investigated for the same substrate. As a result, a deposition mechanism of heterogeneous nucleation has been presented showing that surface energy is an important influencing factor for coating structures. Besides, undercooling of the interface between substrate and vapor phase plays an important role in coating structures.
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110542)the Guangdong Special Support Program(No.2019BT02C629)+5 种基金the National Natural Science Foundation of China(Nos.52005189and 51775196)the Chinese Postdoctoral Science Foundation(No.2020M672617)the Guangzhou Science and Technology Society Project(Nos.X20200301015,201907010008,202007020008and 201807010030)the Chinese Central Universities Funds(No.2018ZD30)supported by Guangdong province Science and Technology Plan Projects(No.2019A1515011841)GDAS Projects(Nos.2020GDASYL-20200402005,2019GDASYL-0501009,2019GDASYL-0502006,2018GDASCX-0111,2018GDASCX-0402 and 2019GDASYL-0402004)。
文摘Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder bed fusion(LPBF).The effect of laser process parameters on interfacial defects was evaluated by X-ray tomography,which indicates a low porosity level of 0.042%therein.Gradient/fine dendritic grains in the interface are incited by high cooling rates,which facilitates interface strengthening.Multiple mechanical tests evaluate the bonding reliability of interface;and the fatigue tests further substantiate the ultrahigh bonding strength in FGMs,which is superior to traditional manufacturing methods.Mechanisms of the high interfacial bond strength were also discussed.
基金financial supports from National Natural Science Foundation of China(No.51801034,No.51771059)Guangdong Academy of Sciences Program(No.2020GDASYL-20200104030,No.2018GDASCX-0402,No.2017GDASCX-0202,No.2017GDASCX-0111)+2 种基金Guangdong Technical Research Program(No.2017B090916002,No.2017A070701027,No.2014B07075007)Guangdong Natural Science Foundation(No.2016A030312015,No.2017A030310315)Guangzhou Technical Research Program(No.201906010015,No.201707010455,No.201707010385).
文摘Plasma spray-physical vapor deposition(i.e.,PS-PVD)is a promising method for obtaining advanced environmental barrier coatings(EBCs).The EBCs must meet some requirements in the application,in which the thermal cycle performance affects the service lifetime.The preparation of artificial vertical cracks in Yb_(2)SiO_(5) coatings is an effective approach for meeting the requirements above because vertical cracks provide a strain tolerance.To clarify the formation mechanism of vertical cracks during the PSPVD,the effects of coating thickness and substrate temperature on the formation of vertical cracks were investigated.In addition,the interactions of spray powder and plasma flame during coating deposition were also characterized by optical spectroscopy.It is indicated that vertical cracks are formed due to a thermal expansion mismatch between Yb_(2)SiO_(5) and mullite coating,transient cooling after deposition and the nucleation of evaporated Yb_(2)SiO_(5) as well.
基金supported by the National Basic Research Program of China ("973" program, No. 2012CB625100)the National Hightech Research and Development Program of China ("863" program, No. 2012AA03A512)
文摘To increase the performance and efficiency of thermal barrier coating (TBC), it is important to improve the thermal insulation property. In this work, a columnar AI film was deposited at the top of 7 wt% yttria- stabilized zirconia (7YSZ) TBC by magnetron sputtering. A vacuum heat treatment was then carried out to improve the insulation property of Al-deposited TBC. Reaction mechanism of AI-ZrO2 system in AIdeposited TBC was studied by differential thermal analysis (DTA). The phase structures of the assprayed TBC, the Al-deposited and vacuum-treated TBC were characterized. The microstructure evolution of M-deposited TBC was illustrated after vacuum heat treatment. And the insulation property of the assprayed TBC and treated TBC was compared. The results show that a multi-scaled layer, consisting of micron/ nano structured α-Al2O3 and AI3Zr grain was in situ synthesized at the top of 7YSZ coating via vacuum heat treatment. The TBC with the multi-scaled overlay has better insulation property than the asspraved TBC.
基金supported by TBCs research team at Guangzhou Research Institute of Non-ferrous Metalsthe National "973" Basic Research Project of China (2012CB625100) for providing financial support
文摘Yttria-stabilized-zirconia (YSZ) hollow spheres are widely utilized for their novel physical and chemical properties. However, developing a simple and low-cost method for preparing such hollow spheres still remains a great challenge. In this paper, an atmospheric plasma spray (APS) method is introduced, and the formation mechanism of hollow 7YSZ (ZrO2-7wt%Y2O3) spheres is presented. The hollow sphere morphology was observed by scanning electron microscopy (SEM) when agglomerated and sintered 7YSZ powders were used. Additionally, additive composition changes, phase transformations, and the thermal behavior of 7YSZ powders were analyzed by energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), thermogravimetric analysis (TG) and differential scanning calorimeter analysis (DSC). Furthermore, the phase transformations of agglomerated and sintered 7YSZ powders, 7YSZ hollow spheres that annealed at various temperatures for different times are analyzed.
基金We would like to acknowledge the financial support from the National Natural Science Foundation of China(52172067)Guangdong Province Outstanding Youth Foundation(2021B1515020038)+1 种基金Guangdong Special Support Program(2019BT02C629)Guangdong Academy of Sciences Program(2020GDASYL-20200104030).
文摘Plasma spray-physical vapor deposition(PS-PVD)as a novel process was used to prepare feather-like columnar thermal barrier coatings(TBCs).This special microstructure shows good strain tolerance and non-line-of-sight(NLOS)deposition,giving great potential application in aero-engine.However,due to serious service environment of aero-engine,particle erosion performance is a weakness for PS-PVD 7YSZ TBCs.As a solution,an Al-modification approach was proposed in this investigation.Through in-situ reaction of Al and ZrO2,anα-Al2O3 overlay can be formed on the surface of 7YSZ columnar coating.The results demonstrate that this approach can improve particle erosion resistance since hardness improvement of Al-modified TBCs.Meanwhile,as another important performance of thermal cycle,it has a better optimization with 350-cycle water-quenching,compared with the as-sprayed TBCs.