An advantageous porous architecture of electrodes is pivotal in significantly enhancing alkaline water electrolysis(AWE)efficiency by optimizing the mass transport mechanisms.This effect becomes even more pronounced w...An advantageous porous architecture of electrodes is pivotal in significantly enhancing alkaline water electrolysis(AWE)efficiency by optimizing the mass transport mechanisms.This effect becomes even more pronounced when aiming to achieve elevated current densities.Herein,we employed a rapid and scalable laser texturing process to craft novel multi-channel porous electrodes.Particularly,the obtained electrodes exhibit the lowest Tafel slope of 79 mV dec^(-1)(HER)and 49 mV dec^(-1)(OER).As anticipated,the alkaline electrolyzer(AEL)cell incorporating multi-channel porous electrodes(NP-LT30)exhibited a remarkable improvement in cell efficiency,with voltage drops(from 2.28 to 1.97 V)exceeding 300 mV under 1 A cm^(-1),compared to conventional perforated Ni plate electrodes.This enhancement mainly stemmed from the employed multi-channel porous structure,facilitating mass transport and bubble dynamics through an innovative convection mode,surpassing the traditional convection mode.Furthermore,the NP-LT30-based AEL cell demonstrated exceptional durability for 300 h under 1.0 A cm^(-2).This study underscores the capability of the novel multi-channel porous electrodes to expedite mass transport in practical AWE applications.展开更多
Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain grow...Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain growth kinetics were investigated.The results suggest that the nanoparticles were obtained through hydroxide dehydration and solid phase reaction.High dispersion was accomplished by ethanol solvent to reduce the hydrogen bond and sodium dodecyl benzene sulfonate(SDBS)surfactant to increase the electrostatic repulsion between the nanoparticles.The grain growth activation energy of GZ powders calcined at lower temperature(<1200°C)is 86.5 kJ/mol(Ql),and the grain growth activation energy of GZ powders calcined at higher temperature(>1200°C)is 148.4 kJ/mol(Qh).The current study shows that the optimal process to synthesize dispersed GZ nanoparticles includes ethanol solvent,3 wt.%SDBS surfactant,and 1100°C as calcining temperature.展开更多
In this work,pure Cu with excellent strength and ductility(UTS of 271 MPa,elongation to fracture of 43.5%,uniform elongation of 30%)was prepared using cold spray additive manufacturing(CSAM),realizing a breakthrough i...In this work,pure Cu with excellent strength and ductility(UTS of 271 MPa,elongation to fracture of 43.5%,uniform elongation of 30%)was prepared using cold spray additive manufacturing(CSAM),realizing a breakthrough in the field.An in-depth investigation was conducted to reveal the microstructure evolution,strengthening and ductilization mechanisms of the CSAM Cu,as well as the single splats.The results show that the CSAM Cu possesses a unique heterogeneous microstructure with a bimodal grain structure and extensive infinitely circulating ring-mounted distribution of twinning.Based on the single splat observation,the entire copper particle forms a gradient nano-grained(GNG)structure after high-speed impact deposition.The GNG-structured single splat serves as a unit to build the heterogeneous microstructure with bimodal grain distribution during the successive deposition in CSAM.The results also show that CSAM can achieve synergistic strengthening and ductilization by controlling the grain refinement and dislocation density.This work provides potential for CSAM technique in manufacturing various metallic parts with the desired combination of high strength and good ductility without additional post-treatments.展开更多
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
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
In this work,a novel computational framework for establishment of atomic mobility database directly from the experimental composition profiles and its uncertainty quantification was developed by merging the Bayesian i...In this work,a novel computational framework for establishment of atomic mobility database directly from the experimental composition profiles and its uncertainty quantification was developed by merging the Bayesian inference with the Markov chain Monte Carlo algorithm into the latest version of the Hit DIC software.By treating the simulation of composition profiles with the composition-dependent coefficients as the forward problem,the inverse coefficient problem that provides the potential way to compute the atomic mobilities directly from composition profiles can be postulated.The values and uncertainties of the atomic mobility parameters of interest were assessed by means of Bayesian inference,where the composition profiles were consumed directly.Benchmark tests that consider the number of diffusion couples and the noise levels were conducted.Practical application of the current framework in determination of atomic mobility descriptions of fcc Ni-Ta and Ni-Al-Ta alloys was performed.Further discussion about the results of the benchmark tests and practical study case indicated that the present computational framework together with numbers of composition profiles from the multiple diffusion couples can help to establish the high-quality atomic mobility database of the target multicomponent alloys.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 support from the National Key R&D Program(2023YFE0108000)the Academy of Sciences Project of Guangdong Province(2019GDASYL-0102007,2021GDASYL-20210103063)+1 种基金GDAS’Project of Science and Technology Development(2022GDASZH-2022010203-003)financial support from the China Scholarship Council(202108210128)。
文摘An advantageous porous architecture of electrodes is pivotal in significantly enhancing alkaline water electrolysis(AWE)efficiency by optimizing the mass transport mechanisms.This effect becomes even more pronounced when aiming to achieve elevated current densities.Herein,we employed a rapid and scalable laser texturing process to craft novel multi-channel porous electrodes.Particularly,the obtained electrodes exhibit the lowest Tafel slope of 79 mV dec^(-1)(HER)and 49 mV dec^(-1)(OER).As anticipated,the alkaline electrolyzer(AEL)cell incorporating multi-channel porous electrodes(NP-LT30)exhibited a remarkable improvement in cell efficiency,with voltage drops(from 2.28 to 1.97 V)exceeding 300 mV under 1 A cm^(-1),compared to conventional perforated Ni plate electrodes.This enhancement mainly stemmed from the employed multi-channel porous structure,facilitating mass transport and bubble dynamics through an innovative convection mode,surpassing the traditional convection mode.Furthermore,the NP-LT30-based AEL cell demonstrated exceptional durability for 300 h under 1.0 A cm^(-2).This study underscores the capability of the novel multi-channel porous electrodes to expedite mass transport in practical AWE applications.
基金This study was supported by the National Key Research and Development Program of China(grant 2017YFB0306100)the Natural Science Foundation of Hunan Province(grant 2018JJ2524)the International scientific technological cooperation projects of China(grants 2015DFR50580 and 2013DFA31440).
文摘Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain growth kinetics were investigated.The results suggest that the nanoparticles were obtained through hydroxide dehydration and solid phase reaction.High dispersion was accomplished by ethanol solvent to reduce the hydrogen bond and sodium dodecyl benzene sulfonate(SDBS)surfactant to increase the electrostatic repulsion between the nanoparticles.The grain growth activation energy of GZ powders calcined at lower temperature(<1200°C)is 86.5 kJ/mol(Ql),and the grain growth activation energy of GZ powders calcined at higher temperature(>1200°C)is 148.4 kJ/mol(Qh).The current study shows that the optimal process to synthesize dispersed GZ nanoparticles includes ethanol solvent,3 wt.%SDBS surfactant,and 1100°C as calcining temperature.
基金the National Natural Science Foundation of China(Nos.52001191,52001078,52061135101)the Shanghai Science and Technology Committee(No.20511107700)+5 种基金Shanghai“Shuguang Program”(No.20SG42)Shanghai Rising-Star Program(No.20QA1403800)Key-Area Research and Development Program of Guangdong Province of China(No.2020B0101330001)Guangzhou Science and Technology Program of China(No.202007020008)the Research Fund of the State Key Laboratory of Solidification Processing(NPU,China)(No.2022-TZ-01)the Guangdong Provincial Key Laboratory of Modern Surface Engineering Technology and the Institute of New Materials,Guangdong Academy of Sciences(No.2020B1212060049).
文摘In this work,pure Cu with excellent strength and ductility(UTS of 271 MPa,elongation to fracture of 43.5%,uniform elongation of 30%)was prepared using cold spray additive manufacturing(CSAM),realizing a breakthrough in the field.An in-depth investigation was conducted to reveal the microstructure evolution,strengthening and ductilization mechanisms of the CSAM Cu,as well as the single splats.The results show that the CSAM Cu possesses a unique heterogeneous microstructure with a bimodal grain structure and extensive infinitely circulating ring-mounted distribution of twinning.Based on the single splat observation,the entire copper particle forms a gradient nano-grained(GNG)structure after high-speed impact deposition.The GNG-structured single splat serves as a unit to build the heterogeneous microstructure with bimodal grain distribution during the successive deposition in CSAM.The results also show that CSAM can achieve synergistic strengthening and ductilization by controlling the grain refinement and dislocation density.This work provides potential for CSAM technique in manufacturing various metallic parts with the desired combination of high strength and good ductility without additional post-treatments.
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financially supported by the National Key Research and Development Program of China(No.2016YFB0301101)the Hunan Provincial Science and Technology Program of China(No.2017RS3002)-Huxiang Youth Talent Plan+1 种基金the Youth Talent Project of Innovation-driven Plan at Central South University(No.2019XZ027)the support from the Fundamental Research Funds for the Central Universities of Central South University(No.2018zzts129)。
文摘In this work,a novel computational framework for establishment of atomic mobility database directly from the experimental composition profiles and its uncertainty quantification was developed by merging the Bayesian inference with the Markov chain Monte Carlo algorithm into the latest version of the Hit DIC software.By treating the simulation of composition profiles with the composition-dependent coefficients as the forward problem,the inverse coefficient problem that provides the potential way to compute the atomic mobilities directly from composition profiles can be postulated.The values and uncertainties of the atomic mobility parameters of interest were assessed by means of Bayesian inference,where the composition profiles were consumed directly.Benchmark tests that consider the number of diffusion couples and the noise levels were conducted.Practical application of the current framework in determination of atomic mobility descriptions of fcc Ni-Ta and Ni-Al-Ta alloys was performed.Further discussion about the results of the benchmark tests and practical study case indicated that the present computational framework together with numbers of composition profiles from the multiple diffusion couples can help to establish the high-quality atomic mobility database of the target multicomponent alloys.
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.