NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse gas.Therefore,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse effect.Am...NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse gas.Therefore,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse effect.Among the technologies for NF_(3)abatement,the destructive sorption of NF_(3)over metal oxides sorbents is an effective way.Thus,the search for a highly reactive and utilized sorbent for NF_(3)destruction is in great demand.In this work,AlOOH supported on carbon-sphere(AlOOH/CS)as precursors were synthesized hydrothermally and heat-treated to prepare the Al_(2)O_(3)sorbents.The influence of AlOOH/CS hydrothermal temperatures on the reactivity of derived Al_(2)O_(3)sorbents for NF_(3)destruction was investigated,and it is shown that the Al2O3 from AlOOH/CS hydro-thermalized at 120℃is superior to others.Subsequently,the optimized Al_(2)O_(3)was covered by Mn(OH)x to prepare Mn/Al_(2)O_(3)sorbents via changing hydrothermal temperatures and Mn loadings.The results show that the Mn/Al_(2)O_(3)sorbents are more utilized than bare Al_(2)O_(3)in NF_(3)destructive sorption due to the promotional effect of Mn_(2)O_(3)as surface layer on the fluorination of Al_(2)O_(3)as substrate,especially the optimal 5%Mn/Al2O3(160℃)exhibits a utilization percentage as high as 90.4%,and remarkably exceeds all the sorbents reported so far.These findings are beneficial to develop more efficient sorbents for the destruction of NF_(3).展开更多
Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but t...Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200℃ using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu-CeO_(2) can promote the formation of adsorbed oxygen(M^(+)-O_(2)^(-))and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.M+O-2Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200°C using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu–CeO_(2) can promote the formation of adsorbed oxygen(–)and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.展开更多
Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within...Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the material.The energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were observed.The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN film.Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy.Luminescence measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions.The evolution of defects at different layers with ion fluence can be obtained.展开更多
The simultaneous investigation on the parameters affecting the flow of electrically conductive fluids such as volumetric radiation,heat absorption,heat generation,and magnetic field(MF)is very vital due to its existen...The simultaneous investigation on the parameters affecting the flow of electrically conductive fluids such as volumetric radiation,heat absorption,heat generation,and magnetic field(MF)is very vital due to its existence in various sectors of industry and engineering.The present research focuses on mathematical modeling to simulate the cooling of a hot component through power-law(PL)nanofluid convection flow.The temperature reduction of the hot component inside a two-dimensional(2D)inclined chamber with two different cold wall shapes is evaluated.The formulation of the problem is derived with the lattice Boltzmann method(LBM)by code writing via the FORTRAN language.The variables such as the radiation parameter(0–1),the Hartmann number(0–75),the heat absorption/generation coefficient(−5–5),the fluid behavioral index(0.8–1.2),the Rayleigh number(103–105),the imposed MF angle(0°–90°),the chamber inclination angle(−90°–90°),and the cavity cold wall shape(smooth and curved)are investigated.The findings indicate that the presence of radiation increases the mean Nusselt number value for the shear-thickening,Newtonian,and shear thinning fluids by about 6.2%,4%,and 2%,respectively.In most cases,the presence of nanoparticles improves the heat transfer(HT)rate,especially in the cases where thermal conduction dominates convection.There is the lowest cooling performance index and MF effect for the cavity placed at an angle of 90°.The application in the design of electronic coolers and solar collectors is one of the practical cases of this numerical research.展开更多
To address the issues of reduced performance and shortened lifespan during the low-carbonizating process of Al_(2)O_(3)-C refractories,nano-crystalline ZrC modified graphite was prepared using Zr powder and flake grap...To address the issues of reduced performance and shortened lifespan during the low-carbonizating process of Al_(2)O_(3)-C refractories,nano-crystalline ZrC modified graphite was prepared using Zr powder and flake graphite as raw materials,with NaCl and NaF mixed salt serving as the medium.The flake graphite was gradually replaced by ZrC modified graphite in the preparation of Al_(2)O_(3)-C refractories,and its impact on the material’s structure and properties was investigated.The results indicate that,compared to samples with only flake graphite,the introduction of 1 mass%to 5 mass%nano-crystalline ZrC modified graphite can significantly enhance the mechanical performance of low-carbon Al_(2)O_(3)-C refractories.When 5 mass%ZrC modified graphite is added,the mechanical properties of the samples are optimal,with the cold modulus of rupture and elastic modulus reaching 22.5 MPa and 65.0 GPa,respectively.展开更多
The influence of cathodic pulse parameters was evaluated on plasma electrolytic oxidation(PEO)coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate(PTO)using pulsed...The influence of cathodic pulse parameters was evaluated on plasma electrolytic oxidation(PEO)coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate(PTO)using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current densities.The coatings were characterized by SEM,EDS,and XRD.EIS was applied to investigate the electrochemical properties.It was observed that the increase of cathodic duty cycle and cathodic current density from 20%and 6 A/dm^(2) to 40%and 12 A/dm^(2) enhances the growth rate of the inner layer from 0.22 to 0.75μm/min.Adding PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters,resulting in an increase of the inner layer growth rate from 0.25 to 1.10μm/min.Based on EDS analysis,Si and Ti were incorporated dominantly in the upper parts of the coatings.XRD technique merely detectedγ-Al_(2)O_(3),and there were no detectable peaks related to Ti and Si compounds.However,the EIS results confirmed that the incorporation of Ti^(4+)into alumina changed the electronic properties of the coating.The coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40%and current density values higher than 6 A/dm^(2) showed highly appropriate electrochemical behavior during 240 d of immersion due to an efficient repairing mechanism.Regarding the effects of studied parameters on the coating properties,the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.展开更多
To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green ...To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO source.Effects of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were investigated.The results are as follows.All samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and corundum.Their bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity increases.Moreover,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing strength.The bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases accordingly.In comprehensive consideration,the properties of the sample from kyanite are the optimal.Its apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.展开更多
基金The financial support from the Natural Science Foundation of Shandong Province (ZR2020KB003)
文摘NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse gas.Therefore,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse effect.Among the technologies for NF_(3)abatement,the destructive sorption of NF_(3)over metal oxides sorbents is an effective way.Thus,the search for a highly reactive and utilized sorbent for NF_(3)destruction is in great demand.In this work,AlOOH supported on carbon-sphere(AlOOH/CS)as precursors were synthesized hydrothermally and heat-treated to prepare the Al_(2)O_(3)sorbents.The influence of AlOOH/CS hydrothermal temperatures on the reactivity of derived Al_(2)O_(3)sorbents for NF_(3)destruction was investigated,and it is shown that the Al2O3 from AlOOH/CS hydro-thermalized at 120℃is superior to others.Subsequently,the optimized Al_(2)O_(3)was covered by Mn(OH)x to prepare Mn/Al_(2)O_(3)sorbents via changing hydrothermal temperatures and Mn loadings.The results show that the Mn/Al_(2)O_(3)sorbents are more utilized than bare Al_(2)O_(3)in NF_(3)destructive sorption due to the promotional effect of Mn_(2)O_(3)as surface layer on the fluorination of Al_(2)O_(3)as substrate,especially the optimal 5%Mn/Al2O3(160℃)exhibits a utilization percentage as high as 90.4%,and remarkably exceeds all the sorbents reported so far.These findings are beneficial to develop more efficient sorbents for the destruction of NF_(3).
基金supported by National Natural Science Foundation of China(nos 12075037 and 22206013)。
文摘Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200℃ using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu-CeO_(2) can promote the formation of adsorbed oxygen(M^(+)-O_(2)^(-))and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.M+O-2Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200°C using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu–CeO_(2) can promote the formation of adsorbed oxygen(–)and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.
文摘Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the material.The energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were observed.The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN film.Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy.Luminescence measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions.The evolution of defects at different layers with ion fluence can be obtained.
文摘The simultaneous investigation on the parameters affecting the flow of electrically conductive fluids such as volumetric radiation,heat absorption,heat generation,and magnetic field(MF)is very vital due to its existence in various sectors of industry and engineering.The present research focuses on mathematical modeling to simulate the cooling of a hot component through power-law(PL)nanofluid convection flow.The temperature reduction of the hot component inside a two-dimensional(2D)inclined chamber with two different cold wall shapes is evaluated.The formulation of the problem is derived with the lattice Boltzmann method(LBM)by code writing via the FORTRAN language.The variables such as the radiation parameter(0–1),the Hartmann number(0–75),the heat absorption/generation coefficient(−5–5),the fluid behavioral index(0.8–1.2),the Rayleigh number(103–105),the imposed MF angle(0°–90°),the chamber inclination angle(−90°–90°),and the cavity cold wall shape(smooth and curved)are investigated.The findings indicate that the presence of radiation increases the mean Nusselt number value for the shear-thickening,Newtonian,and shear thinning fluids by about 6.2%,4%,and 2%,respectively.In most cases,the presence of nanoparticles improves the heat transfer(HT)rate,especially in the cases where thermal conduction dominates convection.There is the lowest cooling performance index and MF effect for the cavity placed at an angle of 90°.The application in the design of electronic coolers and solar collectors is one of the practical cases of this numerical research.
文摘To address the issues of reduced performance and shortened lifespan during the low-carbonizating process of Al_(2)O_(3)-C refractories,nano-crystalline ZrC modified graphite was prepared using Zr powder and flake graphite as raw materials,with NaCl and NaF mixed salt serving as the medium.The flake graphite was gradually replaced by ZrC modified graphite in the preparation of Al_(2)O_(3)-C refractories,and its impact on the material’s structure and properties was investigated.The results indicate that,compared to samples with only flake graphite,the introduction of 1 mass%to 5 mass%nano-crystalline ZrC modified graphite can significantly enhance the mechanical performance of low-carbon Al_(2)O_(3)-C refractories.When 5 mass%ZrC modified graphite is added,the mechanical properties of the samples are optimal,with the cold modulus of rupture and elastic modulus reaching 22.5 MPa and 65.0 GPa,respectively.
文摘The influence of cathodic pulse parameters was evaluated on plasma electrolytic oxidation(PEO)coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate(PTO)using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current densities.The coatings were characterized by SEM,EDS,and XRD.EIS was applied to investigate the electrochemical properties.It was observed that the increase of cathodic duty cycle and cathodic current density from 20%and 6 A/dm^(2) to 40%and 12 A/dm^(2) enhances the growth rate of the inner layer from 0.22 to 0.75μm/min.Adding PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters,resulting in an increase of the inner layer growth rate from 0.25 to 1.10μm/min.Based on EDS analysis,Si and Ti were incorporated dominantly in the upper parts of the coatings.XRD technique merely detectedγ-Al_(2)O_(3),and there were no detectable peaks related to Ti and Si compounds.However,the EIS results confirmed that the incorporation of Ti^(4+)into alumina changed the electronic properties of the coating.The coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40%and current density values higher than 6 A/dm^(2) showed highly appropriate electrochemical behavior during 240 d of immersion due to an efficient repairing mechanism.Regarding the effects of studied parameters on the coating properties,the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.
基金This work was supported by the National Natural Science Foundation of China(5180021223)Henan Provice Science&Technology Programs(232102231046 and 232102231051)Cultivation Programme for Yong Backbone Teachers in Henan University to Technology(2142121).
文摘To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO source.Effects of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were investigated.The results are as follows.All samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and corundum.Their bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity increases.Moreover,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing strength.The bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases accordingly.In comprehensive consideration,the properties of the sample from kyanite are the optimal.Its apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.
