Greenhouse gas emissions from waste plastics have caused global warming all over the world,which has been a central threat to the ecological environment for humans,flora and fauna.Among waste plastics,waste polyethyle...Greenhouse gas emissions from waste plastics have caused global warming all over the world,which has been a central threat to the ecological environment for humans,flora and fauna.Among waste plastics,waste polyethylene terephthalate(PET)is attractive due to its excellent stability and degradation-resistant.Therefore,merging China’s carbon peak and carbon neutrality goals would be beneficial.In this review,we summarize the current state-of-the-art of carbon emission decrease from a multi-scale perspective technologically.We suggest that the carbon peak for waste PET can be achieved by employing the closed-loop supply chain,including recycling,biomass utilization,carbon capture and utilization.Waste PET can be a valuable and renewable resource in the whole life cycle.Undoubtedly,all kinds of PET plastics can be ultimately converted into CO_(2),which can also be feedstock for various kinds of chemical products,including ethyl alcohol,formic acid,soda ash,PU,starch and so on.As a result,the closed-loop supply chain can help the PET plastics industry drastically reduce its carbon footprint.展开更多
To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavio...To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.展开更多
Powder hot isostatic pressing(HIP) is an effective method to achieve near-net-shape manufacturing of high-quality complex thinwalled titanium alloy parts, and it has received extensive attention in recent years. Howev...Powder hot isostatic pressing(HIP) is an effective method to achieve near-net-shape manufacturing of high-quality complex thinwalled titanium alloy parts, and it has received extensive attention in recent years. However, there are few reports about the microstructure characteristics on the strengthening and toughening mechanisms of powder hot isostatic pressed(HIPed) titanium alloys. Therefore, TA15powder was prepared into alloy by HIP approach, which was used to explore the microstructure characteristics at different HIP temperatures and the corresponding tensile properties and fracture toughness. Results show that the fabricated alloy has a “basket-like structure” when the HIP temperature is below 950℃, consisting of lath clusters and surrounding small equiaxed grains belts. When the HIP temperature is higher than 950℃, the microstructure gradually transforms into the Widmanstatten structure, accompanied by a significant increase in grain size. The tensile strength and elongation are reduced from 948 MPa and 17.3% for the 910℃ specimen to 861 MPa and 10% for the 970℃ specimen.The corresponding tensile fracture mode changes from transcrystalline plastic fracture to mixed fracture including intercrystalline cleavage.The fracture toughness of the specimens increases from 82.64 MPa·m^(1/2)for the 910℃ specimen to 140.18 MPa·m^(1/2)for the 970℃ specimen.Specimens below 950℃ tend to form holes due to the prior particle boundaries(PPBs), which is not conducive to toughening. Specimens above 950℃ have high fracture toughness due to the crack deflection, crack branching, and shear plastic deformation of the Widmanstatten structure. This study provides a valid reference for the development of powder HIPed titanium alloy.展开更多
The intermetallic compound Zr1-xTixCo was prepared and its suitability for hydrogen storage was investigated. The alloys obtained by magnetic levitation melting with the composition of Zr1-xTixCo (x=0, 0.1, 0.2 and 0....The intermetallic compound Zr1-xTixCo was prepared and its suitability for hydrogen storage was investigated. The alloys obtained by magnetic levitation melting with the composition of Zr1-xTixCo (x=0, 0.1, 0.2 and 0.3, at.%) show single cubic phase by X-ray diffraction. A single sloping plateau was observed on each isothermal, and pressure-composition-temperature (PCT) measurement results show that the equilibrium hydrogen desorption pressure of Zr1-xTixCo alloy increases with increasing Ti content. The desorption temperatures for supplying 100 kPa hydrogen are about 665, 642, 621 and 614 K for ZrCo, Zr0.9Ti0.1Co, Zr0.8Ti0.2Co and Zr0.7Ti0.3Co alloy, respectively. Repeated hydrogen absorption and desorption cycles do not generate separated ZrCo, TiCo and ZrH2 phases, indicating that alloys have good thermal and hydrogen stabilization.展开更多
316L stainless steel（SS 316L） is quite attractive as bipolar plates in proton exchange membrane fuel cells（PEMFC）.In this study,graphite-polypyrrole was coated on SS 316L by the method of cyclic voltammetry.The su...316L stainless steel（SS 316L） is quite attractive as bipolar plates in proton exchange membrane fuel cells（PEMFC）.In this study,graphite-polypyrrole was coated on SS 316L by the method of cyclic voltammetry.The surface morphology and chemical composition of the graphite-polypyrrole composite coating were investigated by scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）.A simulated working environment of PEMFC was applied for testing the corrosion properties of graphite-polypyrrole coated SS 316L.The current densities in the simulated PEMFC anode and cathode conditions are around 3×10-9 and 9×10-5 A·cm-2,respectively.In addition,the interfacial contact resistance（ICR） was also investigated.The ICR value of graphite-polypyrrole coated SS 316L is much lower than that of bare SS 316L.Therefore,graphite-polypyrrole coated SS 316L indicates a great potential for the application in PEMFC.展开更多
Effect of Ce addition on microstructure and hydrogen storage performance of Ti24Cr17.5V50Fe8.5Cex（x=0, 0.5at.%, 0.8at.% and 1.0at.%） alloys was studied by X-ray diffraction, scanning electron microscopy and P-C-isot...Effect of Ce addition on microstructure and hydrogen storage performance of Ti24Cr17.5V50Fe8.5Cex（x=0, 0.5at.%, 0.8at.% and 1.0at.%） alloys was studied by X-ray diffraction, scanning electron microscopy and P-C-isotherm measurements.The results indicated that Ce addition was a useful way to improve the flatness of the plateau and increase hydrogen storage capacity of Ti24Cr17.5V50Fe8.5 alloy.It was indicated that both homogenization of composition and increase of hydrogen diffusion coefficient were the main reasons for improving the hydrogen storage performance of Ti24Cr17.5V50Fe8.5Cex alloys.展开更多
The powder space holder （PSH） and powder injection molding （PIM） methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, mi...The powder space holder （PSH） and powder injection molding （PIM） methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, micro-porous Ti6Al4V alloy （Ti64） parts were produced by the PSH-PIM process. Ti64 alloy powder and spherical polymethylrnethacrylate （PMMA） particles were used as a space holder material. After molding, binder debinding was performed by thermal method under inert gas. Debinded samples were sintered at 1250℃ for 60min in a vacuum （10-4 Pa）. Metallographic studies were conducted to determine densification and the corresponding microstructural changes. The surface of sintered samples was examined by SEM. The compressive stress and elastic modulus of the rificro-porous Ti64 samples were determined. The effects of fraction of PMMA on the properties of sintered micro-porous Ti64 alloy samples were investigated. It was shown that the fraction of PMMA could be controlled to affect the properties of the Ti alloy.展开更多
Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached...Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...展开更多
Thermoelectric(TE)materials are a kind of functional materials which can be used to convert directly heat energy to electricity or reversely.The thermoelectric effects hold great potential for application in power gen...Thermoelectric(TE)materials are a kind of functional materials which can be used to convert directly heat energy to electricity or reversely.The thermoelectric effects hold great potential for application in power generation and refrigeration.Bi_(2)Te_(3)and its alloys are well known as best TE materials currently available near room temperature.This paper studies respectively the effects of spark plasma sintering(SPS)on electric performance of Bi_(0.5)Sb_(1.5)Te_(3)thermoelectric materials that are prepared through vacuum melting and ball milling.Through X-ray Diffraction and cold field emission scanning electric microscope s4800,the phase constituent and microstructure of the TE materials samples were analyzed.Electric conductivity and power factor can be improved with the rise of Spark Plasma Sintering temperature(from 300 to 500℃)and pressure(from 30 to 60 MPa),and the density and mechanical strength of Bi_(0.5)Sb_(1.5)Te_(3)thermoelectric material increase,too.展开更多
Mg-xwt.%CuY(x=15,20,25)composites were successfully prepared by reactive mechanical alloying(RMA).X-ray diffraction(XRD)measurement shows that main phases of the as milled composites are MgH_(2) and Mg_(2)Cu,and they ...Mg-xwt.%CuY(x=15,20,25)composites were successfully prepared by reactive mechanical alloying(RMA).X-ray diffraction(XRD)measurement shows that main phases of the as milled composites are MgH_(2) and Mg_(2)Cu,and they converted into Mg and MgCu_(2) after dehydrogenation,respectively.Pressure-Composition-Isotherm(PCI)test shows that the composites exhibit double pressure plateau at each isothermal desorption process.The hydrogen absorption and desorption kinetics of the composites become worse with increasing x content,indicating that Mg-Cu phase has a negative effect on the hydrogen sorption properties of the composites.It is supposed that the good hydrogen sorption properties of the composites attribute to the catalyst effect of yttrium hydride distributed in Mg substrate and the particles size reduction and crystal defects formed by RMA.展开更多
Low-temperature performance and high-rate discharge capability of AB5-type non-stoichiometric hydrogen storage are studied. X-ray diffraction(XRD),pressure-composition-temperature(PCT) curves and electrochemical imped...Low-temperature performance and high-rate discharge capability of AB5-type non-stoichiometric hydrogen storage are studied. X-ray diffraction(XRD),pressure-composition-temperature(PCT) curves and electrochemical impedance spectroscopy(EIS) are applied to characterize the electrochemical properties of ABx(x=4.8,4.9,5.0,5.1,5.2) alloys. The results show that the non-stoichiometric alloys exhibit better electrochemical properties compared with that of the AB5 alloy.展开更多
Novel SiO_(2)-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope(SEM),particle size analysis,and Fourier transform infrared spectroscopy(FT-IR).The ...Novel SiO_(2)-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope(SEM),particle size analysis,and Fourier transform infrared spectroscopy(FT-IR).The water vapor sorption and desorption of the formulated microcapsules was then experimentally studied using dynamic vapor sorption(DVS),with the results fitted to three kinds of adsorption kinetics models.In addition,the specific surface area(SSA)was also calculated based on BET theory;and the thermal performance was investigated by laser flash analysis(LFA).Experimental results show a change of 103%in mass of the microcapsule sample under 90%relative humidity(RH)at 30℃after water vapor sorption.The fitting of results indicates that the adsorption process is mainly governed by the intra-particle diffusion mechanism,followed by the pseudo-first-order adsorption process.In comparison with most conventional pavement materials,it is found that the SSA of the formulated microcapsules is much larger while the thermal conductivity is lower.The unique properties of the formulated SiO_(2)-LiBr microcapsules have significant potential to take the edge off the urban heat island effect and reduce rutting when applied to water-retaining pavement materials.展开更多
The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated.The thermal storage properties,cyclic property and thermal storage mechanism were studied by...The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated.The thermal storage properties,cyclic property and thermal storage mechanism were studied by pres sure-composition-temperature(PC T),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The Van't Hoff curve indicates that the formation enthalpy of Mg-16 wt%LaNi is 74.62 kJ·mol^(-1),which approaches to the theoretical values of MgH2.The isothermal measurement indicates that Mg-16 wt%LaNi can absorb 6.263 wt%H_(2)within 30 min at 390℃for the first absorption,the absorption reaction fraction within2 min is over 90.00%,and the desorption reaction fraction within 2 min is 72.63%,increasing by 55.36%compared with that of Mg.Mg-16 wt%LaNi has better cyclic stability than that of Mg,only decreasing by 0.609 wt%after 80cycles.The enhancement in thermal storage performances of Mg by adding LaNi is mainly ascribed to the formed Mg_(2)NiH_(4),H_(0.3)Mg_(2)Ni and La_(4)H_(12.19)during the cyclic process which act as catalysts and inhibit the growth of Mg.The above results prove that Mg-16 wt%LaNi is suitable for use as a heat storage material.展开更多
P-type thermoelectric material(Bi0.25Sb0.75)2Te3 was sintered by spark plasma sintering(SPS) process in the temperature range of 320-420 ℃. The microstructures of sintered materials were found to be well aligned,part...P-type thermoelectric material(Bi0.25Sb0.75)2Te3 was sintered by spark plasma sintering(SPS) process in the temperature range of 320-420 ℃. The microstructures of sintered materials were found to be well aligned,particularly when sintered at lower sintering temperatures. The electrical conductivity of the material became larger as the sintering temperature increased. The Seebeck coefficient showed a general decreasing tendency with an increase in sintering temperature. In terms of the power factor,the optimum sintering temperature was found to be 380 ℃ for a maximum value of around 2.6 mW/K.展开更多
The Co(Ⅲ)-coated spherical nickel hydroxide powder is optimum as positive electrode of high power Ni-MH battery because of its excellent property. But the performances at high temperature(above 50 ℃) is still not sa...The Co(Ⅲ)-coated spherical nickel hydroxide powder is optimum as positive electrode of high power Ni-MH battery because of its excellent property. But the performances at high temperature(above 50 ℃) is still not satisfied. In the present paper,the effect of element erbium,used as additive by different methods to prepare positive electrode,on the high temperature performances of the Ni-MH batteries is studied. It is found that the charge acceptance ability of the spherical Ni(OH)2 electrode with element erbium as additive is improved. The discharge capacities of Ni(OH)2 coated with 1%(atomic fraction) Er(OH)3 and mechanically added with 1%(atomic fraction) Er2O3 at 1C are 12.6% and 11.7%,respectively,higher than those of the samples without erbium at 70 ℃.展开更多
Zirconia separator is one of the key materials of nickel-hydrogen battery,thereby zirconia separators are prepared by precursor process in which cellulose textiles immersed with zirconium salts are oxidized,infrared s...Zirconia separator is one of the key materials of nickel-hydrogen battery,thereby zirconia separators are prepared by precursor process in which cellulose textiles immersed with zirconium salts are oxidized,infrared spectra show that viscose textile is an excellent precursor for preparing zirconia separator. The dominant factors in immersion are studied,it is revealed that the solution concentration and the temperature are the most important factors with regard to the area density of zirconia separator. The main reactions of immersed textiles during heat treatment are investigated by TG-DSC. The prepared zirconia separators are analyzed by SEM,XRD and infrared spectroscopy,which lead to kown that the separators maintain the same morphology of precursor textiles and contain little organic components,the main phase of the separators is tetragonal zirconia,the rate and the amount of alkaline absorption are about 5 cm/min and 220% respectively.展开更多
Rare earth(RE) elements are excellent modifiers for non-metallic inclusions that inevitably appear in steel and affect steel properties. This paper reviews the research status of inclusions modification by RE elements...Rare earth(RE) elements are excellent modifiers for non-metallic inclusions that inevitably appear in steel and affect steel properties. This paper reviews the research status of inclusions modification by RE elements and the changes it cause on steel properties. First, the inclusion changes caused by RE modification are described. Generally, after adding pure RE, the main evolution of inclusions occurs as M →M + RE-Al-O → RE-Al-O + RE_(2)O_(2)S → RE_(2)O_(2)S + RE—S/RE_(2)O_(2)S + RE-O with an increase in the RE content(M represents the inclusions before RE addition). The type of final inclusion obtained after RE modification is related to the relative contents of S and O in the steel. Moreover, fine, regular, and uniformly distributed inclusions can be obtained with appropriate RE addition. However, the effectiveness of inclusions modification by adding both RE and non-RE elements is closely related to the order of their addition. Second, the applications and advantages of thermodynamic calculations in the study of RE-modified inclusions are introduced. Third, the changes in the corrosion resistance, impact properties,and other properties of steel caused by the modification of inclusions by RE are reviewed. Finally, the perspectives and trends of inclusions modified by RE elements in the steel industry are presented.展开更多
Mathematical(data-driven)models based on state-of-the-art(SOTA)machine learning and deep learning models and data collected from 12,786 heats were established to predict the values of temperature,sample,and carbon(TSC...Mathematical(data-driven)models based on state-of-the-art(SOTA)machine learning and deep learning models and data collected from 12,786 heats were established to predict the values of temperature,sample,and carbon(TSC)test,including temperature of molten steel(TSC-Temp),carbon content(TSC-C)and phosphorus content(TSC-P),which made prepa-ration for eliminating the TSC test.To maximize the prediction accuracy of the proposed approach,various models with different inputs were implemented and compared,and the best models were applied to the production process of a Hesteel Group steelmaking plant in China in the field.The number of tabular features(hot metal information,scrap,additives,blowing practices,and preset values)was expanded,and time series(off-gas profiles and blowing practice curves)that could reflect the entire steelmaking process were introduced as inputs.First,the latest machine learning models(LightGBM,CatBoost,TabNet,and NODE)were used to make predictions with tabular features,and the best coefficient of determination R^(2)values obtained for TSC-P,TSC-C and TSC-Temp predictions were 0.435(LightGBM),0.857(Cat-Boost)and 0.678(LightGBM),respectively,which were higher than those of classic models(backpropagation and support vector machine).Then,making predictions was performed by using SOTA time series regression models(SCINet,DLinear,Informer,and MLSTM-FCN)with original time series,SOTA image regression models(NesT,CaiT,ResNeXt,and GoogLeNet)with resized time series,and the proposed Concatenate-Model and Parallel-Model with both tabular features and time series.Through optimization and comparisons,it was finally determined that the Concatenate-Model with MLSTM-FCN,SCINet and Informer as feature extractors performed the best,and its R^(2)values for predicting TSC-P,TSC-C and TSC-Temp reached 0.470,0.858 and 0.710,respectively.Its field test accuracies for TSC-P,TSC-C and TSC-Temp were 0.459,0.850 and 0.685,respectively.A related importance analysis was carried out,and dynamic control methods based on prediction values were proposed.展开更多
Metal hydrides high temperature thermal heat storage technique has great promising future prospects in solar power generation, industrial waste heat utilization and peak load regulating of power system. This article i...Metal hydrides high temperature thermal heat storage technique has great promising future prospects in solar power generation, industrial waste heat utilization and peak load regulating of power system. This article introduces basic principle of metal hydrides for thermal storage, and summarizes developments in advanced metal hydrides high-temperature thermal storage materials, numerical simulation and thermodynamic calculation in thermal storage systems, and metal hydrides thermal storage prototypes. Finally, the future metal hydrides high temperature thermal heat storage technique is been looked ahead.展开更多
The effect of LaNi and Ti on thermal storage properties of MgH_(2)was investigated.The thermal storage performances of Mg are significantly improved by adding LaNi and Ti.The pressure-composition-temperature(PCT)curve...The effect of LaNi and Ti on thermal storage properties of MgH_(2)was investigated.The thermal storage performances of Mg are significantly improved by adding LaNi and Ti.The pressure-composition-temperature(PCT)curves indicate that the formation enthalpy for Mg-15 wt%Ti-5 wt%LaNi sample is 73.00 kJ·mol^(-1),which approaches to the theoretical values of pure MgH_(2).The isothermal measurement indicates that,for the Mg-15wt%Ti-5 wt%LaNi,the first absorption reaction fraction within 2 min is 93.77%,increasing by 0.32%,0.24%and0.08%compared with those for Mg,Mg-5 wt%LaNi and Mg-15 wt%Ti,respectively.The first desorption reaction fraction within 2 min is 73.18%,increasing by 55.91%,9.79%and 8.12%compared with those for Mg,Mg-5wt%LaNi and Mg-15 wt%Ti,respectively.Moreover,Mg-15 wt%Ti-5 wt%LaNi has the best cyclic stability in all the samples.The thermal storage performances of Mg by adding both LaNi and Ti are improved mainly ascribed to synergistic effect of in situ formed La_(4)H_(12.19),Mg_(2)NiH_(4),H_(0.3)Mg_(2)Ni and TiH_(2)particles during cyclic process.The above analysis demonstrates that Mg-15 wt%Ti-5wt%LaNi is suitable for using as a heat storage material.展开更多
基金The authors acknowledge the financial support provided by the Key R&D Program of Shaanxi Province(No.2022SF-168)Xi’an Programs for Science and Technology Plan(Nos.2020KJRC0090 and 21XJZZ0045)+5 种基金Xi’an Beilin District Programs for Science and Technology Plan(No.GX2247)the Outstanding Chinese and Foreign Youth Exchange Program of China Association for Science and Technology(CAST)in 2019the Opening Project of Shanxi Key Laboratory of Advanced Manufacturing Technology(No.XJZZ202001)the Scientific Research Project of Shaanxi Education Department(No.20JS108)Open Foundation of Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry,Ministry of Education,Shaanxi University of Science and Technology(No.KFKT2021-01)Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology,Shaanxi University of Science and Technology(No.KFKT2021-01).
文摘Greenhouse gas emissions from waste plastics have caused global warming all over the world,which has been a central threat to the ecological environment for humans,flora and fauna.Among waste plastics,waste polyethylene terephthalate(PET)is attractive due to its excellent stability and degradation-resistant.Therefore,merging China’s carbon peak and carbon neutrality goals would be beneficial.In this review,we summarize the current state-of-the-art of carbon emission decrease from a multi-scale perspective technologically.We suggest that the carbon peak for waste PET can be achieved by employing the closed-loop supply chain,including recycling,biomass utilization,carbon capture and utilization.Waste PET can be a valuable and renewable resource in the whole life cycle.Undoubtedly,all kinds of PET plastics can be ultimately converted into CO_(2),which can also be feedstock for various kinds of chemical products,including ethyl alcohol,formic acid,soda ash,PU,starch and so on.As a result,the closed-loop supply chain can help the PET plastics industry drastically reduce its carbon footprint.
基金funded by the National Key Research and Development Program of China(2018YFB0104400)supported by the Beijing Natural Science Foundation(2214066)。
文摘To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.
基金financially supported by the National Natural Science Foundation of China (Nos. 51874037 and 51922004)the Beijing Natural Science Foundation (No. 2212035)+1 种基金the Fundamental Research Funds for the Central Universities (No. FRF-TP-19005C1Z)the National Defense Basic Research Project (No. JCKY2017213004)。
文摘Powder hot isostatic pressing(HIP) is an effective method to achieve near-net-shape manufacturing of high-quality complex thinwalled titanium alloy parts, and it has received extensive attention in recent years. However, there are few reports about the microstructure characteristics on the strengthening and toughening mechanisms of powder hot isostatic pressed(HIPed) titanium alloys. Therefore, TA15powder was prepared into alloy by HIP approach, which was used to explore the microstructure characteristics at different HIP temperatures and the corresponding tensile properties and fracture toughness. Results show that the fabricated alloy has a “basket-like structure” when the HIP temperature is below 950℃, consisting of lath clusters and surrounding small equiaxed grains belts. When the HIP temperature is higher than 950℃, the microstructure gradually transforms into the Widmanstatten structure, accompanied by a significant increase in grain size. The tensile strength and elongation are reduced from 948 MPa and 17.3% for the 910℃ specimen to 861 MPa and 10% for the 970℃ specimen.The corresponding tensile fracture mode changes from transcrystalline plastic fracture to mixed fracture including intercrystalline cleavage.The fracture toughness of the specimens increases from 82.64 MPa·m^(1/2)for the 910℃ specimen to 140.18 MPa·m^(1/2)for the 970℃ specimen.Specimens below 950℃ tend to form holes due to the prior particle boundaries(PPBs), which is not conducive to toughening. Specimens above 950℃ have high fracture toughness due to the crack deflection, crack branching, and shear plastic deformation of the Widmanstatten structure. This study provides a valid reference for the development of powder HIPed titanium alloy.
文摘The intermetallic compound Zr1-xTixCo was prepared and its suitability for hydrogen storage was investigated. The alloys obtained by magnetic levitation melting with the composition of Zr1-xTixCo (x=0, 0.1, 0.2 and 0.3, at.%) show single cubic phase by X-ray diffraction. A single sloping plateau was observed on each isothermal, and pressure-composition-temperature (PCT) measurement results show that the equilibrium hydrogen desorption pressure of Zr1-xTixCo alloy increases with increasing Ti content. The desorption temperatures for supplying 100 kPa hydrogen are about 665, 642, 621 and 614 K for ZrCo, Zr0.9Ti0.1Co, Zr0.8Ti0.2Co and Zr0.7Ti0.3Co alloy, respectively. Repeated hydrogen absorption and desorption cycles do not generate separated ZrCo, TiCo and ZrH2 phases, indicating that alloys have good thermal and hydrogen stabilization.
文摘316L stainless steel（SS 316L） is quite attractive as bipolar plates in proton exchange membrane fuel cells（PEMFC）.In this study,graphite-polypyrrole was coated on SS 316L by the method of cyclic voltammetry.The surface morphology and chemical composition of the graphite-polypyrrole composite coating were investigated by scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）.A simulated working environment of PEMFC was applied for testing the corrosion properties of graphite-polypyrrole coated SS 316L.The current densities in the simulated PEMFC anode and cathode conditions are around 3×10-9 and 9×10-5 A·cm-2,respectively.In addition,the interfacial contact resistance（ICR） was also investigated.The ICR value of graphite-polypyrrole coated SS 316L is much lower than that of bare SS 316L.Therefore,graphite-polypyrrole coated SS 316L indicates a great potential for the application in PEMFC.
基金supported by Hi-Tech Research and Development Program of China (2006AA05Z144)
文摘Effect of Ce addition on microstructure and hydrogen storage performance of Ti24Cr17.5V50Fe8.5Cex（x=0, 0.5at.%, 0.8at.% and 1.0at.%） alloys was studied by X-ray diffraction, scanning electron microscopy and P-C-isotherm measurements.The results indicated that Ce addition was a useful way to improve the flatness of the plateau and increase hydrogen storage capacity of Ti24Cr17.5V50Fe8.5 alloy.It was indicated that both homogenization of composition and increase of hydrogen diffusion coefficient were the main reasons for improving the hydrogen storage performance of Ti24Cr17.5V50Fe8.5Cex alloys.
基金supported by the Scientific Research Project Program of Marmara University (No.FEN-C-YLP-280110-0004)Marmara University for their financial support and the provision of laboratory facilities
文摘The powder space holder （PSH） and powder injection molding （PIM） methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, micro-porous Ti6Al4V alloy （Ti64） parts were produced by the PSH-PIM process. Ti64 alloy powder and spherical polymethylrnethacrylate （PMMA） particles were used as a space holder material. After molding, binder debinding was performed by thermal method under inert gas. Debinded samples were sintered at 1250℃ for 60min in a vacuum （10-4 Pa）. Metallographic studies were conducted to determine densification and the corresponding microstructural changes. The surface of sintered samples was examined by SEM. The compressive stress and elastic modulus of the rificro-porous Ti64 samples were determined. The effects of fraction of PMMA on the properties of sintered micro-porous Ti64 alloy samples were investigated. It was shown that the fraction of PMMA could be controlled to affect the properties of the Ti alloy.
基金supported by the 863 National Research and Development Project Foundation of China (2006AA11A151)
文摘Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...
文摘Thermoelectric(TE)materials are a kind of functional materials which can be used to convert directly heat energy to electricity or reversely.The thermoelectric effects hold great potential for application in power generation and refrigeration.Bi_(2)Te_(3)and its alloys are well known as best TE materials currently available near room temperature.This paper studies respectively the effects of spark plasma sintering(SPS)on electric performance of Bi_(0.5)Sb_(1.5)Te_(3)thermoelectric materials that are prepared through vacuum melting and ball milling.Through X-ray Diffraction and cold field emission scanning electric microscope s4800,the phase constituent and microstructure of the TE materials samples were analyzed.Electric conductivity and power factor can be improved with the rise of Spark Plasma Sintering temperature(from 300 to 500℃)and pressure(from 30 to 60 MPa),and the density and mechanical strength of Bi_(0.5)Sb_(1.5)Te_(3)thermoelectric material increase,too.
文摘Mg-xwt.%CuY(x=15,20,25)composites were successfully prepared by reactive mechanical alloying(RMA).X-ray diffraction(XRD)measurement shows that main phases of the as milled composites are MgH_(2) and Mg_(2)Cu,and they converted into Mg and MgCu_(2) after dehydrogenation,respectively.Pressure-Composition-Isotherm(PCI)test shows that the composites exhibit double pressure plateau at each isothermal desorption process.The hydrogen absorption and desorption kinetics of the composites become worse with increasing x content,indicating that Mg-Cu phase has a negative effect on the hydrogen sorption properties of the composites.It is supposed that the good hydrogen sorption properties of the composites attribute to the catalyst effect of yttrium hydride distributed in Mg substrate and the particles size reduction and crystal defects formed by RMA.
基金Project(2006AA11A151) supported by the National Hi-Tech Research and Development Program of China
文摘Low-temperature performance and high-rate discharge capability of AB5-type non-stoichiometric hydrogen storage are studied. X-ray diffraction(XRD),pressure-composition-temperature(PCT) curves and electrochemical impedance spectroscopy(EIS) are applied to characterize the electrochemical properties of ABx(x=4.8,4.9,5.0,5.1,5.2) alloys. The results show that the non-stoichiometric alloys exhibit better electrochemical properties compared with that of the AB5 alloy.
基金financial support of The National Scholarship Foundation of China,China Scholarship Council([2018]3101)。
文摘Novel SiO_(2)-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope(SEM),particle size analysis,and Fourier transform infrared spectroscopy(FT-IR).The water vapor sorption and desorption of the formulated microcapsules was then experimentally studied using dynamic vapor sorption(DVS),with the results fitted to three kinds of adsorption kinetics models.In addition,the specific surface area(SSA)was also calculated based on BET theory;and the thermal performance was investigated by laser flash analysis(LFA).Experimental results show a change of 103%in mass of the microcapsule sample under 90%relative humidity(RH)at 30℃after water vapor sorption.The fitting of results indicates that the adsorption process is mainly governed by the intra-particle diffusion mechanism,followed by the pseudo-first-order adsorption process.In comparison with most conventional pavement materials,it is found that the SSA of the formulated microcapsules is much larger while the thermal conductivity is lower.The unique properties of the formulated SiO_(2)-LiBr microcapsules have significant potential to take the edge off the urban heat island effect and reduce rutting when applied to water-retaining pavement materials.
基金financially supported by the Beijing Municipal Commission of Science and Technology of China(No.D141100002014001)。
文摘The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated.The thermal storage properties,cyclic property and thermal storage mechanism were studied by pres sure-composition-temperature(PC T),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The Van't Hoff curve indicates that the formation enthalpy of Mg-16 wt%LaNi is 74.62 kJ·mol^(-1),which approaches to the theoretical values of MgH2.The isothermal measurement indicates that Mg-16 wt%LaNi can absorb 6.263 wt%H_(2)within 30 min at 390℃for the first absorption,the absorption reaction fraction within2 min is over 90.00%,and the desorption reaction fraction within 2 min is 72.63%,increasing by 55.36%compared with that of Mg.Mg-16 wt%LaNi has better cyclic stability than that of Mg,only decreasing by 0.609 wt%after 80cycles.The enhancement in thermal storage performances of Mg by adding LaNi is mainly ascribed to the formed Mg_(2)NiH_(4),H_(0.3)Mg_(2)Ni and La_(4)H_(12.19)during the cyclic process which act as catalysts and inhibit the growth of Mg.The above results prove that Mg-16 wt%LaNi is suitable for use as a heat storage material.
文摘P-type thermoelectric material(Bi0.25Sb0.75)2Te3 was sintered by spark plasma sintering(SPS) process in the temperature range of 320-420 ℃. The microstructures of sintered materials were found to be well aligned,particularly when sintered at lower sintering temperatures. The electrical conductivity of the material became larger as the sintering temperature increased. The Seebeck coefficient showed a general decreasing tendency with an increase in sintering temperature. In terms of the power factor,the optimum sintering temperature was found to be 380 ℃ for a maximum value of around 2.6 mW/K.
基金Project(2006AA11A151) supported by the National Hi-Tech Research and Development Program of China
文摘The Co(Ⅲ)-coated spherical nickel hydroxide powder is optimum as positive electrode of high power Ni-MH battery because of its excellent property. But the performances at high temperature(above 50 ℃) is still not satisfied. In the present paper,the effect of element erbium,used as additive by different methods to prepare positive electrode,on the high temperature performances of the Ni-MH batteries is studied. It is found that the charge acceptance ability of the spherical Ni(OH)2 electrode with element erbium as additive is improved. The discharge capacities of Ni(OH)2 coated with 1%(atomic fraction) Er(OH)3 and mechanically added with 1%(atomic fraction) Er2O3 at 1C are 12.6% and 11.7%,respectively,higher than those of the samples without erbium at 70 ℃.
文摘Zirconia separator is one of the key materials of nickel-hydrogen battery,thereby zirconia separators are prepared by precursor process in which cellulose textiles immersed with zirconium salts are oxidized,infrared spectra show that viscose textile is an excellent precursor for preparing zirconia separator. The dominant factors in immersion are studied,it is revealed that the solution concentration and the temperature are the most important factors with regard to the area density of zirconia separator. The main reactions of immersed textiles during heat treatment are investigated by TG-DSC. The prepared zirconia separators are analyzed by SEM,XRD and infrared spectroscopy,which lead to kown that the separators maintain the same morphology of precursor textiles and contain little organic components,the main phase of the separators is tetragonal zirconia,the rate and the amount of alkaline absorption are about 5 cm/min and 220% respectively.
基金Project supported by the Development of High-Quality High-Temperature Vanadium-Containing Bearing Steel(2022YFG0097)。
文摘Rare earth(RE) elements are excellent modifiers for non-metallic inclusions that inevitably appear in steel and affect steel properties. This paper reviews the research status of inclusions modification by RE elements and the changes it cause on steel properties. First, the inclusion changes caused by RE modification are described. Generally, after adding pure RE, the main evolution of inclusions occurs as M →M + RE-Al-O → RE-Al-O + RE_(2)O_(2)S → RE_(2)O_(2)S + RE—S/RE_(2)O_(2)S + RE-O with an increase in the RE content(M represents the inclusions before RE addition). The type of final inclusion obtained after RE modification is related to the relative contents of S and O in the steel. Moreover, fine, regular, and uniformly distributed inclusions can be obtained with appropriate RE addition. However, the effectiveness of inclusions modification by adding both RE and non-RE elements is closely related to the order of their addition. Second, the applications and advantages of thermodynamic calculations in the study of RE-modified inclusions are introduced. Third, the changes in the corrosion resistance, impact properties,and other properties of steel caused by the modification of inclusions by RE are reviewed. Finally, the perspectives and trends of inclusions modified by RE elements in the steel industry are presented.
基金This research has been supported by the Natural Science Foundation of Hebei Province,China(E2022318002).Thanks are given to Tangsteel Co.,Ltd.of Hesteel Group and Digital Co.,Ltd.of Hesteel Group for providing detailed data,hardware and software support for model development and field production test.
文摘Mathematical(data-driven)models based on state-of-the-art(SOTA)machine learning and deep learning models and data collected from 12,786 heats were established to predict the values of temperature,sample,and carbon(TSC)test,including temperature of molten steel(TSC-Temp),carbon content(TSC-C)and phosphorus content(TSC-P),which made prepa-ration for eliminating the TSC test.To maximize the prediction accuracy of the proposed approach,various models with different inputs were implemented and compared,and the best models were applied to the production process of a Hesteel Group steelmaking plant in China in the field.The number of tabular features(hot metal information,scrap,additives,blowing practices,and preset values)was expanded,and time series(off-gas profiles and blowing practice curves)that could reflect the entire steelmaking process were introduced as inputs.First,the latest machine learning models(LightGBM,CatBoost,TabNet,and NODE)were used to make predictions with tabular features,and the best coefficient of determination R^(2)values obtained for TSC-P,TSC-C and TSC-Temp predictions were 0.435(LightGBM),0.857(Cat-Boost)and 0.678(LightGBM),respectively,which were higher than those of classic models(backpropagation and support vector machine).Then,making predictions was performed by using SOTA time series regression models(SCINet,DLinear,Informer,and MLSTM-FCN)with original time series,SOTA image regression models(NesT,CaiT,ResNeXt,and GoogLeNet)with resized time series,and the proposed Concatenate-Model and Parallel-Model with both tabular features and time series.Through optimization and comparisons,it was finally determined that the Concatenate-Model with MLSTM-FCN,SCINet and Informer as feature extractors performed the best,and its R^(2)values for predicting TSC-P,TSC-C and TSC-Temp reached 0.470,0.858 and 0.710,respectively.Its field test accuracies for TSC-P,TSC-C and TSC-Temp were 0.459,0.850 and 0.685,respectively.A related importance analysis was carried out,and dynamic control methods based on prediction values were proposed.
文摘Metal hydrides high temperature thermal heat storage technique has great promising future prospects in solar power generation, industrial waste heat utilization and peak load regulating of power system. This article introduces basic principle of metal hydrides for thermal storage, and summarizes developments in advanced metal hydrides high-temperature thermal storage materials, numerical simulation and thermodynamic calculation in thermal storage systems, and metal hydrides thermal storage prototypes. Finally, the future metal hydrides high temperature thermal heat storage technique is been looked ahead.
基金financially supported by the Beijing Municipal Commission of Science and Technology of China(D141100002014001)。
文摘The effect of LaNi and Ti on thermal storage properties of MgH_(2)was investigated.The thermal storage performances of Mg are significantly improved by adding LaNi and Ti.The pressure-composition-temperature(PCT)curves indicate that the formation enthalpy for Mg-15 wt%Ti-5 wt%LaNi sample is 73.00 kJ·mol^(-1),which approaches to the theoretical values of pure MgH_(2).The isothermal measurement indicates that,for the Mg-15wt%Ti-5 wt%LaNi,the first absorption reaction fraction within 2 min is 93.77%,increasing by 0.32%,0.24%and0.08%compared with those for Mg,Mg-5 wt%LaNi and Mg-15 wt%Ti,respectively.The first desorption reaction fraction within 2 min is 73.18%,increasing by 55.91%,9.79%and 8.12%compared with those for Mg,Mg-5wt%LaNi and Mg-15 wt%Ti,respectively.Moreover,Mg-15 wt%Ti-5 wt%LaNi has the best cyclic stability in all the samples.The thermal storage performances of Mg by adding both LaNi and Ti are improved mainly ascribed to synergistic effect of in situ formed La_(4)H_(12.19),Mg_(2)NiH_(4),H_(0.3)Mg_(2)Ni and TiH_(2)particles during cyclic process.The above analysis demonstrates that Mg-15 wt%Ti-5wt%LaNi is suitable for using as a heat storage material.
