Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley a...Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley additive explanation(SHAP)to predict the flue pressure and take targeted adjustment measures.First,the sintering process data were collected and processed.A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP+extremely random-ized trees(ET).The prediction accuracy of the model within the error range of±0.25 kPa was 92.63%.SHAP analysis was employed to improve the interpretability of the prediction model.The effects of various sintering operation parameters on flue pressure,the relation-ship between the numerical range of key operation parameters and flue pressure,the effect of operation parameter combinations on flue pressure,and the prediction process of the flue pressure prediction model on a single sample were analyzed.A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions.The operating parameter combination was then pushed.The flue pressure was increased by 5.87%during the verification process,achieving a good optimization effect.展开更多
As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and com...As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and combustion zone was analyzed in the laboratory.The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56%when the bed depth increased from 600 to 1000 mm.After improving porosity of 1%by adding loosening bars with optimized size and distribution,the bed resistance decreased,and the productivity increased by 5%.The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa.By using a three-stage intensive mixer and pre-adding water for granulation,the moisture of mixture was reduced by 0.6%,and the sintering productivity increased by 4%.Besides,the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm,and the bed resistance increased from 0.70 to 5.62 kPa.The bed resistance of the combustion zone at 900 mm was increased by 90.51%compared to 700 mm.After optimization of the distribution of coke breeze,the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.展开更多
Real-time prediction and precise control of sinter quality are pivotal for energy saving,cost reduction,quality improvement and efficiency enhancement in the ironmaking process.To advance,the accuracy and comprehensiv...Real-time prediction and precise control of sinter quality are pivotal for energy saving,cost reduction,quality improvement and efficiency enhancement in the ironmaking process.To advance,the accuracy and comprehensiveness of sinter quality prediction,an intelligent flare monitoring system for sintering machine tails that combines hybrid neural networks integrating convolutional neural network with long short-term memory(CNN-LSTM)networks was proposed.The system utilized a high-temperature thermal imager for image acquisition at the sintering machine tail and employed a zone-triggered method to accurately capture dynamic feature images under challenging conditions of high-temperature,high dust,and occlusion.The feature images were then segmented through a triple-iteration multi-thresholding approach based on the maximum between-class variance method to minimize detail loss during the segmentation process.Leveraging the advantages of CNN and LSTM networks in capturing temporal and spatial information,a comprehensive model for sinter quality prediction was constructed,with inputs including the proportion of combustion layer,porosity rate,temperature distribution,and image features obtained from the convolutional neural network,and outputs comprising quality indicators such as underburning index,uniformity index,and FeO content of the sinter.The accuracy is notably increased,achieving a 95.8%hit rate within an error margin of±1.0.After the system is applied,the average qualified rate of FeO content increases from 87.24%to 89.99%,representing an improvement of 2.75%.The average monthly solid fuel consumption is reduced from 49.75 to 46.44 kg/t,leading to a 6.65%reduction and underscoring significant energy saving and cost reduction effects.展开更多
Ceramic dielectric materials with high dielectric strength and mechanisms of their internal factors affecting dielectric strength are significantly valuable for industrial application,especially for selection of suita...Ceramic dielectric materials with high dielectric strength and mechanisms of their internal factors affecting dielectric strength are significantly valuable for industrial application,especially for selection of suitable dielectric materials for high-power microwave transmission devices and reliable power transmission.Pure magnesium oxide(MgO),a kind of ceramic dielectric material,possesses great application potential in high-power microwave transmission devices due to its high theoretical dielectric strength,low dielectric constant,and low dielectric loss properties,but its application is limited by high sintering temperature during preparation.This work presented the preparation of a new type of multiphase ceramics based on MgO,which was MgO-1%ZrO_(2)-1%CaCO_(3-x)%MnCO_(3)(MZCM_(x),x=0,0.25,0.50,1.00,1.50,in molar),and their phase structures,morphological features,and dielectric properties were investigated.It was found that inclusion of ZrO_(2) and CaCO_(3) effectively inhibited excessive growth of MgO grains by formation of second phase,while addition of MnCO_(3) promoted the grain boundary diffusion process during the sintering process and reduced activation energy for the grain growth,resulting in a lower ceramic sintering temperature.Excellent performance,including high dielectric strength(Eb=92.3 kV/mm)and quality factor(Q×f=216642 GHz),simultaneously accompanying low dielectric loss(<0.03%),low temperature coefficient of dielectric constant(20.3×10^(–6)℃^(–1),85℃)and resonance frequency(–12.54×10^(–6)℃^(–1)),was achieved in MZCM1.00 ceramics under a relatively low sintering temperature of 1350℃.This work offers an effective solution for selecting dielectric materials for high-power microwave transmission devices.展开更多
Three types of NdFeB magnets with the same composition and different grain sizes were prepared,and then the grain boundary diffusion was conducted using metal Tb under the same technical parameters.The effect of grain...Three types of NdFeB magnets with the same composition and different grain sizes were prepared,and then the grain boundary diffusion was conducted using metal Tb under the same technical parameters.The effect of grain size on the grain boundary diffusion process and properties of sintered NdFeB magnets was investigated.The diffusion process was assessed using X-ray diffractometer,field emission scanning electron microscope,and electron probe microanalyzer.The magnetic properties of the magnet before and after diffusion were investigated.The results show that the grain refinement of the magnet leads to higher Tb utilization efficiency and results in higher coercivity at different temperatures.It can be attributed to the formation of a deeper and more complete core-shell structure,resulting in better magnetic isolation and higher anisotropy of the Nd_(2)Fe_(14)B grains.This work may shed light on developing high coercivity with low heavy rare earth elements through grain refinement.展开更多
High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production meth...High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.展开更多
1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7]...1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7],that indicate their potential for use in actu-ators,sensors,micropumps,energy harvesters,and solid-state re-frigeration[8-10].Among the alloys,Ni-Mn-Sn-based alloys are environment-friendly and cost-effective[6,7,11],and hence,they have received widespread attention.展开更多
Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high en...Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high energy consumption,with typical solid fuel consumption for sintering of about 55 kg/t.In response,a pellet sintering process has been developed and its behavior has been investigated at sintering bed heights of 750 and 1500 mm.Additionally,a technical and economic comparison with traditional sintering methods has been conducted.The results indicate that at a bed height of 750 mm,the pellet sintering method can significantly reduce solid fuel consumption by approximately 30.82%,dropping from 70.75 to 48.95 kg/t.Additionally,the coke rate decreased from 4.55%to 3.20%,and harmful emissions in the flue gas were also reduced.As the bed height increases to 1500 mm,sintering performance improves even further.The coke rate is reduced to 3.00%,and solid fuel consumption decreases to 41.27 kg/t,approaching the world’s advanced level(≤40 kg/t).Technical and economic analysis also indicates that adopting the pellet sintering process can lower sintering costs by about 2.18 dollars/t.展开更多
During the sintering process of iron ore,a large amount of nitrogen oxides is generated,for which there is currently no efficient and economical treatment process.Therefore,it is necessary to implement process control...During the sintering process of iron ore,a large amount of nitrogen oxides is generated,for which there is currently no efficient and economical treatment process.Therefore,it is necessary to implement process control in sintering production to keep the mass concentration of NO_(x)in sintering flue gas at a low level.Through industrial trials at sintering sites,methods such as correlation analysis,path analysis,and multiple linear regression were applied to analyze the influence of various factors on NO emissions during the sintering process.The results indicate that negative correlations exist between nitrogen monoxide(NO)emissions and negative pressure,permeability index,O_(2) concentration,CO concentration,and flue gas temperature.Conversely,positive correlations exist between NO emissions and dust concentration,water vapor volume fraction,and sintering bed speed.Among these factors,O_(2) concentration and dust concentration are identified as the most significant influencing factors on NO emissions.By analyzing the masses and modes of influence of different factors,the mechanisms of action of each factor were obtained.Specifically,O_(2) concentration,dust concentration,permeability index,CO concentration,and flue gas temperature play a direct dominant role in NO emissions during the sintering process,while water vapor volume fraction,sintering trolley speed,and negative pressure have an indirect effect.A predictive model for NO mass concentration in flue gas was established with an accuracy rate of 91.6%,showing consistent overall trends with actual values.Finally,denitrification strategies for sintering industrial production were proposed,along with prospects for preliminary denitrification of sintering flue gas using fluidized bed conditions in the duct.展开更多
The mineral composition of the sinter affects the quality of cold-bonded briquettes(CBB),which are prepared from returned sinter fines and serve as a cleaner blast furnace charge.Pulverization rate,compressive strengt...The mineral composition of the sinter affects the quality of cold-bonded briquettes(CBB),which are prepared from returned sinter fines and serve as a cleaner blast furnace charge.Pulverization rate,compressive strength,reduction disintegration index(RDI)and compressive strength after reduction experiment were tested to analyze the experimental parameters of CBB under the influence of different basicities and sintering time.The results show that when the basicity of CBB is increased from 0.5 to 1.5,the pulverization rate increases,and performance indexes such as compressive strength,RDI,and compressive strength exhibit a decreasing trend.When the basicity is increased from 1.5 to 3.0,all the aforementioned performance indexes are improved.When the sintering time is extended from 0 to 8 h,the properties mentioned above are improved.The results of X-ray diffraction,microstructure,and thermodynamic calculations confirm that the hematite in the mineral composition of CBB tends to convert into calcium ferrite,which leads to the increased compressive strength of CBB.The reasonable basicity and sintering time during sinter preparation not only form the desired mineral composition but also improve the properties of the CBB.展开更多
Limestone was pretreated via the mechanical activation method,and burnt lime was partially substituted by the pretreated limestone for better sinter indices and lower sintering costs.With the reduction in the size dis...Limestone was pretreated via the mechanical activation method,and burnt lime was partially substituted by the pretreated limestone for better sinter indices and lower sintering costs.With the reduction in the size distribution of the pretreated limestone,the particle morphology,the activity of the calcined limestone and the fluidity of the liquid phase during sintering are all improved.When the substitution ratio of the pretreated limestone for burnt lime is kept at 50%,the granulation performance and sinter indices in sinter pot tests are both better compared with that of the base case.Much denser interleaved texture in product sinter is formed with the reduction of sinter porosity and improvement of silico-ferrite of calcium and alumina amount.When the particle size of the pretreated limestone is maintained within the optimal range of 0–2 mm,the tumble index,yield and productivity increase by 7.2%,2.6%and 11.2%,respectively,while the solid fuel rate decreases by 8.7%.In the corresponding sinter industry production,the tumble index and output of the product sinter are comparable to those of the base case,while the coke dosage is reduced by 9.0%.Reduction index and reduction degradation index(RDI_(+3.15))are both higher than 74%.The cost of raw materials in sintering process can be greatly reduced.展开更多
A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indi...A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indicated that the pre-reduction sintering process(PSP)can effectively remove 58.02%of K and 30.68%of Na from raw mixtures and improve yield and tumbler index to 74.40%and 68.69%,respectively.Moreover,PSP was conducive to reducing NO_(x) and SO_(2)emissions and simultaneously increasing CO content in flue gas.Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11%and 32.92%,respectively.Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite,wustite and a small quantity of metallic iron,and very few silicate glass phase was also formed.This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.展开更多
Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rol...Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rolling sludge directly as a raw material for sintering.However,its adhesive nature caused poor mixing with other materials,affecting the quality of the sinter.Herein,the incorporation of steel rolling sludge incineration slag into the sintering process was investigated for experimental purposes.The results indicated that adding 1%incinerated steel rolling sludge to the sintering raw material was feasible.At this proportion,both the yield and the tumbler index of the sinter have improved,primarily due to the oxidation reaction of Fe_(3)O_(4)present in the steel rolling sludge incineration slag during the sintering process,which significantly increases the sensible heat of the sinter and enhances the sintering mineralization reaction.Notably,the addition of steel rolling sludge incineration slag reduced dioxin concentrations in the sintering flue gas.Although CO,NO_(x),and SO_(2)emission concentrations slightly increased,the existing flue gas treatment system effectively controlled their emissions.展开更多
Silica-based ramming mixes are widely used as lining materials in coreless induction furnaces,which serve as the main equipment for iron and steel in foundry industry.The service life of linings made from silica-based...Silica-based ramming mixes are widely used as lining materials in coreless induction furnaces,which serve as the main equipment for iron and steel in foundry industry.The service life of linings made from silica-based ramming mixes depends on the properties of quartzite raw materials.In this paper,quartzites from three regions were selected as raw materials,with boron oxide and boron phosphate as sintering aids.By comparing and testing performance such as the phase composition,permanent linear change,bulk density,apparent porosity,and slag resistance,the effects of raw material characteristics and sintering aids on the performance of the silica-based ramming mixes were investigated.The results showed that boron oxidecontaining ramming mixes prepared from quartzite with a fast phase transition showed lower strength and greater expansion as well as lower slag penetration index.For boron phosphate as a sintering aid,ramming mixes made from quartzites with medium and slow phase transition rates had an approaching slag penetration index comparable to those containing boron oxide,although their strength was lower than the latter.According to the melting requirements of stainless steel,boron phosphate can replace boron oxide as a sintering aid for silica-based ramming mixes.Regarding practical applications for linings of coreless induction furnaces,the selection of quartzite as the raw material for silica-based ramming mixes shall be comprehensively considered from multiple aspects.展开更多
The low coercivity is the major factor inhibiting the large-scale commercial utilization of Nd-Ce-Fe-B sintered magnets.In this work,we achieved a record-high coercivity of 15.04 kOe in Ga-doped Nd-Ce-Fe-B sintered ma...The low coercivity is the major factor inhibiting the large-scale commercial utilization of Nd-Ce-Fe-B sintered magnets.In this work,we achieved a record-high coercivity of 15.04 kOe in Ga-doped Nd-Ce-Fe-B sintered magnets with 30 wt%Ce replacing Nd,demonstrating enormous potential.The Ga-doped Nd-Ce-Fe-B magnets with higher boron(HB)and lower boron(LB)content are designed.The coercivity of the HB magnet increases slightly from 10.80 to 12.26 kOe after annealing,attributed to the optimized distribution of grain boundary(GB)phases.In contrast,the coercivity of the LB magnet remarkably increases from 8.13 to 15.04 kOe after annealing.Microstructural observations indicate that the narrow GB phase in the as-sintered magnet is rich in Fe,and the strong exchange coupling of adjacent grains resulted in low coercivity.The evolution of Ga-rich phases reveals a potential formation mechanism of the RE_(6)Fe_(13)Ga phase,that is the RE-Fe amorphous phase and REGa phase in the as-sintered magnet combine to form the RE_(6)Fe_(13)Ga phase and RE-Ga amorphous phase during post-sinter annealing(RE:rare earth).Moreover,the GB phase of the annealed magnet transforms into a Fe-lean phase with a thickness of 16.4 nm.Magnetization and demagnetization behavior characterizations reveal that the exchange decoupling of adjacent grains induced by the optimized GB phases is the main reason for the remarkable coercivity enhancement,which is also validated by micromagnetic simulations.展开更多
BiCuSeO thermoelectric ceramics were fabricated using self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS),and their phase compositions,microstructure,electrical properties,and the...BiCuSeO thermoelectric ceramics were fabricated using self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS),and their phase compositions,microstructure,electrical properties,and thermal properties were systematically characterized and analyzed.The experimental results demonstrate that applying high-pressure condition during the sintering process will effectively restrict grain growth,reduce porosity,and lead to an increase in electrical conductivity.Simultaneously,high pressure sintering conditions reduce grain size and introduce additional grain boundaries and defects,which strengthens phonon scattering,thereby further decreasing both lattice thermal conductivity and total thermal conductivity.As a result,the high-pressure conditions significantly improve the thermoelectric figure of merit(ZT)of BiCuSeO.In brief,the samples sintered at 600℃under 200 MPa achieve a maximum ZT value of 0.64 at approximately 792 K.展开更多
Sintering is the process that emits the most pollutants in ironmaking,including CO,SO_(2),NO_(x),and dioxins.Flue gas circulation sintering technology can not only reduce the emissions of various pollutants but also d...Sintering is the process that emits the most pollutants in ironmaking,including CO,SO_(2),NO_(x),and dioxins.Flue gas circulation sintering technology can not only reduce the emissions of various pollutants but also decrease the consumption of solid fuels.Therefore,it is necessary to summarize and discuss the research status of flue gas circulation technology.Firstly,the research status,advantages,and disadvantages of five typical flue gas circulation processes and their effects on the emission of different pollutants were analyzed.Then,the impact of O_(2),CO,SO_(2),and temperature in the circulating gas during the sintering flue gas circulation process on the quality of sinter and their reasonable ranges was summarized,and the formation mechanisms of CO_(x),NO_(x),SO_(2),and dioxins during the sintering process were discussed.Furthermore,the optimization and improvement of flue gas circulation technology in recent years were introduced.Finally,issues related to element enrichment,equipment improvements,and fine particulate matter emissions in the flue gas circulation process were reviewed,providing a reference for the optimal application of flue gas circulation sintering technology in the future.展开更多
Controlling the adhesion of potentially corrosive substances from flue gas on grate bar is crucial for extending the operational lifespan of the equipment.The adhesive behaviour and mechanism of ultrafine particulate ...Controlling the adhesion of potentially corrosive substances from flue gas on grate bar is crucial for extending the operational lifespan of the equipment.The adhesive behaviour and mechanism of ultrafine particulate matters(UPM)throughout the sintering process were elucidated,and measures to control adhesion on grate bars were developed.Research findings indicated that a small quantity of UPM were found on grate bar during the initial sintering stages(ignition stage and middle stageⅠandⅡ).The main compositions of UPM were FexOy-rich,CaO-rich,and aluminium silicate-rich particles.In contrast,corrosive substances like alkali metal compounds were almost absent.These UPM adhered onto grate bar primarily through inertial impaction.When moving to the final sintering stages(middle stageⅢand temperature rising stage),many UPM rich in corrosive substances like NaCl and KCl adhered to the grate bar.These UPM adhered to grate bar through thermal diffusion and vortex deposition.Solid waste water washing technology can greatly decrease the quantity of UPM(rich in NaCl and KCl)on the grate bar due to vortex deposition and thermal diffusion,and it represents a potentially promising way to control adhesion and corrosion on grate bars.展开更多
Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical du...Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.展开更多
Carbide dispersion reinforcing has been demonstrated to be an effective way of strengthening metal matrix composites.However,plagued by the nerve-wracking fact that the carbide particles tend to aggregate at the grain...Carbide dispersion reinforcing has been demonstrated to be an effective way of strengthening metal matrix composites.However,plagued by the nerve-wracking fact that the carbide particles tend to aggregate at the grain boundary of the metal matrix,grow up,and form an incoherent interface with it,their improvement in mechanical strength tends to be limited.In this study,spark plasma sintering(SPS)was used to prepare the bulk alloy Ni20Cr and its composites with different carbides including TiC,SiC,and Ti_(3)SiC_(2).Plasma leads to discharge and elevates temperature at the interface to melt the Ni20Cr alloy particles locally.When cooled down,the alloy is heterogeneously solidified on the surface of the carbide and builds up a coherent interface with it.Owing to the decomposition of Ti_(3)SiC_(2) during sintering,it completely transformed into nanosized TiC particles,which are engulfed by the outer melted layer of Ni20Cr and well dispersed within the alloy grains.In comparison to the Ni20Cr alloy,the composite with merely 4 wt%Ti_(3)SiC_(2) gains over three times enhancement in yield strength to 879 MPa,while keeping a moderate high elongation of 17.8%.Finite element analysis demonstrated that the combination of SPS and precursor MAX phase of Ti_(3)SiC_(2),which results in the in-situ precipitation of coherent ultrafine TiC particles in alloy grains,plays the key role in getting a good balance between mechanical strength and ductility for the Ni20Cr matrix composites.展开更多
基金supported by the General Program of the National Natural Science Foundation of China(No.52274326)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202109)the Seventh Batch of Ten Thousand Talents Plan of China(No.ZX20220553).
文摘Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley additive explanation(SHAP)to predict the flue pressure and take targeted adjustment measures.First,the sintering process data were collected and processed.A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP+extremely random-ized trees(ET).The prediction accuracy of the model within the error range of±0.25 kPa was 92.63%.SHAP analysis was employed to improve the interpretability of the prediction model.The effects of various sintering operation parameters on flue pressure,the relation-ship between the numerical range of key operation parameters and flue pressure,the effect of operation parameter combinations on flue pressure,and the prediction process of the flue pressure prediction model on a single sample were analyzed.A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions.The operating parameter combination was then pushed.The flue pressure was increased by 5.87%during the verification process,achieving a good optimization effect.
基金supported by the Basic Science Center Project for the National Natural Science Foundation of China(No.72088101)the S&T Program of Hebei(No.23564101D).
文摘As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and combustion zone was analyzed in the laboratory.The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56%when the bed depth increased from 600 to 1000 mm.After improving porosity of 1%by adding loosening bars with optimized size and distribution,the bed resistance decreased,and the productivity increased by 5%.The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa.By using a three-stage intensive mixer and pre-adding water for granulation,the moisture of mixture was reduced by 0.6%,and the sintering productivity increased by 4%.Besides,the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm,and the bed resistance increased from 0.70 to 5.62 kPa.The bed resistance of the combustion zone at 900 mm was increased by 90.51%compared to 700 mm.After optimization of the distribution of coke breeze,the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.
基金founded by the Open Project Program of Anhui Province Key Laboratory of Metallurgical Engineering and Resources Recycling(Anhui University of Technology)(No.SKF21-06)Research Fund for Young Teachers of Anhui University of Technology in 2020(No.QZ202001).
文摘Real-time prediction and precise control of sinter quality are pivotal for energy saving,cost reduction,quality improvement and efficiency enhancement in the ironmaking process.To advance,the accuracy and comprehensiveness of sinter quality prediction,an intelligent flare monitoring system for sintering machine tails that combines hybrid neural networks integrating convolutional neural network with long short-term memory(CNN-LSTM)networks was proposed.The system utilized a high-temperature thermal imager for image acquisition at the sintering machine tail and employed a zone-triggered method to accurately capture dynamic feature images under challenging conditions of high-temperature,high dust,and occlusion.The feature images were then segmented through a triple-iteration multi-thresholding approach based on the maximum between-class variance method to minimize detail loss during the segmentation process.Leveraging the advantages of CNN and LSTM networks in capturing temporal and spatial information,a comprehensive model for sinter quality prediction was constructed,with inputs including the proportion of combustion layer,porosity rate,temperature distribution,and image features obtained from the convolutional neural network,and outputs comprising quality indicators such as underburning index,uniformity index,and FeO content of the sinter.The accuracy is notably increased,achieving a 95.8%hit rate within an error margin of±1.0.After the system is applied,the average qualified rate of FeO content increases from 87.24%to 89.99%,representing an improvement of 2.75%.The average monthly solid fuel consumption is reduced from 49.75 to 46.44 kg/t,leading to a 6.65%reduction and underscoring significant energy saving and cost reduction effects.
基金Student Training Program for Innovation and Entrepreneurship of Hangzhou Institute for Advanced Study,UCAS(CXCY20230305)Chinese Academy of Sciences Key Project(ZDRW-CN-2021-3-1-18)。
文摘Ceramic dielectric materials with high dielectric strength and mechanisms of their internal factors affecting dielectric strength are significantly valuable for industrial application,especially for selection of suitable dielectric materials for high-power microwave transmission devices and reliable power transmission.Pure magnesium oxide(MgO),a kind of ceramic dielectric material,possesses great application potential in high-power microwave transmission devices due to its high theoretical dielectric strength,low dielectric constant,and low dielectric loss properties,but its application is limited by high sintering temperature during preparation.This work presented the preparation of a new type of multiphase ceramics based on MgO,which was MgO-1%ZrO_(2)-1%CaCO_(3-x)%MnCO_(3)(MZCM_(x),x=0,0.25,0.50,1.00,1.50,in molar),and their phase structures,morphological features,and dielectric properties were investigated.It was found that inclusion of ZrO_(2) and CaCO_(3) effectively inhibited excessive growth of MgO grains by formation of second phase,while addition of MnCO_(3) promoted the grain boundary diffusion process during the sintering process and reduced activation energy for the grain growth,resulting in a lower ceramic sintering temperature.Excellent performance,including high dielectric strength(Eb=92.3 kV/mm)and quality factor(Q×f=216642 GHz),simultaneously accompanying low dielectric loss(<0.03%),low temperature coefficient of dielectric constant(20.3×10^(–6)℃^(–1),85℃)and resonance frequency(–12.54×10^(–6)℃^(–1)),was achieved in MZCM1.00 ceramics under a relatively low sintering temperature of 1350℃.This work offers an effective solution for selecting dielectric materials for high-power microwave transmission devices.
基金Key Research and Development Program of Shandong Province(2021CXGC010310)Shandong Province Science and Technology Small and Medium Sized Enterprise Innovation Ability Enhancement Project(2023TSGC0287,2024TSGC0519)+1 种基金Shandong Provincial Natural Science Foundation(ZR2022ME222)National Natural Science Foundation of China(51702187)。
文摘Three types of NdFeB magnets with the same composition and different grain sizes were prepared,and then the grain boundary diffusion was conducted using metal Tb under the same technical parameters.The effect of grain size on the grain boundary diffusion process and properties of sintered NdFeB magnets was investigated.The diffusion process was assessed using X-ray diffractometer,field emission scanning electron microscope,and electron probe microanalyzer.The magnetic properties of the magnet before and after diffusion were investigated.The results show that the grain refinement of the magnet leads to higher Tb utilization efficiency and results in higher coercivity at different temperatures.It can be attributed to the formation of a deeper and more complete core-shell structure,resulting in better magnetic isolation and higher anisotropy of the Nd_(2)Fe_(14)B grains.This work may shed light on developing high coercivity with low heavy rare earth elements through grain refinement.
基金Natural Science Foundation of Shanghai(24ZR1400800)he Natural Science Foundation of China(U23A20685,52073058,91963204)+1 种基金the National Key R&D Program of China(2021YFB3701400)Shanghai Sailing Program(23YF1400200)。
文摘High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.
基金supported by the National Key R&D Pro-gram of China(No.2022YFB3805701)National Natural Science Foundation of China(NSFC)(No.52371182,51701052,52192592,52192593)+1 种基金Young Elite Scientists Sponsorship Program by CAST(No.2019QNRC001)the Heilongjiang Touyan Innovation Team Program.
文摘1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7],that indicate their potential for use in actu-ators,sensors,micropumps,energy harvesters,and solid-state re-frigeration[8-10].Among the alloys,Ni-Mn-Sn-based alloys are environment-friendly and cost-effective[6,7,11],and hence,they have received widespread attention.
基金financially supported by Huxiang Youth Talent Program of Hunan Province(No.2024RC3008)National Natural Science Foundation China(Nos.52274343 and 52474370)National Key R&D Program of China(Nos.2023YFC3903900 and 2023YFC3903904).
文摘Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high energy consumption,with typical solid fuel consumption for sintering of about 55 kg/t.In response,a pellet sintering process has been developed and its behavior has been investigated at sintering bed heights of 750 and 1500 mm.Additionally,a technical and economic comparison with traditional sintering methods has been conducted.The results indicate that at a bed height of 750 mm,the pellet sintering method can significantly reduce solid fuel consumption by approximately 30.82%,dropping from 70.75 to 48.95 kg/t.Additionally,the coke rate decreased from 4.55%to 3.20%,and harmful emissions in the flue gas were also reduced.As the bed height increases to 1500 mm,sintering performance improves even further.The coke rate is reduced to 3.00%,and solid fuel consumption decreases to 41.27 kg/t,approaching the world’s advanced level(≤40 kg/t).Technical and economic analysis also indicates that adopting the pellet sintering process can lower sintering costs by about 2.18 dollars/t.
基金supported by the National Natural Science Foundation of China(No.51974131)Hebei Outstanding Youth Fund Project(No.E2020209082),Tangshan Key R&D Program project(No.22150232J)Sixth Division Wujiaqu City Science and Technology Plan Project(2410).
文摘During the sintering process of iron ore,a large amount of nitrogen oxides is generated,for which there is currently no efficient and economical treatment process.Therefore,it is necessary to implement process control in sintering production to keep the mass concentration of NO_(x)in sintering flue gas at a low level.Through industrial trials at sintering sites,methods such as correlation analysis,path analysis,and multiple linear regression were applied to analyze the influence of various factors on NO emissions during the sintering process.The results indicate that negative correlations exist between nitrogen monoxide(NO)emissions and negative pressure,permeability index,O_(2) concentration,CO concentration,and flue gas temperature.Conversely,positive correlations exist between NO emissions and dust concentration,water vapor volume fraction,and sintering bed speed.Among these factors,O_(2) concentration and dust concentration are identified as the most significant influencing factors on NO emissions.By analyzing the masses and modes of influence of different factors,the mechanisms of action of each factor were obtained.Specifically,O_(2) concentration,dust concentration,permeability index,CO concentration,and flue gas temperature play a direct dominant role in NO emissions during the sintering process,while water vapor volume fraction,sintering trolley speed,and negative pressure have an indirect effect.A predictive model for NO mass concentration in flue gas was established with an accuracy rate of 91.6%,showing consistent overall trends with actual values.Finally,denitrification strategies for sintering industrial production were proposed,along with prospects for preliminary denitrification of sintering flue gas using fluidized bed conditions in the duct.
基金supported by Distinguished Professor(Tracking Plan)of Oriental Scholars of Shanghai Universities(Grant No.GZ2020013)National 111 Project(The Program of Introducing Talents of Discipline to University)(Grant No.Dl7002)+1 种基金Independent Research Project of State Key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced Ferrometallurgy and Shanghai University(Grant No.SKLASS 2022-Z011)Additionally,the authors are appreciative of the funding from the Academy of Finland with Grant No.349833.
文摘The mineral composition of the sinter affects the quality of cold-bonded briquettes(CBB),which are prepared from returned sinter fines and serve as a cleaner blast furnace charge.Pulverization rate,compressive strength,reduction disintegration index(RDI)and compressive strength after reduction experiment were tested to analyze the experimental parameters of CBB under the influence of different basicities and sintering time.The results show that when the basicity of CBB is increased from 0.5 to 1.5,the pulverization rate increases,and performance indexes such as compressive strength,RDI,and compressive strength exhibit a decreasing trend.When the basicity is increased from 1.5 to 3.0,all the aforementioned performance indexes are improved.When the sintering time is extended from 0 to 8 h,the properties mentioned above are improved.The results of X-ray diffraction,microstructure,and thermodynamic calculations confirm that the hematite in the mineral composition of CBB tends to convert into calcium ferrite,which leads to the increased compressive strength of CBB.The reasonable basicity and sintering time during sinter preparation not only form the desired mineral composition but also improve the properties of the CBB.
基金supported by Natural Science Foundation of Chongqing(No.CSTB2023NSCQ-BHX0166)Postdoctoral Science Foundation of China(No.2024T171095)Fundamental Research Funds for the Central Universities(No.2024CDJXY003).
文摘Limestone was pretreated via the mechanical activation method,and burnt lime was partially substituted by the pretreated limestone for better sinter indices and lower sintering costs.With the reduction in the size distribution of the pretreated limestone,the particle morphology,the activity of the calcined limestone and the fluidity of the liquid phase during sintering are all improved.When the substitution ratio of the pretreated limestone for burnt lime is kept at 50%,the granulation performance and sinter indices in sinter pot tests are both better compared with that of the base case.Much denser interleaved texture in product sinter is formed with the reduction of sinter porosity and improvement of silico-ferrite of calcium and alumina amount.When the particle size of the pretreated limestone is maintained within the optimal range of 0–2 mm,the tumble index,yield and productivity increase by 7.2%,2.6%and 11.2%,respectively,while the solid fuel rate decreases by 8.7%.In the corresponding sinter industry production,the tumble index and output of the product sinter are comparable to those of the base case,while the coke dosage is reduced by 9.0%.Reduction index and reduction degradation index(RDI_(+3.15))are both higher than 74%.The cost of raw materials in sintering process can be greatly reduced.
基金Project(52274290)supported by the National Natural Science Foundation of ChinaProject(72088101)supported by the Basic Science Center Project for National Natural Science Foundation of China。
文摘A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indicated that the pre-reduction sintering process(PSP)can effectively remove 58.02%of K and 30.68%of Na from raw mixtures and improve yield and tumbler index to 74.40%and 68.69%,respectively.Moreover,PSP was conducive to reducing NO_(x) and SO_(2)emissions and simultaneously increasing CO content in flue gas.Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11%and 32.92%,respectively.Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite,wustite and a small quantity of metallic iron,and very few silicate glass phase was also formed.This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.
基金supported by the National Natural Science Foundation of China(52204331)Natural Science Foundation of Anhui Province Youth Project(2208085QE145)the Open Project Program of Key Laboratory of Metallurgical Emission Reduction&Resources Recycling(Anhui University of Technology),Ministry of Education(JKF20-03).
文摘Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rolling sludge directly as a raw material for sintering.However,its adhesive nature caused poor mixing with other materials,affecting the quality of the sinter.Herein,the incorporation of steel rolling sludge incineration slag into the sintering process was investigated for experimental purposes.The results indicated that adding 1%incinerated steel rolling sludge to the sintering raw material was feasible.At this proportion,both the yield and the tumbler index of the sinter have improved,primarily due to the oxidation reaction of Fe_(3)O_(4)present in the steel rolling sludge incineration slag during the sintering process,which significantly increases the sensible heat of the sinter and enhances the sintering mineralization reaction.Notably,the addition of steel rolling sludge incineration slag reduced dioxin concentrations in the sintering flue gas.Although CO,NO_(x),and SO_(2)emission concentrations slightly increased,the existing flue gas treatment system effectively controlled their emissions.
基金grateful to Hubei Province Science and Technology Innovation Talent Plan,and Science and Technology Service Talent Special Project(2023DJC124)for the support on this work.
文摘Silica-based ramming mixes are widely used as lining materials in coreless induction furnaces,which serve as the main equipment for iron and steel in foundry industry.The service life of linings made from silica-based ramming mixes depends on the properties of quartzite raw materials.In this paper,quartzites from three regions were selected as raw materials,with boron oxide and boron phosphate as sintering aids.By comparing and testing performance such as the phase composition,permanent linear change,bulk density,apparent porosity,and slag resistance,the effects of raw material characteristics and sintering aids on the performance of the silica-based ramming mixes were investigated.The results showed that boron oxidecontaining ramming mixes prepared from quartzite with a fast phase transition showed lower strength and greater expansion as well as lower slag penetration index.For boron phosphate as a sintering aid,ramming mixes made from quartzites with medium and slow phase transition rates had an approaching slag penetration index comparable to those containing boron oxide,although their strength was lower than the latter.According to the melting requirements of stainless steel,boron phosphate can replace boron oxide as a sintering aid for silica-based ramming mixes.Regarding practical applications for linings of coreless induction furnaces,the selection of quartzite as the raw material for silica-based ramming mixes shall be comprehensively considered from multiple aspects.
基金supported by the National Natural Science Foundation of China(Nos.52261037,52088101)the Key research project of Jiangxi Province(No.20203ABC28W006)the Double-Thousand Plan of Jiangxi Province(No.jxsq2023101057).
文摘The low coercivity is the major factor inhibiting the large-scale commercial utilization of Nd-Ce-Fe-B sintered magnets.In this work,we achieved a record-high coercivity of 15.04 kOe in Ga-doped Nd-Ce-Fe-B sintered magnets with 30 wt%Ce replacing Nd,demonstrating enormous potential.The Ga-doped Nd-Ce-Fe-B magnets with higher boron(HB)and lower boron(LB)content are designed.The coercivity of the HB magnet increases slightly from 10.80 to 12.26 kOe after annealing,attributed to the optimized distribution of grain boundary(GB)phases.In contrast,the coercivity of the LB magnet remarkably increases from 8.13 to 15.04 kOe after annealing.Microstructural observations indicate that the narrow GB phase in the as-sintered magnet is rich in Fe,and the strong exchange coupling of adjacent grains resulted in low coercivity.The evolution of Ga-rich phases reveals a potential formation mechanism of the RE_(6)Fe_(13)Ga phase,that is the RE-Fe amorphous phase and REGa phase in the as-sintered magnet combine to form the RE_(6)Fe_(13)Ga phase and RE-Ga amorphous phase during post-sinter annealing(RE:rare earth).Moreover,the GB phase of the annealed magnet transforms into a Fe-lean phase with a thickness of 16.4 nm.Magnetization and demagnetization behavior characterizations reveal that the exchange decoupling of adjacent grains induced by the optimized GB phases is the main reason for the remarkable coercivity enhancement,which is also validated by micromagnetic simulations.
基金Funded by the National Natural Science Foundation of China(Nos.52322207 and 52202289)the National Key Research and Development Plan of China(No.2021YFB3701400)+2 种基金the Independent Innovation Projects of the Hubei Longzhong Laboratory(No.2022ZZ-11)Funded by the National Natural Science Foundation of China(Nos.52322207 and 52202289)the National Key Research and Development Plan of China(No.2021YFB3701400)the Independent Innovation Projects of the Hubei Longzhong Laboratory(No.2022ZZ-11)。
文摘BiCuSeO thermoelectric ceramics were fabricated using self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS),and their phase compositions,microstructure,electrical properties,and thermal properties were systematically characterized and analyzed.The experimental results demonstrate that applying high-pressure condition during the sintering process will effectively restrict grain growth,reduce porosity,and lead to an increase in electrical conductivity.Simultaneously,high pressure sintering conditions reduce grain size and introduce additional grain boundaries and defects,which strengthens phonon scattering,thereby further decreasing both lattice thermal conductivity and total thermal conductivity.As a result,the high-pressure conditions significantly improve the thermoelectric figure of merit(ZT)of BiCuSeO.In brief,the samples sintered at 600℃under 200 MPa achieve a maximum ZT value of 0.64 at approximately 792 K.
基金the financial support provided by the National Natural Science Foundation of China(52204335,52374319,52174291)the National Youth Talent Support Program(GJRC2023008)+2 种基金the Beijing New-Star Plan of Science and Technology(Z211100002121115)the Central Universities Foundation of China(06500170)Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-22-004).
文摘Sintering is the process that emits the most pollutants in ironmaking,including CO,SO_(2),NO_(x),and dioxins.Flue gas circulation sintering technology can not only reduce the emissions of various pollutants but also decrease the consumption of solid fuels.Therefore,it is necessary to summarize and discuss the research status of flue gas circulation technology.Firstly,the research status,advantages,and disadvantages of five typical flue gas circulation processes and their effects on the emission of different pollutants were analyzed.Then,the impact of O_(2),CO,SO_(2),and temperature in the circulating gas during the sintering flue gas circulation process on the quality of sinter and their reasonable ranges was summarized,and the formation mechanisms of CO_(x),NO_(x),SO_(2),and dioxins during the sintering process were discussed.Furthermore,the optimization and improvement of flue gas circulation technology in recent years were introduced.Finally,issues related to element enrichment,equipment improvements,and fine particulate matter emissions in the flue gas circulation process were reviewed,providing a reference for the optimal application of flue gas circulation sintering technology in the future.
基金supported by the National Natural Science Foundation of China(No.52274344)the Provincial Natural Science Foundation of Hunan(Nos.2022JJ30723 and 2023JJ20068)the Science and Technology Innovation Program of Hunan Province(2023RC3042).
文摘Controlling the adhesion of potentially corrosive substances from flue gas on grate bar is crucial for extending the operational lifespan of the equipment.The adhesive behaviour and mechanism of ultrafine particulate matters(UPM)throughout the sintering process were elucidated,and measures to control adhesion on grate bars were developed.Research findings indicated that a small quantity of UPM were found on grate bar during the initial sintering stages(ignition stage and middle stageⅠandⅡ).The main compositions of UPM were FexOy-rich,CaO-rich,and aluminium silicate-rich particles.In contrast,corrosive substances like alkali metal compounds were almost absent.These UPM adhered onto grate bar primarily through inertial impaction.When moving to the final sintering stages(middle stageⅢand temperature rising stage),many UPM rich in corrosive substances like NaCl and KCl adhered to the grate bar.These UPM adhered to grate bar through thermal diffusion and vortex deposition.Solid waste water washing technology can greatly decrease the quantity of UPM(rich in NaCl and KCl)on the grate bar due to vortex deposition and thermal diffusion,and it represents a potentially promising way to control adhesion and corrosion on grate bars.
基金Funded by the Key Research and Development Projects of Anhui Province(No.2022a05020026)the Key Technologies R&D Program of CNBM(Nos.2021HX0809,2021HX1011)the Anhui Science and Technology Major Project(No.2021e03020009)。
文摘Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.
基金financially supported by the Liaoning Revitalization Talents Program(No.XLYC2203133)the Fundamental Research Funds for the Central Universities(No.N2302018)+1 种基金the Ningbo Yuyao City Science and Technology Plan Project(No.2023J03010010)the Fourth Batch of Ningxia Youth Talents Supporting Program(No.TJGC2019028).
文摘Carbide dispersion reinforcing has been demonstrated to be an effective way of strengthening metal matrix composites.However,plagued by the nerve-wracking fact that the carbide particles tend to aggregate at the grain boundary of the metal matrix,grow up,and form an incoherent interface with it,their improvement in mechanical strength tends to be limited.In this study,spark plasma sintering(SPS)was used to prepare the bulk alloy Ni20Cr and its composites with different carbides including TiC,SiC,and Ti_(3)SiC_(2).Plasma leads to discharge and elevates temperature at the interface to melt the Ni20Cr alloy particles locally.When cooled down,the alloy is heterogeneously solidified on the surface of the carbide and builds up a coherent interface with it.Owing to the decomposition of Ti_(3)SiC_(2) during sintering,it completely transformed into nanosized TiC particles,which are engulfed by the outer melted layer of Ni20Cr and well dispersed within the alloy grains.In comparison to the Ni20Cr alloy,the composite with merely 4 wt%Ti_(3)SiC_(2) gains over three times enhancement in yield strength to 879 MPa,while keeping a moderate high elongation of 17.8%.Finite element analysis demonstrated that the combination of SPS and precursor MAX phase of Ti_(3)SiC_(2),which results in the in-situ precipitation of coherent ultrafine TiC particles in alloy grains,plays the key role in getting a good balance between mechanical strength and ductility for the Ni20Cr matrix composites.
