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
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
Digital light processing(DLP)is widely used in ceramic additive manufacturing.However,it remains unexplored for metals.In this study,the regulatory mechanisms of the microstructure and mechanical properties of AISI 31...Digital light processing(DLP)is widely used in ceramic additive manufacturing.However,it remains unexplored for metals.In this study,the regulatory mechanisms of the microstructure and mechanical properties of AISI 316L stainless steel were investigated by optimizing a DLP-compatible metal slurry formulation and sintering process.A photosensitive resin system(mass ratio of 5:1:2:2 for U600,LA,ACMO,and HDDA,respectively)with 88 wt%solid content is designed to achieve a slurry with balanced rheology,photocurability,and low pyrolysis residue.Compared to vacuum sintering,which leads to brittle fracture of material,the Ar/H2 mixed gas(5%H2)effectively reduces carbon and oxygen impurities via reduction,mitigating carbide and oxide segregation at grain boundaries and within grains,thereby enhancing strength-ductility.In addition,the prolonged high-temperature sintering inducesδ-ferrite precipitation at grain boundaries,which fills residual pores to improve densification obviously.Under optimized sintering conditions(Ar/H2,1380°C,6 h),the material achieves 96.2%relative density with tensile strength and fracture elongation of 543.5 MPa and 58.7%,respectively,exhibiting uniform dimple-dominated fracture morphology.This synergistic optimization of the slurry formulation and sintering parameters improves the strength-ductility balance in DLP-fabricated metal materials,offering theoretical and technical insights for the additive manufacturing of complex high-performance metal components.展开更多
An ore-blending optimization model for the sintering process is an intelligent system that includes iron ore characteristics, expert knowledge and material balance. In the present work, 14 indices are proposed to repr...An ore-blending optimization model for the sintering process is an intelligent system that includes iron ore characteristics, expert knowledge and material balance. In the present work, 14 indices are proposed to represent chemical composition, granulating properties and high temperature properties of iron ores. After the relationships between iron ore characteristics and sintering performance are established, the ＂two-step＂ method and the simplex method are introduced to build the model by distinguishing the calculation of optimized blending proportion of iron ores from that of other sintering materials in order to improve calculation efficiency. The ore-blending optimization model, programmed by Access and Visual Basic, is applied to practical production in steel mills and the results prove that the present model can take advantage of the available iron ore resource with stable sinter yield and quality performance but at a lower cost.展开更多
The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results sh...The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results show that the Ore-A exhibits good granulation properties, strong liquid flow capability, high bonding phase strength and crystal strength, but poor assimilability. With increasing Ore-A ratio, the tumbler index and the reduction index (RI) of the sinter first increase and then decrease, whereas the softening interval (Delta T) and the softening start temperature (T (10%)) of the sinter exhibit the opposite behavior; the reduction degradation index (RDI+3.15) of the sinter increases linearly, but the sinter yield exhibits no obvious effects. With increasing Ore-A ratio, the distribution and crystallization of the minerals are improved, the main bonding phase first changes from silico-ferrite of calcium and aluminum (SFCA) to kirschsteinite, silicate, and SFCA and then transforms to 2CaO center dot SiO2 and SFCA. Given the utilization of Ore-A and the improvement of the sinter properties, the Ore-A ratio in the high-limonite sintering process is suggested to be controlled at approximately 6wt%.展开更多
Yttria stabilized zirconia (YSZ) has widely been used as electrolyte in solid oxide fuel cell (SOFC). The microstructure of YSZ related to the fabrication process was discussed in the paper. With YSZ nano-powders abou...Yttria stabilized zirconia (YSZ) has widely been used as electrolyte in solid oxide fuel cell (SOFC). The microstructure of YSZ related to the fabrication process was discussed in the paper. With YSZ nano-powders about 40-100 nm as raw material, the YSZ adobe was manufactured by tape calendering process. The named three-step sintering process was performed at 1000 ℃ for 2 h, then raised the temperature with normal rate and as soon as up to 1400 ℃, the furnace was controlled at 1250-1300 ℃ for 10-20 h. The high dense YSZs with the relative density of 96%-99% were obtained; the grain size of YSZ could be reduced to 0.5-3 μm. The above result is benefited to co-fired in the electrode-supported SOFCs.展开更多
The prediction of the alkalinity is difficult during the sintering process. Whether or not the level of the alkalinity of sintering process is successful is directly related to the quality of sinter. There is no very ...The prediction of the alkalinity is difficult during the sintering process. Whether or not the level of the alkalinity of sintering process is successful is directly related to the quality of sinter. There is no very good method for predicting the alkalinity by now owing to the high complexity, high nonlinearity, strong coupling, high time delay, and etc. Therefore, a new technique, the grey squares support machine, was introduced. The grey support vector machine model of the alkalinity enabled the development of new equation and algorithm to predict the alkalinity. During modelling, the fluctuation of data sequence was weakened by the grey theory and the support vector machine was capable of processing nonlinear adaptable information, and the grey support vector machine has a combination of those advantages. The results revealed that the alkalinity of sinter could be accurately predicted using this model by reference to small sample and information. The experimental results showed that the grey support vector machine model was effective and practical owing to the advantages of high precision, less samples required, and simple calculation.展开更多
The emission of dioxins from the iron ore sintering process is the largest emission source of dioxins, and the reduction in dioxin emission from the iron ore sintering process to the environment is increasingly import...The emission of dioxins from the iron ore sintering process is the largest emission source of dioxins, and the reduction in dioxin emission from the iron ore sintering process to the environment is increasingly important. Three approaches to control the emission of dioxins were reviewed： source control, process control, and terminal control. Among them, two terminal control technologies, activated carbon adsorption and selective reduction technology, were discussed in detail. Following a comparison of the reduction technologies, the terminal control method was indicated as the key technology to achieve good control of dioxins during the sintering process. For the technical characteristics of the sintering process and flue gas, multiple methods should be collectively considered, and the most suitable method may be addition of inhibitors ＋ ultra-clean dust collection （electrostatic precipitation/bag filter） ＋ desulphurization ＋ selective catalytic reduction to sufficiently remove multiple pollutants, which provides a direction for the cooperative disposal of flue gas pollutants in future.展开更多
The relationship of time to minerals composition in sinters is investigated by mineragraphy are claritied observation and component analysis,and the effects of temperature and atmosphere on mineralization process.Resu...The relationship of time to minerals composition in sinters is investigated by mineragraphy are claritied observation and component analysis,and the effects of temperature and atmosphere on mineralization process.Results are obtained as follows.The initial melt forms below the eutectic temperature of CaO·Fe2O3 and CaO·2Fe2O3,which is complex substance containing Ca,Fe,Si and Al,rather than the binary calcium ferrite melt.Minerals composition of binding phase is related to local content of silica in melt,which is influenced by temperature.Appearance of the melt promotes the transition from hematite to magnetite,which then alters the mechanism of calcium ferrite formation.Before the formation of magnetite,the contents of Fe and Ca within the multiple calcium ferrite decrease with temperature,but in the case of magnetite presence,the content of Fe increases solely with increase of temperature and decrease of oxygen potential.Temperature and atmosphere determine minerals composition together,and bring influence on sintering process in different ways.It can be deduced that temperature affects kinetics of the mineralization process,but atmosphere just plays a role in thermodynamics.展开更多
An expert system skeleton tool of sintering process was constructed using object-oriented method, which can actualize two functions, i. e. , the shell function and the program function. The skeleton tool offered a pla...An expert system skeleton tool of sintering process was constructed using object-oriented method, which can actualize two functions, i. e. , the shell function and the program function. The skeleton tool offered a platform to build a prototype system, to program class code, and to develop the expert system. Four branch expert systems were developed using the skeleton tool including the control of chemical composition, the control of sintering process state, the control of expended energy, and the diagnosis of abnormity. It is found that the performance of all systems is satisfactory in practice.展开更多
Process control is an effective approach to reduce the NO_(x) emission from sintering flue gas.The effects of different materials adhered on coke breeze on NO_(x) emission characteristics and sintering performance wer...Process control is an effective approach to reduce the NO_(x) emission from sintering flue gas.The effects of different materials adhered on coke breeze on NO_(x) emission characteristics and sintering performance were studied.Results showed that the coke breeze adhered with the mixture of CaO and Fe_(2)O_(3) or calcium ferrite significantly lowers the NO_(x) emission concentration and conversion ratio of fuel-N to NO_(x).Pretreating the coke with the mixture of lime slurry and iron ore fines helped to improve the granulation effect,and optimize the carbon distribution in granules.When the mass ratio of coke breeze,quick lime,water and iron ore fines was 2:1:1:1,the average NO_(x) emission concentration was decreased from 220 mg/m^(3) to 166 mg/m^(3),and the conversion ratio of fuel-N was reduced from 54.2%to 40.9%.展开更多
β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the ...β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope,and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1773 K.展开更多
An oxide ceramic process was adopted to prepare high frequency manganese-zinc(MnZn)power ferrite.In combination with the microstructure analysis of material,the influences of sintering process on initial permeability(...An oxide ceramic process was adopted to prepare high frequency manganese-zinc(MnZn)power ferrite.In combination with the microstructure analysis of material,the influences of sintering process on initial permeability(μ_(i))and high frequency loss in unit volume(P_(cv))of MnZn power ferrite were investigated.The results show that in order to obtain fine microstructure and high frequency properties,the preferable sintering temperature and atmosphere are 1230℃and oxygen partial pressure(P_(O_(2)))of 4%,respectively.展开更多
ZrN-SiAlON composite materials were synthesized at 1 550 ℃ for 6 h via a carbothermal reduction nitridation route using fly ash （≤74 μm）,zircon （≤ 44 μm） and active carbon as starting materials.The processed ...ZrN-SiAlON composite materials were synthesized at 1 550 ℃ for 6 h via a carbothermal reduction nitridation route using fly ash （≤74 μm）,zircon （≤ 44 μm） and active carbon as starting materials.The processed ZrN-SiAlON composite micropowders were mixed with polyvinyl alcohol as binder to prepare ZrN （ZrON）-SiAlON composite ceramics by carbon-embedded pressureless firing at 1 450,1 500 and 1 550 ℃ for 1 h,respectively.Influences of firing temperature on the phase compositions,microstructure and sintering properties of the ceramics were investigated.The results show that：（1） β-SiAlON based composite ceramics with different compositions can be prepared by controlling firing temperature,and the main crystalline phases of the specimen fired at 1 550 ℃ for 1 h involve ZrN,ZrON and β-SiAlON （z =2,Si4Al2O2N6）; （2） ZrN （ZrON）,β-SiAlON and a Fe-Si based compound can be observed in the microstructures of the specimens fired at different temperatures.ZrN （ZrON） particles distribute homogeneously in the β-SiAlON matrix; （3） raising firing temperature can increase the shrinkage ratio of the ceramics,and the volume shrinkage ratio increases from 19.4％ to 40.3％ when the firing temperature rises from 1 450 to 1 550 ℃.展开更多
The general structure of expert system for controlling sintering process has been proposed. It includes knowledge base, inference engine, data acquisition system, learning system, knowledge base management system, exp...The general structure of expert system for controlling sintering process has been proposed. It includes knowledge base, inference engine, data acquisition system, learning system, knowledge base management system, explanation system and so on. The control functions consist of sintering chemical composition control centered on basicity and sintering process state control centered on permeability. The adaptive prediction of sintering chemical composition, the control strategy centered on basicity, the control strategy centered on permeability, the judgement of permeability and the prediction of burn through point were studied. The software of system, which includes about 1 000 expert rules, was successfully applied in off line control of sintering process in a sintering plant.展开更多
To solve the critical problems of lithium rich cathode materials, e.g., structure instability and short cycle life, we have successfully prepared a ZrO2-coated and Zr-doping xLi2MnO3·(1–x)LiMO2 hollow architectu...To solve the critical problems of lithium rich cathode materials, e.g., structure instability and short cycle life, we have successfully prepared a ZrO2-coated and Zr-doping xLi2MnO3·(1–x)LiMO2 hollow architecture via one-time sintering process. The modified structural materials as lithium-ion cathodes present good structural stability and superior cycle performance in LIBs. The discharge capacity of the ZrO2-coated and Zr-doped hollow pristine is 220 mAh g-1 at the 20th cycle at 0.2 C(discharge capacity loss, 2.7%)and 150 m Ah g-1 at the 100 th cycle at 1 C(discharge capacity loss, 17.7%), respectively. However, hollow pristine electrode only delivers 203 m Ah g-1 at the 20 th cycle at 0.2 C and 124 mAh g-1 at the 100 th cycle at 1 C, respectively, and the corresponding to capacity retention is 92.2% and 72.8%, respectively.Diffusion coefficients of modified hollow pristine electrode are much higher than that of hollow pristine electrode after 100 cycles(approach to 1.4 times). In addition, we simulate the adsorption reaction of HF on the surface of ZrO2-coated layer by the first-principles theory. The calculations prove that the adsorption energy of HF on the surface of ZrO2-coated layer is about-1.699 e V, and the ZrO2-coated layer could protect the hollow spherical xLi2MnO3·(1–x)LiMO2 from erosion by HF. Our results would be applicable for systematic amelioration of high-performance lithium rich material for anode with the respect of practical application.展开更多
Polycrystalline YBa2Cu3O6＋δbulks were synthesized by sol-gel method. Sintering processing played a vital role in the evolution of phase structure and microstructure, and thus significantly influenced their supercond...Polycrystalline YBa2Cu3O6＋δbulks were synthesized by sol-gel method. Sintering processing played a vital role in the evolution of phase structure and microstructure, and thus significantly influenced their superconducting properties. The influence of calcination temperature, sintering temperature, on the bulks structure, morphology and superconducting behaviors were investigated. The results showed that the oxygen content drastically increased with calcination temperature and sintering temperature. The SEM images revealed that the grains grew up monotonously with increase of calcination temperature. With increased calcination and sintering temperature, the resistivity was reduced gradually and the superconducting properties increased. Moreover, it was found that the optimal superconducting properties（with the highest superconducting transition temperature Tc^onset and the narrowest transition width ΔT） were obtained at calcination temperature of 900℃ and sintering temperature of 950 ℃.展开更多
The relationship between sintering process and vaporization of the Bi2O3 in ZnO-Bi2O3-based varistor ceramics was investigated.The phase and microstructure evolution during the sintering process were examined.The resu...The relationship between sintering process and vaporization of the Bi2O3 in ZnO-Bi2O3-based varistor ceramics was investigated.The phase and microstructure evolution during the sintering process were examined.The results show that the higher the sintering temperature or the longer the sintering time is,the more the Bi2O3 is volatilized.The heating rate has little effects on the Bi2O3 volatilized in ZnO-Bi2O3-based varistor ceramics.This is in accordance with the relative X-ray diffraction peak area ratio analysis.The results also show that the sintering temperature has the greatest impact on the vaporization of the Bi2O3,then followed by sintering time,and the effect of the heating rate is the minimum.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
This research aims to contribute to the safe methodology for additive manufacturing(AM)of energetic materials.Coating formulation processes were investigated and evaluated to find a suitable method that may enable sel...This research aims to contribute to the safe methodology for additive manufacturing(AM)of energetic materials.Coating formulation processes were investigated and evaluated to find a suitable method that may enable selective laser sintering(SLS)as the safe method for fabrication of high explosive(HE)compositions.For safety and co nvenie nce reasons,the co ncept demonstration was conducted using inert explosive simulants with properties quasi-similar to the real HE.Coating processes for simulant RDXbased microparticles by means of PCL and 3,4,5-trimethoxybenzaldehyde(as TNT simulant)are reported.These processes were evaluated for uniformity of coating the HE inert simulant particles with binder materials to facilitate the SLS as the adequate binding and fabrication method.Suspension system and single emulsion methods gave required particle near spherical morphology,size and uniform coating.The suspension process appears to be suitable for the SLS of HE mocks and potential formulation methods for active HE composites.The density is estimated to be comparable with the current HE compositions and plastic bonded explosives(PBXs)such as C4 and PE4,produced from traditional methods.The formulation method developed and understanding of the science behind the processes paves the way toward safe SLS of the active HE compositions and may open avenues for further research and development of munitions of the future.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 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 National Natural Science Foundation of China(Grant Nos.52205231,52205196)Taishan Scholars Program,and Research Project of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai(Grant Nos.AMGM0613,AMGM0620).
文摘Digital light processing(DLP)is widely used in ceramic additive manufacturing.However,it remains unexplored for metals.In this study,the regulatory mechanisms of the microstructure and mechanical properties of AISI 316L stainless steel were investigated by optimizing a DLP-compatible metal slurry formulation and sintering process.A photosensitive resin system(mass ratio of 5:1:2:2 for U600,LA,ACMO,and HDDA,respectively)with 88 wt%solid content is designed to achieve a slurry with balanced rheology,photocurability,and low pyrolysis residue.Compared to vacuum sintering,which leads to brittle fracture of material,the Ar/H2 mixed gas(5%H2)effectively reduces carbon and oxygen impurities via reduction,mitigating carbide and oxide segregation at grain boundaries and within grains,thereby enhancing strength-ductility.In addition,the prolonged high-temperature sintering inducesδ-ferrite precipitation at grain boundaries,which fills residual pores to improve densification obviously.Under optimized sintering conditions(Ar/H2,1380°C,6 h),the material achieves 96.2%relative density with tensile strength and fracture elongation of 543.5 MPa and 58.7%,respectively,exhibiting uniform dimple-dominated fracture morphology.This synergistic optimization of the slurry formulation and sintering parameters improves the strength-ductility balance in DLP-fabricated metal materials,offering theoretical and technical insights for the additive manufacturing of complex high-performance metal components.
文摘An ore-blending optimization model for the sintering process is an intelligent system that includes iron ore characteristics, expert knowledge and material balance. In the present work, 14 indices are proposed to represent chemical composition, granulating properties and high temperature properties of iron ores. After the relationships between iron ore characteristics and sintering performance are established, the ＂two-step＂ method and the simplex method are introduced to build the model by distinguishing the calculation of optimized blending proportion of iron ores from that of other sintering materials in order to improve calculation efficiency. The ore-blending optimization model, programmed by Access and Visual Basic, is applied to practical production in steel mills and the results prove that the present model can take advantage of the available iron ore resource with stable sinter yield and quality performance but at a lower cost.
基金financially supported by the National Basic Research Program of China (No. 2012CB720401)the National Natural Science Foundation of China (U1260202)
文摘The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results show that the Ore-A exhibits good granulation properties, strong liquid flow capability, high bonding phase strength and crystal strength, but poor assimilability. With increasing Ore-A ratio, the tumbler index and the reduction index (RI) of the sinter first increase and then decrease, whereas the softening interval (Delta T) and the softening start temperature (T (10%)) of the sinter exhibit the opposite behavior; the reduction degradation index (RDI+3.15) of the sinter increases linearly, but the sinter yield exhibits no obvious effects. With increasing Ore-A ratio, the distribution and crystallization of the minerals are improved, the main bonding phase first changes from silico-ferrite of calcium and aluminum (SFCA) to kirschsteinite, silicate, and SFCA and then transforms to 2CaO center dot SiO2 and SFCA. Given the utilization of Ore-A and the improvement of the sinter properties, the Ore-A ratio in the high-limonite sintering process is suggested to be controlled at approximately 6wt%.
基金The project was financiallysupportedby Ministry of Education,China(No.106087)and 863 Program of National High Technology Research Development Project,China(2005AA501050).
文摘Yttria stabilized zirconia (YSZ) has widely been used as electrolyte in solid oxide fuel cell (SOFC). The microstructure of YSZ related to the fabrication process was discussed in the paper. With YSZ nano-powders about 40-100 nm as raw material, the YSZ adobe was manufactured by tape calendering process. The named three-step sintering process was performed at 1000 ℃ for 2 h, then raised the temperature with normal rate and as soon as up to 1400 ℃, the furnace was controlled at 1250-1300 ℃ for 10-20 h. The high dense YSZs with the relative density of 96%-99% were obtained; the grain size of YSZ could be reduced to 0.5-3 μm. The above result is benefited to co-fired in the electrode-supported SOFCs.
基金Sponsored by Provincial Natural Science Foundation of Henan of China(200612001)
文摘The prediction of the alkalinity is difficult during the sintering process. Whether or not the level of the alkalinity of sintering process is successful is directly related to the quality of sinter. There is no very good method for predicting the alkalinity by now owing to the high complexity, high nonlinearity, strong coupling, high time delay, and etc. Therefore, a new technique, the grey squares support machine, was introduced. The grey support vector machine model of the alkalinity enabled the development of new equation and algorithm to predict the alkalinity. During modelling, the fluctuation of data sequence was weakened by the grey theory and the support vector machine was capable of processing nonlinear adaptable information, and the grey support vector machine has a combination of those advantages. The results revealed that the alkalinity of sinter could be accurately predicted using this model by reference to small sample and information. The experimental results showed that the grey support vector machine model was effective and practical owing to the advantages of high precision, less samples required, and simple calculation.
基金The authors acknowledge financial support from the Key Project of National Natural Science Foundation of China（U1660206） and General Program of National Natural Science Foundation of China （51674002）.
文摘The emission of dioxins from the iron ore sintering process is the largest emission source of dioxins, and the reduction in dioxin emission from the iron ore sintering process to the environment is increasingly important. Three approaches to control the emission of dioxins were reviewed： source control, process control, and terminal control. Among them, two terminal control technologies, activated carbon adsorption and selective reduction technology, were discussed in detail. Following a comparison of the reduction technologies, the terminal control method was indicated as the key technology to achieve good control of dioxins during the sintering process. For the technical characteristics of the sintering process and flue gas, multiple methods should be collectively considered, and the most suitable method may be addition of inhibitors ＋ ultra-clean dust collection （electrostatic precipitation/bag filter） ＋ desulphurization ＋ selective catalytic reduction to sufficiently remove multiple pollutants, which provides a direction for the cooperative disposal of flue gas pollutants in future.
基金Item Sponsored by National Natural Science Foundation of China(50974012)National High Technology Research and Development Program of China(2006AA06Z125)
文摘The relationship of time to minerals composition in sinters is investigated by mineragraphy are claritied observation and component analysis,and the effects of temperature and atmosphere on mineralization process.Results are obtained as follows.The initial melt forms below the eutectic temperature of CaO·Fe2O3 and CaO·2Fe2O3,which is complex substance containing Ca,Fe,Si and Al,rather than the binary calcium ferrite melt.Minerals composition of binding phase is related to local content of silica in melt,which is influenced by temperature.Appearance of the melt promotes the transition from hematite to magnetite,which then alters the mechanism of calcium ferrite formation.Before the formation of magnetite,the contents of Fe and Ca within the multiple calcium ferrite decrease with temperature,but in the case of magnetite presence,the content of Fe increases solely with increase of temperature and decrease of oxygen potential.Temperature and atmosphere determine minerals composition together,and bring influence on sintering process in different ways.It can be deduced that temperature affects kinetics of the mineralization process,but atmosphere just plays a role in thermodynamics.
基金National Natural Science Foundation of China (50374080)Innovation Project of Postgraduate Education of Central South University (042310011)
文摘An expert system skeleton tool of sintering process was constructed using object-oriented method, which can actualize two functions, i. e. , the shell function and the program function. The skeleton tool offered a platform to build a prototype system, to program class code, and to develop the expert system. Four branch expert systems were developed using the skeleton tool including the control of chemical composition, the control of sintering process state, the control of expended energy, and the diagnosis of abnormity. It is found that the performance of all systems is satisfactory in practice.
基金Project(2017YFC0210302)supported by the National Key R&D Program of ChinaProjects(U1660206,U1760107)supported by the National Natural Science Foundation of China
文摘Process control is an effective approach to reduce the NO_(x) emission from sintering flue gas.The effects of different materials adhered on coke breeze on NO_(x) emission characteristics and sintering performance were studied.Results showed that the coke breeze adhered with the mixture of CaO and Fe_(2)O_(3) or calcium ferrite significantly lowers the NO_(x) emission concentration and conversion ratio of fuel-N to NO_(x).Pretreating the coke with the mixture of lime slurry and iron ore fines helped to improve the granulation effect,and optimize the carbon distribution in granules.When the mass ratio of coke breeze,quick lime,water and iron ore fines was 2:1:1:1,the average NO_(x) emission concentration was decreased from 220 mg/m^(3) to 166 mg/m^(3),and the conversion ratio of fuel-N was reduced from 54.2%to 40.9%.
基金Project(50274021) supported by the National Natural Science Foundation of China and Baoshan Iron and Steel Co., Ltd.
文摘β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope,and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1773 K.
基金This work was financially supported by the Department of Defense of China(No.41312040509).
文摘An oxide ceramic process was adopted to prepare high frequency manganese-zinc(MnZn)power ferrite.In combination with the microstructure analysis of material,the influences of sintering process on initial permeability(μ_(i))and high frequency loss in unit volume(P_(cv))of MnZn power ferrite were investigated.The results show that in order to obtain fine microstructure and high frequency properties,the preferable sintering temperature and atmosphere are 1230℃and oxygen partial pressure(P_(O_(2)))of 4%,respectively.
基金the financial supports from the National Natural Science Foundation of China ( 51274057 )Fundamental Research Funds for the Central Universities ( N120402006)Educational Commission of Liaoning Province of China ( L2012079)
文摘ZrN-SiAlON composite materials were synthesized at 1 550 ℃ for 6 h via a carbothermal reduction nitridation route using fly ash （≤74 μm）,zircon （≤ 44 μm） and active carbon as starting materials.The processed ZrN-SiAlON composite micropowders were mixed with polyvinyl alcohol as binder to prepare ZrN （ZrON）-SiAlON composite ceramics by carbon-embedded pressureless firing at 1 450,1 500 and 1 550 ℃ for 1 h,respectively.Influences of firing temperature on the phase compositions,microstructure and sintering properties of the ceramics were investigated.The results show that：（1） β-SiAlON based composite ceramics with different compositions can be prepared by controlling firing temperature,and the main crystalline phases of the specimen fired at 1 550 ℃ for 1 h involve ZrN,ZrON and β-SiAlON （z =2,Si4Al2O2N6）; （2） ZrN （ZrON）,β-SiAlON and a Fe-Si based compound can be observed in the microstructures of the specimens fired at different temperatures.ZrN （ZrON） particles distribute homogeneously in the β-SiAlON matrix; （3） raising firing temperature can increase the shrinkage ratio of the ceramics,and the volume shrinkage ratio increases from 19.4％ to 40.3％ when the firing temperature rises from 1 450 to 1 550 ℃.
文摘The general structure of expert system for controlling sintering process has been proposed. It includes knowledge base, inference engine, data acquisition system, learning system, knowledge base management system, explanation system and so on. The control functions consist of sintering chemical composition control centered on basicity and sintering process state control centered on permeability. The adaptive prediction of sintering chemical composition, the control strategy centered on basicity, the control strategy centered on permeability, the judgement of permeability and the prediction of burn through point were studied. The software of system, which includes about 1 000 expert rules, was successfully applied in off line control of sintering process in a sintering plant.
基金the financial support by the Natural Science Foundation of Guangdong Province(2019A1515012111)the National Natural Science Foundation of China(51804199 and 51604081)+2 种基金the Science and Technology Innovation Commission of Shenzhen(JCYJ20190808173815205 and 20180123)the Shenzhen Science and Technology Program(KQTD20180412181422399)“Chenguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(16CG40)。
文摘To solve the critical problems of lithium rich cathode materials, e.g., structure instability and short cycle life, we have successfully prepared a ZrO2-coated and Zr-doping xLi2MnO3·(1–x)LiMO2 hollow architecture via one-time sintering process. The modified structural materials as lithium-ion cathodes present good structural stability and superior cycle performance in LIBs. The discharge capacity of the ZrO2-coated and Zr-doped hollow pristine is 220 mAh g-1 at the 20th cycle at 0.2 C(discharge capacity loss, 2.7%)and 150 m Ah g-1 at the 100 th cycle at 1 C(discharge capacity loss, 17.7%), respectively. However, hollow pristine electrode only delivers 203 m Ah g-1 at the 20 th cycle at 0.2 C and 124 mAh g-1 at the 100 th cycle at 1 C, respectively, and the corresponding to capacity retention is 92.2% and 72.8%, respectively.Diffusion coefficients of modified hollow pristine electrode are much higher than that of hollow pristine electrode after 100 cycles(approach to 1.4 times). In addition, we simulate the adsorption reaction of HF on the surface of ZrO2-coated layer by the first-principles theory. The calculations prove that the adsorption energy of HF on the surface of ZrO2-coated layer is about-1.699 e V, and the ZrO2-coated layer could protect the hollow spherical xLi2MnO3·(1–x)LiMO2 from erosion by HF. Our results would be applicable for systematic amelioration of high-performance lithium rich material for anode with the respect of practical application.
基金Project supported by the National Natural Science Foundation of China(11564021)
文摘Polycrystalline YBa2Cu3O6＋δbulks were synthesized by sol-gel method. Sintering processing played a vital role in the evolution of phase structure and microstructure, and thus significantly influenced their superconducting properties. The influence of calcination temperature, sintering temperature, on the bulks structure, morphology and superconducting behaviors were investigated. The results showed that the oxygen content drastically increased with calcination temperature and sintering temperature. The SEM images revealed that the grains grew up monotonously with increase of calcination temperature. With increased calcination and sintering temperature, the resistivity was reduced gradually and the superconducting properties increased. Moreover, it was found that the optimal superconducting properties（with the highest superconducting transition temperature Tc^onset and the narrowest transition width ΔT） were obtained at calcination temperature of 900℃ and sintering temperature of 950 ℃.
基金Project(06DZ05902)supported by Technical Innovation Team Program of Shanghai Science and Technology Committee of China
文摘The relationship between sintering process and vaporization of the Bi2O3 in ZnO-Bi2O3-based varistor ceramics was investigated.The phase and microstructure evolution during the sintering process were examined.The results show that the higher the sintering temperature or the longer the sintering time is,the more the Bi2O3 is volatilized.The heating rate has little effects on the Bi2O3 volatilized in ZnO-Bi2O3-based varistor ceramics.This is in accordance with the relative X-ray diffraction peak area ratio analysis.The results also show that the sintering temperature has the greatest impact on the vaporization of the Bi2O3,then followed by sintering time,and the effect of the heating rate is the minimum.
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funded by the Council for Scientific and Industrial Research(CSIR)。
文摘This research aims to contribute to the safe methodology for additive manufacturing(AM)of energetic materials.Coating formulation processes were investigated and evaluated to find a suitable method that may enable selective laser sintering(SLS)as the safe method for fabrication of high explosive(HE)compositions.For safety and co nvenie nce reasons,the co ncept demonstration was conducted using inert explosive simulants with properties quasi-similar to the real HE.Coating processes for simulant RDXbased microparticles by means of PCL and 3,4,5-trimethoxybenzaldehyde(as TNT simulant)are reported.These processes were evaluated for uniformity of coating the HE inert simulant particles with binder materials to facilitate the SLS as the adequate binding and fabrication method.Suspension system and single emulsion methods gave required particle near spherical morphology,size and uniform coating.The suspension process appears to be suitable for the SLS of HE mocks and potential formulation methods for active HE composites.The density is estimated to be comparable with the current HE compositions and plastic bonded explosives(PBXs)such as C4 and PE4,produced from traditional methods.The formulation method developed and understanding of the science behind the processes paves the way toward safe SLS of the active HE compositions and may open avenues for further research and development of munitions of the future.
