Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization...Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Baizhi, the raw plant material of Baizhi was ground to 6 μm particles by a high speed centrifugal sheering （HSCS） pulverizer. The micron particles were characterized by optical microscopy and scanning electron microscopy （SEM）. Imperatorin is one of the active ingredients of Baizhi, and its extraction yield is determined to evaluate the chemical characterization of Baizhi powder. Imperatorin was analyzed by high performance liquid chromatography （HPLC）. The results show that after ultrafine pulverization, the plant cell walls are broken into pieces and the extraction yield of imperatorin is increased by 11.93% compared with the normal particles.展开更多
Measurements of hydrogen absorption desorption behavior of Nb Al alloys, Nb ss (Nb solid sloution), Nb ss +Nb 3Al, Nb 3Al, Nb 3Al+Nb 2Al, were carried out under hydrogen pressure from 0 to 3.4 MPa at 353 and 357 K, al...Measurements of hydrogen absorption desorption behavior of Nb Al alloys, Nb ss (Nb solid sloution), Nb ss +Nb 3Al, Nb 3Al, Nb 3Al+Nb 2Al, were carried out under hydrogen pressure from 0 to 3.4 MPa at 353 and 357 K, along with mircostructural observation and X ray diffraction analysis. It was found that single phase alloys of Nb ss and Nb 3Al are not pulverized regardless of a considerable amount of hydrogen absorption, while two phase alloys of Nb ss +Nb 3Al and Nb 3Al+Nb 2Al are readily pulverized. X ray diffraction analysis indicated that no hydride with crystal structure different from constituent phases is formed by hydrogen absorption, but lattice parameters of Nb ss and Nb 3Al are increased. Pulverization of Nb Cr alloys was investigated under a hydrogen atmosphere of 0.1 MPa in an arc melting chamber without exposure to air after arc melting. Similarly, hydrogen pulverization occurs only in two phase alloys consisting of Nb ss and NbCr 2. Based on the measured lattice parameters of Nb ss and Nb 3Al(NbCr 2) in the hydrogenated two phase alloys and the microstructural observations, a mechanism for hydrogen pulverization is discussed.展开更多
In this study, jet milling was used to recycle tin bronze machining chips into powder. The main purpose of this study was to assess the effect of the microstructure of tin bronze machining chips on their breakage beha...In this study, jet milling was used to recycle tin bronze machining chips into powder. The main purpose of this study was to assess the effect of the microstructure of tin bronze machining chips on their breakage behavior. An experimental target jet mill was used to pulverize machining chips of three different tin bronze alloys containing 7wt%, 10wt%, and 12wt% of tin. Optical and electron microscopy, as well as sieve analysis, were used to follow the trend of pulverization. Each alloy exhibited a distinct rate of size reduction, particle size distribution, and fracture surface appearance. The results showed that the degree of pulverization substantially increased with increasing tin content. This behavior was attributed to the higher number of machining cracks as well as the increased volume fraction of brittle δ phase in the alloys with higher tin contents. The δ phase was observed to strongly influence the creation of machining cracks as well as the nucleation and propagation of cracks during jet milling. In addition, a direct relationship was observed between the mean δ-phase spacing and the mean size of the jet-milled product; i.e., a decrease in the δ-phase spacing resulted in smaller particles.展开更多
The crude drug of Liuwei Dihuang was pulverized to nano particles to improve its bioavailability. The appropriate technique parameters were studied. Paeonol, typical marker of Liuwei Dihuang , was extracted with organ...The crude drug of Liuwei Dihuang was pulverized to nano particles to improve its bioavailability. The appropriate technique parameters were studied. Paeonol, typical marker of Liuwei Dihuang , was extracted with organic solveat in ultrasonic and its content was determined by HPLC. The appropriate techrdques parameters are as follows ： rotating speed control 1200 r/ min , grinding time control 50min and mass percent concentration control 3.8% . The experimental results show that the average particle diameter is 161.9 nm and the great majority of the plant cell wall is broken into pieces after nano pulverization. The extraction efficiency of paeonol is increased by 23.5% .展开更多
Degradation behaviors of three typical La-Mg-Ni alloys, La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19, were studied. La1.5- Mg0.5Ni7 with （La,Mg）2Ni7 as main phase presents better discharge capacity and cycling stability. T...Degradation behaviors of three typical La-Mg-Ni alloys, La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19, were studied. La1.5- Mg0.5Ni7 with （La,Mg）2Ni7 as main phase presents better discharge capacity and cycling stability. The three alloys suffer severe pulverization and corrosion after electrochemical cycles, which are considered to be the significant factor attributing to the capacity deterioration. However, the overall corrosion extent of the three cycled alloys aggravates successively, which is inconsistent with the result that LaEMgNi9 presented poor cycling stability and also the assumption that alloy with high Mg content is easy to be corroded. The intrinsic anti-corrosion and anti-pulverization characteristics of the three alloys are mainly focused in this work. Immersion corrosion experiments demonstrate that the Mg-rich phases are more easily to be corroded. The corrosion resistance of the three alloys presents an improved trend which is inversely proportional to abundance of the Mg-rich phases. However, the anti-pulverization abilities present an inverse trend, which is closely related to the mechanical property of various phase structures. LaNi5 with the highest hardness is easy to crack, but the soft （La,Mg）Ni2 is more resistant to crack formation and spreading. Thus, the weaker corrosion of La2MgNi9 after electro- chemical cycling is attributed to the better intrinsic anti-pulverization capability though the anti-corrosion is poor. As La4MgNi19 possesses excellent corrosion resistance, enhancement of the anti-pulverization ability is urgent for improvement in the cycling stability.展开更多
In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and ...In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and cost.Pavements on unstabilized and stabilized subgrade were designed for two regions(Izmir and Van),covering all climate variations.The resilient modulus of the lime stabilized subgrade with different soil pulverization levels for non-freezing and freezing conditions were taken from a previous laboratory study.Frost effects were considered in pavement design using two different approaches,including limited subgrade frost penetration method and reduced subgrade strength method.Detailed application and evaluation were performed for all steps.Lime stabilized subgrades significantly reduced the thickness of base courses,and the benefit of lime stabilization was highly dependent on soil pulverization level.A detailed cost analysis on the unstabilized and stabilized cases found that the use of lime stabilization in the subgrade provided significant initial cost savings.Comparative analysis by using the AASHTO(1993)method and KENPAVE software,and quantity effect of soil pulverization level on the performance of low volume roads from a service life perspective,show that subgrade resilient modulus can be estimated.It is also possible to make correct performance estimation in the field.The results of the study show that lime stabilization is a good solution for low volume roads in the mountainous regions of Türkiye.展开更多
We conducted a series of experimental studies on the metallurgical properties of N-lump and F-lump ores used in Baosteel’s blast furnace, including thermal cracking, low-temperature reduction pulverization, reducibil...We conducted a series of experimental studies on the metallurgical properties of N-lump and F-lump ores used in Baosteel’s blast furnace, including thermal cracking, low-temperature reduction pulverization, reducibility, and droplet properties.The results show that the thermal burst properties of N-lump ore are better than those of F-lump ore.The low-temperature reduction degradation index(RDI) pulverization of the charge is the best when the ratios of N-lump ore and F-lump ore account for 35% each.The reduction performance of the charge is improved when F-lump and N-lump ores are mixed with sinter.In the softening-melting performance experiment, when the proportion of N-lump ore is 40%,the characteristic area value(S) as the charge permeability index is the smallest.When F-lump ore is mixed with sinter, its droplet performance improves compared with that of single F-lump ore.The proportion of F-lump ore should not exceed 15%.展开更多
Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and...Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·℃^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.展开更多
An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image s...An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image segmentation.However,the agglomeration effect of fine powders and the edge effect of granular images caused by scanning electron microscopy greatly affect the precision of particle image segmentation.In this study,we propose a novel image segmentation method derived from mask regional convolutional neural network based on deep learning for recognizing fine coal powders.Firstly,an atrous convolution is introduced into our network to learn the image feature of multi-sized powders,which can reduce the missing segmentation of small-sized agglomerated particles.Then,a new mask loss function combing focal loss and dice coefficient is used to overcome the false segmentation caused by the edge effect.The final comparative experimental results show that our method achieves the best results of 94.43%and 91.44%on AP50 and AP75 respectively among the comparison algorithms.In addition,in order to provide an effective method for particle size analysis of coal particles,we study the particle size distribution of coal powders based on the proposed image segmentation method and obtain a good curve relationship between cumulative mass fraction and particle size.展开更多
The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2(NCA)mater...The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2(NCA)materials in Li ion batteries(LIBs).Surface modification is an effective strategy for NCA cathodes,which could alleviate the degradation associated with surface processes.Herein,a surface structure rearrangement of NCA cathode secondary particles was reported by in-situ forming a solid electrolyte LiBO2.The LiBO2 is beneficial for alleviating the stress during charge/discharge process,thereby slowing down the rate of cracks formation in the secondary particles,which facilitates the Li+de-intercalation as well as prevents penetration of the liquid-electrolyte into the interior of the particles.As a result,the surface structure rearrangement NCA(RS-NCA)delivers a high discharge capacity of 202.5 m Ah g^-1 at 0.1 C,and exhibits excellent cycle stability with discharge capacity retaining 148 m Ah g^-1 after 200 cycles at 2 C.This surface structure rearrangement approach provides a new viewpoint in designing high-performance high-voltage LIBs.展开更多
A system of producing scrap rubber powder with wave cryogenic technology isput forward. Main equipments such as wave refrigerator, vortex pulverizer and fluidized cooler arepresented. The key techniques about silica g...A system of producing scrap rubber powder with wave cryogenic technology isput forward. Main equipments such as wave refrigerator, vortex pulverizer and fluidized cooler arepresented. The key techniques about silica gel refreshing in desiccators and system drying arediscussed. The potential improvement of the system is pointed out. The manufacturing cost is lowerthan the cost of liquid nitrogen cryogenic method, and the quality is better than that of normaltemperature milling. Moreover, wave refrigerators have several advantages over turbine expendersapplied in the cryogenic milling system.展开更多
[Objectives] The research aimed to study the impact on extraction effect of polysaccharide from Ganoderma lucidum( lingzhi) by different pretreatment methods. [Methods] The impacts on extraction of G. lucidum polysacc...[Objectives] The research aimed to study the impact on extraction effect of polysaccharide from Ganoderma lucidum( lingzhi) by different pretreatment methods. [Methods] The impacts on extraction of G. lucidum polysaccharide by soaking,microwave and air flow fine pulverization were contrasted,and the extraction effect of G. lucidum polysaccharide by combining the optimal pretreatment manner with hot water extraction,alcohol extraction,alkali extraction,ultrasonic binding enzyme extraction,and microwave extraction was compared. Finally,the property of G. lucidum polysaccharide obtained after air flow fine pulverization pretreatment was detected and analyzed by high performance liquid chromatography. [Results] The optimal pretreatment method was air flow fine pulverization. Compared with traditional method-direct extraction( coarse grinding combining hot water extraction),crude yield changed little,while polysaccharide content and yield were improved by 114% and 104%. The best combination manner was air flow fine pulverization pretreatment combining with alkali extraction. Compared with traditional method,crude yield,polysaccharide content and yield were improved by 76%,78% and 215% respectively. The property of G. lucidum polysaccharide obtained after air flow fine pulverization pretreatment was detected and analyzed by high performance liquid chromatography. It was found that the treatment method had little impact on the property of G. lucidum polysaccharide. [Conclusions]Air flow fine pulverization pretreatment could greatly improve extraction effect of G. lucidum polysaccharide,which mainly improved the content and yield of G. lucidum polysaccharide,and extraction was more complete,with less impact on the property of the extracted polysaccharide. It was speculated that air flow fine pulverization pretreatment mainly destroyed mechanical support wall membrane structure of G. lucidum fine powder,making that intracellular functional substances completely dissolved out of the cell,and the content would be studied in follow-up experiment.展开更多
The degradation behaviors of the TiV-based multiphase hydrogen storage alloy Ti0.8Zr0.2V3.2Mn0.64 Cr0.96Ni1.2 during electrochemical cycling in alkaline electrolyte have been studied by XRD, SEM, EIS and AES measureme...The degradation behaviors of the TiV-based multiphase hydrogen storage alloy Ti0.8Zr0.2V3.2Mn0.64 Cr0.96Ni1.2 during electrochemical cycling in alkaline electrolyte have been studied by XRD, SEM, EIS and AES measurements. XRD analysis indicates that the alloy consists of a C14-type Laves phase and a V-based solid solution. The lattice parameters of both phases are increased after discharged with cycling, which indicates that more irreversible hydrogen remains not discharged in the alloy. It shold be responsible for the decrease of discharge capacity. SEM micrographs show that after 10 electrochemical cycles, a large number of cracks can be observed in the alloy, existing mainly in the V-based solid solution phase. Moreover, after 30 cycles, the alloy particles are obviously pulverized due to the larger expansion and shrinkage of cell volumes during hydrogen absorption and desorption, which induces the fast degradation of the TiV-based hydrogen storage alloys. EIS and AES measurements indicate that some passive oxide film has been formed on the surface of alloy electrode, which has higher charge-transfer resistance, lower hydrogen diffusivity, and less electro-catalytic activity. Therefore it can be concluded that the pulverization and oxidation of the alloy are the main factors responsible for the fast degradation of the TiV-hased hydrogen storage alloys.展开更多
The degradation of La 0.8 Pr 0.2 Ni 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy electrode during charge discharge cycles was studied with analytical electron microscope (AEM) and scanning electron micro...The degradation of La 0.8 Pr 0.2 Ni 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy electrode during charge discharge cycles was studied with analytical electron microscope (AEM) and scanning electron microscope (SEM). During the cycles, the alloy particles of the negative electrode were pulverized gradually. After 200 cycles, the pulverizing process basically ended and the larger particles were pulverized to below 10 μm. The particles were oxided at the rate of about 0.1 μm/100 times cycles. The oxide layer was porous and consisted of the La(OH) 3 and oxides of Pr, Co and Ni. Most of Pr, Mn and almost all of Al in the oxide layer were dissolved into the electrolyte. The oxidation of the alloy particles was one of the main factors of the decay of the discharge capacity of the negative electrode during the cycles.展开更多
Studies were made of the effect of mechanical pulverization on relaxation,crystallization and brittle-ductile transition of the anneal-embrittled Fe_(75)Si_(10)B_(15) metallic glass rib- bon.Results show that the Curi...Studies were made of the effect of mechanical pulverization on relaxation,crystallization and brittle-ductile transition of the anneal-embrittled Fe_(75)Si_(10)B_(15) metallic glass rib- bon.Results show that the Curie temperature,T_C,decreases and the total enthalpy of relaxation increases gradually with variation of pulverized time.DSC traces reveal an extra exothermic peak,T_X_1,and a distinct glass transition endothermic peak,T_g_1,with increasing pulverized time,T_C,T_X_1,and T_g_1 decrease simultaneously,and the exother- mic peak area corresponding to T_X_1 increases gradually.The surface slip-steps of flaky particles and their corresponding shear are produced by pulverizing the pre-embrittled amorphous glass.The lost ductility of the glass may restore during annealing.展开更多
It’s known that the pulverization-densification mechanism of metal hydride may cause the stress accumulation in metal hydrides reactors. In this paper, this idea is proved based on granulometry and a new idea of cycl...It’s known that the pulverization-densification mechanism of metal hydride may cause the stress accumulation in metal hydrides reactors. In this paper, this idea is proved based on granulometry and a new idea of cycling compression effect is presented, which is caused by the friction between wall and metal hydrides. Through theoretical analysis, the cycling compression effects is shown to increase the localized packing rate from top to down in vertical-placed reactors and thus lead to the maximum deformation in the bottom of reactors, proving that it is the interaction of pulverization-densification effect and cycling compression effect resulting in the stress problems of vertical-placed reactors. Further study points that the effective methods relieving the cycling compress effect are to decrease hydrogen absorption/desorption cycle number, slenderness ratio of reactor, wall friction factor and initial packing rate, or to lower the thermal conductivity and the volume expansion coefficient of metal hydrides.展开更多
For the geological disposal of high level radioactive wastes, an excavation damaged zone （EDZ） having high hydraulic conductivity resulting from the development of fractures in the rock adjacent to the tunnels will ...For the geological disposal of high level radioactive wastes, an excavation damaged zone （EDZ） having high hydraulic conductivity resulting from the development of fractures in the rock adjacent to the tunnels will be one of the potential pathways for radioactive contaminant transport. The potential pathways will be sealed by closure components, that is, a combination of tunnel plug, backfill and grout, the latter material being a clay-based mixture in consideration of the need for long-term stability of the seals. Clay-based grout is one of the effective candidate materials that can be used to interrupt the migration of radionuclides through an EDZ. Laboratory testing of clay-based grout using pulverized bentonite, with the objective of improvement in grout penetration into a rockmass, was conducted. The results showed that the pulverization of clay-based grout had a positive effect on filtration.展开更多
An updated approach to refining the core indicators of pulverized coal used for blast furnace injection based on principal component analysis is proposed in view of the disadvantages of the existing performance indica...An updated approach to refining the core indicators of pulverized coal used for blast furnace injection based on principal component analysis is proposed in view of the disadvantages of the existing performance indicator system of pulverized coal used in blast furnaces. This presented method takes into account all the performance indicators of pulverized coal injection, including calorific value, igniting point, combustibility, reactivity, flowability, grindability, etc. Four core indicators of pulverized coal injection are selected and studied by using principal component analysis, namely, comprehensive combustibility, comprehensive reactivity, comprehensive flowability, and comprehensive grindability. The newly established core index system is not only beneficial to narrowing down current evaluation indices but also effective to avoid previous overlapping problems among indicators by mutually independent index design. Furthermore, a comprehensive property indicator is introduced on the basis of the four core indicators, and the injection properties of pulverized coal can be overall evaluated.展开更多
The combustion characteristics of two kinds of unburned pulverized coal (UPC) made from bituminous coal and anthracite were investigated by thermogravimetric analysis under air. The reaction kinetics mechanisms betwee...The combustion characteristics of two kinds of unburned pulverized coal (UPC) made from bituminous coal and anthracite were investigated by thermogravimetric analysis under air. The reaction kinetics mechanisms between UPC and CO2 in an isothermal experiment in the temperature range 1000–1100°C were investigated. The combustion performance of unburned pulverized coal made from bituminous coal (BUPC) was better than that of unburned pulverized coal made from anthracite (AUPC). The combustion characteristic indexes (S) of BUPC and AUPC are 0.47 × 10^-6 and 0.34 × 10^-6 %2·min^-2·°C^-3, respectively, and the combustion reaction apparent activation energies are 91.94 and 102.63 kJ·mol^-1, respectively. The reaction mechanism of BUPC with CO2 is random nucleation and growth, and the apparent activation energy is 96.24 kJ·mol^-1. By contrast, the reaction mechanism of AUPC with CO2 follows the shrinkage spherical function model and the apparent activation energy is 133.55 kJ·mol^-1.展开更多
The combustion process of pulverized coal injected into blast furnace involves a lot of physical and chemical reactions. Based on the combustion behaviors of pulverized coal, the conception of coal effective calorific...The combustion process of pulverized coal injected into blast furnace involves a lot of physical and chemical reactions. Based on the combustion behaviors of pulverized coal, the conception of coal effective calorific value representing the actual thermal energy provided for blast furnace was proposed. A cost performance evaluation model of coal injection was built up for the optimal selection of various kinds of coal based on effective calorific value. The model contains two indicators: coal effective calorific value which has eight sub-indicators and coal injection cost which includes four sub-indicators. In addition, the calculation principle and application of cost performance evaluation model in a Chinese large-scale iron and steel company were comprehensively introduced. The evaluation results finally confirm that this novel model is of great significance to the optimal selection of blast furnace pulverized coal.展开更多
基金supported by the National High-Tech Research and Development Program of China (No.2009AA043202)the Special Project of State Administration of Traditional Chinese Medicine, China (No.200807054)
文摘Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Baizhi, the raw plant material of Baizhi was ground to 6 μm particles by a high speed centrifugal sheering （HSCS） pulverizer. The micron particles were characterized by optical microscopy and scanning electron microscopy （SEM）. Imperatorin is one of the active ingredients of Baizhi, and its extraction yield is determined to evaluate the chemical characterization of Baizhi powder. Imperatorin was analyzed by high performance liquid chromatography （HPLC）. The results show that after ultrafine pulverization, the plant cell walls are broken into pieces and the extraction yield of imperatorin is increased by 11.93% compared with the normal particles.
文摘Measurements of hydrogen absorption desorption behavior of Nb Al alloys, Nb ss (Nb solid sloution), Nb ss +Nb 3Al, Nb 3Al, Nb 3Al+Nb 2Al, were carried out under hydrogen pressure from 0 to 3.4 MPa at 353 and 357 K, along with mircostructural observation and X ray diffraction analysis. It was found that single phase alloys of Nb ss and Nb 3Al are not pulverized regardless of a considerable amount of hydrogen absorption, while two phase alloys of Nb ss +Nb 3Al and Nb 3Al+Nb 2Al are readily pulverized. X ray diffraction analysis indicated that no hydride with crystal structure different from constituent phases is formed by hydrogen absorption, but lattice parameters of Nb ss and Nb 3Al are increased. Pulverization of Nb Cr alloys was investigated under a hydrogen atmosphere of 0.1 MPa in an arc melting chamber without exposure to air after arc melting. Similarly, hydrogen pulverization occurs only in two phase alloys consisting of Nb ss and NbCr 2. Based on the measured lattice parameters of Nb ss and Nb 3Al(NbCr 2) in the hydrogenated two phase alloys and the microstructural observations, a mechanism for hydrogen pulverization is discussed.
文摘In this study, jet milling was used to recycle tin bronze machining chips into powder. The main purpose of this study was to assess the effect of the microstructure of tin bronze machining chips on their breakage behavior. An experimental target jet mill was used to pulverize machining chips of three different tin bronze alloys containing 7wt%, 10wt%, and 12wt% of tin. Optical and electron microscopy, as well as sieve analysis, were used to follow the trend of pulverization. Each alloy exhibited a distinct rate of size reduction, particle size distribution, and fracture surface appearance. The results showed that the degree of pulverization substantially increased with increasing tin content. This behavior was attributed to the higher number of machining cracks as well as the increased volume fraction of brittle δ phase in the alloys with higher tin contents. The δ phase was observed to strongly influence the creation of machining cracks as well as the nucleation and propagation of cracks during jet milling. In addition, a direct relationship was observed between the mean δ-phase spacing and the mean size of the jet-milled product; i.e., a decrease in the δ-phase spacing resulted in smaller particles.
文摘The crude drug of Liuwei Dihuang was pulverized to nano particles to improve its bioavailability. The appropriate technique parameters were studied. Paeonol, typical marker of Liuwei Dihuang , was extracted with organic solveat in ultrasonic and its content was determined by HPLC. The appropriate techrdques parameters are as follows ： rotating speed control 1200 r/ min , grinding time control 50min and mass percent concentration control 3.8% . The experimental results show that the average particle diameter is 161.9 nm and the great majority of the plant cell wall is broken into pieces after nano pulverization. The extraction efficiency of paeonol is increased by 23.5% .
基金supported financially by the National Natural Science Foundation of China (No. 51761032)the Natural Science Foundation Application of Inner Mongolia (No. 2014MS0526)
文摘Degradation behaviors of three typical La-Mg-Ni alloys, La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19, were studied. La1.5- Mg0.5Ni7 with （La,Mg）2Ni7 as main phase presents better discharge capacity and cycling stability. The three alloys suffer severe pulverization and corrosion after electrochemical cycles, which are considered to be the significant factor attributing to the capacity deterioration. However, the overall corrosion extent of the three cycled alloys aggravates successively, which is inconsistent with the result that LaEMgNi9 presented poor cycling stability and also the assumption that alloy with high Mg content is easy to be corroded. The intrinsic anti-corrosion and anti-pulverization characteristics of the three alloys are mainly focused in this work. Immersion corrosion experiments demonstrate that the Mg-rich phases are more easily to be corroded. The corrosion resistance of the three alloys presents an improved trend which is inversely proportional to abundance of the Mg-rich phases. However, the anti-pulverization abilities present an inverse trend, which is closely related to the mechanical property of various phase structures. LaNi5 with the highest hardness is easy to crack, but the soft （La,Mg）Ni2 is more resistant to crack formation and spreading. Thus, the weaker corrosion of La2MgNi9 after electro- chemical cycling is attributed to the better intrinsic anti-pulverization capability though the anti-corrosion is poor. As La4MgNi19 possesses excellent corrosion resistance, enhancement of the anti-pulverization ability is urgent for improvement in the cycling stability.
基金a joint venture project between Istanbul University and the Turkish General Directorate of Highways by project number KGM-ARGE/2012-25funded by Istanbul University-Cerrahpasa Scientific Research Projects under Project No:ACIP 54739。
文摘In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and cost.Pavements on unstabilized and stabilized subgrade were designed for two regions(Izmir and Van),covering all climate variations.The resilient modulus of the lime stabilized subgrade with different soil pulverization levels for non-freezing and freezing conditions were taken from a previous laboratory study.Frost effects were considered in pavement design using two different approaches,including limited subgrade frost penetration method and reduced subgrade strength method.Detailed application and evaluation were performed for all steps.Lime stabilized subgrades significantly reduced the thickness of base courses,and the benefit of lime stabilization was highly dependent on soil pulverization level.A detailed cost analysis on the unstabilized and stabilized cases found that the use of lime stabilization in the subgrade provided significant initial cost savings.Comparative analysis by using the AASHTO(1993)method and KENPAVE software,and quantity effect of soil pulverization level on the performance of low volume roads from a service life perspective,show that subgrade resilient modulus can be estimated.It is also possible to make correct performance estimation in the field.The results of the study show that lime stabilization is a good solution for low volume roads in the mountainous regions of Türkiye.
文摘We conducted a series of experimental studies on the metallurgical properties of N-lump and F-lump ores used in Baosteel’s blast furnace, including thermal cracking, low-temperature reduction pulverization, reducibility, and droplet properties.The results show that the thermal burst properties of N-lump ore are better than those of F-lump ore.The low-temperature reduction degradation index(RDI) pulverization of the charge is the best when the ratios of N-lump ore and F-lump ore account for 35% each.The reduction performance of the charge is improved when F-lump and N-lump ores are mixed with sinter.In the softening-melting performance experiment, when the proportion of N-lump ore is 40%,the characteristic area value(S) as the charge permeability index is the smallest.When F-lump ore is mixed with sinter, its droplet performance improves compared with that of single F-lump ore.The proportion of F-lump ore should not exceed 15%.
基金supported by the National Natural Science Foundation of China(Nos.52074086,51974073,52074072,52074074)the Fundamental Research Funds for the Central Universities,China(No.N2225039)the Liaoning Provincial Natural Science Foundation of China(No.2019-MS-132)。
文摘Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·℃^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.
基金Supported by the Research and Development Project of Experimental Technology,China University of Mining and Technology(Study on mineral occurrence in coal based on SEM and EDS,S2023Y018)the National Natural Science Foundations of China under Grant 62371451.
文摘An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image segmentation.However,the agglomeration effect of fine powders and the edge effect of granular images caused by scanning electron microscopy greatly affect the precision of particle image segmentation.In this study,we propose a novel image segmentation method derived from mask regional convolutional neural network based on deep learning for recognizing fine coal powders.Firstly,an atrous convolution is introduced into our network to learn the image feature of multi-sized powders,which can reduce the missing segmentation of small-sized agglomerated particles.Then,a new mask loss function combing focal loss and dice coefficient is used to overcome the false segmentation caused by the edge effect.The final comparative experimental results show that our method achieves the best results of 94.43%and 91.44%on AP50 and AP75 respectively among the comparison algorithms.In addition,in order to provide an effective method for particle size analysis of coal particles,we study the particle size distribution of coal powders based on the proposed image segmentation method and obtain a good curve relationship between cumulative mass fraction and particle size.
基金the National Natural Science Foundation of China(51764048,51703118 and 51474191)Yunnan Province Thousand Youth Talents Plan+1 种基金the Application Basis Research Project of Yunnan Province Science and Technology Department(2017FD144)Key Natural Science Foundation of Yunnan Province China(2018FA28)for providing the financial support。
文摘The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2(NCA)materials in Li ion batteries(LIBs).Surface modification is an effective strategy for NCA cathodes,which could alleviate the degradation associated with surface processes.Herein,a surface structure rearrangement of NCA cathode secondary particles was reported by in-situ forming a solid electrolyte LiBO2.The LiBO2 is beneficial for alleviating the stress during charge/discharge process,thereby slowing down the rate of cracks formation in the secondary particles,which facilitates the Li+de-intercalation as well as prevents penetration of the liquid-electrolyte into the interior of the particles.As a result,the surface structure rearrangement NCA(RS-NCA)delivers a high discharge capacity of 202.5 m Ah g^-1 at 0.1 C,and exhibits excellent cycle stability with discharge capacity retaining 148 m Ah g^-1 after 200 cycles at 2 C.This surface structure rearrangement approach provides a new viewpoint in designing high-performance high-voltage LIBs.
文摘A system of producing scrap rubber powder with wave cryogenic technology isput forward. Main equipments such as wave refrigerator, vortex pulverizer and fluidized cooler arepresented. The key techniques about silica gel refreshing in desiccators and system drying arediscussed. The potential improvement of the system is pointed out. The manufacturing cost is lowerthan the cost of liquid nitrogen cryogenic method, and the quality is better than that of normaltemperature milling. Moreover, wave refrigerators have several advantages over turbine expendersapplied in the cryogenic milling system.
文摘[Objectives] The research aimed to study the impact on extraction effect of polysaccharide from Ganoderma lucidum( lingzhi) by different pretreatment methods. [Methods] The impacts on extraction of G. lucidum polysaccharide by soaking,microwave and air flow fine pulverization were contrasted,and the extraction effect of G. lucidum polysaccharide by combining the optimal pretreatment manner with hot water extraction,alcohol extraction,alkali extraction,ultrasonic binding enzyme extraction,and microwave extraction was compared. Finally,the property of G. lucidum polysaccharide obtained after air flow fine pulverization pretreatment was detected and analyzed by high performance liquid chromatography. [Results] The optimal pretreatment method was air flow fine pulverization. Compared with traditional method-direct extraction( coarse grinding combining hot water extraction),crude yield changed little,while polysaccharide content and yield were improved by 114% and 104%. The best combination manner was air flow fine pulverization pretreatment combining with alkali extraction. Compared with traditional method,crude yield,polysaccharide content and yield were improved by 76%,78% and 215% respectively. The property of G. lucidum polysaccharide obtained after air flow fine pulverization pretreatment was detected and analyzed by high performance liquid chromatography. It was found that the treatment method had little impact on the property of G. lucidum polysaccharide. [Conclusions]Air flow fine pulverization pretreatment could greatly improve extraction effect of G. lucidum polysaccharide,which mainly improved the content and yield of G. lucidum polysaccharide,and extraction was more complete,with less impact on the property of the extracted polysaccharide. It was speculated that air flow fine pulverization pretreatment mainly destroyed mechanical support wall membrane structure of G. lucidum fine powder,making that intracellular functional substances completely dissolved out of the cell,and the content would be studied in follow-up experiment.
基金the National Natural Science Foundation of China（No. 50271063 and No. 50471040）.
文摘The degradation behaviors of the TiV-based multiphase hydrogen storage alloy Ti0.8Zr0.2V3.2Mn0.64 Cr0.96Ni1.2 during electrochemical cycling in alkaline electrolyte have been studied by XRD, SEM, EIS and AES measurements. XRD analysis indicates that the alloy consists of a C14-type Laves phase and a V-based solid solution. The lattice parameters of both phases are increased after discharged with cycling, which indicates that more irreversible hydrogen remains not discharged in the alloy. It shold be responsible for the decrease of discharge capacity. SEM micrographs show that after 10 electrochemical cycles, a large number of cracks can be observed in the alloy, existing mainly in the V-based solid solution phase. Moreover, after 30 cycles, the alloy particles are obviously pulverized due to the larger expansion and shrinkage of cell volumes during hydrogen absorption and desorption, which induces the fast degradation of the TiV-based hydrogen storage alloys. EIS and AES measurements indicate that some passive oxide film has been formed on the surface of alloy electrode, which has higher charge-transfer resistance, lower hydrogen diffusivity, and less electro-catalytic activity. Therefore it can be concluded that the pulverization and oxidation of the alloy are the main factors responsible for the fast degradation of the TiV-hased hydrogen storage alloys.
文摘The degradation of La 0.8 Pr 0.2 Ni 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy electrode during charge discharge cycles was studied with analytical electron microscope (AEM) and scanning electron microscope (SEM). During the cycles, the alloy particles of the negative electrode were pulverized gradually. After 200 cycles, the pulverizing process basically ended and the larger particles were pulverized to below 10 μm. The particles were oxided at the rate of about 0.1 μm/100 times cycles. The oxide layer was porous and consisted of the La(OH) 3 and oxides of Pr, Co and Ni. Most of Pr, Mn and almost all of Al in the oxide layer were dissolved into the electrolyte. The oxidation of the alloy particles was one of the main factors of the decay of the discharge capacity of the negative electrode during the cycles.
文摘Studies were made of the effect of mechanical pulverization on relaxation,crystallization and brittle-ductile transition of the anneal-embrittled Fe_(75)Si_(10)B_(15) metallic glass rib- bon.Results show that the Curie temperature,T_C,decreases and the total enthalpy of relaxation increases gradually with variation of pulverized time.DSC traces reveal an extra exothermic peak,T_X_1,and a distinct glass transition endothermic peak,T_g_1,with increasing pulverized time,T_C,T_X_1,and T_g_1 decrease simultaneously,and the exother- mic peak area corresponding to T_X_1 increases gradually.The surface slip-steps of flaky particles and their corresponding shear are produced by pulverizing the pre-embrittled amorphous glass.The lost ductility of the glass may restore during annealing.
文摘It’s known that the pulverization-densification mechanism of metal hydride may cause the stress accumulation in metal hydrides reactors. In this paper, this idea is proved based on granulometry and a new idea of cycling compression effect is presented, which is caused by the friction between wall and metal hydrides. Through theoretical analysis, the cycling compression effects is shown to increase the localized packing rate from top to down in vertical-placed reactors and thus lead to the maximum deformation in the bottom of reactors, proving that it is the interaction of pulverization-densification effect and cycling compression effect resulting in the stress problems of vertical-placed reactors. Further study points that the effective methods relieving the cycling compress effect are to decrease hydrogen absorption/desorption cycle number, slenderness ratio of reactor, wall friction factor and initial packing rate, or to lower the thermal conductivity and the volume expansion coefficient of metal hydrides.
文摘For the geological disposal of high level radioactive wastes, an excavation damaged zone （EDZ） having high hydraulic conductivity resulting from the development of fractures in the rock adjacent to the tunnels will be one of the potential pathways for radioactive contaminant transport. The potential pathways will be sealed by closure components, that is, a combination of tunnel plug, backfill and grout, the latter material being a clay-based mixture in consideration of the need for long-term stability of the seals. Clay-based grout is one of the effective candidate materials that can be used to interrupt the migration of radionuclides through an EDZ. Laboratory testing of clay-based grout using pulverized bentonite, with the objective of improvement in grout penetration into a rockmass, was conducted. The results showed that the pulverization of clay-based grout had a positive effect on filtration.
基金financially supported by the Young Talent Cultivation Fund in Universities (No. FRF-TP-12-020A)the National Natural Science Foundation of China (Nos. 51204013 and 51174023)
文摘An updated approach to refining the core indicators of pulverized coal used for blast furnace injection based on principal component analysis is proposed in view of the disadvantages of the existing performance indicator system of pulverized coal used in blast furnaces. This presented method takes into account all the performance indicators of pulverized coal injection, including calorific value, igniting point, combustibility, reactivity, flowability, grindability, etc. Four core indicators of pulverized coal injection are selected and studied by using principal component analysis, namely, comprehensive combustibility, comprehensive reactivity, comprehensive flowability, and comprehensive grindability. The newly established core index system is not only beneficial to narrowing down current evaluation indices but also effective to avoid previous overlapping problems among indicators by mutually independent index design. Furthermore, a comprehensive property indicator is introduced on the basis of the four core indicators, and the injection properties of pulverized coal can be overall evaluated.
基金financially supported by the National Natural Science Foundation of China (Nos. 51874080, 51604069, and 51774071)the Fundamental Research Funds for the Central Universities, China (No. N162504004)
文摘The combustion characteristics of two kinds of unburned pulverized coal (UPC) made from bituminous coal and anthracite were investigated by thermogravimetric analysis under air. The reaction kinetics mechanisms between UPC and CO2 in an isothermal experiment in the temperature range 1000–1100°C were investigated. The combustion performance of unburned pulverized coal made from bituminous coal (BUPC) was better than that of unburned pulverized coal made from anthracite (AUPC). The combustion characteristic indexes (S) of BUPC and AUPC are 0.47 × 10^-6 and 0.34 × 10^-6 %2·min^-2·°C^-3, respectively, and the combustion reaction apparent activation energies are 91.94 and 102.63 kJ·mol^-1, respectively. The reaction mechanism of BUPC with CO2 is random nucleation and growth, and the apparent activation energy is 96.24 kJ·mol^-1. By contrast, the reaction mechanism of AUPC with CO2 follows the shrinkage spherical function model and the apparent activation energy is 133.55 kJ·mol^-1.
基金Project(51134008)supported by the National Natural Science Foundation of ChinaProject(2012CB720401)supported by the National Basic Research Program of China
文摘The combustion process of pulverized coal injected into blast furnace involves a lot of physical and chemical reactions. Based on the combustion behaviors of pulverized coal, the conception of coal effective calorific value representing the actual thermal energy provided for blast furnace was proposed. A cost performance evaluation model of coal injection was built up for the optimal selection of various kinds of coal based on effective calorific value. The model contains two indicators: coal effective calorific value which has eight sub-indicators and coal injection cost which includes four sub-indicators. In addition, the calculation principle and application of cost performance evaluation model in a Chinese large-scale iron and steel company were comprehensively introduced. The evaluation results finally confirm that this novel model is of great significance to the optimal selection of blast furnace pulverized coal.
