淬火温度对气瓶用Fe-Cr-Ni-Mo钢组织和力学性能的影响

为了优化一种气瓶用Fe-Cr-Ni-Mo钢的淬火工艺,采用SEM,TEM,EBSD和拉伸、冲击等观察和检测手段,研究了淬火温度对一种气瓶用Fe-Cr-Ni-Mo钢微观组织和力学性能的影响。结果表明,不同淬火温度处理后的合金钢,均呈现为板条马氏体组织,其碳化物析出和板条亚结构基本保持不变,而原始奥氏体晶粒则随淬火温度的提高而出现明显的粗化,由800℃的4.3µm长大到930,1200℃的29.6,371.1µm,同时有效晶粒尺寸(EGS)也逐渐增加,800,930,1200℃的EGS分别为0.60,1.20,3.22µm。淬火温度对合金钢的室温抗拉、屈服强度和断后伸长率影响较小,而随着淬火温度的提高,冲击吸收能量则出现了显著的下降,由800℃的119 J,下降到930,1200℃的68,38 J。EGS增大导致冲击断裂时出现解理断裂,是较高淬火温度合金钢冲击吸收能量下降的主要原因。淬火温度为800~860℃时,Fe-Cr-Ni-Mo钢具有良好的强韧性匹配,该研究结果对Fe-Cr-Ni-Mo钢制气瓶的工业化生产具有指导意义。

粉末锻造Al_(2)O_(3)颗粒增强Fe–Ni–Mo–C–Cu复合材料的组织与性能

通过粉末锻造技术制备了不同含量微米级Al_(2)O_(3)颗粒强化的Fe–Ni–Mo–C–Cu(Q61)复合材料,并对调质态和淬火态复合材料的组织和性能进行了研究。结果表明:当Al_(2)O_(3)质量分数为0.15%时,增强颗粒在基体内分布均匀;相较于同种状态下不添加增强颗粒的单一Q61,调质态复合材料的硬度从HRC 38增至HRC 39.8,屈服强度从1106 MPa增至1121 MPa,延伸率从12%降至6.5%;淬火态复合材料的硬度从HRC 61.5增至HRC 63.2,磨损率从5.27×10^(-6)mm^(3)·m^(-1)·N^(-1)降至3.08×10^(-6)mm^(3)·m^(-1)·N^(-1),低于对比试验用的典型齿轮材料40Cr的磨损率(3.34×10^(-6)mm^(3)·m^(-1)·N^(-1))。当Al_(2)O_(3)质量分数大于0.15%时,Al_(2)O_(3)颗粒逐渐偏聚,虽然调质态下复合材料屈服强度仍继续小幅增加,但塑性严重退化,且淬火态复合材料磨损率增加,耐磨性变差。综合来看,添加0.15%Al_(2)O_(3)颗粒强化Q61复合材料在调质态下具有较高的综合力学性能,而在淬火态下表现出良好的抗摩擦磨损能力。

Surface organic modification of Fe_3O_4 nanoparticles by silane-coupling agents

Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution.

Surface Organic Modification of Fe_3O_4 Magnetic Nanoparticles

The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer＇s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.

Modification ofβ-Al_5FeSi Compound in Recycled Al-Si-Fe Cast Alloy by Using Sr,Mg and Cr Additions

The effects of Sr,Mg,Cr,Sr/Mg and Sr/Cr combined additions on the Fe-containing intermetallic phase in a recycled Al-Si-Fe cast alloy are investigated.The experimental results show that the additions of Cr and Sr/Cr successfully modified the platelet and flake-likeβ-Al-5FeSi phases （β-compound） into the fibrousα-Al-8Fe-2Si （α-compound）.The additions of Sr and Sr/Mg were less effective to modify theβ-compound into theα-compound,while the eutectic Si was fully modified into the fibrous morphology.A small secondary dendrite arm spacing （DAS） was found in the Sr-added,Cr-added and Sr/Cr-added alloys,especially in a steel mold.The Sr,Sr/Cr and Sr/Mg combined additions modify the eutectic Si simultaneously.A sludge phase was found in the addition of Cr-added,Sr/Cr-added and Mg-added alloys,especially in the graphite mold casting.The volume fraction ofβ-compounds was decreased by the addition of various modifying elements. The Cr and Sr/Cr combined additions are very effective to modify theβ-compound for the recycled Al-Si-Fe based alloys.

Modification of Fe_3O_4 Magnetic Nanoparticles by L-dopa or Dopamine as an Enzyme Support

Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin （EC： 3.4.21.4） on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.

Surface modification of (Tb_(0.3)Dy_(0.7))Fe_(1.95) alloy by ion nitriding process

Effect of ion nitriding modification on surface hardness, corrosion resistance and magnetostriction of （Tb0.3Dy0.7）Fe1.95 alloy was investigated. Results demonstrated that a 100-200 nm thick nitrided layer was formed on the sample surface by ion nitriding treatment, which improved obviously surface hardness, wear, and corrosion resistance properties of （Tb0.3Dy0.7）Fe1.95 alloys. The surface hardness was increased from HV587 to HV622 after ion nitriding at 650 K for 6 h. Furthermore, ion nitriding treatment had almost no influence on mag- netostrictive performance as the nitrided layer was quite thin and the treatment temperature was not too high. The results might provide us a new approach for surface modification of （Tb0.3Dy0.7）Fe1.95 alloy.

Modification Mechanism of Coconut Husk Activated Carbon Using FeSO4 and Fe(NO3)3

Modification conditions determine the surface topography and the active material phase composition of a catalyst.To study the influence of modification on a carbon-based sorbent,coconut husk activated carbon(AC)which was activated using HNO3 and modified by FeSO4 and Fe(NO3)3 was examined.The pore textures and surface chemical characteristics of the carbon materials were examined by scanning electron microscopy(SEM),Brunner-Emmet-Teller(BET),X-ray diffraction(XRD)and Fourier transform infrared(FTIR)spectroscopy.The surface topography,the pore structure,active materials,and functional groups of AC,AC modificated by HNO3(HNO3/AC for short),and AC modificated by FeSO4 and Fe(NO3)3(Fe/AC for short)were systematically studied.Subsequently,the mechanism of modifying the conditions for the carbon materials was determined.Results showed that the surface micro topography of HNO3/AC became unsystematic and disordered.After modification with FeSO4,the ferriferous oxide was mainly present as a near-spherical crystal.Ferriferous oxides from Fe(NO3)3 modification mainly exhibited a plate shape.HNO3 modification could enlarge the pores but decrease the specific surface area of AC.FeSO4 modification resulted in a new net post structure in the pore canal of AC.Fe(NO3)3 modification caused the pore space structure to develop in the interior,and a higher calcination temperature was useful for ablation.The ash content of the AC was substantially reduced upon HNO3 modification.Upon FeSO4 modification,α-FeOOH,α-Fe2O3 andγ-Fe2O3 coexisted under the condition of a lower concentration of FeSO4 and a lower calcination temperature,and a higher FeSO4 concentration and calcination temperature generated moreα-Fe2O3.The same Fe(NO3)3 modification and a higher calcination temperature were beneficial to the minor chipping formation ofγ-Fe2O3.A higher Fe(NO3)3 loading produced a lower graphitization degree.HNO3 modification formed various new oxygen-containing functional groups and few nitrogen-containing groups.Based on the cover,FeSO4 and Fe(NO3)3 modification could decrease the oxygen-containing and nitrogen-containing functional groups.These results could optimize the modification condition and improve physical and chemical properties of carbon-based sorbents.

Distributions of Sr and Fe and their influence on modification of hypoeutectic Al-Si alloy

The influence of cooling rate and Fe-containing phases on Sr-modification of Si phases in hypoeutectic Al-Si alloys, a problem with great industrial importance, was investigated. The microstructures of samples were examined using scanning electron microscopy(SEM) with energy-dispersive X-ray spectroscopy(EDX). A new method of electron probe microanalysis(EPMA) map scanning was used to analyze the Sr distribution, which gave quantitative results covering more Si particles. EPMA map scanning, together with SEM with EDX, was also used in analyzing the distribution of Fe phases. Results show that Fe-containing phase was related to the unmodified Si particles in samples with partial modification failure and the plate-like Si phases in samples without modification failure. Such a relationship was further confirmed by the microstructure observation.In conclusion, a partial failure of Sr-modification can be caused by both slow cooling rate and Fe-containing phases.

Modification of short-range repulsive interactions in ReaxFF reactive force field for Fe–Ni–Al alloy

The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulations.In this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)potential.The modified interaction covers three ranges,including short range,smooth range,and primordial range.The short range is totally predominated by ZBL potential.The primordial range means the interactions in this range is the as-is ReaxFF with no changes.The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function.Both energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in LAMMPS.This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.

电子束熔丝沉积Mo‑Fe双金属制备工艺与性能研究

电子束熔丝沉积技术由于所制备的材料具有晶粒细小、致密度高、综合力学性能好等诸多优点得到广泛应用。以TZM钼合金为基体,采用电子束为热源在基体表面沉积304不锈钢,制备Mo‑Fe双金属材料,并研究电子束熔丝沉积工艺参数对双金属显微组织、熔合线元素分布、硬度及耐磨性的影响。试验结果表明:不同工艺参数下,钼合金与304不锈钢双金属结合良好;随热输入的增加,材料显微硬度和耐磨性能显著提高。当电子束束流为33 mA,送丝速度为1600 mm/min,行进速度为150 mm/min时,所得样品组织最为精细、硬度最高(503 HV)、耐磨性能最好。

Fe/g-C_(3)N_(4)表面改性及其对CO加氢产物分布的影响

采用尿素热缩合法制备了氮化碳(g-C_(3)N_(4)),经H_(2)O_(2)、NH_(3)·H_(2)O处理、浸渍法负载Fe制得改性Fe/g-C_(3)N_(4),对比研究了改性前后催化剂的CO加氢性能。结合XRD、SEM、FT-IR、CO_(2)-TPD、CO-TPD、H_(2)-TPR、接触角测试和N_(2)物理吸附-脱附等系列表征,探究了表面预处理对Fe/g-C3N4催化剂织构性质以及CO加氢产物分布的影响。结果表明,不同改性方法对催化剂的织构性质和CO加氢性能影响显著。尿素热缩合法制备的g-C_(3)N_(4)具有典型蜂窝状结构,Fe与g-C_(3)N_(4)相互作用较强,且高度分散;改性前后样品均呈亲水性,且H_(2)O_(2)、 NH_(3)·H_(2)O处理后亲水性增强,H_(2)O_(2)处理增强了表面羟基,NH_(3)·H_(2)O处理增加了表面氨基,促进了CO吸附,促使Fe(NCN)物相生成;预处理后的催化剂表面碱性增强。在CO加氢反应中,两步改性后的Fe/AM-g-C3N4催化剂,CO_(2)选择性降至11.61%;Fe/AM-g-C_(3)N_(4)表面碱性增强,抑制了烯烃二次加氢,烯烃选择性较高,C_(2)^(=)-C_(4)^(=)达32.37%,O/P值3.23。

Modification Behavior of Trace Rare Earth on Impurity Phases in Commercial Purity Aluminum

Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).

Fe-modified HZSM-5 catalysts for ethanol conversion into light olefins

A series of Fe/HZSM-5 catalysts with different iron loadings were prepared by impregnation method.Characterization was performed by N2 adsorption-desorption,X-ray diffraction（XRD）,NH3 temperature-programmed desorption（NH3-TPD）,temperature-programmed reduction （TPR）,temperature-programmed oxidation（TPO）and thermogravimetry（TG）analysis.Iron content in the synthesized samples varied from 1.1 wt%to 20 wt%.The obtained samples have been used for ethanol conversion into light olefins.It was found that the amount of strong acidity at 300 -5 50-C on Fe-modified samples was decreased,going with another new acid site appearance at 550- 600-C and that Fe/HZSM-5 catalysts were highly selective towards light olefins,especially the 9FZ sample.In addition,Fe-modified catalysts suppressed the conversion of ethanol to aromatics and paraffins and enhanced their anti-carbon deposit ability.

表面改性Fe/CS调控CO加氢产物分布研究

CO加氢经费托合成制取高附加值化学品是实现煤炭清洁高效利用的重要途径之一,研发高效催化剂是实现产物分布定向调控、提高目标产物选择性并抑制C1副产物生成的关键。催化剂表面性质对CO的吸附活化、加氢活性和产物分布具有重要影响。以无水葡萄糖为碳源、乙二醇为溶剂,采用溶剂热法制得碳载体,经H_(2)O_(2)、NH_(3)•H_(2)O表面改性和掺氮处理后,采用浸渍法分别制备了5Fe/CS-H_(2)O_(2)、5Fe/CS-NH_(3)•H_(2)O和5Fe/CS-N催化剂,探究了表面改性对费托合成产物分布的影响。采用XRD、SEM、TEM、N_(2)吸/脱附、TG-DTG、FT-IR、Zeta电位、XPS和拉曼光谱等对样品进行了表征。结果表明,不同表面改性方式对催化剂表面物化性质和催化性能影响显著。H_(2)O_(2)改性增加了催化剂表面—OH的数量,增强了表面亲水性,促进了Fe在载体上的分散,催化剂的热稳定性提高。在300℃、1.5MPa、空速为1000h^(-1)和n(H_(2)):n(CO)=2的条件下进行CO加氢反应活性测试结果表明,改性后的催化剂显著抑制了CH4的生成,提高了低碳烯烃选择性,从5Fe/CS的24.39%分别提高到5Fe/CS-NH_(3)•H_(2)O的34.94%、5Fe/CS-N的37.63%以及5Fe/CS-H_(2)O_(2)的43.57%。通过表面改性和掺氮处理调控催化剂表面性质实现了对产物分布的优化。

Absorption performance of DMSA modified Fe_3O_4@SiO_2 core/shell magnetic nanocomposite for Pb^(2+) removal

The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.

Effect of Mn and Mo on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy

Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of theα-Al_(15)(FeMnMo)_(3)Si_(2) phase formed during solidification.Theα-Al_(15)(FeMnMo)_(3)Si_(2) phase reaches a minimum value of about 16.3μm at 0.2wt.%Mo and 0.1wt.%Mn addition.After solution treatment,theα-Al(FeMnMo)Si dispersed phase is precipitated.When only Mn is added,theα-Al(FeMnMo)Si dispersed phase mainly distributes near the grain boundaries,while when only Mo is added,it primarily distributes in the central region of the matrix.When both Mn and Mo are added,the dispersed phase has a larger and denser dispersed region and is uniformly distributed near the Al matrix and grain boundaries.Moreover,the best overall mechanical properties of the alloy are obtained with the combined addition of 0.1wt.%Mn and 0.2wt.%Mo,due to the smaller size ofα-Al_(15)(FeMnMo)_(3)Si_(2) phase and the larger area fraction and higher density of theα-Al(FeMnMo)Si dispersed phase.The yield strength,ultimate tensile strength,and elongation are respectively improved 67.7 MPa,48.5 MPa and 5.3%,respectively,compared to that of the alloy with only 0.3wt.%Mn.

卤化钾改性Mn-Co-Fe尖晶石脱除气相Hg0的性能研究

为提高Mn-Co-Fe尖晶石吸附剂的脱汞性能,该研究首先采用溶胶凝胶自燃烧法和浸渍法结合制备了KX(X表示Cl、Br和I)改性的Mn-Co-Fe尖晶石吸附剂。然后,分别利用SEM、SEM结合EDS能谱Mapping、BET、XRD和VSM来表征其表面形貌、表面元素占比及分布、比表面积及总孔容积、晶相结构和比饱和磁化特性。并通过固定床探究了卤化钾种类、KI负载量、吸附温度和入口汞浓度对模拟燃煤烟气中汞脱除性能的影响。最后,通过动力学模拟、XPS表征和程序升温脱附实验研究了吸附剂对汞脱除的控制步骤、机制以及汞在吸附剂表面的存在形态。研究结果表明:在相同实验条件下,0.10KX@MCFS对汞的平均脱除效率KI(92.84%)>KBr(88.39%)>KCl(86.61%)。此外,增加KI的负载量、吸附温度和入口汞浓度在一定程度上能够促进改性MCFS的脱汞性能。虽然KI的负载导致了MCFS的磁性能下降,但综合分析得出:0.10KI@MCFS具有一个相对优异的汞脱除性能和饱和磁化强度值(34.0 emu/g)。因此,该研究的这一发现对汞污染排放控制和吸附剂磁回收的实践研究具有重要的参考价值。

Catalytic performance of Fe modified K/Mo_2C catalyst for CO hydrogenation

Fe modified and un-modified K/Mo2C were prepared and investigated as catalysts for CO hydrogenation reaction. Compared with K/Mo2C catalyst, the addition of Fe increased the production of alcohols, especially the C2＋OH. Meanwhile, considerable amounts of C5＋ hydrocar- bons and C2= -C4= were formed, whereas methane selectivity greatly decreased. Also, the activity and selectivity of the catalyst were readily affected by the reaction pressure and temperature employed. According to the XPS results, Mo4＋ might be responsible for the production of alcohols, whereas the low valence state of Mo species such as Mo^0 and/or Mo^2＋ might be account for the high activity and selectivity toward hydrocarbons.

Mo^(0)协同Fe^(3+)活化过碳酸钠降解水中罗丹明B的研究

采用Mo^(0)协同Fe^(3+)活化过碳酸钠体系去除水中罗丹明B,验证了Mo^(0)/Fe^(3+)/过碳酸钠反应体系降解水中罗丹明B的有效性,探究了溶液初始pH、Mo^(0)投加量、Fe^(3+)、过碳酸钠和罗丹明B初始浓度以及无机阴离子对罗丹明B降解效果的影响,并确定了该体系中活性物种的类型。结果表明,Mo^(0)协同Fe^(3+)活化过碳酸钠显著地降解水中罗丹明B;在溶液初始pH=3.0、Mo^(0)质量浓度为0.1 g/L,Fe^(3+)和过碳酸钠浓度分别为0.5 mmol/L和0.6 mmol/L时,罗丹明B的降解效果最佳;溶液中Cl^(-)与NO_(3)^(-)的存在对罗丹明B降解的影响不大,而HCO_(3)^(-)与H_(2)PO_(4)^(-)对罗丹明B降解的抑制效果明显。此外,Mo^(0)表现出良好的稳定性。猝灭实验结果表明,反应体系共存自由基和非自由基物种。