均匀化处理对挤压态Mg-Al-Zn-0.1Y合金热变形行为及织构的影响

利用250～400℃、0.01～10 s^-1 Gleeble 3500热模拟机等温热压缩试验研究了均匀化处理对稀土Y微合金化挤压态Mg-Al-Zn合金热变形行为的影响,利用电子背散射衍射(EBSD)研究了均匀化热处理对其热变形织构的影响。建立了挤压态和均匀化处理态Mg-Al-Zn-0.1Y镁合金的Arrhenius型本构方程,绘制了代表稳态流动的0.5应变加工图。研究了均匀化热处理对合金热加工图的影响,发现均匀化处理拓宽了合金低温可加工区,提升了合金的低温可加工性,确定了挤压态合金的适宜加工区为(325～375℃、0.01～0.1 s^-1)和(350～375℃、1～10 s^-1),均匀化热处理态合金的适宜加工区为(275～325℃、0.01～0.1 s^-1)。均匀化热处理提升了合金的动态再结晶能力,弱化了挤压态合金热变形基面织构强度,提升了软取向部分比例,提高了挤压态镁合金的热成形性。     

缓蚀剂分子结构与抗硫性能及其缓蚀机理研究

用饱和H₂S/CO₂失重法、高压H₂S/CO₂动态失重法、原子力显微镜（AFM）、环境扫描电镜（SEM）和X射线能量色散光谱（EDX）研究了咪唑啉衍生物、曼尼希碱、吡啶季铵盐、喹啉季铵盐和新稠杂环季铵盐5种不同分子结构缓蚀剂对N80钢的抗硫性能。结果表明5种缓蚀剂对N80钢的抗硫性能均随缓蚀剂浓度的增加而增强,各缓蚀剂的抗硫性能优劣顺序为：新稠杂环季铵盐>喹啉季铵盐>吡啶季铵盐>咪唑啉衍生物>曼尼希碱。静电吸附作用较强、空间位阻效应较小且中心吸附原子的电子云密度较大的缓蚀剂抗硫效果更好,其缓蚀机理主要是有效抑制CO₂/Cl^-腐蚀且促使试片表面生成致密的硫化物保护膜。     

Fabrication of gold nanoparticles with different morphologies in HEPES buffer

Gold nanoparticles with different morphologies, such as spindle, octahedron, and decahedron were obtained by using different molar ratios of HAuCl4/HEPES in the presence and absence of surfactants at room temperature.These nanoparticles were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), scanning electron microcopy(SEM), energy-dispersive X-rays analysis(EDX), and selected area electron diffraction(SAED).The kinetics o...     

Er、Zr微合金化5083铝合金的超塑性

针对5E83合金(Er、Zr微合金化5083合金),采用超塑性拉伸试验、扫描电镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM),探究了Er、Zr微合金元素、晶粒尺寸、变形温度、应变速率对合金超塑性的影响。通过再结晶退火、空冷和水冷的搅拌摩擦加工(FSP),分别获得了晶粒尺寸为7.4、5.2、3.4μm的完全再结晶组织,作为初始状态进行超塑性拉伸。结果表明,初始晶粒尺寸越细小,超塑性伸长率越高。当晶粒尺寸>5μm时,超塑性变形过程晶粒粗化缓慢,细化初始晶粒可显著提高超塑性;而当晶粒尺寸<5μm时,超塑性变形过程晶粒粗化严重,进一步细化初始晶粒对超塑性的提高有限。不同变形温度、应变速率的超塑性拉伸结果显示在变形温度为450～540℃、应变速率为1.67×10^-4～1.67×10^-1 s^-1,超塑性伸长率随变形温度和应变速率的提高呈现先上升后下降再上升的趋势;变形温度为520℃、应变速率为1.67×10^-3 s^-1条件下,水冷FSP态合金获得最大伸长率330%...     

Preparation and H_2S Gas-Sensing Performances of Coral-Like SnO_2–CuO Nanocomposite

Nanocomposites composed of SnO2 and CuO were prepared by hydrothermal method. The microstructures of obtained SnO2–CuO powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption test. The results show that the nanocomposites exhibited coral-like nanostructure, and the average crystalline size of SnO2 was 12 nm. The specific surface area of the four samples, SnO2–0.2CuO, SnO2–0.5CuO, SnO2–1.0CuO and SnO2–2.0CuO are 72.97, 58.77, 49.72 and 54.95 m2/g, respectively. The gassensing performance of the four samples to ethanol, formaldehyde and H2 S was studied. The sensor of SnO2–0.5CuO exhibited high response to hydrogen sulfide(4173 to 10 ppm H2S, where ppm represent 10-6), and low response to ethanol and formaldehyde. The good selectivity exhibited that the SnO2–0.5CuO nanocomposite can be a promising candidate for highly sensitive and selective gas-sensing material to H2S.     

Mg-6Gd-1.2Y-0.53Zr合金的热变形行为及热加工图

采用热模拟试验法研究了变形温度(340～500℃)和应变速率(0.01～25 s^-1)对均匀化态Mg-6Gd-1.2Y-0.53Zr合金动态再结晶(DRX)临界应变及体积分数的影响,通过构建热加工图优化了其热加工工艺参数范围。结果表明,在0.01～1 s^-1的低应变速率下,该合金的动态再结晶(DRX)临界应变量随变形温度的升高而升高,而在10～25 s^-1高应变速率下,DRX临界应变量随变形温度的升高而略微下降。应变速率及变形温度的升高都使DRX体积分数增大,在500℃、25 s^-1条件下,合金的动态再结晶体积分数最高,达90.0%。根据构建的热加工图,当变形量在30%～80%之间时,较佳的热加工工艺区间为400～500℃、0.01～1 s^-1以及420～500℃、10～25 s^-1。在10～25 s^-1应变速率下,当变形量为10%～80%时,合金最适宜的变形温度为460～500℃。     

Effects of H2O2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

The effects of H₂O₂ pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA) were investigated by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF) soaking test. It is found that the H₂O₂ pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni₂O₃, Na₂TiO₃ and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment. As a result, the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na⁺ ions from Na₂TiO₃ phase with H₃O⁺ ions in SBF, which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H₂O₂ pretreatment.     

Activity coefficients and partial molar volumes of boron in platinum-rhodium alloys

Activity coefficients of B in the phase of Pt and of three Pt---Rh alloys with 3, 6, and 10 wt.% Rh were obtained by equilibration of B₂O₃ with H₂-H₂O mixtures between 750 and 1000 °C and subsequent determination of the B mole fraction x_B 0.06 by the mass gain of the samples or by photometric analysis. Additions of Rh to Pt have rather large but opposing effects on the partial molar enthalpies and entropies of B, resulting in partial molar excess Gibbs energies within the modest range between −40 and −55 kJ mol⁻¹. The change in the lattice contraction from −13.5 to −3.2 pm/x_B in the phase of Pt and of Pt-10Rh can be fully described in terms of a substitutional solution model with strictly constant partial molar volumes of 9.09 cm³ mol⁻¹ and 8.28 cm³ mol⁻¹ for Pt and Rh respectively and a partial molar volume for B that increases linearly from 8.2 to 8.9 cm³ mol⁻¹ between pure Pt and Pt-10Rh.     

F40MnVS非调质钢大规格棒材热加工图的构建

采用Gleeble-2000D热模拟试验机对F40MnVS非调质钢进行了热模拟压缩试验,分析了该钢在850~1 050 ℃和0.01~10 s^-1条件下的热模拟压缩变形特征。同时,根据Prasad提出的动态材料模型(DMM)并结合有限元模拟,建立了适用于F40MnVS非调质钢φ156 mm规格棒材的热加工图。研究结果表明,在低应变速率(0.01~0.1 s^-1)下,材料呈现典型的动态再结晶特征;在高应变速率(1~10 s^-1)下,材料发生动态回复;由所建立的热加工图确定了F40MnVS非调质钢的最佳的热变形工艺,即变形温度900~950 ℃,应变速率0.03~0.1 s^-1。热加工图为F40MnVS非调质钢大规格棒材的加工性能分析和工艺优化提供了参考依据。     

2195铝锂合金的热变形行为

在Gleeble-1500热模拟机上实施热压缩试验,研究2195铝锂合金在变形温度360~500 ℃,应变速率0.1~10 s^-1时的热变形行为,并通过OM和EBSD研究了热变形中微观组织的演变。基于动态材料模型理论及Zener-Holloman参数,构建了2195铝锂合金的应变量为50%时的加工图及本构方程。结果表明,流变应力随变形温度降低或者应变速率的增加而提高,高温软化机制包括动态回复与动态再结晶。利用加工图及显微组织分析确定了试验参数范围内热变形过程的最佳工艺参数为480 ℃/10 s^-1;发现失稳区形变组织和再结晶组织呈层状交替分布,且随着变形温度降低,形变组织层厚度增加;稳定区的微观组织具有明显的动态再结晶特征,形变组织基本消失。     

盐酸埃他卡林对H2O2所致PC12细胞损伤的保护

目的: 研究 K_ATP 通道开放剂盐酸埃他卡林(iptakalim hydrochloride, Ipt) 对 H₂O₂ 所致 PC12 细胞损伤的保护作用及其作用机制。方法: 采用培养的PC12细胞, MTT 法测定细胞存活率, HPLC 法测定细胞培养液中谷氨酸(Glu) 的含量, 荧光法测定胞内钙离子([Ca²⁺]_i) 浓度。结果: Ipt 可浓度依赖性的拮抗H₂O₂ 介导的细胞毒性, 提高细胞生存率, 降低胞外Glu的释放以及胞内 Ca²⁺ 浓度。该保护作用可被200 μmol°L^-1 5-HD(线粒体K ATP 通道阻断剂) 部分拮抗。结论: Ipt 可拮抗 H₂O₂ 介导的细胞损伤作用, 该保护作用可能与线粒体ATP 敏感性钾通道相关。     

阳极反应气氛氢气对聚苯胺/不锈钢耐蚀性的影响

目的 为了提高双极板在质子交换膜燃料电池(PEMFC)工作环境下的耐蚀性.方法 在1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])离子液体中,在316 L不锈钢(SS)基体上电聚合聚苯胺(PANI)膜.用红外光谱(FTIR)、拉曼光谱(Raman)、X射线光电子能谱(XPS)和扫描电子显微镜(SEM)进行微...     

Hot Deformation Behavior and Workability of(SiC_p + Mg_2B_2O_(5w))/6061 Al Hybrid and SiC_p/6061 Al Composites

The hot deformation behavior of(3 vol%SiC_p + 3 vol%Mg_2B_2O_(5w))/6061 Al(W_3P_3) hybrid composite and6 vol%SiCp/6061 Al(P_6) composite have been characterized in the temperature range of 300-450 ℃ and strain rate range of 0.0001-0.1 s~(-1) using isothermal constant true strain rate tests.The flow behavior and processing maps have been investigated using the corrected data to eliminate the effect of friction.Under the same deformation conditions,the compressive resistance of the singular composite remains superior to that of the hybrid composites.The processing map of W_3P_3 hybrid composite exhibits a single hot working domain at the temperature between 350 and 450 ℃ with strain rate between 0.0001 and 0.003 s~(-1)(domain A).Two hot working domains exist for P_6 composite:(i) 300-400 ℃/0.0001-0.003 s~(-1)(domain Bl);(ii) 380-450 ℃/0.01-0.1 s~(-1)(domain B2).The processing maps also reveal the flow instability of the two composites,which is associated with whiskers breakage,whisker/matrix interfacial debonding,SiCp/matrix interfacial decohesion,adiabatic shear bands or flow localization,and wedge cracking in the corresponding regions.The estimated apparent activation energies are about 224 kJ mol~(-1) in domain A for W3P3 hybrid composite,177 kJ mol~(-1) in domain Bl and 263 kJ mol~(-1) in domain B2 for P_6 composite,respectively.These values are higher than that for self-diffusion in Al(142 kJ mol~(-1)),suggesting that there is a significant contribution from the back stress caused by the presence of particles and/or whiskers in the matrix.The deformation mechanisms corresponding to domain Bl and domain B2 are dislocation climb controlled creep and cross-slip for P_6 composite,respectively.For W_3P_3 hybrid composite,the deformation mechanisms contain dislocation climb controlled creep and grain boundary sliding caused by DRX in domain A.     

Ag42In42Ca16二十面体准晶与2/1立方近似相Ag42In45Ca13的稳定性研究

Ag3In3Ca中的主要合金相是简单立方Ag42In45Ca13(空间群为Pa3↑-,α=2．496nm),它是Ag42In42Ca16二十面体稳定准晶的2／1立方近似相．选区电子衍射(SAED)实验表明,2／1立方近似相与二十面体准晶有相似的局部结构．X射线能谱(EDS)、电子能量损失谱(EELS)和X射线粉晶衍射分析表明,Ag3In3Ca合金中的立方相Ag42In45Ca13不稳定．薄膜电镜样品在空气中易发生化学反应,产物中主要是Ca和O,还有少量C．块状合金在空气中放置14d后,其中的立方相Ag42In45Ca13分解,二元合金相AgIn2和In4Ag9的含量明显增加．在550℃保温55h后,立方近似相Ag42In45Ca13的含量显著减少．在相同条件下,二十面体准晶Ag42In42Ca16保持不变,具有高的结构和化学稳定性。     

Technological Aspect of Processing Maps for the AA2099 Alloy

Results of an experimental and modelling study of forming processes in the AA2099 Al–Cu–Li alloy, for a wide range of temperatures, strains and strain rates, are presented. The analyses are based on tensile testing at 20 °C at a strain rate of 0.02 s-1and uniaxial compression testing in the temperature range 400–550 °C at strain rates ranging from0.001 to 100 s-1, for constant values of true strain of 0.5 and 0.9. The stability of plastic deformation and its relationship with a sensitivity of stress to strain rate are considered. The power dissipation efficiency coefficient, g(%), and the flow instability parameter, n B 0, were determined. The complex processing maps for hot working were determined and quantified, including process frames for basic forging processes: conventional forging and for near-superplastic and isothermal conditions. A significant aspect is the convergence of power dissipation when passing through the 500 °C peak.Deformation, temperature and strain-rate-dependent microstructures at 500 °C for strain rates of 0.1, 1, 10 and 100 s-1are described and analysed for the conventional die forging process frame, corresponding to 465–523 °C and strain rates of50–100 s-1.     

姜黄素对过氧化氢诱导的血管内皮细胞损伤的双重作用

目的: 研究姜黄素(Cur) 对过氧化氢(H₂O₂) 诱导的血管内皮细胞ECV304 的作用及可能机制;方法:胎盘兰计数法分组观察在不同的时间点加入姜黄素后对H₂O₂ 诱导的ECV304 细胞氧化损伤的作用。流式细胞仪分析细胞周期及细胞凋亡率的变化,试剂盒检测一氧化氮(NO) 、丙二醛(MDA) 含量及超歧化物氧化酶(SOD) 、谷胱甘肽还原酶(GR) 活性的变化。结果: 姜黄素0 ~ 100μmol·L^-1 与H₂O₂500μmol·L^-1同时作用5 h,随姜黄素浓度升高细胞存活率升高;25 ~ 100μmol·L^-1姜黄素预先作用1 h,再换为H₂O₂ 500μmol·L^-1作用4 h,细胞存活率明显下降;H₂O₂500μmol·L^-1 作用4 h,再加入25 ~ 100μmol·L^-1姜黄素作用1 h,细胞存活率也升高。姜黄素对H₂O₂ 诱导的细胞凋亡没有明显的影响,但同时作用组、H₂O₂ 先作用组S 期细胞所占比例升高,姜黄素先作用组S 期细胞所占比例下降。同时作用组、H₂O₂ 先作用组的SOD 、NO 、Gr水平相对升高,MDA 水平下降,姜黄素先作用组的SOD 、NO 、Gr水平相对下降,MDA 水平升高。结论: 姜黄素对H₂O₂诱导的血管内皮细胞ECV304 有双重效应,即有保护效应也有细胞毒效应,与其作用时间点有关。     

HST2425钛合金动态力学行为及本构模型

使用电子万能试验机和分离式霍普金森杆装置(SHPB)研究了HST2425钛合金在温度为293～673 K、应变速率为0.0001～6500 s^-1下的准静态和动态力学性能。结果表明,HST2425钛合金的最大应力和最大应变均随应变速率的增大而增加,但是应变速率超过3500 s^-1后最大应力的增加程度降低,在应变速率超过5500 s^-1后最大应变的增加程度也降低。随变形温度的升高,流变应力显著降低,并且温度和应变速率在动态压缩过程中具有交互作用。根据试验结果建立了HST2425钛合金的原始Johnson-Cook(J-C)模型及其修正模型,且修正模型与试验值的相关性比原始模型更好,表明修正模型在预测HST2425钛合金动态冲击变形行为方面具有更高的准确性和适用性。     

两种冶炼工艺下A286高温合金的热变形行为

为了探究真空感应+真空自耗(VIM+VAR)和电炉+精炼+真空自耗(EAF+LF+VAR)两种工艺冶炼A286高温合金的热变形行为,利用Gleeble-3800热模拟试验机在温度950~1150 ℃和应变速率0.01~10 s^-1范围内进行热压缩试验。基于摩擦和绝热加热修正后的真应力-真应变曲线和应变硬化率曲线建立了A286合金的Arrhenius本构方程,确定了VIM+VAR合金和EAF+LF+VAR合金的热激活能分别为358.15和372.54 kJ·mol^-1。利用临界应变和动态再结晶体积分数50%应变引入动态再结晶速度参数k_v,建立新的动态再结晶模型。采用Prasad 准则绘制两种钢在应变0.2、0.5和0.9下的热加工图,并结合组织分析,确定VIM+VAR合金的最佳热加工工艺条件为1050~1100 ℃,0.01~1 s^-1和1100~1150 ℃,0.1~10 s^-1;EAF+LF+VAR合金的最佳热加工工艺条件为1050~1100 ℃,0.01~1 s^-1和1100~1150 ℃,0.1~3 s^-1,得出VIM+VAR合金的热加工区间较宽,其热加工性能优于EAF+LF+VAR合金。     

Facile Synthesis of Ag@AgCl Plasmonic Photocatalyst and Its Photocatalytic Degradation under Visible Light

采用简单的沉淀-光还原法合成了具有可见光催化降解有机物高活性的Ag@AgCl等离子共振光催化剂。采用扫描电镜、X射线能谱、透射电镜、XRD、紫外-可见漫反射光谱和XPS等手段对催化剂进行了表征。通过可见光下降解甲基橙进行光催化活性测试。结果显示,Ag@AgCl由于Ag纳米粒子的等离子共振效应而具有较强的吸收可见光性能。对光催化反应参数如投加量、光还原时间及pH值等进行了优化,在最优条件下,经过120 min可将83%的甲基橙降解。优异的光催化活性归因于银纳米颗粒的等离子共振效应。最后对光致电荷的分离机理进行了讨论。     

铁素体-马氏体钢P91和P92在超临界水中腐蚀后氧化膜多孔性分析

用X射线衍射（XRD）和扫描电镜-电子能谱（SEM-EDX）技术研究P91、 P92在500℃/25 MPa和550℃/25 MPa超临界水中腐蚀后氧化膜的多孔性成因。结果表明,两种材料氧化膜均为双层结构,外层氧化膜为 Fe₃O₄相,内层氧化膜为Fe₃O₄和FeCr₂O₄相,P92在接近氧化膜区域的基体内存在一个内氧化区。P91和P92在超临界环境中腐蚀后氧化膜的多孔性与外层氧化膜Fe₃O₄的缺陷类型有关,富氧Fe₃O₄中的缺陷主要类型为氧空位,在超临界状态下,当氧空位浓度达到一定程度后,空位坍塌即形成小孔。