Influence of thermo hydrogen treatment on microstructure and mechanical properties of Ti-5Al-2.5Sn ELI alloy

Thermo hydrogen treatment(THT) of titanium is a process in which hydrogen is used as a temporary alloying element in titanium alloys. It is an attractive approach for controlling the microstructure and thereby improving the final mechanical properties. In the present study, the microstructure of the original(non-hydrogenated) sample has only α phase and the grains is coarse with an average size of ~ 650 μm. While the grain size of thermo hydrogen treated Ti-5Al-2.5Sn ELI alloy became finer and the mechanical properties were improved significantly. When the hydrogen content of the hydrogenated Ti-5Al-2.5Sn ELI alloy is 0.321 wt.%, β phase and δ titanium hydride appear. Also the average grain size decreases to 450 μm. When the hydrogen content is 0.515 wt.%, the grain size decreases to 220 μm. The mechanical properties were tested after dehydrogenation, and the mechanical properties improved significantly compared to the unhydrogenated specimens. The tensile strength of the Ti-5Al-2.5Sn ELI alloy improved by 17.7% when the hydrogen content increased to 0.920 wt.%, at the same time the percentage reduction of area(Z) increased by 33% and the impact toughness increased by 37%.

Influence of thermo hydrogen treatment on hot deformation behavior of Ti600 alloy

Hot compressive deformation of Ti600 alloy after thermo hydrogen treatment (THT) was carried out within hydrogen content range of 0-0.5%, temperature range of 760-920 ℃ and strain rate range of 0.01-10 s-1. The flow stress of Ti600 alloy after THT was obtained under hot deformation condition, and the influence of hydrogen on work-hardening rate (S*), strain energy density (U*), and deformation activation energy (Q) was analysed. The results show that the flow stress of Ti600 alloy decreases remarkably with the increase of hydrogen when the hydrogen content is less than 0.3%. Both S* and U* decrease with the increase of hydrogen when the hydrogen content is less than 0.3%, and when the hydrogen content is more than 0.3%, S* and U* increase with hydrogen addition. The value of Q decreases with the increase of strain at the same hydrogen content. The addition of small quantity of hydrogen leads to an increase of Q at small strain values, and when the strain reaches 0.6, the value of Q decreases gradually with the increase of hydrogen. When the hydrogen content is within the range of 0.1%-0.3%, the flow stress of Ti600 alloy is decreased when being deformed at the temperature range of 760-920 ℃.

Hydrogen Treatment of Cast Ti-6Al-4V Alloy

This paper presents the results of an investiga- tion of the effect of hydrogen treatment on microstructures and tensile and low cycle fatigue properties of a Ti-6Al-4V cast alloy.The phase transformation and the refining mechanism of the cast microstructure during the process of hydrogen treatment were studied.It was found that after hydrogen treatment,the coarse Widmansttten structure of the as-cast Ti alloy was transformed into a very fine and equiaxed α+β microstructure without any GBα phase.The tensile strength and ductility and the low cycle fatigue life of the hydrogen treated specimens were significantly im- proved.

Microstructure Evolution and Phase Transformation of Ti–6.5Al–2Zr–Mo–V Alloy During Thermohydrogen Treatment

Thermohydrogen treatment （THT） is an effective way to refine microstructure and improve the mechanical properties of the titanium alloys. In the current work, as-cast Ti-6.5Al-2Zr-Mo-V alloy was hydrogenated with different hydrogen contents and processed solution aging. Accordingly, the microstructure evolution and phase transformation were analyzed. Results show that during solution aging, eutectoid decomposition occurs and the product is a mixture of coarse primaryα, fine eutectoid product and undecomposed βH. The size of primary α is closely dependent on the hydrogen content, and large primary α can be obtained at medium hydrogen content. Further, the influence of hydrogen content on the growth of primary α phase was revealed. The primary α is much fine, and the eutectoid product is relatively homo- geneous with 0.984 wt% H. After THT, the ultimate strength is beyond 1,100 MPa that has increased by 23.15% compared with that in as-cast state.

CO_2 selective hydrogenation to synthetic natural gas(SNG) over four nano-sized Ni/ZrO_2 samples:ZrO_2 crystalline phase & treatment impact

Two type zirconia (monoclinic and tetragonal phase ZrO2) carriers were synthesized via hydrothermal route, and nano-sized zirconia supported nickel catalysts were prepared by incipient impregnation then followed thermal treatment at 300 °C to 500 °C, for the CO2selective hydrogenation to synthetic natural gas (SNG). The catalysts were characterized by XRD, CO2-TPD-MS, XPS, TPSR (CH4, CO2) techniques. For comparison, the catalyst NZ-W-400 (monoclinic) synthesized in water solvent exhibited a better catalytic activity than the catalyst NZ-M-400 (tetragonal) prepared in methanol solvent. The catalyst NZ-W-400 displayed more H2absorbed sites, more basic sites and a lower temperature of initial CO2activation. Then, the thermal treatment of monoclinic ZrO2supported nickel precursor was manufactured at three temperature of 350, 400, 500 °C. The TPSR experiments displayed that there were the lower temperature for CO2activation and initial conversion (185 °C) as well as the lower peak temperature of CH4generation (318 °C), for the catalyst calcined at 500 °C. This sample contained the more basic sites and the higher catalytic activity, evidenced byCO2-TPD-MS and performance measurement. As for the NZ-W-350 sample, which exhibited the less basic sites and the lower catalytic activity, its initial temperature for CO2activation and conversion was higher (214 °C) as well as the higher peak temperature of CH4formation (382 °C). © 2016 Science Press

Effect of surface treatment on the structure and high-rate dischargeability properties of AB_5-type hydrogen storage alloy

Surface-treated MmNi3.55Co0.75Mn0.4Al0.3 alloy as negative electrode material of nickel-metal hydride battery was employed to improve the high-rate dischargeability. Surface treatment was realized by dipping and stirring the alloy into a HCl aqueous solution with various concentrations at room temperature. The microstructure of the alloy before and after surface treatment was analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The electrochemical properties before and after surface treatment were compared, and the alloy treated in 0.025 mol/L HCl solution showed the optimal high-rate dischargeability.

Healing of hydrogen-attacked cracks in split specimens with recovering heat treatment in vacuum

The healing mechanism of hydrogen-attacked cracks in low carbon steel andCr-Mo steel and its influencing factors during the healing process were studied by recovering heattreatment of split specimens in vacuum. The result showed that crack pacing turns much smaller underthe condition of pure heating, especially for crack tips. The healing effect is well related to thelength of cracks with the shorter in priority. By the primary mechanism of thermal diffusion, ironand carbon atoms must diffuse at the high speed in steel to realize that plasticity deformationenergy exceeds and overcomes surface tensile force energy. In addition, phase transformation andstress-stain relationship also have positive effects on the process.

Surface Modification of AB_2 and AB_5 Hydrogen Storage Alloy Electrodes by the Hot-Charging Treatment

The effect of the hot-charging treatment on the performance of AB(2) and AB(5) hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (VPR), the high rate discharge ability (HRDA), the diffusion coefficient of hydrogen DH and the discharge capacity of the AB2 hydrogen storage alloy electrode. The SEM analysis showed that the hot-charging treatment brings about a Ni-rich surface due to the dissolution of Zr oxides. It is also very helpful for the improvement of the kinetic properties of AB2 hydrogen storage alloy electrode because the microcracking of the surface results in fresh surface. This can be the basic modification treatment for NiMH battery used in electric vehicles (EVs) in the future. But for AB(5) type alloys, the treatment has the disadvantage of impairing the comprehensive electrochemical properties, because the surface of the alloy may be corroded during the treatment. The mechanism of the surface modification of the electrode is also proposed.

Effect of Heat-Treatment Process on Properties of Rare Earth Mg-Based System Hydrogen Storage Alloys with AB_3-Type

The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau voltage of the alloy which was heat-treated in various temperatures and times had different changes during the cycle process, the optimum heat-treatment conditions of this alloy were determined by this work.

Influences of heat treatment on electrochemical characteristics of La_(0.75)Mg_(0.25)Ni_(2.8)Co_(0.5) hydrogen storage electrode alloy

The influences of annealing treatment on the electrochemical and structural properties of La 0.75Mg 0.25- Ni 2.8Co 0.5 hydrogen storage alloy were investigated by means of electrochemical studies and X-ray diffraction(XRD) analyses. The XRD results reveal that the peak width gets narrower with increasing annealing temperature, which can be ascribed to the structural change and more homogeneous composition after being annealed. Electrochemical studies show that the discharge capacity and the cycle stability of the alloy electrodes increase after being annealed. The maximum discharge capacity, exchange current density J 0 and limiting current density J L of the as-cast alloy are 388 mA·h/g, 340.5 mA/g and 3 068 mA/g, respectively, and they are increased to 400 mA·h/g, 372.1 mA/g and 3 399 mA/g for the alloy annealed at 1 123 K for 8 h, respectively. Meanwhile, as the discharge current density is 1 250 mA/g, the high rate dischargeability(HRD) increases from 77.4% for the as-cast alloy to 83.3% for the alloy annealed at 1 123 K.

TC21合金在不同温度下进行连续多步置氢处理时的显微组织及室温力学性能

利用OM、XRD、TEM以及压缩试验等方法研究TC21钛合金经不同温度连续多步置氢处理后的显微组织及室温力学性能。结果表明:当氢处理温度超过1073 K时,α相的尺寸明显降低,β相成为主要相。随着氢处理温度的升高,δ氢化物的含量呈先增加后逐渐降低的趋势。当氢处理温度超过1073 K时,TC21钛合金在室温压缩变形过程中出现应变软化现象,且该现象随氢处理温度的升高而越来越显著。随着氢处理温度的升高,TC21钛合金的极限变形率呈先降低后增加的趋势。当氢处理温度为1123 K时,TC21钛合金的极限变形率比原始合金增加67.51%。

基于逆电渗析原理的能量转换利用技术专利进展

逆电渗析技术是依靠离子交换膜选择性将溶液盐差梯度转换为膜电势,进而可用于发电或驱动电化学反应的技术。文章着眼于我国逆电渗析技术相关专利前沿进展,首先,从膜阻、膜厚、离子选择性、离子交换容量、耐污抗菌、稳定性等角度探讨了适配离子交换膜的权衡考量机制,分析了膜的改性方法与优化发展方向;然后,重点介绍了逆电渗析技术在发电、制氢、污水处理及海水淡化等领域的发展与专利布局情况,厘清(热能→)盐差能→(电能→)氢能等多条能源转换技术路线,并阐释了循环工作溶液的再生方法与发展脉络。逆电渗析技术与电渗析技术、可再生能源发电技术、低品位热回收技术相耦合是实现各技术优势互补、提高能效与产出的有效策略。

光电催化矿物材料的制备及应用研究进展

光电催化技术是解决环境污染和能源短缺问题最具应用前景的方法之一。基于半导体矿物的光电化学性质或非半导体矿物的天然物理特性,将矿物与光电催化功能体复合构建的光电催化矿物材料具有成本低、环境相容性好、性能优异等特点,其在矿物利用的新兴领域受到了广泛关注。本文在限定了光电催化矿物材料研究是否属于矿物应用范畴的基础上,介绍了光电催化矿物材料包含的矿物组分及特征,提出了光电催化矿物材料的分类,并对光电催化矿物材料的制备方法及矿物增强光电催化活性的机制进行了讨论。最后,概述了光电催化矿物材料用于水中污染物治理、光电催化水分解产氢、CO_(2)能源化等领域的研究现状;指出应重点关注矿物本征光电属性、有效建立材料复合结构与效能的联系、明确材料矿物学属性影响光电催化的机制等问题,拓展光电催化矿物材料在新能源、化学品合成和矿物/微生物作用等领域的应用研究。

废棉纤维纳米纤维素晶须制备及其表征

为实现废弃资源的高值化回用,以棉坯布磨毛整理过程中产生的废棉纤维为原料,通过去离子水洗涤、异丙醇处理除去废棉纤维表面的杂质,再经过氧化氢处理和硫酸水解,成功提取出纳米纤维素晶须(SCNCs)。测试结果表明,所提取的纳米纤维素晶须呈短棒状,长度为100 nm~400 nm,直径为10 nm~25 nm,晶型为Ⅰ型,结晶度达85.17%。此外,热重分析得出纳米纤维素晶须的初始分解温度为303℃,在600℃下的残留率为25.448%。

炼油厂加氢装置设备的防腐措施研究

炼油厂加氢装置作为辅助炼油的关键设备,直接影响炼油的质量以及效率。加氢装置设备会受到诸多因素的影响出现腐蚀状况,对设备造成损坏,所以常规防腐蚀材料难以适应整体耐腐蚀的管理要求,对腐蚀防护提出了更高要求,文章对加氢装置设备的防腐措施进行了分析探讨。

V-Ti-Fe三元合金显微组织、氢传输行为及耐蚀性能研究

Nb-Ti-Fe双相合金已被证实具有优异的渗氢性能,有望成为替代传统Pd膜的渗氢材料。V和Nb同属于5B族,具有类似的物理化学性质,但是,V-Ti-Fe双相合金组织转变规律和渗氢性能至今无人研究。基于此,本工作对V-Ti-Fe三元合金的显微组织和渗氢行为开展了详细研究,并探索了热处理和电化学腐蚀对改善渗氢性能的可能性。研究结果表明:V-Ti-Fe三元合金体系中存在一个包共晶凝固反应,即L+TiFe_(2)→Bcc-(V,Ti)+TiFe(1626 K)。液相面投影图中存在三个相区,分别为TiFe相区、TiFe_(2)相区和Bcc-(V,Ti)相区。其中,TiFe相区合金室温组织由初生TiFe相和{Bcc-(V,Ti)+TiFe}共晶结构组成,TiFe_(2)相区合金室温组织由初生TiFe相、TiFe_(2)相和Bcc-(V,Ti)相构成,Bcc-(V,Ti)相区合金室温组织由初生Bcc-(V,Ti)相和TiFe相组成,渗氢性能测试证实了该系合金抗氢脆性能较弱。具体来说,上述三区域内部铸态合金在渗氢实验前均发生了不同程度的破碎,仅V_(2.5)Ti_(62.5)Fe_(35)合金能够渗氢,不过,该合金在渗氢后期发生断裂。最后,本工作采用电化学腐蚀和真空热处理两种方法改善该合金体系的渗氢性能,其中,V_(2.5)Ti_(62.5)Fe_(35)合金具有较高的耐腐蚀性能,经热处理后该合金的渗氢性能明显提升,其在623 K下的氢渗透性能为1.03×10^(-9)mol H_(2)m^(-1)·s^(-1)·Pa^(-0.5)。

高温对含氢DLC涂层的微观结构及力学性能的影响

目的针对含氢DLC涂层热稳定性很差的问题,探究高温下含氢DLC涂层的微观组织变化特征,以及高温对其力学性能的影响。方法采用等离子体强化化学气相沉积(Plasma Enhanced Chemical Vapor Deposition,PECVD)在S136模具不锈钢表面沉积以Si为过渡层的含氢DLC复合涂层,利用光学显微镜、扫描电镜、拉曼光谱、X射线电子衍射仪、三维轮廓仪研究DLC涂层的微观结构,采用划痕测试仪、往复式摩擦磨损试验机、纳米压痕仪研究DLC涂层的力学性能,并通过LAMMPS软件,利用液相淬火法建立含氢DLC模型,模拟分析经高温处理后涂层的组织变化特征和纳米压痕行为。结果在400℃、2 h的退火条件下,拉曼谱峰强度ID/IG由未退火的0.7增至1.5,涂层发生了石墨化转变,同时基线斜率下降,H元素析出;XPS结果表明,在此条件下涂层中sp^(2)杂化组织相对增加,氧元素增多,涂层粗糙度增大;在600℃、2 h退火条件下,DLC发生了严重氧化,LAMMPS模拟结果表明,在400℃高温下涂层的分子键长变短,表明sp3杂化组织在高温下吸收能量,并向sp^(2)杂化转变。纳米压痕模拟结果显示,在400℃下退火后,涂层的硬度下降。结论在400℃下退火处理后,涂层中的H元素释放,涂层内应力减小,保证了涂层的强度;在600℃退火条件下,过渡层的Si和DLC在高温下形成了C—Si键,使得DLC薄膜部分被保留;LAMMPS模拟结果表明,在高温下涂层发生了石墨化转变,涂层的硬度减小。

回采面机载式同步吸收硫化氢设备工艺及应用研究

针对回采工作面割煤时硫化氢大量涌出严重危害作业工人的健康问题,以晋牛煤矿1303工作面为例,采用煤矿井下机载同步式硫化氢处理装置,在采煤机割煤破煤的瞬间,利用机头、机尾2个负压泵的强力抽吸作用,将机头和机尾的硫化氢引到碱液箱处,碱液箱处安设的喷嘴喷雾能够快速将硫化氢消除。研究结果表明,机载同步式消除硫化氢装置除了控制采煤机在割煤过程中产生的硫化氢外,它对风流的强力抽吸作用还能够增强采煤机机头和机尾附近风流的流动速度,防止硫化氢在机头和机尾处积聚,提高采煤机在工作面割煤的安全性,从而降低工作面硫化氢的浓度。通过在1303工作面的试验表明,采用机载同步式硫化氢处理装置,回采工作面的硫化氢平均浓度从125×10^(-6)降低到了50×10^(-6),降低幅度可达60%,回采工作面硫化氢治理效果显著,大幅度降低了人工成本和工程施工投入,抽吸硫化氢的同时,从而保证回采面的安全高效生产。

某油田生产流程硫化氢治理技术研究

通过分析某油田的生产历史和硫化氢成因机理,制定针对性的生产流程硫化氢治理方案,并在现场采用两种治理药剂,对油田生产流程中的硫化氢污染进行加药治理。通过对现场生产水中SO42-、S2-、VFA及伴生气中的硫化氢浓度检测结果说明,两种药剂均有明显治理效果;在硫化氢浓度和产量两个指标上分析,药剂I的治理效果优于药剂II的治理效果;同时两种药剂均对有益菌NRB的增殖和SRB的抑制效果起到促进作用。

空气气氛热处理对Pd膜氢渗透性能的影响

为了研究空气气氛热处理对Pd膜氢渗透性能的影响,采用化学镀沉积Pd膜,并对在573 K空气气氛热处理前后的Pd膜氢渗透性能进行分析评价。用X射线衍射(XRD)、扫描电子显微镜(SEM)、原子力显微镜(AFM)和氢渗透方法对Pd膜进行了表征,结果表明:沉积态Pd膜结构致密无缺陷,厚度为5μm左右,Pd膜在673、723、773 K的氢渗透率分别为3.62×10^(-9)、5.12×10^(-9)、6.80×10^(-9)mol/(m·s·Pa^(0.5))。573 K空气气氛热处理会导致Pd膜表面粗糙度增加,表面积增大,氢在膜表面的解离吸附位点增加,进而提升膜的氢渗透性能。热处理后,Pd膜在673、723、773 K的氢渗透率分别为5.32×10^(-9)、6.44×10^(-9)、7.31×10^(-9)mol/(m·s·Pa^(0.5)),较热处理前提高了1.1~1.5倍。