Influence of hydrogen content on room temperature compressive properties of Ti-6Al-4V alloy at high strain rate

Electromagnetic forming tests were done at room temperature to reveal the influence of hydrogen content on the compressive properties of Ti-6Al-4V alloy at high strain rate. Microstructure was observed to reveal the mechanism of hydrogen-enhanced compressive properties. The experimental results indicate that hydrogen has favorable effects on the compressive properties of Ti-6Al-4V alloy at high strain rate. Compression of Ti-6Al-4V alloy first increases up to a maximum and then decreases with the increase of hydrogen content at the same discharge energy under EMF tests. The compression increases by 47.0% when 0.2% (mass fraction) hydrogen is introduced into Ti-6Al-4V alloy. The optimal hydrogen content for cold formation of Ti–6Al–4V alloy under EMF was determined. The reasons for the hydrogen-induced compressive properties were discussed.

Effect of hydrogen content and stress state on room-temperature mechanical properties of Ti-6Al-4V alloy

This work aims to investigate the effects of hydrogen content(in the range of 0%-0.5%,mass fraction)and stress state (tension and compression)on the room-temperature mechanical properties of Ti-6Al-4V alloy through mechanical properties tests. The effects of hydrogen content on microstructure evolution of Ti-6Al-4V alloy is also examined by optical microscopy,X-ray diffractometry,transmission electron microscopy and scanning electron microscopy.The results show that hydrogen content and stress state have important effects on the room-temperature mechanical properties of Ti-6Al-4V alloy.Tensile strength and ultimate elongation decrease with increasing the hydrogen content,while compressive strength and ultimate reduction are improved after hydrogenation.The reason is that the intergranular deformation dominates at the state of tension.Hydrogen atoms in solid solution and hydrides at grain boundaries increase with increasing the hydrogen content and they can promote the initiation and propagation of cracks along grain boundaries.While the intragranular deformation dominates at the state of compression.The plastic beta phase and hydrides increase with increasing the hydrogen content and they improve the ultimate reduction and compressive strength.

Hydrogen Content and Porosity Behavior of Hypereutectic Aluminum-silicon Alloy with Phosphorus

By making castings that pick up gas from moisture in red sand molds,the porosity generated at different cooling rates was discussed during solidification of hypereutectic Al-25%Si alloy without and with phosphorus additions. The effect of phosphorus addition on hydrogen content in the melt was also studied. It was observed that the phosphorus addition made hydrogen content in alloy melts present a “see-saw' tendency.In addition to primary silicon refinement,the phosphorus promoted gas porosity formed not only in slowly cooled sections, but also in rapidly cooled sections. There was a small difference in density of full dense sample between P-refined and unrefined castings, with a larger density associated with phosphorous addition. The change of the surface tension seemed more reasonable to explain the mechanism of porosity behavior.

Influence of S Contents on the Hydrogen Blistering and Hydrogen Induced Cracking of A350LF2 Steel

In the present work, the effects of chemical compositions on the hydrogen blistering and hydrogen induced cracking of A350LF2 steel with different S contents were studied. Four types of A350LF2 steels were evaluated by immersing samples in H2S-saturated NACE solution. The hydrogen blistering, crack length rate(CLR), crack thickness rate(CTR) and crack sensitivity rate(CSR) were evaluated. The results show that there are many hydrogen blisters on the sample surface with S content of 0.021%, a few on the sample surface with S content of 0.019% and 0.012% and no one on the surface with S content of 0.002%. There were 12, 2 and 1 strips of cracks of longer than 0.3 mm on the evaluated cross sections with S content of 0.021%, 0.019% and 0.012%, respectively. There was no any crack in the sample with 0.002% S. The corrosion rate was also evaluated. The S content has no obvious influence on the corrosion rate.

Effect of hydrogen content on dielectric strength of the silicon nitride film deposited by ICP-CVD

The inductively coupled plasma chemical vapor deposition(ICP-CVD) deposited silicon nitride(SiN_(x)) thin film was evaluated for its application as the electrical insulating film for a capacitor device.In order to achieve highest possible dielectric strength of SiN_(x),the process parameters of ICP-CVD were carefully tuned to control hydrogen in SiN_(x) films by means of tuning N_(2)/SiH_(4) ratio and radio frequency(RF) power.Besides electrical measurements,the hydrogen content in the films was measured by dynamic secondary ion mass spectrometry(D-SIMS).Fourier transform infrared spectroscopy(FTIR) and micro Raman spectroscopy were used to characterize the SiN_(x) films by measuring Si-H and N-H bonds’ intensities.It was found that the more Si-H bonds lead to the higher dielectric strength.

Hydrogenation reaction of metallic titanium prepared by molten salt electrolysis

The hydrogenation reaction of electrolyzed titanium, as the first step during hydrogenation-dehydrogenation for the preparation of titanium powder, was studied. The titanium hydride was prepared through the reaction between electrolyzed titanium and hydrogen at different hydrogenation temperatures and different time. The evolutions of hydrogen and oxygen contents, density, hardness and phase composition before and after hydrogenation were characterized under different hydrogenation conditions. The results show that the main phases of titanium hydride were TiHl.924, TiH1.971 and TiH2. Increasing the hydrogenation temperature could not enhance the hydrogen content but increase the oxygen content. The effect of the hydrogenation time on the hydrogen content was not obvious. The optimal parameters of the hydrogenation process were obtained： beating at 400℃ and holding for 2 h, by which the hydrogen content of 3.63% and oxygen content of 0.18% （mass fraction） can be obtained. In addition, the microstructure, orientations and tissues of electrolyzed titanium and titanium hydride were detected.

核电用钢316H电渣重熔氢含量分析与工艺优化

为找出电渣重熔过程中电渣锭氢含量变化规律,并在此基础上,对各工序进行优化以实现电渣锭氢含量合格率提高,以核电用钢316H为研究对象,依托15t电渣炉对熔炼速度、充填比、渣料成分、渣料加入量、电极初始氢、水蒸气分压相关工艺参数进行分析研究,结果表明,电渣重熔过程中各阶段增氢不同,电渣锭中的氢含量与空气中水蒸气分压的平方根成正比关系;渣料组元中CaO能够促进增氢,MgO能够防止增氢;加大熔炼速度降低渣量,增加充填比,提高电极表面洁净度有利于防止电渣锭增氢;电极初始w[H]<2×10^(-6)时,电渣重熔过程吸氢较严重,当电极初始w[H]处于2×10^(-6)~4×10^(-6)时,电渣重熔过程吸氢变弱,当电极初始w[H]>4×10^(-6)时,电渣重熔过程则会出现脱氢。经过工艺优化后,H合格率平均达到97.5%,较工艺优化前的94.7%提高2.8%。

Water Content Effect on Oxides Yield in Gas and Liquid Phase Using DBD Arrays in Mist Spray

Electric discharge in and in contact with water can accompany ultraviolet（UV）radiation and electron impact, which can generate a large number of active species such as hydroxyl radicals（OH）, oxygen radical（O）, ozone（O_3） and hydrogen peroxide（H_2O_2）. In this paper, a nonthermal plasma processing system was established by means of dielectric barrier discharge（DBD）arrays in water mist spray. The relationship between droplet size and water content was examined,and the effects of the concentrations of oxides in both treated water and gas were investigated under different water content and discharge time. The relative intensity of UV spectra from DBD in water mist was a function of water content. The concentrations of both O_3 and nitrogen dioxide（NO_2） in DBD room decreased with increasing water content. Moreover, the concentrations of H_2O_2, O_3 and nitrogen oxides（NOx） in treated water decreased with increasing water content,and all the ones enhanced after discharge. The experimental results were further analyzed by chemical reaction equations and commented by physical principles as much as possible. At last,the water containing phenol was tested in this system for the concentration from 100 mg/L to9.8 mg/L in a period of 35 min.

EFFECT OF LASER CLADDING ON HYDROGEN EMBRITTLEMENT RESISTANCE OF AUSTENITIC STAINLESS STEEL

A plasma spraying plus laser remelting technique has been performed. onaustenite stainless steel (22Cr-13Ni-5Mn ) with a newly developed hydrogen resistantcoating material. The results show that the surface cladding layer can effectively reducethe hydrogen content increasing of the stainless steel under the atmosphere of high pres-sure (30MPa), high temperature (300℃) and high purity (99. 995%) hydrogen andgreatly improve the hydrogen embrittlement resistance of the stain1ess steel. Throughanalysis of microstructure, a mechanism of hydrogen embrittlement resistance is presentedthat at room temperature, the surface oxidation films, both existing on the surface ofcoated and uncoated specimens, inhibit the adsorption and diffusion of hydrogen molecu-lae. However, at high temperature, it is the surface cladding layer with relatively low sol-ubility and Permeability for hydrogen that significantly reduces the amount of hydrogenentering into the interior of the material and improves its hydrogen embrittfement resis-tance.

A method of estimating and subtracting the hydrogen background in the natural carbon target used in the ^(12)C + ^(12)C experiment

The experimental data of 100 A MeV12C +12C elastic scattering are checked by using two-body kinematic calculation and12 C + p elastic scattering. It is shown that the measured data are true and reliable. In the paper,the transformation between the excited energy spectra of the12 C +12C system and the ground state energy spectra of the12 C + p system is introduced. The method of subtraction of the hydrogen background in the natural carbon target used in the experiment is elaborately described and the results are discussed. It is indicated that this method of subtraction of hydrogen background is reasonable and can be used in the data analysis. Based on the elastic scattering cross section of the previous experiment of12C+p at 95.3A MeV, the hydrogen content entered into the reaction is analyzed. The final hydrogen content in the natural carbon target is(2.73 ± 0.12)%.

Establishment of hydrogen measurement system for magnesium alloy melt

The equations of hydrogen solubility in pure magnesium and its alloy were deduced based on thermodynamic analysis: for pure magnesium, lgc(H)=0.51g p(H3)-1 332/T+0.568; for AZ91 alloy, lgc(H)=0.51g p(H2)-1 332/T+0.483. Based on the above equations, a rapid and reliable measurement system for hydrogen content in magnesium melt was set up with CPU controller and electric circuit. With this instrument, measurement experiments were carried out to determine hydrogen content in AZ91 melt. The results show that the actual hydrogen level of AZ91 melt under gas protection varies from 0.06 mL/g to 0.14 mL/g at the temperature range from 650℃to 750℃, and hydrogen content lineally increases with the increase of temperature.

Hydrogen isotopic composition of plant leaf wax in response to soil moisture in an arid ecosystem of the northeast Qinghai-Tibetan Plateau, China

The hydrogen isotopic composition of plant leaf wax（δDwax） is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological factors in determining δDwax values still remains incomplete. To identify the effects of soil moisture and plant physiology on δDwax values in an arid ecosystem, and to explore the implication of these values for paleoclimatic reconstruction, we measured δD values of soil water（δDwater） and δDwax values in surface soils along two distance transects extending from the lakeshore to wetland to dryland around Lake Qinghai and Lake Gahai on the northeast Qinghai-Tibetan Plateau. The results showed that the δDwater values were negatively correlated with soil water content（SWC）（R^2=0.9166）, and ranged from –67‰ to –46‰ with changes in SWC from 6.2% to 42.1% in the arid areas of the Gangcha（GCh） and Gahai（GH） transects. This indicated that evaporative D-enrichment in soil water was sensitive to soil moisture in an arid ecosystem. Although the shift from grasses to shrubs with increasing aridity occurred in the arid area of the GH transect, the δDwax values in surface soils from the arid areas of the two transects still showed a negative correlation with SWC（R^2=0.6835）, which may be due to the controls of primary evaporative D-enrichment in the soil water and additional transpirational D-enrichment in the leaf water on the δDwaxvalues. Our preliminary research suggested that δDwax values can potentially be applied as a paleo-humidity indicator on the northeast Qinghai-Tibetan Plateau.

Hydrogen Absorption of Nd-Fe-B Alloys

The technical parameters of HD process were studied, including the effects of temperature and neodymium contents on the incubation period of hydrogen absorption, hydrogen concentration and the rate of hydrogen absorbed. The results show that the incubation period is shortened and the rate of hydrogen absorbed is accelerated with rising temperature and surface area. These are attributed to the rising rate of hydrogen diffusion at higher temperature. The change of the incubation period and the rate of hydrogen absorbed have the similar trend resulted from the increasing content of the Nd-rich phase owing to the rising temperature. Moreover, the percent of the Nd-rich phase in the ingot can be calculated according to the total hydrogen weight gain.

中子成像技术在元素分析中的应用

中子成像作为一种快速、直观的无损检测技术,在核工业、航空航天、新能源、地质、考古、先进制造等多个领域得到广泛应用。中子成像利用中子不带电、穿透能力强、对轻元素敏感、可区分同位素和近邻元素等特性,非常适合开展含氢元素、近邻元素和同位素等材料的无损检测。通过概述中子成像技术的基本原理及特点,并结合中国先进研究堆(CARR)中子成像装置上的应用案例,重点综述了国内外中子成像技术在储氢材料、燃料电池、岩石、核燃料元件、古代文物等领域的典型应用。随着中子成像技术的不断发展和广泛应用,有望为我国更多领域研究提供更强有力的技术支撑。

Hydrogen bonds are related to the thermal stability of 16S rRNA

The number of base pairs in the 16S rRNA secondary structures of 51 bacterial sequences was counted, and the number of hydrogen bonds was estimated. The number of hydrogen bonds was highly correlated with the optimal growth temperature (OGT) rather than with the G + C content. Paired and unpaired nucleotides in mesophiles were compared to those in thermophiles. OGT exhibited a relationship with paired nucleotides but not with unpaired nucleotides. The total number of paired as well as unpaired nucleotides in mesophiles was very similar to that in thermophiles. However, the components in base pairs in mesophiles significantly differed from those in thermophiles. As compared with mesophiles, the number of G·C base pairs in thermophiles was high whereas that of A·U base pairs was low. In this study, we showed that hydrogen bonds are important for stabilizing 16S rRNAs at high temperatures.

超大规格风电用连铸圆坯的氢含量控制

针对直径大于等于800 mm的超大规格风电用连铸圆坯因氢含量高出现探伤不合缺陷的问题,通过检测原辅料水分、利用Hydris定氢仪探究全工序钢水氢含量的变化规律。结果表明,铸坯氢含量的主要来源是原辅料水分、炉气气氛潮湿、耐火材料不完全分解。为降低铸坯氢含量,提出了工艺改进措施:转炉吹炼8 min后应不加或加入水分含量较低的原辅料;LF精炼工序投入较少的原辅料;入VD工序前小渣量控制,破空后低速喂线,控制喂线数量及种类在较小范围;小火烘烤连铸中间包60 min,定期清理中间包透气孔。工艺优化后,VD到站钢水w(H)≤3.6×10^(-6),VD离站钢水w(H)≤0.77×10^(-6),连铸中间包首炉钢水w(H)≤2.0×10^(-6),第2炉w(H)≤1.6×10^(-6),连浇炉次w(H)≤1.1×10^(-6),成功降低了超大规格风电用连铸圆坯的氢含量,保证了成品锻件的质量。

Co替代Ni对汽车电池用La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金电化学性能的影响

采用磁悬浮熔炼炉制备了铸态La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金,研究了Co含量对La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金相结构和电化学性能的影响。结果表明,不同Co含量的La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金主要由LaNi_(5)相、Ce_(5)Co_(19)相、Pr_(5)Co_(19)相和CeNi_(2)相组成,La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金中x值增大(Co含量增加)会促使Ce_(5)Co_(19)相向Pr_(5)Co_(19)相转变,且当x=1.05时储氢合金中LaNi_(5)相含量最小。随着x值增大,储氢合金的放氢平台先减小后增大、最大储氢量先增大后减小、第100次充放电后的容量保持率(S_(100))先增大后减小,当x=0.15时储氢合金的最大放电容量和S_(100)取得最大值,分别为352.39 mA·h/g和81.29%。随着La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金中x值从0.65增加至2.25,储氢合金电极的交流阻抗逐渐增大,交换电流密度逐渐减小,氢扩散系数先增大后减小并在x=1.05时取得最大值,电流密度为300、600、900 mA/g时的高倍率放电性能均逐渐减小。结果表明,交换电流密度是决定La_(0.8)Mg_(0.2)Ni_(3.8-x)Co_(x)储氢合金电极高倍率放电性能的关键因素。

用于MTO装置中的乙炔选择加氢催化剂研究

在MTO工艺装置生产乙烯的过程中,乙烯中常含有50~200μL/L左右的微量乙炔,现有的石油烃蒸汽裂解制乙烯装置中常用的碳二加氢催化剂或适用于微量乙炔选择加氢的乙烯精制催化剂并不是MTO工艺中乙炔选择加氢的最好选择。通过研究Pd含量变化对催化剂性能的影响,发现降低Pd含量能够提高催化剂的乙烯选择性,降低催化剂的乙炔合格温度,在保证乙炔加氢合格的情况下,通过控制较低的氢炔比还能获得更好的乙烯选择性。通过添加适当的助剂,控制助剂的用量也能够提高催化剂的乙烯选择性。和商业碳二加氢催化剂BC2相比,采用浸渍法制备的BC2-MTO催化剂活性组分Pd含量降低了50%以上,活性金属Pd的分散度提高了69%,能够在较低的反应温度和氢炔比条件下使用,具有更好的催化活性和乙烯选择性。

煤层硫化氢含量测定装置及方法综述

为使煤层硫化氢含量测定朝着信息化、智能化、自动化方向发展,需革新测定装置及技术方法。首先通过分析硫化氢在煤层中的吸附特性,从硫化氢测定装置构造便捷性、精确性等方面总结近年来测定装置研发及应用方面取得的成果;然后阐述国内外煤层硫化氢含量测定方法的研究现状;最后基于煤层硫化氢测定装置及方法的局限性,展望未来煤层硫化氢测量技术的发展方向,提出完善煤层硫化氢损失量计算误差的技术体系,构建煤样井下一体化破碎解吸系统、解吸气体自动化计量系统、智能化监测与自动化数据分析处理系统等。结果表明:采用内外双钻杆的煤矿井下取样方法,可补偿钻进取样过程中硫化氢损失量;测定装置配备井下直接粉碎设备、过滤器、负压真空罐及传感器,可用于井下直接抽气,以提高煤层硫化氢含量测定的准确性。

碘量法测定天然气中硫化氢标准适应性研究

GB/T 11060.1—2010中碘量法是天然气气质中硫化氢限制指标的测定方法之一,是GB 17820—2018《天然气》中硫化氢含量的仲裁方法。现行GB/T 11060.1—2010被广泛应用,在应用中发现存在的主要技术问题:(1)硫代硫酸钠标准滴定溶液配制和标定与GB/T 601—2016规定不完全相同;(2)对于产品天然气中硫化氢含量低,按该标准要求分析一个样品需要4~9 h,方法使用受到限制;(3)按标准规定的试样参考用量,吸收硫化氢的溶液中硫化锌沉淀多、颗粒大,滴定终点的颜色不明显,影响测量结果准确度。通过开展GB/T 11060.1—2010标准适应性研究,考察了标准溶液的配制和标定方法,以及不同的取样量、取样流速和吸收器等对测量结果的影响。研究结果表明:按照GB/T 601—2016配制的0.1 mol/L硫代硫酸钠标准滴定溶液并标定,由于滴定管校准、滴定速度和分析天平精度原因,标定结果不能完全符合GB/T 601—2016要求;硫化氢含量<28.7 mg/m^(3)试样参考用量降低为50 L,其重复性和再现性完全满足标准要求。根据实验结果、标准适用性和操作性等因素,提出了GB/T11060.1—2010的修订内容并修订发布GB/T 11060.1—2023。针对GB/T1106.1—2023新标准进行解读,以便使用者能更好地理解和掌握新标准,确保新标准的有效实施。