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Platinum on nitrogen doped graphene and tungsten carbide supports for ammonia electro-oxidation reaction

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 930-938 doi: 10.1007/s11705-021-2130-2

摘要: Ammonia electrooxidation reaction involving multistep electron-proton transfer is a significant reaction for fuel cells, hydrogen production and understanding nitrogen cycle. Platinum has been established as the best electrocatalyst for ammonia oxidation in aqueous alkaline media. In this study, Pt/nitrogen-doped graphene (NDG) and Pt/tungsten monocarbide (WC)/NDG are synthesized by a wet chemistry method and their ammonia oxidation activities are compared to commercial Pt/C. Pt/NDG exhibits a specific activity of 0.472 mA∙cm–2, which is 44% higher than commercial Pt/C, thus establishing NDG as a more effective support than carbon black. Moreover, it is demonstrated that WC as a support also impacts the activity with further 30% increase in comparison to NDG. Surface modification with Ir resulted in the best electrocatalytic activity with Pt-Ir/WC/NDG having almost thrice the current density of commercial Pt/C. This work adds insights regarding the role of NDG and WC as efficient supports along with significant impact of Ir surface modification.

关键词: Ammonia electro-oxidation reaction     electrocatalyst supports     platinum     nitrogen doped graphene     tungsten carbide    

Kawai型碳化钨多面砧压机的压力突破 Review

Takayuki Ishii, 刘兆东, Tomoo Katsura

《工程(英文)》 2019年 第5卷 第3期   页码 434-440 doi: 10.1016/j.eng.2019.01.013

摘要:

在众多领域中都需要扩大Kawai型碳化钨(tungsten carbide, WC)多面砧压机的压力范围,尤其是在地球科学领域。然而,40年来,在压力产生方面没有取得重大进展。

关键词: 高压     多面砧压机     碳化钨压砧     烧结的金刚石压砧     下地幔    

Optimization of multi machining characteristics in WEDM of WC-5.3%Co composite using integrated approach of Taguchi, GRA and entropy method

Kamal JANGRA, Sandeep GROVER, Aman AGGARWAL

《机械工程前沿(英文)》 2012年 第7卷 第3期   页码 288-299 doi: 10.1007/s11465-012-0333-4

摘要:

Wire electrical discharge machining (WEDM) is a well known process for generating intricate and complex geometries in hard metal alloys and metal matrix composites with high precision. In present work, intricate machining of WC-5.3%Co composite on WEDM has been reported. Taguchi’s design of experiment has been utilised to investigate the process parameters for four machining characteristics namely material removal rate, surface roughness, angular error and radial overcut. In order to optimize the four machining characteristics simultaneously, grey relational analysis (GRA) coupled with entropy measurement method has been employed. Through GRA, grey relational grade has been computed as a performance index for predicting the optimal parameters setting for multi machining characteristics. Using Analysis of Variance (ANOVA) on grey relational grade, significant parameters affecting the multi-machining characteristics has been determined. Confirmatory results prove the potential of present approach.

关键词: tungsten carbide composite     wire electrical discharge machining (WEDM)     Taguchi method     grey relational analysis (GRA)     entropy measurement method    

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0715-1

摘要: Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments. In this study, a high-performance ultrasonic elliptical vibration cutting (UEVC) system is developed to solve the precision machining problem of tungsten heavy alloy. A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed, and its design process is greatly simplified. The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes. A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus, which is verified by finite element method. The vibration unit can display different three-degree-of-freedom (3-DOF) UEVC characteristics by adjusting the corresponding position of the unit and workpiece. A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit, which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2 μm. Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system, which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词: tungsten heavy alloy     ultrasonic elliptical vibration cutting     Timoshenko’s theory     resonant mode of bending     finite element method    

Silicon carbide waste as a source of mixture materials for cement mortar

Zhengwu Jiang, Qiang Ren, Haoxin Li, Qing Chen

《环境科学与工程前沿(英文)》 2017年 第11卷 第5期 doi: 10.1007/s11783-017-0974-y

摘要: This paper presents an investigation of the feasibility of recycling silicon carbide waste (SCW) as a source of mixture materials in the production of cement mortar. Mortars with SCW were prepared by replacing different amounts of cement with SCW, and the properties of the resulting mortars, such as the fluidity, strength and shrinkage, were studied in this work. Thermogravimetry-differential scanning calorimetry and scanning electron microscopy were employed to understand the reasons for the property changes of the mortars. The results indicate that SCW decreases the initial and 1-h fluidity of fresh mortar but improves the loss of fluidity. The mortar with SCW exhibits a lower strength at 3 d and 7 d but a higher strength at 28 d and 56 d compared to the control. The shrinkage rate of cement mortar with SCW shows an obvious decrease as the replacement ratio increases. In addition, the content of calcium hydroxide in hardened paste also shows that SCW has some impact on the hydration of the cement-SCW system. The microstructures of the hardened paste also show evidence for a later strength change of mortar containing SCW. This work provides a strategic reference for possibly applying SCW as a mixture material in the production of cement mortar.

关键词: Silicon carbide waste     Cement mortar     Fluidity     Strength     Shrinkage    

Synthesis, characterization and hydrotreating performance of supported tungsten phosphide catalysts

SUN Guida, LI Cuiqing, ZHOU Zhijun, LI Fengyan

《化学科学与工程前沿(英文)》 2008年 第2卷 第2期   页码 155-164 doi: 10.1007/s11705-008-0038-8

摘要: Supported tungsten phosphide catalysts were prepared by temperature-programmed reduction of their precursors (supported phospho-tungstate catalysts) in H and characterized by X-ray diffraction (XRD), BET, temperature-programmed desorption of ammonia (NH-TPD) and X-ray photoelectron spectroscopy (XPS). The reduction-phosphiding processes of the precursors were investigated by thermogravimetry and differential thermal analysis (TG-DTA) and the suitable phosphiding temperatures were defined. The hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities of the catalysts were tested by using thiophene, pyridine, dibenzothiophene, carbazole and diesel oil as the feedstock. The TiO, -AlO supports and the Ni, Co promoters could remarkably increase and stabilize active W species on the catalyst surface. A suitable amount of Ni (3%–5%), Co (5%–7%) and V (1%–3%) could increase dispersivity of the W species and the BET surface area of the WP/-AlO catalyst. The WP/-AlO catalyst possesses much higher thiophene HDS and carbazole HDN activities and the WP/TiO catalyst has much higher dibenzothiophene (DBT) HDS and pyridine HDN activities. The Ni, Co and V can obviously promote the HDS activity and inhibit the HDN activity of the WP/-AlO catalyst. The G-Ni5 catalyst possesses a much higher diesel oil HDS activity than the sulphided industrial NiW/-AlO catalyst. In general, a support or promoter in the WP/-AlO catalyst which can increase the amount and dispersivity of the active W species can promote its HDS and HDN activities.

关键词: tungsten phosphide     differential thermal     catalyst surface     industrial NiW/-AlO     general    

Effect of potassium carbonate on catalytic synthesis of calcium carbide at moderate temperature

Dejun SHI, Ke QIAO, Zifeng YAN

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 372-375 doi: 10.1007/s11705-010-0570-1

摘要: Calcium carbide was successfully synthesized by carbothermal reduction of lime with coke at 1973 K for 1.5 h. The effect of potassium carbonate as additive on the composition and morphology of the product was investigated using X-ray diffraction and scanning electron microscope. Addition of potassium carbonate increased the yield of calcium carbide. The sample in the presence of potassium carbonate generated acetylene gas of 168.3 L/kg, which was 10% higher than that in the absence of potassium carbonate. This result confirmed the catalytic effect of potassium carbonate on the synthesis of calcium carbide. A possible mechanism of the above effects was that the additive, which was melted at the reduction temperature, dissolved CaO and so promoted the contact between CaO and carbon, which was essential for the solid-solid reaction to form calcium carbide.

关键词: calcium carbide     synthesis     catalysis    

adsorption onto a niobium wire for electrothermal atomization atomic absorption spectrometry with a tungsten

Satoshi KANECO, Hiroaki KITANAGA, Hideyuki KATSUMATA, Tohru SUZUKI

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 432-435 doi: 10.1007/s11705-012-1219-z

摘要: In the present work, a new preconcentration method of trace elements by adsorption onto a niobium wire has been developed for electrothermal atomization atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. Detection limits (pg·mL ) by this method combined with ETAAS were 45 for bismuth, 7.0 for cadmium, 20 for copper, 1.3 for gold, 36 for lead, 65 for manganese, 9.5 for rhodium and 19 for silver.

关键词: preconcentration     adsorption onto niobium wire     electrothermal atomization atomic absorption spectrometry     tungsten tube atomizer     trace elements    

钨矿物原料NaOH分解过程中抑制杂质的研究

李洪桂,李运姣,孙培梅,刘茂盛

《中国工程科学》 2000年 第2卷 第3期   页码 59-61

摘要:

从理论上较全面地研究了钨矿物原料在NaOH分解过程中直接用白钨矿及其分解产物Ca(OH)2作为抑制剂,抑制磷、砷、硅等杂质浸出的可能性及生成物的形态。进而通过实验证明在有白钨矿存在的条件下,分解所得的粗Na2WO4溶液中砷、硅的含量均比经典法低一个数量级,接近经典法净化以后的水平。

关键词: 钨冶金     NaOH分解     抑制杂质    

Gold modified microelectrode for direct tetracycline detection

Hongtao WANG, Huimin ZHAO, Xie QUAN

《环境科学与工程前沿(英文)》 2012年 第6卷 第3期   页码 313-319 doi: 10.1007/s11783-011-0323-5

摘要: The residues of tetracycline antibiotics in water have attracted many concerns due to their harmful impact to human health. This paper reports an electrochemical sensor for the determination of tetracycline (TC) by the microelectrode, which was fabricated by electrodeposited gold colloids on tungsten tip. Cyclic voltammerty was used to study the electrochemical behavior of TC on the microelectrode. Well anodic wave was obtained at about 1.5 V in acidic solutions. Electrochemical determination of tetracycline was investigated using microelectrode by cyclic voltammetry. Under optimized conditions, the calibration curves for TC were obtained. The oxidation peak currents were linearly related to TC concentrations in the range of 1–10 mg·L and 10–100 mg·L , respectively. The detection limit was 0.09 mg·L ( / = 3).

关键词: microelectrode     tungsten tip     gold colloids     tetracycline    

钨合金的冲击拉伸行为及其本构和断裂判据的表述

张宝,丁淳彤,刘宝华,陈雪莲

《中国工程科学》 2003年 第5卷 第3期   页码 44-50

摘要:

利用飞轮式Hopkinson拉杆实验技术对钨质量分数为93% 的钨合金在-50~100℃温度范围、应变率ε=102~103s-1区间的动态拉伸性态进行了测试,提供了相应的σ-ε曲线和最大拉伸失效应变,并以此为依据建立了该合金动态拉伸行为的本构关系,提出了该合金受动载发生塑性失稳以致发生拉断的判据。利用断口分形分析理论,对试件拉伸断口微观特征所作的分析和对宏观力学性态实验所作的结论给予了有力的支持。

关键词: 动态拉伸本构模型     钨合金     断裂失效判据    

CuO/zeolite catalyzed oxidation of gaseous toluene under microwave heating

Longli BO, Jianbo LIAO, Yucai ZHANG, Xiaohui WANG, Quan YANG

《环境科学与工程前沿(英文)》 2013年 第7卷 第3期   页码 395-402 doi: 10.1007/s11783-012-0417-8

摘要: The development of a combined process of catalytic oxidation and microwave heating for treatment of toluene waste gas was described in this work. Toluene, a typical toxic volatile organic compound, was oxidized through a fixed bed reaction chamber containing zeolite-supported copper oxide (CuO/zeolite) catalyst mixed with silicon carbide (SiC), an excellent microwave-absorbing material. The target compound was efficiently degraded on the surface of the catalyst at high reaction temperature achieved by microwave-heated SiC. A set of experimental parameters, such as microwave power, air flow and the loading size of CuO etc., were investigated, respectively. The study demonstrated these parameters had critical impact on toluene degradation. Under optimal condition, 92% toluene was removed by this combined process, corresponding to an 80%–90% TOC removal rate. Furthermore, the catalyst was highly stable even after eight consecutive 6-h runs. At last, a hypothetical degradation pathway of toluene was proposed based on the experimental data obtained from gas chromatography-mass spectrum and Fourier transform infrared spectroscopy analyses.

关键词: microwave     catalytic oxidation     CuO/zeolite catalyst     silicon carbide (SiC)     toluene    

Highly efficient and selective removal of vanadium from tungstate solutions by microbubble floating-extraction

《化学科学与工程前沿(英文)》 2023年 第17卷 第5期   页码 581-593 doi: 10.1007/s11705-022-2235-2

摘要: Selective separation of dissolved tungsten and vanadium is of great significance for the utilization of the secondary resources of these elements. In this work, selective removal of vanadium from tungstate solutions via microbubble floating-extraction was systematically investigated. The results indicated that vanadium can be more easily mineralized over tungsten from tungstate solutions using methyl trioctyl ammonium chloride as mineralization reagent under weak alkaline conditions. Owing to the higher bubble and interface mass transfer rates, high-efficiency enrichment and deep separation of vanadium could be achieved easily. Additionally, the deep recovery of tungsten and vanadium from the floated organic phase could be easily realized using a mixed solution of sodium hydroxide and sodium chloride as stripping agents. The separation mechanism mainly included the formation of hydrophobic complexes, their attachment on the surface of rising bubbles, and their mass transfer at the oil–water interface. Under the optimal conditions, the removal efficiency of vanadium reached 98.5% with tungsten loss below 8% after two-stage microbubble floating-extraction. Therefore, the microbubble floating-extraction could be an efficient approach for separating selectively vanadium from tungstate solutions, exhibiting outstanding advantages of high separation efficiency and low consumption of organic solvents.

关键词: tungsten     vanadium     selective separation     reagent mineralization     microbubble floating-extraction    

基于高效清洁生产的全过程污染控制(WPPC)——中国钨行业典型案例研究 Article

曹宏斌, 赵赫, 张笛, 刘晨明, 林晓, 李玉平, 宁朋歌, 孙家君, 张懿, 孙峙

《工程(英文)》 2019年 第5卷 第4期   页码 768-776 doi: 10.1016/j.eng.2019.01.010

摘要:

本研究开发了一种称为全过程污染控制(WPPC)的成本效益方法,以提高过程优化的有效性。本方法以成本及环境影响最小化为目标,将废物处理作为生产过程的一部分。主要从以下方面开展了研究:①物质能量流调查,基于潜在污染物的分布和理化性质进行系统分析;②过程优化,提高不同元素的利用效率,减少污染物排放;③综合成本评估,揭示最佳优化方案。本研究选择仲钨酸铵生产作为案例,选取成本效益因子和环境影响指标进行不同优化方案的评价比较。本研究表明,考虑到潜在污染物的性质、技术创新、经济可行性、环境影响和法规要求,WPPC可有效地优化金属生产过程。

关键词: 全过程污染控制     过程优化     工业污染        

选区激光熔化纯钨——粉末粒径对激光吸收的影响和扫描轨迹形成机理研究 Article

章佳窈, 顾冬冬, 杨莹, 张红梅, 陈洪宇, 戴冬华, 林开杰

《工程(英文)》 2019年 第5卷 第4期   页码 736-745 doi: 10.1016/j.eng.2019.07.003

摘要:

本文建立了基于线迹追踪的三维激光吸收模型,用于描述选区激光熔化(SLM)成形纯钨粉末时激光束与粉末层的相互作用,研究了粉末粒径大小对粉末激光吸收率和吸收行为的影响。本文给出了激光吸收率、粉层吸收辐照度及其分布、激光扫描轨迹的表面形貌和几何特征(如接触角、宽度和高度,以及重熔深度)之间的内在关系。模拟结果表明,粉末层的吸收率大大超过单一的粉末颗粒或致密平板材料的吸收率。随着粉末粒径增加,粉末层吸收的激光能量减少。当粒径为5 μm时,纯钨粉末层的吸收率最大达到0.6030。激光辐照度在粉床颗粒表面的分布与粒径大小、方位角和粉末在基板上的位置有关。当粒径从5 μm增加到45 μm时,粉末层中的最大辐照度从1.117 × 10–3 W·μm–2降低到0.85 × 10–3 W·μm–2,并且位于中心辐照区域的辐照度分布轮廓逐渐收缩。对SLM纯钨扫描轨迹的表面形貌和横截面几何特征进行了研究,结果验证了模拟的粉末激光吸收行为。该工作对线迹追踪模型预测SLM扫描轨迹润湿性和铺展性的应用提供了科学依据,从而更好地获得优异的激光成形性能。

关键词: 选区激光熔化         线迹追踪模型     吸收率     激光扫描轨迹    

标题 作者 时间 类型 操作

Platinum on nitrogen doped graphene and tungsten carbide supports for ammonia electro-oxidation reaction

期刊论文

Kawai型碳化钨多面砧压机的压力突破

Takayuki Ishii, 刘兆东, Tomoo Katsura

期刊论文

Optimization of multi machining characteristics in WEDM of WC-5.3%Co composite using integrated approach of Taguchi, GRA and entropy method

Kamal JANGRA, Sandeep GROVER, Aman AGGARWAL

期刊论文

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

期刊论文

Silicon carbide waste as a source of mixture materials for cement mortar

Zhengwu Jiang, Qiang Ren, Haoxin Li, Qing Chen

期刊论文

Synthesis, characterization and hydrotreating performance of supported tungsten phosphide catalysts

SUN Guida, LI Cuiqing, ZHOU Zhijun, LI Fengyan

期刊论文

Effect of potassium carbonate on catalytic synthesis of calcium carbide at moderate temperature

Dejun SHI, Ke QIAO, Zifeng YAN

期刊论文

adsorption onto a niobium wire for electrothermal atomization atomic absorption spectrometry with a tungsten

Satoshi KANECO, Hiroaki KITANAGA, Hideyuki KATSUMATA, Tohru SUZUKI

期刊论文

钨矿物原料NaOH分解过程中抑制杂质的研究

李洪桂,李运姣,孙培梅,刘茂盛

期刊论文

Gold modified microelectrode for direct tetracycline detection

Hongtao WANG, Huimin ZHAO, Xie QUAN

期刊论文

钨合金的冲击拉伸行为及其本构和断裂判据的表述

张宝,丁淳彤,刘宝华,陈雪莲

期刊论文

CuO/zeolite catalyzed oxidation of gaseous toluene under microwave heating

Longli BO, Jianbo LIAO, Yucai ZHANG, Xiaohui WANG, Quan YANG

期刊论文

Highly efficient and selective removal of vanadium from tungstate solutions by microbubble floating-extraction

期刊论文

基于高效清洁生产的全过程污染控制(WPPC)——中国钨行业典型案例研究

曹宏斌, 赵赫, 张笛, 刘晨明, 林晓, 李玉平, 宁朋歌, 孙家君, 张懿, 孙峙

期刊论文

选区激光熔化纯钨——粉末粒径对激光吸收的影响和扫描轨迹形成机理研究

章佳窈, 顾冬冬, 杨莹, 张红梅, 陈洪宇, 戴冬华, 林开杰

期刊论文