材料期刊网

WELDING BETWEEN HIGH MANGANESE STEEL AND HIGH CARBON STEEL

M. H. Guo , D. C. Shao , Z. G Dong and J. C Yang National Key Laboratory Advanced Welding Production Technology , Harbin institute of Technology , Harbin 150001 , China

金属学报(英文版)

Manuscript received 30 July 1999 Abstract The shielded metal arc welding (SMAW) of a manganese steel part as a crossing of railway track to a carbon steel part as the rails of the railroad is the welding of dissimilar steel. It are was known that it is not possible to the the rail of railroad directly to the cross- ing of railway track made from a steel containing about 14% of manganese (wt. ) because of so many differences between the two kinds of steels such as composition, microstructure,mechanical properties and weldability.A method was used to solve the problem by presetting an intermediate layer on each side of the joint and other special procedures were used.The result of test indicated that a good weld joint was obtained.

关键词: high manganese steel , null , null , null

NEW ACHIEVEMENTS ON THE THEORY AND TECHNOLOGY OF EXPLOSIVE WELDING

C.G.Shi , Y.H.Wang , L.G.Cai , C.H.Zhou

金属学报(英文版)

There are four new achievements of this work on the theory and technology of explosive welding.(1) It has been found and defined three kinds of bonding interfaces: big wavy, small wavy and micro wavy, and the micro wavy interface is the best. In a cladding plate,it is for the first time to find that the form of interface presents regular distribution.(2) Although the interface has the features of melt, diffusion and pressure welding in the mean time, the seam and "hole" brought by the melt weaken the bonding strength of interface greatly, and the effect of melt on interface must be eliminated in explosive welding, so explosive welding is not a melt weld. The diffusion welding is a kind of form of pressure welding, and the diffusion is not the reason of the bonding of interface but the result of interface high pressure. So the diffusion welding cannot also explain the bonding mechanism of it. The experiment and theory make clear that explosive welding is a special pressure one.(3) To get good interface of no melt, explosive charge must be selected on the low limit of welding windows. In explosive welding, the drive plate should be treated as the viscous and plastoelastic body, not incompressible fluid. The bending moment under the explosive welding loading must be greater than that under dynamic limit of drive plate. According to the condition, the lower limit of explosive welding is obtained. It is about 20 1.019373e-312ss than that obtained by tradition calculation, and suitable for engineering application.(3) It is for the first time to test and study on soil anvil characteristics and change regularity under explosive welding impact loading. Through soil anvil parameter optimization analysis, it is the best for explosive welding with sandy soil of water content 17.00and density 1.74g/cm^3.

关键词: explosive welding , null , null

g-C(3)N(4) coated SrTiO(3) as an efficient photocatalyst for H(2) production in aqueous solution under visible light irradiation

International Journal of Hydrogen Energy

A highly active photocatalyst based on g-C(3)N(4) coated SrTiO(3) has been synthesized simply by decomposing urea in the presence of SrTiO(3) at 400 degrees C. The catalyst demonstrates a high H(2) production rate similar to 440 mu mol h(-1)/g catalyst in aqueous solution under visible light irradiation, which is much higher than conventional anion doped SrTiO(3) or physical mixtures of g-C(3)N(4) and SrTiO(3). The improved photocatalytic activity can be ascribed to the close interfacial connections between g-C(3)N(4) and SrTiO(3) where photo-generated electron and holes are effectively separated. The newly synthesized catalyst also exhibited a stable performance in the repeated experiments. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词: Carbon nitride;Photocatalyst;Visible light;SrTiO(3);tio2 nanotube photocatalyst;hydrogen-production;water;generation;oxynitride

Study of Hollow Cathode Arc Welding Technology for Ti Alloys

Zhihua LIU , Qing ZHAO , Deqing LI

材料科学技术（英文）

In this paper, technology margin experiment of hollow cathode fusion are welding (FAW) and penetrating are welding (PAW) is presented in detail. The advantages of PAW, compared with FAW, are better weld formation, narrower welds, as well as a larger welding technology margin. Technological experiment and hydraulic test for the Ti alloy pressure vessels with PAW are described. Also, the weld formation control on Ti alloys is preliminarily analyzed. Finally, conclusions are addressed.

关键词:

Development of Production Technology of Castle Composite Materials

Irina N.Mutilina

材料科学技术（英文）

The application of mechanical and chemical syntheses in an high-energy vibration mill of the FESTU makes easy the process of the introduction of reinforced powders in castle composite materials on the Al basis. The obtained reinforced phases of Al-Ti-C composition have high specific Surface due to peculiarities of explosive mechanical and chemical syntheses. It increases the uniformity of their distribution in a matrix melt during the mixing process and also increases properties of castle composite materials

关键词:

Beta-Sialon(Si_6-zAl_zO_zN_8-z):Eu²⁺: A Promising Narrow-band Green Phosphor for Light-emitting Diode Backlights

Rongjun XIE , Tianliang ZHOU , Kohei TAKAHAHIS , Naoto HIROSAKI

应用化学 doi:10.11944/j.issn.1000-0518.2016.08.160240

GaN-based white light-emitting diode(LED) is now an emerging backlight technology for large color gamut and high efficiency liquid crystal displays. In this technology, phosphors are key materials to control the color-space coverage, luminous efficiency, and lifetime of the backlight units, which are required to have a desired emission and a narrow emission band. β-Sialon:Eu²⁺(sialon:silicon aluminum oxynitride, Si_6-zAl_zO_zN_8-z) is such a green phosphor because it has an emission band centered at 525~545 nm and a small band width(~55 nm). This contribution overviews the synthesis, luminescence, electronic and crystal structure, reliability and applications of β-sialon:Eu²⁺. From both structure calculations and experimental observations, Eu²⁺ is seen to be accommodated into a large void along the c-axis, and coordinated to six nitrogen/oxygen atoms at an equivalent distance. The narrow emission band is thus ascribed to the high symmetry of the local structure of Eu²⁺. Both of the emission band and the band width of β-sialon:Eu²⁺ can be tuned by tailoring the composition(e.g., the z value), and β-sialon:Eu²⁺ with shorter wavelengths and narrower bands can be achieved at lower z values. Combined with other red phosphors, β-sialon:Eu²⁺ enables to produce wider color gamut backlights(15% up) than the conventional yttrium aluminum garnet(YAG)-based ones. Both the excellent luminescence properties and reliability make β-sialon:Eu²⁺ to be an extremely important green phosphor for use in advanced displays.

关键词: rare earth , nitride , beta-sialon:Eu²⁺ , phosphor , electronic structure , light-emitting diode , backlighting

Development of an advanced A-TIG (AA-TIG) welding method by control of Marangoni convection

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

A new type of tungsten inert gas (TIG) welding has been developed, in which an ultra-deep penetration is obtained. In order to control the Marangoni convection induced by the surface tension gradient on the molten pool, He gas containing a small amount of oxidizing gas was used. The effect of the concentration Of O-2 and CO2 in the shielding gas on the weld shape was studied for the bead-on-plate TIG welding of SUS304 stainless under He-O-2 and He-CO2 mixed shielding gases. Because oxygen is a surface active element for stainless steel, the addition of oxygen to the molten pool can control the Marangoni convection from the outward to inward direction on the liquid pool surface. When the oxygen content in the liquid pool is over a critical value, around 70ppm, the weld shape suddenly changes from a wide shallow shape to a deep narrow shape due to the change in the direction of the Marangoni convection. Also, for He-based shielding gas, a high welding current will strengthen both the inward Marangoni convection on the pool surface and the inward electromagnetic convection in the liquid pool. Accordingly, at a welding speed of 0.75 mm/s, the welding current of 160 A and the electrode gap of I mm under the He-0.4%O-2 shielding, the depth/width ratio reaches 1.8, which is much larger for Ar-O-2 shielding gas (0.7). The effects of the welding parameters, such as welding speed and welding current were also systematically investigated. In addition. a double shielding gas method has been developed to prevent any consumption of the tungsten electrode. (c) 2008 Elsevier B.V. All rights reserved.

关键词: Weld shape;Oxygen;Helium;Marangoni convection;Electromagnetic;convection;Double shielding gas;gas tungsten arc;shape variations;oxide fluxes;penetration;parameters

Z型复合催化剂g-C3N4/Vo-ZnO光催化活性的研究

刘亚男 , 王瑞霞 , 杨正坤 , 杜虹 , 姜一帆 , 申丛丛 , 梁况 , 徐安武

催化学报 doi:10.1016/S1872-2067(15)60985-8

随着科学技术的不断进步和经济的快速发展,人类对自然资源的需求量越来越大,在开发利用自然资源的同时,大量的有机污染物也随之进入自然环境.这些物质不仅污染环境、破坏生态,更对人类的生活和健康带来了巨大的威胁.研究证实,半导体光催化剂在光照条件下可以破坏有机污染物的分子结构,最终将其氧化降解成CO2、H2O或其它不会对环境产生二次污染的小分子,从而净化水质.近年来,有关光催化降解有机污染物的报道日益增多. ZnO作为一种广泛研究的光催化降解材料,因其无毒、低成本和高效等特点而具有一定的应用前景.但是ZnO较大的禁带宽度(3.24 eV)导致其只能吸收紫外光部分,而对可见光的吸收效率很小,极大地制约了其实际应用.除此之外, ZnO受光激发产生的电子-空穴分离效率较低、光催化过程中的光腐蚀严重也是制约其实际应用的重要因素.为了提高ZnO的光催化活性和稳定性,本文合成了用g-C3N4修饰的氧空位型ZnO(g-C3N4/Vo-ZnO)复合催化剂,在有效调控ZnO半导体能带结构的同时,通过负载一定量的g-C3N4以降低光生电子-空穴对的复合速率和反应过程中ZnO的光腐蚀,增强催化剂的光催化活性和稳定性.本文首先合成前驱体Zn(OH)F,然后焙烧三聚氰胺和Zn(OH)F的混合物得到g-C3N4/Vo-ZnO复合催化剂,并采用电子顺磁共振波谱(EPR)、紫外-可见光谱(UV-vis)、高分辨透射电镜(HRTEM)和傅里叶变换红外光谱(FT-IR)等表征了它们的结构及其性质. EPR结果表明,ZnO焙烧后具有一定浓度的氧空位,导致其禁带宽度由3.24 eV降至3.09 eV,因而提高了ZnO对可见光的吸收效率. UV-vis结果显示, Vo-ZnO复合g-C3N4后对可见光的吸收显著增强. HRTEM和FT-IR结果均表明, g-C3N4纳米片和Vo-ZnO颗粒之间通过共价键形成了强耦合,这对g-C3N4/Vo-ZnO复合催化剂中光生载流子的传送和光生电子-空穴对的有效分离起到重要作用.可见光催化降解甲基橙(MO)和腐殖酸(HA)的实验进一步证明, g-C3N4/Vo-ZnO复合材料具有较好的光催化活性,优于单一的g-C3N4或Vo-ZnO材料.同时还发现, g-C3N4的负载量对光催化活性有显著影响,当氮化碳的负载量为1 wt%时,所制材料具有最高的光催化活性：可见光照射60 min后,MO降解率可达到93%, HA降解率为80%.复合材料光催化活性的增强一方面是因为氧空位的形成减小了ZnO的禁带宽度,使得ZnO对可见光的吸收能力大大增强；另一方面, g-C3N4和Vo-ZnO的能带符合了Z型催化机理所需的有效能带匹配,使得光生电子-空穴对得到了有效的分离,从而提高了光催化活性.降解MO的循环实验表明, g-C3N4/Vo-ZnO催化剂具有很好的稳定性且不容易发生光腐蚀.与此同时,我们对比了用不同方法制备的g-C3N4/ZnO材料的催化性能.结果显示,本文制备的g-C3N4/Vo-ZnO复合材料具有更好的降解效率.总体而言,对于降解有机污染物, g-C3N4/Vo-ZnO可能是一个更为有效可行的催化体系.此外,本文也为设计与制备其他新型光催化剂提供了一条新的思路.

关键词: 氧空位氧化锌 , 石墨化氮化碳 , 复合光催化剂 , 光降解 , Z型

Welding TiB¬2 Ceramics and Metal Mo with Combustion Reaction Technology

Daihua HE , Zhengyi FU , Qingjie ZHANG

材料科学技术（英文）

Combustion reaction welding, one promising method to weld ceramics and metals, was used to weld TiB¬2 and Mo. The results showed that the reacted products through combustion reaction were TiB¬2 and MoB when the Mo contents in reactants were 20 wt pct and 40 wt pct while there was Mo besides MoB and TiB¬2 when there were 60 wt pct and 80 wt pct Mo in reactants. Diffusion of elements occurred at the interfaces of the two substrates. The interfaces between the reacted and the two substrates were indistinct after being welded. The welding temperature strongly affected properties of the samples. The value of bending strength of the sample with 80 wt pct Mo in reactant welded at 1500℃ was the highest, 368.52 MPa. The highest value of shear strength among all the samples was that of the one with 40 wt pct Mo in reactant welded at 1500℃, 50.97 MPa.

关键词: Combustion reaction welding , null , null , null

利用Ni(OH)x助催化剂修饰提高g-C3N4纳米片/WO3纳米棒Z型纳米体系的可见光产氢活性的研究

何科林 , 谢君 , 罗杏宜 , 温九青 , 马松 , 李鑫 , 方岳平 , 张向超

催化学报 doi:10.1016/S1872-2067(17)62759-1

光催化技术是目前解决能源和环境问题最具前景的手段之一,因此寻找高效光催化剂已成为光催化技术的研究热点.而在众多半导体催化剂中,廉价、环保且性能稳定的g-C3N4光催化剂在太阳光开发利用方面尤其引人关注.然而,由于g-C3N4的比表面小,活性位点少,以及光生电子/空穴对易复合等不足,严重导致其较低的光催化量子效率.因此,构造Z型体系和负载助催化剂等策略被广泛应用于提高g-C3N4光催化效率.在过去几年中,TiO2,Bi2WO6,WO3,Bi2MoO6,Ag3PO4和ZnO已经被成功证实可以与g-C3N4耦合而构造Z型光催化剂体系.其中,WO3/g-C3N4光催化剂体系,具有可见光活性的WO3导带中的光生电子和g-C3N4价带中的光生空穴容易实现Z型复合,从而保留了WO3的强氧化能力和g-C3N4的高还原能力,最终大幅度提高了整个体系的光催化活性.在g-C3N4的各种产氢助催化剂中,由于常用的Pt,Ag和Au等贵金属的高成本和低储量等问题严重限制了它们的实际应用,所以近年来各种非贵金属助催化剂(包括纳米碳,Ni,NiS,Ni(OH)2,WS2和MoS2等)得到了广泛的关注.我们采取廉价且丰富的Ni(OH)x助催化剂修饰g-C3N4/WO3耦合形成的Z型体系,开发出廉价高效的WO3/g-C3N4/Ni(OH)x三元产氢光催化体系.在该三元体系中,Ni(OH)x和WO3分别用于促进g-C3N4导带上光生电子和价带的光生空穴的分离及利用,从而使得高能的g-C3N4的光生电子在Ni(OH)x富集并应用于光催化产氢,而高能的WO3的光生空穴被应用于氧化牺牲剂三乙醇胺,最终实现了整个体系的高效光催化产氢活性及稳定性.我们通过直接焙烧钨酸铵和硫脲制备出WO3纳米棒/g-C3N4,并采用原位光沉积方法将Ni(OH)x纳米颗粒负载到WO3/g-C3N4上.随后,我们采取X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱分析(XPS)和比表面和孔径分布等表征手段来研究光催化剂的结构与形貌;采取紫外-可见漫反射表征方法来研究其光学性能;采取荧光光谱,阻抗和瞬态光电流曲线等表征手段来测试光催化剂的电荷分离性能;采取极化曲线和电子自旋共振谱等表征手段来证明光催化机理;采取光催化分解水产氢的性能测试来研究光催化剂的光催化活性与稳定性.XRD,HRTEM和XPS表征结果,表明WO3为有缺陷的正交晶系的晶体,直径为20–40纳米棒且均匀嵌入在g-C3N4纳米片上;Ni(OH)x为Ni(OH)2与Ni的混合物,其Ni(OH)2与Ni的摩尔比为97.4 : 2.6,Ni(OH)x粒径为20–50 nm且均匀分散在g-C3N4纳米片上,WO3/g-C3N4/Ni(OH)x催化剂界面之间结合牢固,其中WO3和Ni(OH)x均匀分布在g-C3N4上.紫外-可见漫反射表征结果表明,随着缺陷WO3的负载量增加,复合体系的吸收边与g-C3N4相比产生明显的红移,而加入Ni(OH)x助催化剂使得催化剂体系的颜色由黄变黑,明显地增加了可见光的吸收.荧光光谱,阻抗和瞬态光电流曲线结果表明,WO3和Ni(OH)x的加入能有效地促进光生电子/空穴的分离.极化曲线结果表明,掺入WO3和Ni(OH)x能降低g-C3N4的析氢过电位,从而提高光催化剂表面的产氢动力学.?O2?和?OH 电子自旋共振谱表明成功形成了WO3/g-C3N4 耦合Z 型体系.光催化分解水产氢的性能测试表明,20%WO3/g-C3N4/4.8%Ni(OH)x产氢效率最高(576 μmol/(g?h)),分别是g-C3N4/4.8%Ni(OH)x,20%WO3/g-C3N4和纯g-C3N4的5.7,10.8和230倍.上述结果充分证明,Ni(OH)x助催化剂修饰和g-C3N4/WO3 Z型异质结产生了极好的协同效应,最终实现了三元体系的极高的光催化产氢活性.

关键词: 光催化产氢 , 稳定的Ni(OH)x催化剂 , g-C3N4 , Z型体系 , 异质结