JIN Nengyun Shanghai Jiaotong University
,
Shanghai Jin Nengyun
,
Department of Materials Science
,
Shanghai Jiaotong University
,
Shanghai 200030
,
ChinaPresent address:Max-Planck-Institut für Metallforschung-Institut für Physik
,
Stuttgart 80
,
FRG
金属学报(英文版)
Cyclic stress-strain responses and dislocation structure of copper single crystals with various tensile axes were systematically studied and compared with each other.Experimental results reveal that the evolution of microscopic dislocation configurations in a crystal and, accordingly,its macroscopic cyclic behaviours are closely related with its orientation.Re- markable secondary slip has been observed in some crystals with orientations well inside the crystallographic triangle, which are usually considered as single-slip ones.Their cyclio behaviours and dislocation structures at saturation are similar to those of their neighbouring multi-slip crystals.These results have constructed the experimental basis for the newly pro- posed dislocation interaction model Jor cyclic deformation of fee crystals,which will be des- cribed in the second part of this article.
关键词:
Copper
,
null
,
null
,
null
,
null
,
null
,
null
Jinyu GUO
,
Ke WANG
,
Lei LU
材料科学技术（英文）
High density nano-scale deformation twins were introduced in the surface layer of Cu sample by means of surface mechanical attrition treatment (SMAT) at room temperature. The Cu sample with deformation twins shows a yield strength of about 470 MPa in tension tests. The significant strengthening may be attributed to the effective inhibition of slip dislocations by abundant twin boundaries.
关键词:
Copper
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表面机械研磨
,
变形孪晶
,
强化
王帅
,
刘海超
催化学报
doi:10.1016/S1872-2067(14)60094-2
分别采用均匀共沉淀法、沉积-沉淀法和传统的共沉淀法制备了3种具有相似组成的Cu-ZnO-Al2O3催化剂(CZA-HP, CAZ-DP和CZA-CP)；同时还采用均匀共沉淀法制备了Cu-ZnO催化剂(CZ-HP)以用于比较. X射线衍射表征结果表明,以上方法制备的Cu-Zn-Al碱式碳酸盐前体中Cu2+, Zn2+和Al3+的混合均匀程度的顺序为CZA-DP90%). Cu-ZnO-Al2O3催化剂表面单位Cu原子的本征活性顺序为CZA-DP < CZA-CP < CZ-HP < CZA-HP,与它们的氧化还原能力相一致.此外, Al2O3的添加还显著地抑制了Cu粒子在反应过程中的聚集,提高了催化剂的稳定性.经6次循环使用后, CZ-HP中Cu粒子的粒径从13.2增至45.2 nm,活性相应下降了45%；而CZA-HP中Cu粒子的粒径从8.3增至19.0 nm,活性仅下降了10%.
关键词:
甘油
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选择性氢解
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丙二醇
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铜
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氧化锌
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氧化铝
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碱式碳酸盐前体
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构效关系
,
催化剂稳定性
Guisheng ZOU
,
Jun YANG
,
Aaiping WU
,
Genghua HUANG
,
Deku ZHANG
,
Jialie REN
,
Qing WANG
材料科学技术（英文）
Ti foil and Ti/Ni/Ti multiple interlayers were selected for the bonding of tungsten to copper and CuCrZr alloy. The effects of processing conditions on the microstructures and shear strength of the joints were investigated. When Ti foil is used for bonding of tungsten to pure copper but not transformed into liquid solution during the holding time, the strength of the joints is relatively low because of the multiple compound layers with brittleness formed in the bonding zone. The strength of the joints increases significantly if the Ti foil is transformed into liquid solution and is mostly extruded out of the bonding zone. The same phenomena are found in the case when Ti/Ni/Ti multi-interlayers are used for bonding tungsten to CuCrZr alloy.
关键词:
Tungsten
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null
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null
,
null
Khalid M.HAFEZ
,
Masaaki NAKA
材料科学技术（英文）
An ultrasonic wave was applied during brazing of alumina to Cu. First alumina was metallized by applying ultrasonic wave in braze bath. Then the metallized alumina was brazed with Cu using the same filler alloy. The filler used were Zn-Al alloys and Zn-Sn Alloys. The weight percent of Al in filler was ranging between 0, 5%, 10%, respectively. The weight percent of tin in filler was ranging between 0, 30%, 60% and 91%, respectively. The joining mechanism was investigated by measuring the joining strength, hardness and analyzing the microstructure at interface of the joint. The shear strength and microstructure of the joint strongly depend on the filler composition. The effect of ultrasound was derived primarily from acoustic cavitations, impact and friction of the filler against alumina ceramic. This improved the wetting between alumina and the filler, and reflected to improve the joint strength. Another ultrasonic advantage as to reduce of the joining temperature, that reduced the thermal stress in the braze joint.
关键词:
Alumina
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null
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null
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null
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null
,
null
S.K.Sadrnezhaad
,
E.Ahmadi
,
M.Mozammel
材料科学技术（英文）
Kinetics of dissolution of silver present in precious metal scraps in HNO3 was studied in temperature range of 26~85℃. Dissolution rate of silver was much faster than that of copper at all temperatures. Effects of particle size, stirring speed, acid concentration and temperature on the rate of dissolving of silver were evaluated. Dissolution rate decreases with particle size and increases with temperature. Dissolving was accelerated with acid concentrations less than 10 mol/L. Concentrations greater than 10 mol/L resulted in slowing down of the dissolution rate. Shrinking core model with internal diffusion equation t/τ=1-3(1-x)2/3+2(1-x) could be used to explain the mechanism of the reaction. Silver extraction resulted in activation energies of 33.95 kJ/mol for Ag-Au0:04-Cu0:10 and 68.87 kJ/mol for Ag-Cu0:23 particles. Inter-diffusion of silver and nitrate ions through the porous region of the insoluble alloying layer was the main resistance to the dissolving process. Results were tangible for applications in recycling of the material from electronic silver-bearing scraps, dental alloys, jewelry, silverware and anodic slime precious metal recovery.
关键词:
Silver
,
null
,
null
,
null
,
null
,
null
徐群杰
,
朱律均
,
齐航
,
曹为民
,
周国定
金属学报
用光电化学方法研究了Cu在不同浓度NaCl的硼酸--硼砂溶液中的腐蚀以及缓蚀剂聚天冬氨酸(PASP)对Cu的缓蚀作用. Cu在硼酸--硼砂缓冲溶液中, 表面的Cu2O膜为p型半导体. 当Cu所在的溶液中存在少量NaCl (小于0.5 g/L)时, Cu表面Cu2O膜会受轻微Cl-掺杂但不会改变半导体性质; 当溶液中存在较多NaCl (0.5-15 g/L)时, Cu2O膜会受Cl-较严重的侵蚀, Cl-掺杂使Cu2O膜部分转成n型; 当溶液中存在大量NaCl (大于15 g/L)时, Cu$_{2}$O膜完全被Cl-掺杂而转型成n型. 缓蚀剂PASP的加入能够对Cu起到缓蚀作用：当NaCl浓度为2 g/L时, PASP与溶液中的Cl-在Cu表面竞争吸附, 明显抑制了Cl-对Cu2O膜的掺杂, Cu2O受到了保护仍为p型; 在NaCl浓度为30 g/L时, PASP与Cl-竞争吸附只能削弱Cl-对Cu2O膜的掺杂, Cu2O膜仍受Cl-掺杂而转成n型, 但n型性质变弱. 对Cu2O膜性质的Mott-Schottky测试结果与光电化学结果一致.
关键词:
Cu
,
Photoelectrochemistry
,
Corrosion
,
Inhibitor
,
PASP
徐丹
,
贾丽华
,
郭祥峰
催化学报
doi:10.1016/S1872-2067(11)60487-7
将Cu作为第二金属,制备了不同Cu掺杂量的和不同温度下焙烧的双金属改性的Cu/VOx-TiO2复合催化剂,并用于液相苯直接羟基化制苯酚反应中.固定钒的含量为4.3％,合成了一系列不同Cu掺杂量(w=0.29％～2.5％)的催化剂,并在不同的温度下(350～650℃)进行了焙烧.利用X射线衍射、N2吸附-脱附、扫描电镜、透射电镜、H2程序升温还原以及X射线光电子能谱对催化剂进行了表征.结果表明,加入Cu后催化剂仍保持有序的介孔结构,并且有效地促进了VOx物种在载体TiO2上的分散和VOx物种的还原,同时提高了催化剂的热稳定性,其中Cu以+2价的形态存在于催化剂中.另外,考察了催化剂用量,反应温度等对苯羟基化反应性能的影响.
关键词:
铜
,
钒物种
,
介孔二氧化钛
,
苯
,
羟基化
,
苯酚
