期刊文献+
共找到699篇文章
< 1 2 35 >
每页显示 20 50 100
El Niño and the AMO Sparked the Astonishingly Large Margin of Warming in the Global Mean Surface Temperature in 2023 被引量:2
1
作者 Kexin LI Fei ZHENG +1 位作者 Jiang ZHU Qing-Cun ZENG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第6期1017-1022,共6页
In 2023,the majority of the Earth witnessed its warmest boreal summer and autumn since 1850.Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming ... In 2023,the majority of the Earth witnessed its warmest boreal summer and autumn since 1850.Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming has become one of the hottest topics in the scientific community and is closely connected to the future development of human society.We analyzed the monthly varying global mean surface temperature(GMST)in 2023 and found that the globe,the land,and the oceans in 2023 all exhibit extraordinary warming,which is distinct from any previous year in recorded history.Based on the GMST statistical ensemble prediction model developed at the Institute of Atmospheric Physics,the GMST in 2023 is predicted to be 1.41℃±0.07℃,which will certainly surpass that in 2016 as the warmest year since 1850,and is approaching the 1.5℃ global warming threshold.Compared to 2022,the GMST in 2023 will increase by 0.24℃,with 88%of the increment contributed by the annual variability as mostly affected by El Niño.Moreover,the multidecadal variability related to the Atlantic Multidecadal Oscillation(AMO)in 2023 also provided an important warming background for sparking the GMST rise.As a result,the GMST in 2023 is projected to be 1.15℃±0.07℃,with only a 0.02℃ increment,if the effects of natural variability—including El Niño and the AMO—are eliminated and only the global warming trend is considered. 展开更多
关键词 record-breaking temperature global mean surface temperature El niño AMO global warming
下载PDF
TWIP钢表面Ni-P化学镀层组织结构及性能研究
2
作者 岳丽杰 薛广成 +2 位作者 谢鲲 韩金生 孙一品 《表面技术》 EI CAS CSCD 北大核心 2024年第16期89-102,共14页
目的在孪生诱发塑性钢(TWIP)表面制备Ni-P镀层,提高TWIP钢的耐腐蚀性能。方法通过化学镀工艺在TWIP钢表面制备了高磷Ni-P镀层,并进行不同温度的热处理,利用扫描电镜及能谱仪、X射线衍射仪及原子力显微镜等探究了热处理温度和时间对Ni-P... 目的在孪生诱发塑性钢(TWIP)表面制备Ni-P镀层,提高TWIP钢的耐腐蚀性能。方法通过化学镀工艺在TWIP钢表面制备了高磷Ni-P镀层,并进行不同温度的热处理,利用扫描电镜及能谱仪、X射线衍射仪及原子力显微镜等探究了热处理温度和时间对Ni-P镀层形貌和组织结构的影响。通过电化学方法研究了TWIP钢表面镀层的耐蚀性能。结果随着热处理温度的升高,镍磷原子发生迁移,胞状组织边界模糊,粗糙度降低,其中600℃热处理镀层表面最为致密平整。随着热处理温度的升高,镀层组织结构演变过程如下:非晶态(普通镀层)→非晶态部分晶化,Ni12P5、Ni5P2等亚稳态镍磷化合物析出(300℃)→非晶态完全晶化、稳态Ni3P相长大(400℃)→晶粒长大(500℃、600℃)。Ni-P镀层能够明显提升TWIP钢的耐腐蚀性能。随着热处理温度的升高,镀层的耐蚀性能先降低后升高。600℃热处理1h镀层的腐蚀电流密度为0.25μA/cm^(2),与普通Ni-P镀层相比降低了80.9%,与TWIP钢基体相比降低了99.6%。600℃热处理镀层光滑致密无缺陷的表面促进了保护性氧化膜的产生,使镀层的耐蚀性能提高。结论合适的热处理工艺提高了Ni-P镀层的致密性和保护能力,光滑致密无缺陷的镀层能够为TWIP钢提供良好的防护。 展开更多
关键词 TWIP钢 ni-P镀层 表面处理 热处理 耐蚀性能
下载PDF
Prediction and sensitivity analysis of the surface quality in Ni60/WC coatings 被引量:1
3
作者 杨江淮 练国富 +1 位作者 陈昌荣 冯美艳 《China Welding》 CAS 2023年第1期35-45,共11页
For laser cladding a large temperature gradient easily weakened the surface quality by generating cracks and irregular coating surfaces,which in turn affected the bearing capacity and corrosion resistance of coatings ... For laser cladding a large temperature gradient easily weakened the surface quality by generating cracks and irregular coating surfaces,which in turn affected the bearing capacity and corrosion resistance of coatings in the rapid heating and cooling process.The response surface methodology(RSM)was used to predict coating cracks by changing the powder ratio,energy density,and preheating temperature,which obtained the relevant mathematical model.After that,the sensitivity of the crack length to process parameters was analyzed based on the sensitivity analysis method.The effect of Ni60/WC composite powder process parameters on the surface quality was revealed in laser cladding.The crack length first decreased and then increased,and the Smooth decreased with the increased powder ratio.The crack length and Smooth increased with the increased energy density.The crack length decreased and Smooth increased with the increased preheating temperature.Sensitivity analysis showed that the crack length and Smooth were the most sensitive to the powder ratio.Therefore,the process parameters were reasonably selected to control the surface quality.The mathematical model and sensitivity analysis method in the work could improve the surface quality,which provided a theoretical basis for the prediction and control of laser cladding cracks. 展开更多
关键词 laser cladding ni60/WC surface quality mathematical model sensitivity analysis
下载PDF
Growth mechanism of palladium clusters on rutile TiO_2 (110) surface 被引量:3
4
作者 Weina Zhao Huaxiang Lin +3 位作者 Yi Li Yongfan Zhang Xin Huang Wenkai Chen 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2012年第5期544-555,共12页
Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for ... Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n (n=1-5) clusters adsorbed on TiO2 (110) surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states (TSs) search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional (3D) models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts. 展开更多
关键词 density functional theory TiO2 110 surface palladium cluster ADSORPTION
下载PDF
基于Ni纳米颗粒的SERS基底制备及其性能
5
作者 疏港 陈福彬 +3 位作者 张烨 苏艳梅 张冶金 潘教青 《微纳电子技术》 CAS 2024年第9期118-124,共7页
以Ni纳米材料为研究对象,提出了一种新的基于超声辅助的表面增强Raman散射(SERS)基底的制备方法,以实现对生物分子罗丹明6G(R6G)的高灵敏检测。首先,通过超声辅助法制备Ni纳米溶液,然后,采用旋涂法制备SERS基底,以R6G为探针分子,研究了... 以Ni纳米材料为研究对象,提出了一种新的基于超声辅助的表面增强Raman散射(SERS)基底的制备方法,以实现对生物分子罗丹明6G(R6G)的高灵敏检测。首先,通过超声辅助法制备Ni纳米溶液,然后,采用旋涂法制备SERS基底,以R6G为探针分子,研究了基底的SERS活性、重复性以及在基底制备过程中加入表面活性剂甲基丙烯酸甲酯(MMA)对基底SERS活性的影响。结果表明,在加入MMA的实验条件下,基底表面的纳米颗粒分散更加均匀,能提供的SERS热点更多,有助于增强基底的SERS强度。该SERS基底对R6G的最低检测限(LOD)为1×10^(-6)mol/L,增强因子约为2.56×10^(4),重复性测试的相对标准偏差为10.19%(R6G浓度为1×10^(4)mol/L)。该方法经济、简单、快速、有效,可以作为未来生物传感应用的候选方法。 展开更多
关键词 表面增强Raman散射(SERS) ni纳米颗粒 超声辅助 罗丹明6G(R6G) 表面活性剂
下载PDF
WC-Ni基硬质合金的光固化增材制造
6
作者 刘展赫 陈子航 +5 位作者 王日初 彭超群 时凯华 周科朝 马格达西·什洛莫 王小锋 《稀有金属与硬质合金》 CAS CSCD 北大核心 2024年第2期76-88,共13页
采用光固化增材制造(3D打印)技术制备WC-Ni基硬质合金,研究了浆料配比和增材制造工艺参数对浆料流变性能和固化性能的影响以及WC-Ni基硬质合金的性能。结果表明:当浆料固含量为40%(体积分数)、分散剂为ZN-1344且加入量为粉体质量的2%时,... 采用光固化增材制造(3D打印)技术制备WC-Ni基硬质合金,研究了浆料配比和增材制造工艺参数对浆料流变性能和固化性能的影响以及WC-Ni基硬质合金的性能。结果表明:当浆料固含量为40%(体积分数)、分散剂为ZN-1344且加入量为粉体质量的2%时,WC-Ni浆料的流变性能满足增材制造工艺需求,当剪切速率为100 s^(-1)时,浆料黏度为2.718 Pa·s;该浆料的最大单层固化厚度可达144μm,对应工艺参数为0.01 mm线间距、90%激光功率和2 000 mm/s扫描速度;采用响应曲面法拟合数据获得的浆料单层固化厚度计算模型,计算值与实际值误差为3.4%,可起理论预测作用;光固化增材制造WC-15%Ni硬质合金的密度和相对密度最高,分别为13.51 g/cm^(3)和96.5%,加入1%晶粒长大抑制剂Cr_(3)C_(2)后,硬质合金维氏硬度显著提高,达到945 HV_(30),接近同等Ni含量但不含有Cr_(3)C_(2)的传统硬质合金硬度。 展开更多
关键词 WC-ni基硬质合金 光固化增材制造 3D打印 响应曲面法 晶粒长大抑制剂 复杂结构
下载PDF
煅烧温度对钠离子电池O3-NaNi_(0.33)Fe_(0.33)Mn_(0.33)O_(2)正极材料的影响
7
作者 刘冬梅 何一芃 +2 位作者 余凌智 周旺 陈杰 《现代化工》 CAS CSCD 北大核心 2024年第12期176-180,187,共6页
O3型正极材料因较高的理论比容量成为钠离子电池正极材料研究的热点。采用共沉淀法制备Ni_(0.33)Fe_(0.33)Mn_(0.33)(OH)_(2)前驱体并配钠煅烧为O3-NaNi_(0.33)Fe_(0.33)Mn_(0.33)O_(2)正极材料,探究煅烧温度对该正极材料物相结构与电... O3型正极材料因较高的理论比容量成为钠离子电池正极材料研究的热点。采用共沉淀法制备Ni_(0.33)Fe_(0.33)Mn_(0.33)(OH)_(2)前驱体并配钠煅烧为O3-NaNi_(0.33)Fe_(0.33)Mn_(0.33)O_(2)正极材料,探究煅烧温度对该正极材料物相结构与电化学性能的影响。结果表明,煅烧温度影响正极材料表面钠残渣含量,进而影响其电化学性能。2.0~4.0 V的电压范围内,850℃下制备的NaNi_(0.33)Fe_(0.33)Mn_(0.33)O_(2)正极材料表现出最优电化学性能,1 C下循环100次后容量保持率为71.08%,5 C下放电比容量为91.67 mAh/g。 展开更多
关键词 钠离子电池 ni/Fe/Mn基正极材料 表面残碱
下载PDF
超音速微粒轰击时间对Ni-W-Co-Ta合金组织和性能的影响
8
作者 杨苗苗 熊毅 +2 位作者 杜楠 汤金金 厉勇 《塑性工程学报》 CAS CSCD 北大核心 2024年第10期198-210,共13页
采用超音速微粒轰击(SFPB)技术对冷轧态Ni-W-Co-Ta合金进行表面纳米化处理,系统研究了恒定气体压力(1.0 MPa)条件下SFPB时间对冷轧态Ni-W-Co-Ta合金的表面完整性、微观组织及力学性能的影响。结果表明:SFPB处理后,新型Ni-W-Co-Ta合金表... 采用超音速微粒轰击(SFPB)技术对冷轧态Ni-W-Co-Ta合金进行表面纳米化处理,系统研究了恒定气体压力(1.0 MPa)条件下SFPB时间对冷轧态Ni-W-Co-Ta合金的表面完整性、微观组织及力学性能的影响。结果表明:SFPB处理后,新型Ni-W-Co-Ta合金表层形成一定厚度的梯度纳米结构,随着SFPB时间的延长,合金表面晶粒尺寸可细化至9.74 nm左右,相应的形变层深度、力学性能(强度、残余压应力、显微硬度)均呈现出增大趋势;当SFPB时间为120 s时,合金表面粗糙度最小的同时其力学性能指标达到峰值;SFPB时间继续增加至150 s后,合金表面出现数量众多的微裂纹,残余压应力松弛的同时相应的力学性能有所下降;SFPB处理前、后新型Ni-W-Co-Ta合金的伸长率无明显变化,断口形貌均呈现出典型的韧-脆混合型断裂特征。 展开更多
关键词 超音速微粒轰击 表面纳米化 ni-W-Co-Ta合金 微观组织 力学性能
下载PDF
助剂Ni对Cu(111)表面催化NH_(3)还原NO反应影响的理论研究
9
作者 王旭慧 郭洋 +2 位作者 吴娇 郭聪秀 牛煜 《低碳化学与化工》 CAS 北大核心 2024年第10期66-71,80,共7页
针对商用钒钛脱硝催化剂存在的环境污染和易中毒问题,采用无毒环保的单金属铜催化剂并使用助剂Ni掺杂提高其脱硝性能。基于密度泛函理论(DFT),探究了助剂Ni对Cu(111)表面催化NH_(3)还原NO反应的影响。通过分析催化剂表面反应物种的吸附... 针对商用钒钛脱硝催化剂存在的环境污染和易中毒问题,采用无毒环保的单金属铜催化剂并使用助剂Ni掺杂提高其脱硝性能。基于密度泛函理论(DFT),探究了助剂Ni对Cu(111)表面催化NH_(3)还原NO反应的影响。通过分析催化剂表面反应物种的吸附、反应机理和电子结构,对比了助剂Ni掺杂前后Cu(111)表面的催化活性。结果表明,所有反应物种在CuNi(111)表面上的吸附效果均优于在Cu(111)表面的吸附效果。CuNi(111)表面发生的三步基元反应需克服的能垒均低于Cu(111)表面,其中,速控步骤(NH_(2)NO→N_(2)+H_(2)O)的能垒降低了63.6 kJ/mol,可见CuNi(111)表面催化活性明显较高。相比Cu(111)表面,CuNi(111)表面的d带中心更靠近费米能级,说明助剂Ni的掺杂增强了Cu(111)表面电子的活跃性,从而提高了其催化活性。 展开更多
关键词 Cu表面 ni助剂 脱硝 密度泛函理论
下载PDF
时效处理对Fe-Ni基奥氏体合金耐点蚀性能的影响
10
作者 郑军宝 闫英杰 曹睿 《电焊机》 2024年第3期18-23,79,共7页
针对Fe-Ni基奥氏体合金在740℃时效处理后的析出相随时效时间的演变进行探究;并通过电化学腐蚀试验以及Mott-Schottky分析,研究了时效处理对合金耐腐蚀性能的影响。结果表明:740℃时效处理可以促进γ′沉淀强化相[Ni_(3)(Al,Ti)]在合金... 针对Fe-Ni基奥氏体合金在740℃时效处理后的析出相随时效时间的演变进行探究;并通过电化学腐蚀试验以及Mott-Schottky分析,研究了时效处理对合金耐腐蚀性能的影响。结果表明:740℃时效处理可以促进γ′沉淀强化相[Ni_(3)(Al,Ti)]在合金中的析出;随时效时间的增加,γ′析出相的密度和尺寸增加;同时,时效处理会增加合金表面点缺陷数量,降低合金钝化膜致密性,从而导致合金耐点蚀性降低;通过恒电位阳极极化处理能够有效降低合金表面点缺陷数量,提高合金耐点蚀性。 展开更多
关键词 Fe-ni基奥氏体合金 时效处理 γ′析出相 耐点蚀性能 表面改性
下载PDF
Co-adsorption of O_2 and H_2O on α-uranium(110) surface:A density functional theory study
11
作者 Xin Qu Ru-Song Li +2 位作者 Bin He Fei Wang Kai-Long Yuan 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第7期417-423,共7页
First-principles calculations based on density functional theory corrected by Hubbard parameter U (DFT+U) are applied to the study on the co-adsorption of O2 and H2O molecules to a-U(110) surface. The calculation... First-principles calculations based on density functional theory corrected by Hubbard parameter U (DFT+U) are applied to the study on the co-adsorption of O2 and H2O molecules to a-U(110) surface. The calculation results show that DFT+U method with Ueff = 1.5 eV can yield the experimental results of lattice constant and elastic modulus of a-uranium bulk well. Of all 7 low index surfaces of a-uranium, the (001) surface is the most stable with lowest surface energy while the (110) surface possesses the strongest activity with the highest surface energy. The adsorptions of O2 and H2O molecules are investigated separated. The O2 dissociates spontaneously in all initial configurations. For the adsorption of H2O molecule, both molecular and dissociative adsorptionsoccur. Through calculations of co-adsorption, it can be confirmed that the inhibition effect of O2 on the corrosion of uranium by water vapor originates from the preferential adsorption mechanism, while the consumption of H atoms by O atoms exerted little influence on the corrosion of uranium. 展开更多
关键词 CO-ADSORPTION α-U(110 surface DFT+U inhibition mechanism
下载PDF
Theoretical Study on the Structural and Electronic Properties of the Reduced SnO_2 (110) Surface
12
作者 ZHANG Yong-Fan LIN Wei WANG Qi-Wei LI Yi LI Jun-Qian 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2007年第5期606-612,共7页
The reduced SnO2(110) surface has been investigated by using first-principles method with a slab model. By examining the vacancy formation energy of three kinds of reduced SnO2(110) surfaces, the most energeticall... The reduced SnO2(110) surface has been investigated by using first-principles method with a slab model. By examining the vacancy formation energy of three kinds of reduced SnO2(110) surfaces, the most energetically favorable defect surface is confirmed to be the surface with the coexistence of bridging and in-plane oxygen vacancies, which is different with the traditional model by only removing bridging oxygen. The results of band structure calculations indicate that the electronic structure of this defect surface is similar to the SnO surface. 展开更多
关键词 SnO2(110 surface band structure defect state
下载PDF
THE PREPARATION OF TITANIUM OXIDE OVERLAYER ON Fe(110) FOR SURFACE SCIENCE STUDIES
13
作者 Jun Zhuo DENG Hong Li WANG 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第1期79-82,共4页
The preparation, characterization and properties of titania overlayer on Fe(110) substrate is hereby reported. The TiO_X overlayer was found to form in a layer-by-layer mode with a suboxide of titanium in the form of ... The preparation, characterization and properties of titania overlayer on Fe(110) substrate is hereby reported. The TiO_X overlayer was found to form in a layer-by-layer mode with a suboxide of titanium in the form of TiO migrating into the Fe substrate and Fe migrating into the deposited layer of TiO_X simultaneously during the deposition. 展开更多
关键词 THE PREPARATION OF TITAniUM OXIDE OVERLAYER ON Fe FOR surface SCIENCE STUDIES TIO 110
下载PDF
The Ab Initio Studies of NO Chemisorption on TiO_2(110) Surface
14
作者 吴立明 章永凡 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 1999年第4期304-309,共6页
The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were ... The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were calculated by use of ab initio cluster method. We carried out optimization of the geometry, calculation of the chemisorption energy and analysis of the Mulliken population to those adsorption models. According to the calculation results, it can be got that the adsorbed decomposition of NO on defect surface is more advantageous and M6 and M12 are the important models to NO chemisorption and decomposition on TiO2 surface. 展开更多
关键词 TiO2 (110) surface NO CHEMISORPTION quantum chemistry
全文增补中
Ni(110)-p2mg(2×1)-CO表面的几何结构和电子态 被引量:1
15
作者 赵新新 陶向明 +2 位作者 宓一鸣 陈戍 谭明秋 《物理化学学报》 SCIE CAS CSCD 北大核心 2009年第11期2305-2311,共7页
利用密度泛函理论(DFT)总能计算研究了Ni(110)-p2mg(2×1)-CO表面的原子结构和电子态.计算结果表明:CO分子吸附于该表面的短桥位附近,分子吸附能为1.753eV,CO分子的键长dC—O为0.117nm,分子与表面竖直方向的夹角为20.0°,碳原... 利用密度泛函理论(DFT)总能计算研究了Ni(110)-p2mg(2×1)-CO表面的原子结构和电子态.计算结果表明:CO分子吸附于该表面的短桥位附近,分子吸附能为1.753eV,CO分子的键长dC—O为0.117nm,分子与表面竖直方向的夹角为20.0°,碳原子和短桥位中点的连线与竖直方向的夹角为20.9°;吸附的CO分子内原子间的伸缩振动频率为1876和1803cm-1.态密度研究结果表明吸附作用主要来自CO分子π、σ轨道与衬底d轨道间的杂化作用.CO分子σ轨道和衬底表面镍原子dxz轨道杂化形成的表面电子态主要位于费米能以下-10.4至-8.8eV和-7.4至-5.1eV范围内.σ和dxz轨道间的杂化作用可能是形成p2mg表面对称性的重要因素之一. 展开更多
关键词 密度泛函理论 ni(110)-p2mg(2×1)-CO 吸附能 分子振动 态密度
下载PDF
HCN在Ni(111),Ni(100)和Ni(110)面吸附的密度泛函理论研究 被引量:2
16
作者 辛振东 李巧玲 +1 位作者 任君 贾秀梅 《中北大学学报(自然科学版)》 CAS 北大核心 2012年第6期709-715,共7页
针对乙腈加氢反应机理的研究,采用密度泛函方法计算了HCN在Ni(111),Ni(100)和Ni(110)表面上的吸附,并在1/4覆盖度的基础上讨论了表面吸附结构及吸附能.结果表明:在Ni(111)面,最稳定的吸附构型为HCN分子中C-N键,几乎平行吸附在表面上,其... 针对乙腈加氢反应机理的研究,采用密度泛函方法计算了HCN在Ni(111),Ni(100)和Ni(110)表面上的吸附,并在1/4覆盖度的基础上讨论了表面吸附结构及吸附能.结果表明:在Ni(111)面,最稳定的吸附构型为HCN分子中C-N键,几乎平行吸附在表面上,其吸附结构为f-η3(N)-h-η3(C),吸附能为1.369eV.在Ni(100)上,最优吸附构型为HCN吸附在表面上的fcc位,其中C-N键与4个相邻的Ni原子成键,吸附能为1.932eV.在Ni(110)上,HCN吸附构型与其它两个表面相类似,位于两个long-bridge位,其吸附能为1.780eV.同时,也通过电子电荷及态密度分析了HCN在Ni(111),Ni(100)和Ni(110)表面上的成键机理,表明吸附的HCN在表面上已重新杂化,形成了非线性弯曲的吸附结构,这更有利于加氢反应的发生. 展开更多
关键词 HCN ni表面 吸附 催化加氢 密度泛函理论
下载PDF
甲烷在Ni(110)面吸附的密度泛函理论研究 被引量:5
17
作者 李萍 刘子忠 +2 位作者 刘红霞 刘东升 葛湘巍 《内蒙古师范大学学报(自然科学汉文版)》 CAS 北大核心 2015年第3期389-395,共7页
采用广义梯度近似密度泛函理论方法(GGA/PW91),结合周期平板模型,研究了甲烷在Ni(110)面不同位置的吸附行为,找到最稳定的吸附方式,并对其稳定结构进行电荷和态密度分析.结果表明:甲烷在Ni(110)面24种吸附方式中,顶位T4的吸附能(4.59kJ/... 采用广义梯度近似密度泛函理论方法(GGA/PW91),结合周期平板模型,研究了甲烷在Ni(110)面不同位置的吸附行为,找到最稳定的吸附方式,并对其稳定结构进行电荷和态密度分析.结果表明:甲烷在Ni(110)面24种吸附方式中,顶位T4的吸附能(4.59kJ/mol)最大,是最稳定的吸附方式,且为物理吸附;从C-H键长和CH4吸附前后的振动频率分析可知,C-H1或C-H4键易断裂;通过Mulliken电荷布居的分析可知,相对于吸附前,吸附后电子从被吸附物Ni的4s、4p轨道以及吸附物中C的2s、2p轨道转移给吸附物中H1或H4的1s轨道;能带结构和态密度分析表明,在-10^-5eV的能带区间出现了新峰,该能带由C的2p轨道、H的1s轨道以及Ni的4s、4p轨道构成,说明CH4在Ni(110)晶面吸附有相互作用. 展开更多
关键词 CH4 ni(110) 吸附 密度泛函理论 周期平板模型
下载PDF
Effect of surface preparation on corrosion properties and nickel release of a NiTi alloy 被引量:6
18
作者 MIAO Weidong MI Xujun XU Guodong LI Huachu 《Rare Metals》 SCIE EI CAS CSCD 2006年第z2期243-245,共3页
Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy... Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied. Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system. Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed. Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film. 展开更多
关键词 ni Ti alloy surface preparation corrosion properties nickel realease
下载PDF
Theoretical Study of Cr Doped into TiO_2(110) Surface 被引量:2
19
作者 DINGKai-Ning ZHANGYong-Fan +1 位作者 LIYi LIJun-Qian 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2005年第6期673-678,共6页
The Cr doped into TiO2(110) surface has been studied systematically by using periodic DFT/B3LYP method with slab model. It is found that doping Cr into perfect TiO2 (110) surface can reduce the value of band-gap from ... The Cr doped into TiO2(110) surface has been studied systematically by using periodic DFT/B3LYP method with slab model. It is found that doping Cr into perfect TiO2 (110) surface can reduce the value of band-gap from 3.13 to 1.16 eV, and then photocatalysis reaction may be achieved in visual light area. The results are in good agreement with the experiments. 展开更多
关键词 DFT rutile 110 surface Cr doped
下载PDF
Microstructure of Ni /WC Surface Composite Layer on Gray Iron Substrate 被引量:2
20
作者 杨贵荣 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第5期861-866,共6页
The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as... The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as raw materials.The microstructures of surface infiltrated composite layer,the interface structures between surface composite layer and the substrate,the changes of macro-hardness with the increasing of WC content and the micro-hardness distribution are investigated.The infiltrated composite layer includes a surface composite layer and a transition layer,and the thickness of the transition layer decreases with the increasing content of WC.The thickness of transition layer with 20%WC content in the surface infiltrated composite layer was 170 μm which was the thickest for all transition layers with different WC content.The surface composite layer was mainly composed of WC,W2C,FeB and NiB,along with Ni-Cr-Fe,Ni (Cr) solid solution,Ni (Si) solid solution and Ni (Fe) solid solution.The transition layer was composed of Ni (Cr) solid solution,Ni (Fe) solid solution,Ni (Si) solid solution,Fe (Ni) solid solution and eutectic.The surface macro-hardness and micro-hardness of the infiltrated layer had been evaluated.The macro-hardness of the surface composite layer decreases with the WC content increasing,and the average macro-hardness is HRC60.The distribution of micro-hardness presents gradient change.The average micro-hardness of the infiltrated layer is about HV1000. 展开更多
关键词 ni/WC surface composite layer vacuum infiltration casting technique gray iron substrate MICROSTRUCTURE hardness of the infiltrated composite layer
下载PDF
上一页 1 2 35 下一页 到第
使用帮助 返回顶部