2004 Mechanical strength improvement of electrical discharge machined

2004年发表的文章2004年发表的文章一、国外刊物上发表的文章1.Carbon monoxide oxidation over Cu/CeO2 catalystsXiaolan Tang, Baocai Zhang, Y ong Li, Y ide Xu, Qin Xin, Wenjie ShenCatalysis Today, 93(2004)191-1982.Methane dehydroaromatization over Mo/HZSM-5 catalysts in theabsence of oxygen: effects of silanation in HZSM-5 zeolite Hongmei Liu, Y ong Li, Wenjie Shen, Xinhe Bao, Yide XuCatalysis Today, 93(2004)65-733.Pd/CeO2–TiO2 catalyst for CO oxidation at low temperature: A TPRstudy with H2 and CO as reducing agentsHuaqing Zhu, Zhangfeng Qin, Wenjuan Shan, Wenjie Shen and Jianguo Wang Journal of Catalysis, 225(2004)267-2774.Oxidative steam reforming of methanol on Ce0.9Cu0.1O Y catalystsprepared by deposition-precipitation,co-precipitation andcomplexation-combustion methodsWenjuan Shan, Zhaochi Feng, Zhonglai Li, Jing Zhang, Wenjie Shen, Can Li Journal of Catalysis, 228(2004)206-2175.In-situ magnetic resonance investigation on the mechanism of styreneoxidation over TS-1 zeolitesJianqin Zhuang, Gang Y ang, Ding Ma, Xijie Lan, Xiumei Liu, Xiuwen Han, Xinhe Bao, Ulrich MuellerAngew. Chem.-Int. Edit., 116(2004)6377-63816.In situ assembly of zeolitic building blocks into high-order structuresGang Hu, Ding Ma, Lin Liu, Mojie Cheng, Xinhe BaoAngew. Chem.-Int. Edit., 43(2004)3452-34567.A mechanism for enhanced photocatalytic activity of silver-loadedtitanium dioxideS.X. Liu, Zhenping Qu, Xiuwen Han, C.L. SunCatal. Today, 93-95(2004)877-8848.Asymmetric hydrogenation of quinolines catalyzed by iridium with chiralferrocenyloxazoline derived N,P ligandsShengmei Lu, Xiuwen Han, Y onggui ZhouAdvanced synthesis & catalysis, 346(2004)909-9129.Kinetic study on the photo-catalytic degradation of pyridine in TiO2 suspensionsystemsHong Zhao, Suohong Xu, Junbo Zhong, Xinhe BaoCatal. Today, 93-95(2004)857-86110.CO selective oxidation in H2-rich gas over Ag nanoparticles-effect of oxygentreatment temperature on the activity of silver particles mechanicallymixed with SiO2Zhenping Qu, Mojie Cheng, Xinglong Dong and Xinhe Bao Catal. Today, 93-95(2004)247-25511.Solid state MAS NMR studies on the hydrothermal stability of the zeolitecatalysts for residual oil selective catalytic crackingJianqin Zhuang, Ding Ma, Gang Y ang, Zhinmin Y an, XiumeiLiu,Xianchun Liu, Xiuwen Han, Xinhe Bao, Peng Xie, Zhongmin LiuJ. Catal., 228(2004)234-24212.Effect of Ag+ cations on nonoxidative activation of methane toC2-hydrocarbonShaojun Miao, Y an Wang, Ding Ma, Qingjun Zhu, Shutian Zhou,Lingling Su, Dali Tan, and Xinhe BaoJ. Phys. Chem. B, 108(2004)17866-1787113.Density functional theory study of chemical composition on the acidityof H-MCM-22 zeoliteY an Wang , Gang yang , Danhong Zhou , Xianchun Liu , Xinhe BaoJ. Phys. Chem. B, 108(2004)18228-1823314.On the propagation rate of the chemical waves observed during thecourse of CO oxidation on a Ag/Pt(110) composite surface Weixin Huang, and Xinhe BaoJ. Phys. Chem. B, 108(2004)8390-839615.Unusual mesoporous SBA-15 with parallel channels runningalong the short axisHe Zhang, Junming Sun, Ding Ma, Xinhe Bao, Achim Klein-Hoffmann, Giesela Weinberg, Dangsheng Su and Robert Schlogl J. Am. Chem. Soc., 126(2004)7440-744116.Study on the external surface acidity of MCM-22 zeolite: Theoreticalcalculation and 31P MAS NMRY an Wang, Jianqin Zhuang, Gang Yang, Danhong Zhou, Ding Ma,Xiuwen Han, and Xinhe BaoJ. Phys. Chem. B, 108(2004)1386-139117.Solid-state MAS NMR detection of the oxidation center in TS-1 zeoliteby in-situ probe reactionJianqin Zhuang, Ding Ma, Xiumei Liu, Xiuwen Han, Xinhe Bao, Xuewu Liu, Xinwen Guo, Xiangsheng WangJ. Catal., 221(2004)670-67318.Investigation on the catalytic roles of silver species in the selectivecatalytic reduction of NOx with methaneChuan Shi, Mojie Cheng, Zhenping Qu, Xinhe BaoAppl. Catal. B-Environ., 51(2004)171-18119.Chiral synthesis on catalysts immobilized in microporousand mesoporous materialsCan LiCatal. Rev., 46(2004)419-49220.On the surface sites of MoP/SiO2 catalyst under sulfiding conditions:IR spectroscopy and catalytic reactivity studiesZili Wu, Fuxia Sun, Zhaochi Feng, Weicheng Wu, Changhai Liang, Can Li J. Catal., 222(2004)41-5221.Ultra-deep desulfurization of diesel: Oxidation with a recoverablecatalyst assembled in emulsionCan Li, Zongxuan Jiang, Jinbo Gao, Yongxing Yang, Shaojun Wang,Fuping Tian, Fuxia Sun, Xiuping Sun, Pinliang Ying, Chongren HanA European Journal - Chemistry, 10(2004)2277-228022.Direct synthesis of Al-SBA-15 mesoporous materials viahydrolysis-controlled approachYing Li, Wenhua Zhang, Lei Zhang, Qihua Y ang, Zhaobin Wei, Zhaochi Feng, Can LiJ. Phys. Chem. B, 108(2004) 9739-974423.Water reduction and oxidation on Pt-Ru/Y2Ta2O5N2 catalyst under visiblelight irradiationMeiying Liu, Wansheng Y ou, Zhibin Lei, Guohua Zhou, Jianjun Y ang,Guopeng Wu, Guijun Ma, Guoyou Luan, Tuyoshi Takata, Michikazu Hara, Kazunari Domen, Can LiChem. Commun., (2004)2192-219324.Enhancement of alpha-oxygen formation and N2O decomposition onFe/ZSM-5 catalysts by extraframework AlKeqiang Sun, Haidong Zhang, Haian Xia, Can LiChem. Commun., (2004)2480-248125.ZnO clusters encapsulated inside micropores of zeolites studied by UVRaman and laser-induced luminescence spectroscopiesJun Chen, Zhaochi Feng, Pinliang Ying, Can LiJ. Phys. Chem. B, 108(2004)12669-1267626.Dibenzothiophene hydrodesulfurization activity and surface sites ofsilica-supported MoP, Ni2P and Ni-Mo-P catalystsFuxia Sun, Weicheng Wu, Zili Wu, Jun Guo, Zhaobin Wei, Yongxing Y ang, Zongxuan Jiang, Fuping Tian, and Can Li J. Catal., 228(2004)298–31027.Synthesis of nanostructured ceria, zirconia and ceria-zirconia solidsolutions using an ultrahigh surface area carbon material as a templateChanghai Liang, Jieshan Qiu, Zhonglai Li, Can LiNanotechnology, 15(2004) 843-84728.Hydrothermal stability and catalytic activity of aluminum-containingmesoporous ethane-silicasQihua Y ang, Ying Li, Lei Zhang, Jie Y ang, Jian Liu, Can LiJ. Phys. Chem. B, 108 (2004)7934-793729.The reaction route and active site of catalytic decomposition of hydrazineover molybdenum nitride catalystXiaowei Chen, Tao Zhang, Zili Wu, Weicheng Wu, Can LiJ. Catal., 224(2004)473-47830.n-Heptane isomerization over mesoporous MoO x and Ni–MoO x catalystsXinping Wang, Can Li, Yingjun Wang and Tian-Xi CaiCatalysis Today, 93-95(2004)135-14031.Catalytic performance of MCM-22 zeolite for alkylation of toluenewith methanolZhirong Zhu, Qingling Chen, Wei Zhu, Dejin Kong and Can Li Catalysis Today, 93-95(2004)321-32532.Effect of (n)SiO2/(n)B2O3 in the precursor on chemical–physicsproperties of Ti-ZSM-5 synthesized by gas–solid methodMin Liu, Xinwen Guo, Xiangsheng Wang, Chang-hai Liang and Can LiCatalysis Today, 93-95(2004)659-66433.Novel cobalt-free oxygen permeable membraneXuefeng Zhu, Haihui Wang and Weishen YangChemical Communications, (2004) 1130-113134.Molecular sieving MFI-type zeolite membranes for pervaporationseparationof xylene isomersWenhui Y uan, Y. S. Lin and Weishen Y angJournal of the American chemical society35.Formation of a novel type of reverse microemulsion system and itsapplication in synthesis of the nanostructured La0.95Ba0.05MnAl11O19 catalyst Fei Teng, Jinguang Xu, Zhijian Tian, Junwei Wang, Yunpeng Xu,Zhusheng Xu, Guoxing Xiong, Liwu LinChemical Communications, (2004)1858-185936.Cataltic partial oxidation of gasoline to syngas in a dense membrane reactorWenliang Zhu, Guoxing Xiong, Wei Han, Weishen Y angCatalysis Today, 93-95(2004)257-26137.Preparation of CdS-SiO2 core-shell particles and hollow SiO2 sphereranging from nanometers to microns in the nonionic reverse microemulsions Fei Teng, Zhijian Tian, Guoxing Xiong, Zhusheng XuCatalysis Today, 93-95(2004)651-65738.Effects of reaction conditions on the selective oxidation of propane toacrylic acid on Mo-V-Te-Nb oxidesBaichun Zhu, Hongbo Li, Weishen Yang, Liwu LinCatalysis Today, 93-95(2004)229-23439.An improved palladium-based DMFCs cathode catalystHuanqiao Li, Qin Xin, Wenzhen Li, Zhenhua Zhou, Luhua Jiang,Shaohua Y ang, Gongquan SunChemical Communications, (2004)2776-277740.The effect of methanol and ethanol crossover on the performance ofPtRu based anode DAFCsShuqin Song, Weijiang Zhou, Zhenxing Liang, Rui Cai, Gongquan Sun,Qin Xin, V aios Stergiopoulos, Panagiotis TsiakarasApplied Catalysis B: Environmental, 55(2004)65-7241.Homogeneous and controllable Pt particles deposited on mutil-wall carbonnanotubes as cathode catalyst for direct methanol fuel cells Wenzhen Li, Changhai Liang, Weijiang Zhou, Jieshan Qiu,Huanqiao Li, Gongquan Sun, Qin XinCarbon, 42(2004) 436-43942.Preparation and characterization of PtSn/C anode electrocatalysts fordirect ethanol fuel cellLuhua Jiang, Gongquan Sun, Zhenhua Zhou, Weijiang Zhou, Qin XinCatalyst Today, 93-95(2004)665-67043.Preparation of highly active 40 wt.% Pt/C cathode electrocatalysts forDMFC via different routesZhenhua Zhou, Weijiang Zhou, Suli Wang, Guoxiong Wang, Luhua Jiang, Huanqiao Li, Gongquan Sun, Qin XinCatalysis Today, 93-95(2004) 523-52844.Oxidation of p-cresol to p-hydroxybenzaldehyde with molecular oxygenin the presence of CuMn/oxide heterogeneous catalystFeng Wang, Guang Y ang, Wei Zhang, Wenhai Wu, Jie XuAdvanced Synthesis & Catalysis, 346(2004)633-63845.Metathesis of ethylene and butylene-2 to popylene with Mo onHβ-Al2O3 catalystsShenglin Liu, Shengjun Huang, Wenjie Xin, Jie bai, Sujuan Xie, Longya Xu Catalysis Today, 93-95(2004)471-47646.The PPh3 ligand modified Rh/SiO2 catalyst for hydroformylation of olefinsH.J. Zhu, Y.J. Ding, L. Y an, J.M. Xiong, Y. Lu, L.W. LinCatalysis Today, 93-95(2004)389-39347.NO reduction by CH4 in the presence of excesss O2 over Mn/sulfatedzirconia catalystsNing Li, Aiqin Wang, Xiaodong Wang, Mingyuan Zheng,Ruihua Cheng, Tao ZhangApplied Catalysis B, 48(2004)259-26548.NO reduction by CH4 in the presence of excess O2 over Pd/sulfatedalumina catalystsNing Li, Aiqin Wang, Lin Li, Xiaodong Wang, Lili Ren, Tao ZhangApplied Catalysis B, 50(2004)1-749.Probing into the catalytic nature of Co/sulfated zirconiafor selectivereduction of NO with methaneNing Li, Aiqin Wang, Mingyuan Zheng, Xiaodong Wang,Ruihua Cheng, Tao ZhangJ. Catal., 225(2004)307-315/doc/cd15189216.html,bined single-pass conversion of methane via oxidative couplingand dehydro-aromatization: A combination of La2O3/BaO andMo/HZSM-5 catalyst systemY onggang Li, Hongmei Liu, Wenjie Shen,Yide Xu, Xinhe Bao Studies in surface science and catalysis, 147 (2004)583-58851.Methane dehydto-aromatization process on alkali-treated MCM-22supported Mo catalyst: the effect of pore structureLingling Su, Y onggang Li, Wenjie Shen, Yide Xu, Xinhe Bao Studies in surface science and catalysis, 147(2004)595-60052.Coking kinetics on the catalyst during alkylation of fcc off-gaswith benzene to ethylbenzeneLongya Xu, Jinxiang Liu, Qingxia Wang, Shenglin Liu, Wenjie Xin, Yide Xu Applied Catalysis A: General, 258(2004)47–5353.Structural features and catalytic properties of Pt/CeO2 catalystsprepared by modified reduction- deposition techniquesXiaolan Tang, Baocai Zhang, Y ong Li, Y ide Xu, Qin Xin, Wenjie ShenCatalysis Letters, 97/3-4(2004)163-16954.Kinetics of selective oxidation of dimethyl ether to formaldehyde overAl2O3 -supported VO x and MoO x catalystsXiumin Huang, Y onggang Li, Yide Xu, Wenjie ShenCatalysis letters, 97/3-4(2004)185-19055.Facile synthesis of ginsenoside RoWenjie Peng, Jiansong Sun, Feng Lin, Xiuwen Han, Biao Y u Synlett, (2004)(2)259-26256.A facile preparation of uronates via selective oxidation withTEMPO/KBr/Ca(OCl)(2) under aqueous conditionsFeng Lin, Wenjie Peng, Wen Xu, Xiuwen Han, Biao Y uCarbohydr. Res., 339(2004)1219-122357.Synthesis of a typical glucuronide-containing saponin, 28-O-beta-D-glucopyranosyl oleanate 3-O-beta-D-galactopyranosyl-(1 ->2)-[beta-D-glucopyranosyl-(1 -> 3)]-beta-D-glucuronopyranosideWenjie Peng, Xiuwen Han, Biao Y uSynthesis, (2004)(10)1641-164758.Thermodynamic studies of monuronLiguo Kong, Zhicheng Tan, Jianting Mei, Lixian Sun, Xinhe BaoThermochimica Acta, 414(2004)131-13559.Evidence for perimeter sites over SmOx-modified Rh(100) surface by COchemisorptionZhiquan Jiang, Weiping Zhou, Dali Tan, Runsheng Zhai, Xinhe BaoSurf. Sci., 565(2004)269-27860.Direct synthesis, characterization and catalytic activity of titanium-substitutedSBA-15 mesoporous molecular sievesY angying Chen, Y anlei Huang, Jinghai Xiu, Xiuwen Han, Xinhe BaoAppl. Catal. A-Gen., 273(2004)185-19161.A DFT study on isomorphously substituted MCM-22 zeoliteY an Wang, Danhong Zhou, Gang Y ang, Shaojun Miao,Xianchun Liu, Ding Ma, Xinhe BaoJ. Phys. Chem. A, 108(2004)6730-673462.On the reactivity of Mo species for methane partial oxidation onMo/HMCM-22 catalystsShaojun Miao, Lin Liu, Y uxiang Lian, Xiangxue Zhu, Shutian Zhou,Y an Wang, and Xinhe BaoCatal. Lett., 97(2004)209-21563.Syntheses and structures of sodium aluminodiphosphonates with differentmorphologies (diphosphonate=1-hydroxyethylidenediphosphonate)Zongbin Wu , Zhongmin Liu , Peng Tian , Y ue Y ang , Lei Xu , Haibin Song , Xinhe Bao , Xiumei Liu and Xianchun Liu J. Cryst. Growth, 264(2004)400-40864.Density functional theory study of proto hopping in MCM-22 zeoliteY an Wang, Danhong Zhou, Gang Y ang, Xianchun Liu, Ding Ma,DongBa Liang, Xinhe BaoChem. Phy. Lett., 388(2004)363-36665.On the nature of reaction-controlled phase transferepoxidation of olefin: a 31P NMR investigationY angying Chen, Jianqin Zhuang, Xiumei Liu, Jinbo Gao, Xiuwen Han,Xinhe Bao*, Ning Zhou, Shuang Gao, Zuwei XiCatal. Lett., 93(2004)41-4666.Effect of acidity in TS-1 zeolites on product distribution of the styreneoxidation reactionJianqin Zhuang, Ding Ma, Zhimin Y an, Xiumei Liu, Xiuwen Han,Xinhe Bao, Yihua Zhang, Xinwen Guo, Xiangsheng WangAppl. Catal. A-Gen., 258(2004)1-667.Adsorption and decomposition of Mo(CO)6 on thin Al2O3 films: fabricationof metallic molybdenum model catalystZhiquan Jiang, Weixin Huang, Jian Jiao, Hong Zhao, Dali Tan, Runsheng Zhai, Xinhe BaoAppl. Surf. Sci., 229(2004)43-5068.An IR study on the surface passivation of Mo2C/Al2O3 catalyst with O2,H2O and CO2Weicheng Wu, Zili Wu, Changhai Liang, Pinliang Ying, Zhaochi Feng, Can Li Phys. Chem. Chem. Phys., (2004)5603-560869.Adsorption and reaction of thiophene and H2S on Mo2C/Al2O3 catalyststudied by in situ FT-IR spectroscopyWeicheng Wu, Zili Wu, Zhaochi Feng, Pinliang Ying, Can Li Phys. Chem. Chem. Phys., (2004)5596-560270.Ammonia synthesis on graphitic-nanofilament supportedZhonglai Li, Changhai Liang, Dezheng Wang, Can LiJ. Mol. Catal. A: Chem., 211 (2004)103-10971.The visible luminescent characteristics of ZnO supported on SiO2 powderJun Chen, Zhaochi Feng, Pinliang Ying, Meijun Li, Bo Han,Jianying Shi, Can LiPhys. Chem. Chem. Phys., (2004)4473-447972.SbOx/SiO2 catalysts for the selective oxidation of methane to formaldehydeusing molecular oxygen as oxidantHaidong Zhang, Pinliang Ying, Jing Zhang, Changhai Liang, Zhaochi Feng, Can LiStud. Surf. Sci. & Catal., (147): 547-552 200473.Catalytic decomposition of hydrazine over α-Mo2C/γ-Al2O3 catalystsXiaowei Chen, Tao Zhang, Zili Wu, Weicheng Wu, Can LiInd. Eng. Chem. Res., 43(2004)6040-604774. A spectroscopic study on the reaction-controlled phase transfer catalystfor the epoxidation of cyclohexeneJinbo Gao, Yangying Chen, Bo Han, Zhaochi Feng, Ning Zhou, Shuang Gao, Zuwei Xi, Can LiJ. Mol. Catal. A: Chem., 210 (2004)197-20475.CO-FTIR Characterization of PVP-Protected Pt Nanoclusters on Zeolite BetaJinghong Ma, Shuhua Reng, Ruifeng Li, Weicheng Wu, Can Li, Kecheng XieInternational Journal of Nanoscience, 3(2004)247-25476.Ammonia-treated activated carbon as support of a Ru-Bacatalystfor ammonia synthesisChanghai Liang, Zhaobin Wei, Qin Xin, Can LiReact. Kinet. Catal. Lett., 83 (2004)39-4577.Characterization of the formation of NaA zeolite membrane undermicrowave radiationXiaobo Chen, Weishen Yang, Jie Liu, Liwu LinJournal of Materials Science, 39 (2004) 671– 67378.Low-temperature partial oxidation of n-heptane to CO+H2 overRh-based/γ-Al2O3 catalystsRan Ran, Guoxing Xiong, Shishan Sheng, Weishen YangReaction Kinetics and Catalysis Letters, 81(2004) 27-3279.Synthesis of NaA zeolite membrane on a ceramic hollow fiberXiaochun Xu,Weishen Y ang, Jie Liu, Liwu Lin, Norbert Stroh, Herwig Brunner Journal of membrane science, 229(2004) 81-8580.Oxidative activation of light alkanes on dense ionic oxygenconducting membranesM.Rebeilleau,A.C.V an V een,D.Farrusseng,C.Mirodatos,Z.Shao,G.XiongStudies in surface science and catalysis,147(2004) 655-660 /doc/cd15189216.html,bustion synthesis, annealing, and oxygen permeation propertiesof SrFeCo0.5O y membranesZ.Q. Deng, W. Liu, D.K. Peng, C.S. Chen, Weishen Y angMaterials Research Bulletin, 39(2004)963–96982.Germanium and iron co-substituted SrCoO2.5+δ asoxygen permeable membraneZ.Q. Deng, W. Liu, C.S. Chen, H. Lu, Weishen Y angSolid State Ionics 170 (2004)187–19083.Test of the hydrogen separation from gas mixture using a thin Pd/ceramichollow fiber membrane moduleW.P. Wang, Xiulian Pan, X.L. Zhang, Guoxing Xiong, Weishen Y angInorganic Membranes (Proceedings of Eighth International Conferenceon Inorganic Membranes), (2004)301-304 (ISBN1-929612-67-2)84.Ba0.5Sr0.5Co0.8Fe0.2O3 membrane reactors for catalytic partial oxidationof hydrocarbon to syngasWenliang Zhu, Guoxing Xiong, Wei Han, Weishen Y angInorganic Membranes (Proceedings of Eighth International Conferenceon Inorganic Membranes), (2004) 355-358 (ISBN1-929612-67-2)85.Novel cobalt-free oxygen permeable membraneXuefeng Zhu, Haihui Wang, Y ou Cong, Weishen YangInorganic Membranes (Proceedings of Eighth International Conferenceon Inorganic Membranes), (2004)22-25 (ISBN1-929612-67-2)86.Dehydration of mixed-alcohols produced by fischer-tropsch process byzeolite-A membranesY anshuo Li, Hongliang Chen, Aisheng Huang, Jie Liu,Y uesheng Lin and Weishen Y angInorganic Membranes (Proceedings of Eighth International Conferenceon Inorganic Membranes), (2004)613-617(ISBN1-929612-67-2)87.Preparation of A-type zeolite membranes by using electrophoretic techniqueAisheng Huang, Jie Liu, Y anshuo Li, Y. S. Lin, Weishen Y ang Inorganic Membranes (Proceedings of Eighth International Conferenceon Inorganic Membranes)( 2004)224-228 (ISBN1-929612-67-2)88.Thermal evolution of the structure of a Mg-Al-CO3 layered double hydroxide:Sorption reversibility aspectsYongman Kim, Weishen Yang, Paul K.T.Liu, Muhammad Sahimi,Theodore T.TsotsisIndustrial & Engineering Chemistry Research, 43(2004)4559-457089.Microwave-assisted hydrothermal synthesis of hydroxy-sodalitezeolite membraneXiaochun Xu, Yun Bao, Chunshan Song, Weishen Yang, Jie Liu, Liwu LinMicroporous and Mesoporous Materials, 75(2004)173–18190.Synthesis and properties of A-type zeolite membranes by secondarygrowth method with vacuum seedingAisheng Huang, Y.S. Lin, Weishen YangJournal of Membrane Science, 245(2004)41–5191.Experimental and modeling studies on Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF)tubular membranes for air separationHaihui Wang, Rong Wang, David Tee Liang, Weishen YangJournal of Membrane Science,243(2004)405-41592.Performance comparison of low-temperature direct alcohol fuelcells with different anode catalystsWeijiang Zhou, Bing Zhou, Wenzhen Li, Zhenhua Zhou, Shuqin Song, Gongqun Sun, Qin Xin, S. Douvartzides，M. Goula，P. TsiakarasJournal of Power Sources, 126(2004)16-2293.FT-IR study of the microstructure of nafion? membraneZhenxing Liang, Weimin Chen, Jianguo Liu, Suli Wang, Zhenhua Zhou, Wenzhen Li, Gongqun Sun, Qin XinJournal of Membrane Science, 233(2004) 39-4494.Nano-structured Pt-Fe/C as cathode catalyst in direct methnol fuel cellWenzhen Li, Weijiang Zhou, Huanqiao Li, Zhenhua Zhou, Bing Zhou,Gongquan Sun, Qin XinElectrochimica Acta, 49(2004)1045-105595.The mechanism studies of ethanol oxidation on PdO catalysts byTPSR techniquesRui Lin, Mengfei Luo, Qin Xin, Gongquan SunCatalysis letters, 93(3-4)(2004) 139-14496.Effects of treatment in different atmosphere on Pt3Sn/C electrocatalystsfor ethanol electro-oxidationLuhua Jiang, Zhenhua Zhou, Wenzhen Li, Weijiang Zhou, Shuqin Song,Gonguan Sun, Qin XinEnergy & Fuels, 18(2004) 866-87197.Multi-walled carbon nanotubes supported Pt-Fe cathodic catalyst for direct methanolfuel cellWenzhen Li, Changhai Liang, Weijiang Zhou, Jieshan Qiu, Huanqiao Li,Gongquan Sun, Qin XinReaction Kinetics and Catalysis Letters, 82(2004) 235-24098.Liquid-phase hydrodechlorination of chlorinated benzenes over activecarbon supported nickel catalysts under mild conditionsWenhai Wu, Jie XuCatalysis Comm., 5(2004)591-59599.Pd/C-catalyzed hydrodehalogenation of aromatic halides in aqueoussolutions at room temperature under normal pressureChuanghai Xia, Jie Xu, Wenzhong Wu, Xinmiao LiangCatalysis Comm., 5(2004)383-386100.Multi-scale phenomena in heterogeneous catalytic processes─impact of chemical phenomena under the micro-scale level oncatalyst development and designZhijian Tian, Y unpeng Xu, Liwu LinChemical Engineering Science, 59(2004)1745-1753101.Effect of drying methods on the structure and catalytic combustionactivity of mn-substituted hexaaluminate catalystsJinguang Xu, Zhijian Tian, Junwei Wang, Y unpeng Xu,Zhusheng Xu, Liwu LinReact. Kinet. Catal. Lett., 82(2004)19-25102.The role of acid strength of zeolites in liquid-phase alkylation ofbenzene with ethyleneXinde Sun, Qingxia Wang, Longya Xu, Shenglin LiuCatalysis Letters, 94(2004)75-79/doc/cd15189216.html,parison of 6Mo/MCM-22 and 6Mo/ZSM-5 in the MDA process Jie Bai, Shenglin Liu, Sujuan Xie, Longya Xu, Liwu LinReact. Kinet. Catal. Lett., 82(2004)279-286104.The effect of acidity on olefin aromatization over potassiummodified ZSM-5 catalystsY ueqin Song, Xiangxue Zhu, Sujuan Xie, Qiangxia Wang, Longya XuCatalysis Letters, 97(2004)31-36105.The role of coke in the deactivation of Mo/MCM-22 catalyst for methane dehydroaromatization with CO2 Jie Bai, Shenglin Liu, Sujuan Xie, Longya Xu, Liwu LinStudies in surface science and catalysis, 147(2004)715-720 106.Catalytic alcohols synthesis from CO and H2O on TiO2 catalysts calcined at various temperaturesDeehun Ji, Shenglin Liu, Qingxia Wang, Longya XuStudies in surface science and catalysis, 147(2004)433-438 107.Metathesis of ethylene and 2-butlene to popylene on W/Al2O3-HY catalysts with different HY contentsShengjun Huang, Shenglin Liu, Wenjie Xin, Jie Bai, Sujuan Xie,Qingxia Wang, Longya XuJournal of Molecular Catalysis A: Chemical, 226(2004)61-68 108.Fischer-tropsch synthesis over activated-carbon-supported cobalt catalysts: effect of Co loading and promoters on catalyst performanceWenping Ma, Tunjie Ding, Liwu LinInd. Eng. Chem. Res., 42(2004)2391-2398109.The remarkable effect of In2O3 on the catalytic activity of In/HZSM-5 for the reduction of NO with CH4Lili Ren, Tao Zhang, Changhai Xu, Liwu LinTopics in Catalysis, 30-31(2004)55-57110.Pd/sulfated alumina - a new effective catalyst for the selective catalyticreduction of NO with CH4Ning Li, Aiqin Wang, Lili Ren, Mingyuan Zheng, Xiaodong Wang, Tao Zhang T opics in Catalysis, 30-31(2004)103-105二、在国内刊物上发表的英文文章(仅刊摘要)111.Effect of dimethyl ether Co-feed on catalytic performance of methane dehydroaromatization over Mo/HZSM-5 catalystHuiying Chen, Y onggang Li, Wenjie Shen, Yide Xu, Xinhe Bao Journal of Natural Gas Chemistry, 13/3(2004)，1-7112.Catalytic performance of zeolite NU-87 with 10- and 12-member ring for methane dehydroaromatizationHuiying Chen, Liu Lin, Longya Xu, Wenjie Shen, Yide Xu, Xinhe BaoChin. J. Catal., 25(2004)845-846113.A new way to obtain Mo/HZSM-5 catalyst with high activity and selectivity for methane dehydro-aromatization Hongmei Liu, Y ong Li, Wenjie Shen, Xinhe Bao, Yide XuChin. J. Catal., 25(2004)175-176114.Kinetics study of the effect of oxygen on ammonia decomposition on Ru Zhonglai Li, Changhai Liang, Dezheng Wang, Can LiChinese Journal of Catalysis, 25 (2004)1-2115.A novel highly active hydrodesulfurization catalyst: nickelphosphide supported on silicaFuxia Sun, Zhaobin Wei, Pinliang Ying, Xiuping Sun, Zhongxuan Jiang,Fuping Tian, Y ongxing Y ang, Can LiChinese Journal of Catalysis, 25 (2004)685-687116.Preparation of A-type zeolite membranes on nonporous metalsupports by using electrophoretic techniqueAisheng Huang, Jie Liu, Yanshuo Li, Yuesheng Lin, Weishen YangChinese science bulletin, 49(2004)1226-1230117.Enlarged Area A-type Zeolite Membranes Prepared by V acuum Seeding MethodAi Sheng Huang, Jie Liu, Wei Shen Y angChinese Chemical Letters, 15(2004)1120-1122118.The effects of CO2 addition on the partial oxidation of heptane for hydrogen generationRan Ran, Guo Xing Xiong, Shi Shan Sheng, Wei Shen YangChinese Chemical Letters, 15(2004) 605-608三、国内刊物上发表的文章(仅刊摘要)119.分子筛的酸处理对Mo/HZSM-5催化甲烷无氧芳构化反应性能的影响，刘红梅，申文杰，刘秀梅，包信和，徐奕德催化学报，25(2004)688-692120.负载型MoO_x和VO_x催化剂上二甲醚选择氧化制甲醛反应黄秀敏, 徐奕德, 申文杰催化学报，25(2004)267-271121.Co助剂对甲烷脱氢芳构化反应中Mo/MCM-22催化剂积碳行为的影响刘红梅. 申文杰, 包信和，徐奕德催化学报，25(2004)495-500122.分子筛的酸处理对Mo/HZSM-5催化甲烷无氧芳构化反应性能的影响刘红梅，申文杰，刘秀梅，包信和，徐奕德催化学报，25(2004)688-692123.硅烷化处理对Mo/ HZSM25 催化剂上甲烷脱氢芳构化活性的影响王红霞，谭大力，徐奕德，包信和催化学报，25(2004)445-449124.Al-MSU-S 介孔及介孔-微孔分子筛的合成、表征及其催化性能朱金红，刘靖，赵文江，王祥生，刘秀梅，包信和催化学报，25(2004)741-747125.Ag担载对TiO2光催化活性的影响刘守新，曲振平，韩秀文，孙承林，包信和催化学报，25(2004)133-137126.模板剂与MCM-22分子筛匹配作用的分子模拟计算周丹红，杨明媚，王妍，杨刚，刘宪春无机化学学报，20(2004)41-47127.ZnO SiO2的激光诱导发光光谱研究陈钧，冯兆池，应品良，李灿高等学校化学学报，25(2004)2074-2077128.Cu/SiO2催化剂上丙烯在空气中的直接环氧化反应鲁继青，罗孟飞，李灿催化学报，25(2004) 5-9129.易分离的高效纳米铂氢化催化剂姜鹏，关业军，李晓红，应品良，李灿应用化学，21(2004)646-648130.激光散射法测试超细颗粒粒度分布的研究滕飞，宁桂玲，田志坚，熊国兴光散射学报，16(2004)172-176131.微波辐射法制备NiW/TiO2-Al2O3加氢脱硫催化剂刘百军，查显俊，盛世善，杨维慎，熊国兴催化学报，25(2004)770-774132.微乳液双连续微结构控制的0.5Ce0.5Ba1Mn11AlO x纳米催化剂形态滕飞，田志坚，马怀军，徐平，熊国兴，林励吾石油化工，33(2004)1116-1118133.汽油催化转化制氢过程研究冉然，熊国兴，盛世善，杨维慎。

西北工业大学2004年硕士研究生入学考试试题
腐蚀与防护
一、简答题：（25分）
1）在某腐蚀介质中，含有一定量Cl-、Br-、I-离子，如此时加入强氧化剂，哪一种优先被氧化？为什么？（ψ0(Cl
2
/Cl-)=1.36V,ψ
0(Br
2/Br-)=1.08V,ψ0(F
2
/F-)=0.53V。

2）什么是液接电位？说明消除它的
途径和依据。

3）图1为一典型的腐蚀体系的电化
学交流阻抗（EIS）的全频段复平面
图，说明①、②、③频段的图形所表
示的含义。

4）写出能斯特（Nernst）公式，并
说明其适用条件。

5）电化学反应或相应的电化学方法可概括为两类，是哪两类？说明其内容。

二、在图2中，用粗线表示的电流J
ex
是可以测定的。

试叙述（推算）用细
的虚线表示的各个部分电流（如J
cor 、J
lim
）值的获得方法。

（15
分）。

• The EDM process can be used on any material that is an electrical conductor • The EDM process does not involve mechanical energy, therefore, materials with high hardness and strength can easily be machined. • Applications include producing die cavity for large components, deep small holes, complicated internal cavities • EDM is not a fast method; some jobs can take days to produce holes, so its use is limited to jobs that cannot easily be done in other ways (e.g. oblong slots or complex shapes, sometimes in very hard material). • Note too the work must be conductive so it does not work on materials such as glass or ceramic, or most plastics.
4/2/2016
Electrical Discharge MachiningEDM
Schematic illustration of the electrical-discharge-machining process. Based on erosion of metals by spark discharge. The cavity is is formed by the shape of the electr

Nanostructure formation in the surface layer of metals under influence of high-power electric current pulseA.Vinogradov ÆA.Mozgovoi Æzarev ÆS.Gornostai-Polskii ÆR.Okumura ÆS.HashimotoReceived:9April 2009/Accepted:15June 2009/Published online:1July 2009ÓSpringer Science+Business Media,LLC 2009Abstract The possibility to tailor the microstructure of metals is explored utilising a skin-effect for surface treat-ment.The theoretical simulation of the electric and mag-netic fields in a metallic cylinder shows that melting followed by rapid quenching can occur in a skin layer of 5–10-l m thickness if the amplitude of a single electric pulse of several nanoseconds duration is of the order of hundreds kiloamperes.The experiments using the SUS304stainless steel show that besides a thin amorphous layer,a specific nano-twin structure can form at the near-surface region.The appearance of nano-twins is explained considering the stress components arising at the surface layer and in the bulk of the specimen during shock wave propagation caused by temperature gradients and the Lorentz force.It is shown that the high stress amplitudes can arise locally,furnishing the required conditions for twin nucleation and resulting in intensive plastic deformation of the sub-surface layer.IntroductionMany physical and mechanical properties of materials depend strongly on the surface state.For instance,hard-ness,fatigue life and wear resistance benefit from surfacestrengthening which can be achieved in a variety of tech-niques including severe plastic deformation,plating,ion implantation,laser irradiation,etc.The ultimate properties have been achieved in materials in their nano-and amor-phous states [1].Both nano-and amorphous structures are commonly obtained in metals from melts of very specific chemical compositions by utilising a variety of rapid quenching techniques where a rather high critical cooling rate of 105–107K/s is achieved as required for amorphi-sation.At lower quenching rates,ordinary crystallisation or formation of ultrafine grain or nano-structure is observed with characteristic grain dimensions from few nanometres to few hundred nanometres,respectively.Numerous rapid quenching techniques allow obtaining thin films,ribbons,flakes and powders of micrometre dimensions [2].In con-trast,severe plastic deformation is capable of producing bulk articles with the ultrafine grain and nano-structure [3].In this study,we explore the possibility to create novel microstructures by combining both rapid quenching and severe plastic deformation.We make use of a skin-effect in conductors,arising from the short electric current pulse flowing through the conductor,for their surface heating up to melting followed by rapid cooling due to heat transfer the bulk.It was supposed that various ultrafine grain,nano-and even amorphous structures can be produced in the surface layer of metals in this way [4].The first theoretical attempt has been made in ref.[4]to simulate the behaviour of the electric and magnetic fields in a metallic cylinder subject to a rapid discharge of a bank of capacitors as shown schematically in Fig.1.It was demonstrated that melting followed by rapid quenching can occur in a skin layer of 5–10-l m thickness if the amplitude of the passing electric pulse of several nano-seconds duration is high enough,i.e.of the order of 102kA.Furthermore,it appeared that since solidification of the molten layer occurs within a microsecond or sub-microsecond timeA.Vinogradov (&)ÁS.HashimotoOsaka City University,Osaka 558-8585,Japan e-mail:alexei@imat.eng.osaka-cu.ac.jpA.Mozgovoi Ázarev ÁS.Gornostai-Polskii ÁR.Okumura Institute of Experimental Physics,Sarov 607190,Russia Present Address:R.OkumuraMaterials Engineering Department,Denso Corp.,Kariya 448-8661,JapanJ Mater Sci (2009)44:4546–4552DOI 10.1007/s10853-009-3689-zscale,very high quenching rates of108–109K/s are achiev-able,providing an appealing novel opportunity for amorphi-sation or significant modification and nano-structurisation of the surface layer in conductors.The possibility to obtain thickness of5–10l m amorphous layer in the commercial SUS304stainless steel was then successfully demonstrated by the same authors[5],which agrees with common estimates of the skin layer thickness[6].Theoretical calculations in this study show that the extremely high stresses may arise from the temperature gradients and Lorenz force action resulting in intensive plastic deformation of the sub-surface layer.The experiments under this study utilising an ultra-high power generator producing a short electric current pulseflowing through copper or SUS304stainless steel cylindrical speci-mens reveal that a specific nano-twin structure can be formed in the surface layer and in the bulk of the specimens depending on the electric pulse parameters.The appearance of nano-twins is explained from the theoretical consideration of the stress components arising at the surface vicinity and in the bulk of the specimen.Use of skin-effect for surface heating,melting and rapid quenchingLet us consider an endless conducting cylinder with the symmetry axis Z in a circuit shown in Fig.1.The proce-dure,which allows evaluating the parameters of the external circuit such as the resistance R,capacitance C, inductance L and the initial voltage U0,as well as the dimensions of the metallic cylinder l and r0,is given in[4] to ensure melting and rapid quenching in the surface layer.The initial system of differential equations describing a given problem can be written in a classic Maxwell’s form for the electric E and magnetic Hfields together with a heat transfer equation:rÂH¼1 q E;rÂE¼Àl a o H o t;q m c V o To t¼rÁðk r TÞþ1qj E j2;ð1Þwhere the right-hand side of the last equation includes theJoule heating term proportional to j E j2as a heat source.Here,q m is the materials density,l a is the magneticpermeability,c V is the specific heat capacity and k is theheat conductivity of the material.Apparently,the system ofequations(1)should be completed with the ordinaryelectric equations for the external circuit given asLd Id tþRIÀUðtÞþlE zðt;r0Þ¼0;d Ud t¼ÀIðtÞC;ð2Þwith initial conditions setting the initial discharge voltageU0Uð0Þ¼U0;Ið0Þ¼0:ð3ÞIn order to model the dynamics of various processes inthe actual experimental installation utilising the electricalenergy of the bank of capacitors discharging on a low-inductance load,the system of equations(2)and(3)wassolved together.The details of the problem formulation andsolution have been reported in[4,5].For instance,for acopper cylinder having the length l=10mm and radiusr0=0.1–0.5mm at T0=300K,C=0.1l F,R=0.3Ohm,L=5nHn and U0=100kV,the peak currentmagnitude reaches180–250kA while the pulse duration isas short as40–50ns.The maximum thickness of the moltenlayer R m was found to be10l m,and the melting time was230ns.Cooling until complete solidification occurredwithin approximately1l s.The maximum temperature onthe surface reached almost2,000K,which is between themelting point T m=1,356K and vaporization temperatureT v=2,868K.The maximum quenching rate,q T/q t,was of29108K s-1.This quenching rate is still not enoughfor amorphisation of pure metals;it is,however.within therange of typical quenching rates attained in melt-spinningtechniques used for production of a broad variety of amor-phous alloys[2].Using the model constituted by Eqs.1and3,one can show that the depth of the molten layer varies in arange of0.1–40l m,depending on the specimen dimensionsand initial voltage provided that the parameters of theexperiment have been the realistically chosen[4,5].Hence,utilising a high-power generator described briefly in[7],which was modified tofit the cylindrical specimens of1-mmdiameter,the proposed scheme vas validated using Cu andSUS304stainless steel.It was demonstrated that formationof the amorphous(glassy-like)layer in the intimate prox-imity(from zero to about30l m depending on the initialvoltage U0)to a free surface of the SUS304steel(Fe–18Cr–8Ni)is possible after melting followed by rapid quenchingcaused by the short high power electric pulse.For this study,the most interestingfinding reported in ref.[4]is that aspecific twin structure is formed in the subsurfacelayer,extending up to 100l m inside the material from the surface as illustrated in Fig.2(the details of experimental procedure,specimen preparation and observation can be found in [5]).Transmission electron microscopy (TEM)with the selected area electron diffraction pattern (SAEDP)analysis reveals that this structure differs drastically from that is commonly found in the bulk of the as-received specimens.After the ‘skin’treatment,the structure near the surface consists primarily of regions which are multiply twinned along {111}planes with the nanometre scale twin spacing.The very fine twin lamellae,parallel to each other can be readily found here and there in TEM foils.Apparently,the density of twin population reduces with depth from the surface,c.f.Fig.2a–d.Figure 2b shows that the twins in the bulk of the specimen are limited to the initial grain size which is of the order of 2–3l m.The appearance of such a very fine nano-scaled twin structure,induced by the ‘skin’treatment,is difficult to explain by annealing-type effects caused by the temperature rise at the specimen surface due to the skin electric current.Since the cooling rate has been proven very high [4,5],the time interval over which the surface layer is exposed to the high temperature influence is too short to facilitate diffusion processes controlling the annealing effects.Besides,the twin structure appearance does not resemble typical annealing twin patterns,for example [8].On the other hand,it is well known that the fine twin lamellae with the nano-scale spacing can be produced mechanically at high stresses due to plastic deformation [9–11].Appearanceof mechanical twins assumes two factors of primary importance:(i)high stresses approaching a sizable fraction of the theoretical cohesive strength s /l =10with l —shear modulus of the material,(ii)impeded alternative accom-modative mechanisms such as dislocation motion.In the course of conventional plastic deformation,the dislocation motion can be blocked by high internal stresses arising from dislocation accumulation during strain hardening.In the experiments under this study,the dislocation motion is limited due to a very short influence from the electric pulse.The mechanical twins form very fast,with the velocity of sound [10]and can be highly possible candidates for alternative sources of plastic deformation.Therefore,the internal stresses arising from the influence of electric and magnetic fields during the ‘‘skin’’treatment of the metal surface should be evaluated to shed light on the feasibility of twin nucleation.This will be accomplished in the next section.Stress calculation Problem statementThe pressure caused by the electromagnetic field acting on the specimen in the geometry shown in Fig.1is pro-portional to the Pointing vector,i.e.to the vectorproductFig.2Nano-scaled twinstructure below the surface of a ‘‘skin-’’treated SUS304stainless steel a 25l m below the surface;SEADP is indicative of the twinnedstructure;b 100l m below the surface;c and d 100l m below the surface.The initial discharge voltage is 70kV (a ,b )and 90kV (c ,d ),respectivelyE 9H .The displacement vector U ,will have both axial and radial components U ={U r ,0,U z }.In order to calculate the stresses which arise in the metallic specimen when the high power electric pulse is passing through,the equation for the vector U should be added to the system of Maxwell equations for electric and magnetic vectors.The equation describing the mechanical behaviour of an isotropic deforming media is written as q m o 2Uo t¼r Á½r þF ;ð4Þwhere the Lorentz force term and the linear isotropic expansion term are incorporated in the right hand side;[r ]is the stress tensor,F is the net bulk force vector.In the axially symmetrical case the stress tensor takes a form½r ¼r r 0r rz0r u 0r zr 0r z 0@1A ;ð5Þwith the components given as r rr u r z rrz0B B B @1C C C A ¼k 1Àm m 11011Àm m 10111Àm m00001À2mm0B B @1C C A e r Àa T ðT ÀT 0Þe u Àa T ðT ÀT 0Þe z Àa T ðT ÀT 0Þe rz 0B B @1C C A ð6ÞComponents of the strain tensor [e ]are given as:e r ¼o U r o r ;e u ¼U r r ;e z ¼o U z o z ;e rz ¼12o U r o z þo U z o r:ð7ÞHence,the initial system of equations takes a form:r ÂH ¼1q E ;r ÂE ¼Àl a o H o t;q m co T o t ¼r Áðk r T Þþ1qj E j 2;q m o 2Uo t2¼ðk þ2l Þrðr ÁU ÞÀl r Âðr ÂU ÞÀa T K r T þl a 1ÁE ÂH ;l ¼E u 2ð1þm Þ;k ¼E u m ð1þm Þð1À2m Þ;K ¼E u3ð1À2m Þ:ð8ÞHere,E u ,l and K are the Young’s,shear and bulk moduluses,respectively,m is the Poisson ratio,e ij are the strain tensor components,U r ,U z are the displacement vector components,a T is the linear heat expansion coefficient and k is the Lame constant.The right-hand side of the third equation includes the Joule heating termproportional to j E j 2as a heat source.The system is said tobe thermally isolated because the energy losses due to irradiation have been proven negligible [4].Using Raleigh damping,which is commonly used to provide a source of energy dissipation in analyses of structures responding to dynamic loads and having H ={0,H ,0},E ={E r ,0,E z }and U ={U r ,0,U z },the equations (8)in cylindrical coordinates {r,z }take a final form:l a 1q o H u o t ¼1r r o 2H u o r 2þo H u o r ÀH u rþo 2H uo z 2;E z ¼q r o o r rH u ÀÁ;E r ¼Àq o H u o z;q m c o T o t ¼k o 2T o r þo 2T o zþk r o T o r þ1q E 2rþE 2z ÀÁ;q m o 2U r ¼ðk þ2l Þo 2V r þo V rþl o 2V r o z 2þðk þl Þo 2V zo r o z Àl a q E z H u Àa T K o T o r þa R q mo U ro t ;q m o 2U z o t 2¼ðk þ2l Þo 2V z o z 2þl o 2V z o r 2þ1r o V z o rþðk þl Þo 2V r o r o z þ1r o V ro zþl a q E r H u Àa T K o T o z þa R q mo U zo t;V r ¼U r þb R o U r o t ;V z ¼U z þb R o U zo t:ð9Þwhere,U r and U z are the radial and axial components of thedisplacement vector U ,respectively,and a R and b R are the coefficients of Raleigh damping,which are commonly expressed as a R ¼4pnf min f maxmin max;b R ¼nmin max ;ð10Þwhere n is the damping efficiency ranging between 0and 1,f min and f max stand for the lower and upper frequency in the working frequency range,respectively.For numeric cal-culations,f min and f max are chosen as 0.5an 90MHz,respectively.Initial and boundary conditions are set as H u ð0;r ;z Þ¼0;U z ð0;r ;z Þ¼0;U r ð0;r ;z Þ¼0;H u ðt ;r 0Þ¼I ðt Þ2p r 0;T ð0;r ;z Þ¼T 0;o T o r r ¼0¼0;o T o r r ¼r 0¼0;o E z o rr ¼0¼0ð11ÞThe free surface state determines boundary conditions for U z and U r in the Lame equation on the surface of the specimen:r r j y ¼r 0¼ð2l þk Þo U r o r þk o U z o z þU rr¼0;r u y ¼r 0¼ð2l þk ÞU r r þko U z o z þo U ro r¼0;r z j y ¼r 0¼ð2l þk Þo U z o z þk o U r o r þU rr¼0:ð12ÞThe boundary conditions on the Z axis in the centre ofthe specimen (r =0)take a form (due to the axial symmetry):U r ðt ;0;z Þ¼0;o U z o rt ;r ¼0;z¼0:ð13ÞThus,together with Eqs.2and 3,the problem is fully defined and can be solved numerically.Numerical estimates and discussionEquations 6,7,9and10were solved together with electric equations (2)and initial and boundary conditions (3,11–13).Numeric solutions were obtained using finite element method within a mesh constructed in r -z space having 1440elements and 794nodes.The Lagrange polynomial func-tions of the second order were taken for approximations.For illustrative purposes,the calculations of internal stresses caused by high-power short electric pulse passing through a conductive material have been performed for Cu cylinder of r 0=0.5-mm initial radius and 5-mm length (regretfully,for the SUS304steel,only few required material constants are known,which makes it impossible to perform quantitative modelling).All the other conditions were set the same as in [4],i.e.T 0=300K,C =0.1l F,R =0.3ohm,L =5nH and U 0=100kV.Figures 3and 4show the cumulative von Mises stresses arising from the linear thermal expansion and Lorentz force componentsr Von ÀMises ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffir 2r þr 2h þr 2z Àr r r h Àr r r z Àr h r z þ3r 2rzq ð14Þand its components calculated in cylindrical coordinates(r ,h ,z)for r =0(specimen axis)and r =0.5mm (specimen surface)in the middle of the specimen z =2.5mm.The shock-wave character of the stress tem-poral and spatial distribution is evident,particularly in Fig.5,where the snapshots of the axial component of von Mises stresses distribution over the specimen are shown in subsequent instants of time.The shock wave propagates from the surface to the bulk and back in an oscillating manner with attenuation caused by Raleigh damping introduced in Eqs.9.The duration of wave propagation depends on materials’properties and may vary from sev-eral microseconds to several milliseconds which is quite enough to activate subsonic or even trasonic dislocation motion and mechanical twinning,which can be viewed as a cooperative motion of several partial dislocations.While the r rz component is negligible both at the surface and in the bulk,the radial r r and axial r z and r u components may attain very high peak magnitudes of several gigapascals,which is not unexpected for shock wave loading.The average magnitude of stress components near the surface is notably higher than that in the bulk which accounts for the higher possibility to find the twinned domains in the sur-face proximity,i.e.decreasing twin density with the depth from the surface.Gerland et al.[12]used a surface treatment with shock waves caused by explosion in a thin layer applied to a 316L stainless steel.Similar to the results in this study,the near surface structure was found to be composed ofmechanicalFig.3Cumulative von Mises stress on the axis r =0and on the surface r =0.5mm of Cu cylinder subjected to theinfluence of the ultrahigh power short electric current pulse.The electric current magnitude I and surface temperature T areplotted for comparison and time scaling.T m —melting temperaturetwins,the density of which decreased with increasing depth.Firrao et al.[13]have also shown that mechanical twins are readily formed in the 304stainless steel subjected to stress impact caused by explosions of small charges in the surface vicinity.The benefits for the mechanical properties of the nanostructured steels produced by explo-sion influence is argued in [12,13].Ample evidence exists in the literature showing twin formation due to severe plastic deformation caused by intense ultrasonic shot peening [14],mechanical attrition [15]or shock pulse loading [16].The minute mechanisms of twin formation under shock wave loading have yet to be explored,possibly with the help of atomistic molecular dynamic simulations in a way similar to those performed in [17].The results of this study may serve as a starting point for further quan-titative modelling.They suggest that the high local stress conditions required for twin nucleation in the surface layer are fulfilled.Indeed,assuming the shear stress required for twin nucleation given as [18]s %c SFE b 1;ð15Þwhere c SFE is the stacking fault energy and b 1is the Burgers vector of the twinning dislocation b 1¼a 6121h i for an f.c.c.crystal with a —lattice parameter,and taking c SFE for the 304Fe–Cr–Ni steel of 17mJ/m 2[19],one estimates s &0.12GPa,which is notably smaller than the possible peak values of stress components in elastic waves arising in the body due to the ‘skin’treatment by a high-power electric pulse.Furthermore,twinning can be plausibly expected in the materials with much higher stacking fault energy under the same treatment conditions.Significant changes in the microstructure of skin-treated specimens and the formation of twin colonies in the sub-surface layer suggest that macrocharacteristics of treated metals may alter considerably.The Vickers microhardness HV was measured using a Shmiadzu dynamic Ultra-hard-ness tester DUH-1at 20-g load and 20-s exposure time.Ten to twenty measurements along the specimen gauge part were averaged.The depth of indentation did not exceed 2–3l m.The HV values in the specimens subjected to ‘skin’treatment with the capacitor discharge from 70,75and 80kV are found to be of 200±23HV,161±25HV and 140±27,respectively.All these values are notably higher than that for the reference of the ‘‘as-received’’SUS304sample—124±6HV,which is consistent with formation of the hardened twin nano-structure in thesurfaceFig.4Stress–tensor components (normal and shear)on the axis (a )and on the surface (b )of Cu cylinder subjected to the influence of the ultrahigh power short electric currentpulseFig.5Snapshots showing the von Mises stress distribution over the cylindrical specimen of 0.5-mm radius and 5-mm length in subsequent instants of timelayer.Interestingly,that discharging capacitors from smal-ler voltage (70kV)results in the highest hardness of the surface layer which agrees with microstructural observa-tions:populations of twins are easier to see in the 70-kV-treated specimens while the density of twins reduces with increasing voltage (this has been noticed earlier in ref.[5]).Furthermore,this is also consistent with numeric evaluation of the temperature profile in the subsurface layer,Fig.6:the thickness of the heated layer is found to be typically of the order of 100l m almost independently of the discharge voltage,which is considerably wider than the skin layer (50–10l m).However,the maximum temperature reached in the proximate vicinity of surface reduces sharply with voltage reduction.Even though this temperature reduces very quickly as we have discussed above (see [5]for details),this can be another argument why the nano-twin structure is more clearly seen after discharge from 70kV.One can 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