In this study, compounded surface modification technology-high current pulsed electron beam （HCPEB） ＋ micro-plasma oxidation （MPO） was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of...In this study, compounded surface modification technology-high current pulsed electron beam （HCPEB） ＋ micro-plasma oxidation （MPO） was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB＋MPO compounded treatment were investigated by SEM. The results showed that the density of the ceramic layer of HCPEB＋MPO-treated ZK60 Mg alloy was improved and defects were reduced compared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treated by HCPEB＋MPO was divided into three zones, namely the top loose ceramic zone, middle compact zone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy before and after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamic polarization curves. It was found that the corrosion current density of ZK60 Mg alloys could be reduced by about three orders of magnitude, from 311μA/cm^2 of the original sample to 0.2μA/cm^2 of the HCPEB＋MPO-treated sample. This indicates the great application potential of the HCPEB＋MPO compounded surface modification technology in improving the corrosion resistance of ZK60 Mg alloys in the future.展开更多
The effect of boron doping on the sensitivity to environmental embrittlement of Ni3Al-based alloys was investigated in this paper. The results show that the ductilizing effect of boron in Ni3Al is partly to suppress ...The effect of boron doping on the sensitivity to environmental embrittlement of Ni3Al-based alloys was investigated in this paper. The results show that the ductilizing effect of boron in Ni3Al is partly to suppress moisture-induced hydrogen embrittlement.The mechanism of this suppressing effect of boron relates to its severely decreasing the hydrogen diffusivity by boron segregated at the grain boundaries. The surface reaction of Fe3Al with water vapor and oxygen was experimentally confirmed by AES and XPS analysis. The kinetics of these reactions can be used to explain the different ductility behavior of aluminides in various environments.展开更多
This paper treats adaptation to the machining precision and productivity of compound free-form surfaces. The principle of a mixed NC machining method (surface direct interpolating (SDI[1])and discrete NC programming) ...This paper treats adaptation to the machining precision and productivity of compound free-form surfaces. The principle of a mixed NC machining method (surface direct interpolating (SDI[1])and discrete NC programming) is introduced- Three adaptive procedures are discussed : ( 1 ) adaptivedivision of the machining areas, (2) adaptive triangulation for generating interference-free tool pathsfrom compound surfaces, (3) machining along surface/surface intersection (SSI ) curves with anadaptive step length. They upgrade the intelligence of machining compound surfaces.展开更多
Pathological effects of asbestos are probably dependent on the special surface properties of the fibers, such as surface charge, surface metal ions. The present study was designed to determine whether the pretreatment...Pathological effects of asbestos are probably dependent on the special surface properties of the fibers, such as surface charge, surface metal ions. The present study was designed to determine whether the pretreatment of chrysotile asbestos fibers (CAF) with rare earth compounds (REC) solution can reduce their pathogenicity. The results showed that REC-pretreated CAF induced less nitrogen oxide (NO) production by alveolar macrophages (AM). In addition, the pretreatment lowered the capacity of hemolysis and the methylene blue (MB) adsorption of the native CAF. These findings suggested that the pretreatment of CAF with REC solution reduced the in vitro toxicity of CAF by lessening its surface charges. Nevertheless, the pathogenicity and the carcinogenicity of REC-pretreated CAF in vivo remain to be investigated.展开更多
The surface composite modification of the 7050 aluminum alloy friction stir-welded joints was performed by shot peening(SP)/multiple rotation rolling(MRR)and MRR/SP,and the fatigue performance of the nugget zone(NZ)wa...The surface composite modification of the 7050 aluminum alloy friction stir-welded joints was performed by shot peening(SP)/multiple rotation rolling(MRR)and MRR/SP,and the fatigue performance of the nugget zone(NZ)was investigated.The results demonstrated that the fatigue life of SP/MRR samples is longer than that of MRR/SP.On the plane 150μm below the surface.The grains with high angle grain boundary account for 71.5%and 34.3%for MRR/SP and SP/MRR samples,respectively.The crack propagation path of the MRR/SP is transgranular and intergranular,and it is intergranular for the MRR/SP.Multitudinous fatigue striations and some voids appeared at the fracture during the stable crack propagation stage.However,fatigue striations for SP/MRR are with smaller spacing,fewer holes,and smaller size under SP/MRR compared with fatigue fracture of MRR/SP.The differences in fatigue properties and fracture characteristics of the NZ are related to the microstructure after the two combined surface modifications.展开更多
Two compounds,[Zn2（Hcppp）2（cppp）2（H2O）2]·2 NO3·6 H2O（1） and [Cd（Hcppp）2Cl2]· 3H2O（2）（Hcppp = 1-（2-carboxyl-phenyl）-3-（pyridin-2-yl）pyrazole）,are synthesized and characterized by IR,TGA...Two compounds,[Zn2（Hcppp）2（cppp）2（H2O）2]·2 NO3·6 H2O（1） and [Cd（Hcppp）2Cl2]· 3H2O（2）（Hcppp = 1-（2-carboxyl-phenyl）-3-（pyridin-2-yl）pyrazole）,are synthesized and characterized by IR,TGA and X-ray single-crystal/powder diffraction.Compound 1 crystallizes in monoclinic system,space group P21/c with a = 9.894（2）,b = 15.856（3）,c = 20.430（4） A,β = 101.70（3）°,V = 3138.5（11） A3,Z = 2,Mr = 1457.94,Dc = 1.543 g/cm^3,F（000） = 1504,R = 0.0278 and wR = 0.0749 for 6157 observed reflections（I 〉 2σ（I））.Compound 2 crystallizes in triclinic system,space group P1 with a = 9.1424（4）,b = 11.6427（5）,c = 16.1345（7） A,α = 102.6430（10）°,β = 95.4530（10）°,γ = 104.0060（10）°,V = 1605.94（12） A3,Z = 2,Mr = 767.88,Dc = 1.588 g/cm^3,F（000） = 776,R = 0.0307 and wR = 0.0764 for 6275 observed reflections（I 〉 2σ（I））.Compound 1 exhibits a binuclear structure while compound 2 shows a mononuclear structure.In compound 1,two cppp-ligands display the μ2-kN,N′：k O and two Hcppp ligands show the μ1-kN,N′ coordination modes.However,two Hcppp ligands connect one Cd（Ⅱ） cation and exhibit the μ1-kN,N′ binding mode in compound 2.The compounds are both studied using Hirshfeld surface analyses and 2D fingerprint plots.The luminescent properties are also discussed.展开更多
The parent compounds of the high-temperature cuprate superconductors are Mott insulators.It has been generally agreed that understanding the physics of the doped Mott insulators is essential to understanding the mecha...The parent compounds of the high-temperature cuprate superconductors are Mott insulators.It has been generally agreed that understanding the physics of the doped Mott insulators is essential to understanding the mechanism of high temperature superconductivity.A natural starting point is to elucidate the basic electronic structure of the parent compound.Here we report comprehensive high resolution angle-resolved photoemission measurements on Ca_2CuO_2Cl_2,a Mott insulator and a prototypical parent compound of the cuprates.Multiple underl.ying Fermi surface sheets are revealed for the first time.The high energy waterfall-like band dispersions exhibit different behaviors near the nodal and antinodal regions.Two distinct energy scales are identified：a d-wave-like low energy peak dispersion and a nearly isotropic lower Hubbard band gap.These observations provide new information of the electronic structure of the cuprate parent compound,which is important for understanding the anomalous physical properties and superconductivity mechanism of the high temperature cuprate superconductors.展开更多
A new trough imaging solar collector with multiple compounding curved surfaces has been designed. Its working principle and design parameters have been introduced. The experimental curve of temperature rising of the s...A new trough imaging solar collector with multiple compounding curved surfaces has been designed. Its working principle and design parameters have been introduced. The experimental curve of temperature rising of the system with time under the real weather has been given. The system efficiency and the relation between efficiency and temperature have been calculated. The test result shows that the system has the advantages of high collecting temperature and not obvious variety of the collecting efficiency with the operating temperature. Therefore, this collector is a quite ideal medium temperature solar collector.展开更多
Research work and recent progress made toward the industrial applications of the Ni_3Al in CISRI are discussed in present paper. The development of a Ni_3Al base alloy named MX-246 hardened by carbides and fine disper...Research work and recent progress made toward the industrial applications of the Ni_3Al in CISRI are discussed in present paper. The development of a Ni_3Al base alloy named MX-246 hardened by carbides and fine dispersion of disordered γ is summaried. This alloy,with higher peak temperature of yield strength and higher strain hardening rate than alloyIC-218,has been successfully used as the material of rolling guider at elevated temperatures and in wear conditions. The Ni3Al base alloy of GH264 has been made into welding electrodes by horizontal continuous casting process, and recently successfully surfacing welded on hydraulic blades as cavitation erosion resistance material. The process of remelting Ni3Al base alloy in air was also developed. The processes of producing welding electrodes and remelting in air set the base of industrial applications of Ni3Al in welding, repairing and casting in mass production and into components of large size. Another application of the compound, manufacturing the jet engine rivets used at about 1300℃ , can be attributed to its excellent oxidation resistance and still keeping high strength up to the melting point.展开更多
Here, a new idea was proposed for template-free synthesis of hierarchical m-ZrO2 nanorods and ＂their＂ possible formation mechanism based on a series of chemical reactions by simple hydrothermal method. The tradition...Here, a new idea was proposed for template-free synthesis of hierarchical m-ZrO2 nanorods and ＂their＂ possible formation mechanism based on a series of chemical reactions by simple hydrothermal method. The traditional preparation methods of hierarchical ZrO2 nanorods involved inexpensive equipment, complicated process, and high production cost. The as-synthesized products composed of many nanorods with 180-200 nm in diameter and 5-7 μm in length. The fi nal product after annealing involved hierarchical monoclinic ZrO2（m-ZrO2） nanorods, namely, the big nanorod was made up of many small nanorods with 40-50 nm in diameter and 500-600 nm in length. The experimental results were useful in understanding the chemical properties of ZrB2 and ZrO2 and the design of the derivatives for m-ZrO2 nanomaterials.展开更多
Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The r...Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled.展开更多
基金supported by Liaoning BaiQianWan Talents Program of China (No. 2008921028)Doctoral Fund of Ministry of Education of China (No. 200801451082)
文摘In this study, compounded surface modification technology-high current pulsed electron beam （HCPEB） ＋ micro-plasma oxidation （MPO） was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB＋MPO compounded treatment were investigated by SEM. The results showed that the density of the ceramic layer of HCPEB＋MPO-treated ZK60 Mg alloy was improved and defects were reduced compared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treated by HCPEB＋MPO was divided into three zones, namely the top loose ceramic zone, middle compact zone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy before and after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamic polarization curves. It was found that the corrosion current density of ZK60 Mg alloys could be reduced by about three orders of magnitude, from 311μA/cm^2 of the original sample to 0.2μA/cm^2 of the HCPEB＋MPO-treated sample. This indicates the great application potential of the HCPEB＋MPO compounded surface modification technology in improving the corrosion resistance of ZK60 Mg alloys in the future.
文摘The effect of boron doping on the sensitivity to environmental embrittlement of Ni3Al-based alloys was investigated in this paper. The results show that the ductilizing effect of boron in Ni3Al is partly to suppress moisture-induced hydrogen embrittlement.The mechanism of this suppressing effect of boron relates to its severely decreasing the hydrogen diffusivity by boron segregated at the grain boundaries. The surface reaction of Fe3Al with water vapor and oxygen was experimentally confirmed by AES and XPS analysis. The kinetics of these reactions can be used to explain the different ductility behavior of aluminides in various environments.
文摘This paper treats adaptation to the machining precision and productivity of compound free-form surfaces. The principle of a mixed NC machining method (surface direct interpolating (SDI[1])and discrete NC programming) is introduced- Three adaptive procedures are discussed : ( 1 ) adaptivedivision of the machining areas, (2) adaptive triangulation for generating interference-free tool pathsfrom compound surfaces, (3) machining along surface/surface intersection (SSI ) curves with anadaptive step length. They upgrade the intelligence of machining compound surfaces.
文摘Pathological effects of asbestos are probably dependent on the special surface properties of the fibers, such as surface charge, surface metal ions. The present study was designed to determine whether the pretreatment of chrysotile asbestos fibers (CAF) with rare earth compounds (REC) solution can reduce their pathogenicity. The results showed that REC-pretreated CAF induced less nitrogen oxide (NO) production by alveolar macrophages (AM). In addition, the pretreatment lowered the capacity of hemolysis and the methylene blue (MB) adsorption of the native CAF. These findings suggested that the pretreatment of CAF with REC solution reduced the in vitro toxicity of CAF by lessening its surface charges. Nevertheless, the pathogenicity and the carcinogenicity of REC-pretreated CAF in vivo remain to be investigated.
基金supported by the National Natural Science Foundation of China(Grants 51865028)the Gansu Provincial Science and Technology Planning Project(Grant No.20YF8GA056).
文摘The surface composite modification of the 7050 aluminum alloy friction stir-welded joints was performed by shot peening(SP)/multiple rotation rolling(MRR)and MRR/SP,and the fatigue performance of the nugget zone(NZ)was investigated.The results demonstrated that the fatigue life of SP/MRR samples is longer than that of MRR/SP.On the plane 150μm below the surface.The grains with high angle grain boundary account for 71.5%and 34.3%for MRR/SP and SP/MRR samples,respectively.The crack propagation path of the MRR/SP is transgranular and intergranular,and it is intergranular for the MRR/SP.Multitudinous fatigue striations and some voids appeared at the fracture during the stable crack propagation stage.However,fatigue striations for SP/MRR are with smaller spacing,fewer holes,and smaller size under SP/MRR compared with fatigue fracture of MRR/SP.The differences in fatigue properties and fracture characteristics of the NZ are related to the microstructure after the two combined surface modifications.
基金supported by the National Natural Science Foundation of China(Nos.21571118 and 21671124)the Natural Science Foundation of Shanxi Province(2015021031)A portion of this work was performed on the Scientific Instrument Center of Shanxi University of China
文摘Two compounds,[Zn2（Hcppp）2（cppp）2（H2O）2]·2 NO3·6 H2O（1） and [Cd（Hcppp）2Cl2]· 3H2O（2）（Hcppp = 1-（2-carboxyl-phenyl）-3-（pyridin-2-yl）pyrazole）,are synthesized and characterized by IR,TGA and X-ray single-crystal/powder diffraction.Compound 1 crystallizes in monoclinic system,space group P21/c with a = 9.894（2）,b = 15.856（3）,c = 20.430（4） A,β = 101.70（3）°,V = 3138.5（11） A3,Z = 2,Mr = 1457.94,Dc = 1.543 g/cm^3,F（000） = 1504,R = 0.0278 and wR = 0.0749 for 6157 observed reflections（I 〉 2σ（I））.Compound 2 crystallizes in triclinic system,space group P1 with a = 9.1424（4）,b = 11.6427（5）,c = 16.1345（7） A,α = 102.6430（10）°,β = 95.4530（10）°,γ = 104.0060（10）°,V = 1605.94（12） A3,Z = 2,Mr = 767.88,Dc = 1.588 g/cm^3,F（000） = 776,R = 0.0307 and wR = 0.0764 for 6275 observed reflections（I 〉 2σ（I））.Compound 1 exhibits a binuclear structure while compound 2 shows a mononuclear structure.In compound 1,two cppp-ligands display the μ2-kN,N′：k O and two Hcppp ligands show the μ1-kN,N′ coordination modes.However,two Hcppp ligands connect one Cd（Ⅱ） cation and exhibit the μ1-kN,N′ binding mode in compound 2.The compounds are both studied using Hirshfeld surface analyses and 2D fingerprint plots.The luminescent properties are also discussed.
基金Supported by the National Key Research and Development Program of China(2016YFA0300300)the National Natural Science Foundation of China(11334010 and 11534007)+1 种基金the National Basic Research Program of China(2015CB921000)the Strategic Priority Research Program(B)of Chinese Academy of Sciences(XDB07020300)
文摘The parent compounds of the high-temperature cuprate superconductors are Mott insulators.It has been generally agreed that understanding the physics of the doped Mott insulators is essential to understanding the mechanism of high temperature superconductivity.A natural starting point is to elucidate the basic electronic structure of the parent compound.Here we report comprehensive high resolution angle-resolved photoemission measurements on Ca_2CuO_2Cl_2,a Mott insulator and a prototypical parent compound of the cuprates.Multiple underl.ying Fermi surface sheets are revealed for the first time.The high energy waterfall-like band dispersions exhibit different behaviors near the nodal and antinodal regions.Two distinct energy scales are identified：a d-wave-like low energy peak dispersion and a nearly isotropic lower Hubbard band gap.These observations provide new information of the electronic structure of the cuprate parent compound,which is important for understanding the anomalous physical properties and superconductivity mechanism of the high temperature cuprate superconductors.
基金Acknowledgments This work is supported by the National Natural Science Foundation of China （No.50576004） and National ＂863＂ Hi-Tech Development Program of China （No.2007AA05Z433）.
文摘A new trough imaging solar collector with multiple compounding curved surfaces has been designed. Its working principle and design parameters have been introduced. The experimental curve of temperature rising of the system with time under the real weather has been given. The system efficiency and the relation between efficiency and temperature have been calculated. The test result shows that the system has the advantages of high collecting temperature and not obvious variety of the collecting efficiency with the operating temperature. Therefore, this collector is a quite ideal medium temperature solar collector.
文摘Research work and recent progress made toward the industrial applications of the Ni_3Al in CISRI are discussed in present paper. The development of a Ni_3Al base alloy named MX-246 hardened by carbides and fine dispersion of disordered γ is summaried. This alloy,with higher peak temperature of yield strength and higher strain hardening rate than alloyIC-218,has been successfully used as the material of rolling guider at elevated temperatures and in wear conditions. The Ni3Al base alloy of GH264 has been made into welding electrodes by horizontal continuous casting process, and recently successfully surfacing welded on hydraulic blades as cavitation erosion resistance material. The process of remelting Ni3Al base alloy in air was also developed. The processes of producing welding electrodes and remelting in air set the base of industrial applications of Ni3Al in welding, repairing and casting in mass production and into components of large size. Another application of the compound, manufacturing the jet engine rivets used at about 1300℃ , can be attributed to its excellent oxidation resistance and still keeping high strength up to the melting point.
基金Funded by the Ministry of Science and Technology of China(S2010GR0771)the National Natural Science Foundation of China(51161140399)
文摘Here, a new idea was proposed for template-free synthesis of hierarchical m-ZrO2 nanorods and ＂their＂ possible formation mechanism based on a series of chemical reactions by simple hydrothermal method. The traditional preparation methods of hierarchical ZrO2 nanorods involved inexpensive equipment, complicated process, and high production cost. The as-synthesized products composed of many nanorods with 180-200 nm in diameter and 5-7 μm in length. The fi nal product after annealing involved hierarchical monoclinic ZrO2（m-ZrO2） nanorods, namely, the big nanorod was made up of many small nanorods with 40-50 nm in diameter and 500-600 nm in length. The experimental results were useful in understanding the chemical properties of ZrB2 and ZrO2 and the design of the derivatives for m-ZrO2 nanomaterials.
基金supported by the National Basic Research Program of China (No.2011CB606404)the National Natural Science Foundation of China (No.51171195)the GM Research Project
文摘Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled.
