In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in har...In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.展开更多
Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃...Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃ for 24 h after being heat treated at 1400 ℃ for 0.5 h. The in-situ composites consist of γ+α2 lamellar colonies, equiaxed y grains and Ti2AlN reinforcements. Matrix with nearly fully lamellar structure formed after solution and subsequently aging treatment. With the increase of Ti2AlN content, the nearly fully lamellar structure becomes instable for the aged composites. According to TEM study, fine Ti2AlN precipitates are found to distribute at the grain boundaries of lamellar colony. Needle-like Ti3AlN precipitates arrange in line with growing axis parallel to [001] direction of the γ-TiAl matrix and another needle-like Ti3AlN precipitates with lager size distribute at the dislocations. Key words:展开更多
Ternary Ag/AgC l/BiO IO3 composite photocatalysts are prepared by a facile method. Enhanced visible-light absorption and charge carrier separation are achieved after the introduction of Ag/AgC l particles into BiO IO3...Ternary Ag/AgC l/BiO IO3 composite photocatalysts are prepared by a facile method. Enhanced visible-light absorption and charge carrier separation are achieved after the introduction of Ag/AgC l particles into BiO IO3 systems,as revealed by ultraviolet-visible diffuse-reflectance spectrometry,photocurrent response and electrochemical impedance spectroscopy. The Ag/AgC l/BiO IO3 composites are applied to the visible-light photocatalytic oxidization of NO in air and exhibit an enhanced activity for NO removal in comparison with Ag/AgC l and pure BiO IO3. A possible photocatalytic mechanism for Ag/AgC l/BiO IO3 is proposed,which is related to the surface plasmon resonance effects of Ag metal and the effective carrier separation ability of BiO IO3. This work provides insight into the design and preparation of BiO IO3-based materials with enhanced visible-light photocatalysis ability.展开更多
Ag3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corro...Ag3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corrosion resistance of Ag3PO4. Herein, the Z-scheme WO3(H2O)0.333/Ag3PO4 composites are successfully prepared through microwave hydrothermal and simple stirring. The WO3(H2O)0.333/Ag3PO4 composites are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. In the degradation of organic pollutants, WO3(H2O)0.333/Ag3PO4 composites exhibit excellent performance under visible light. This is mainly attributed to the synergy of WO3(H2O)0.333 and Ag3PO4. Especially, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is the highest, and the methylene blue can be completely degraded in 4 min. In addition, the stability of the composites is also greatly enhanced. After five cycles of testing, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is not obviously decreased. However, the degradation efficiency of Ag3PO4 was only 20.2%. This indicates that adding WO3(H2O)0.333 can significantly improve the photoetching resistance of Ag3PO4. Finally, Z-scheme photocatalytic mechanism is investigated.展开更多
The effects of Ag on the microstructure, mechanical properties, and electrical conductivity of AA2024 aluminum alloy coating were investigated. It was fabricated by friction surfacing as an additive manufacturing proc...The effects of Ag on the microstructure, mechanical properties, and electrical conductivity of AA2024 aluminum alloy coating were investigated. It was fabricated by friction surfacing as an additive manufacturing process. To carry out this investigation, Ag was added by 5.3, 10.6, and 16.0 wt.% to an AA2024 consumable rod by inserting holes in it. It was found that due to the strengthening by solid solution and the formation of precipitates and intermetallic containing Ag, the driving force for grain growth is reduced and consequently the grain size of the coating is decreased. After artificial aging heat treatment, the electrical conductivities of the coatings containing 0 and 16.0 wt.% Ag are increased by 4.15%(IACS) and decreased by 2.15%(IACS), respectively. While considering a linear relationship, it can be proposed that for a 1 wt.% Ag increase, the strength and hardness of the coating will be increased by 1.8% and 1.0%, respectively. It was established that the effect of Al6(Cu,Ag)Mg4 precipitate formation on strengthening is greater than that of Ag-rich intermetallic.展开更多
Microstructure evolution and mechanical properties of the aging treated AlN/AZ91 composites were systematically investigated by optical microscopy(OM),high resolution scanning electron microscopy(HRSEM)with an energy ...Microstructure evolution and mechanical properties of the aging treated AlN/AZ91 composites were systematically investigated by optical microscopy(OM),high resolution scanning electron microscopy(HRSEM)with an energy dispersive spectrum(EDS),and high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM).The results show that the higher fracture elongation(14±1%)and ultimate tensile strength(275±6 MPa)were simultaneously obtained in the peak-aged AlN/AZ91 composites.Comparied with AZ91 matrix alloy,the strength was increased by about 44%and the elongation was approximately five times higher,which mainly attributed to the precipitation of nano-sizedγ-Mg_(17)Al_(12)phase and the activation of non-basal slip systems induced by in-situ AlN particles at room temperature.However,the in-situ formation of AlN reinforcements consumed part of Al element in the matrix alloy,which resulted into the volume fraction decreasing ofγ-Mg_(17)Al_(12)precipitates,and then the age hardening and strengthening efficiency were reduced in the AlN/AZ91 composites.On the other hand,the mismatch of thermal expansion coefficient between AlN particles and AZ91 matrix generated high density dislocations around AlN particles,which promoted the precipitation ofγ-Mg_(17)Al_(12)phase,and then the peak aging time and temperature were decreased.展开更多
The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic me...The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic method, an investigation has been undertaken by means of Vickers hardness measurement, scanning electron microscopy (SEM) and energy spectrum analyzing apparatus. The box-type heat treatment furnace was used in the study. The results showed that no discontinuous cellular precipitation is observed at the grain boundaries in the magnesium matrix of the composite while the MglTAI12 preferentially precipitates in the matrix. The time to reach the peak hardness for AZ61 alloy or SiCp/AZ61 magnesium matrix composites is reduced with the increase of aging temperature. At the same temperature, the composite exhibit an accelerated aging manner but lower aging efficiency, compared with the unreinforced matrix alloy. The microhardness of the composite is higher than that of the unreinforced matrix alloy, because that the SiC particles distributes homogeneously in the matrix alloy under the ultrasonic processing condition.展开更多
The complex nature of laser-material interaction causes non-stoichiometric ablation of alloy samples.This is attributed to matrix effect, which reduces analyzing capability. To address this issue, the analytical perfo...The complex nature of laser-material interaction causes non-stoichiometric ablation of alloy samples.This is attributed to matrix effect, which reduces analyzing capability. To address this issue, the analytical performance of three different normalization methods, namely normalization with background, internal normalization and three point smoothing techniques at different parameter settings is studied for quantification of Ag and Zn by Laser induced breakdown spectroscopy(LIBS).The LIBS spectra of five known concentration of silver zinc binary composites have been investigated at various laser irradiances(LIs). Calibration curves for both Ag(I) line(4d^(10)5s^2S_(1/2)→4d^(10)5p^2P_(1/2) at 338.28 nm) and Zn(I) line(4s5s^3S_1→4s4p^3P_2 at 481.053 nm) have been determined at LI of 5.86?×?10^(10)W cm^(-2). Slopes of these calibration curves provide the valuation of matrix effect in the Ag–Zn composites. With careful sample preparation and normalization after smoothing at optimum parameter setting(OPS), the minimization of sample matrix effect has been successfully achieved. A good linearity has been obtained in Ag and Zn calibration curve at OPS when normalized the whole area of spectrum after smoothing and the obtained coefficients of determination values were R^2?=?0.995 and 0.998 closer to 1. The results of matrix effect have been further verified by analysis of plasma parameters. Both plasma parameters showed no change with varying concentration at OPS. However, at high concentration of Ag, the observed significant changes in both plasma parameters at common parameter setting PS-1 and PS-2 were the gesture of matrix effect. In our case, the better analytical results were obtained at smoothing function with optimized parameter setting that indicates it is more efficient than normalization with background and internal normalization method.展开更多
Al2O3 short fiber reinforced Al-Cu composites containing 1%, 3%, 5% and 7% Cu were fabricated by a squeeze casting technique. The as-cast Al2O3/Al-Cu composites were solution treated at 535 ℃ and then aged at 170, 19...Al2O3 short fiber reinforced Al-Cu composites containing 1%, 3%, 5% and 7% Cu were fabricated by a squeeze casting technique. The as-cast Al2O3/Al-Cu composites were solution treated at 535 ℃ and then aged at 170, 190 and 210 ℃, respectively. Age hardening behavior of the Al2O3/Al-Cu composites was analyzed by measuring the hardness of the samples at different aging temperatures and aging time. Microstructures of the composites were observed by transmission electron microscope(TEM). The results indicate that the hardness of the Al2O3/Al-Cu composites containing 7% Cu is much higher than that containing 1%-5% Cu because of the large amount of CuAl2 precipitant in the Al2O3/Al-Cu composite. With the increase of Cu content from 1% to 7%, the time needed for the appearance of peak hardness shortened, indicating that the addition of Cu can accelerate the kinetic of CuAl2 precipitation in the Al2O3/Al-Cu composites. The Al2O3/Al-Cu composite containing 7% Cu shows the highest increment of hardness by aging treatment. Therefore, in order to get a higher peak hardness, the Al2O3/Al-Cu composites need more Cu addition as compared with the un-reinforced Al-Cu alloys.展开更多
The process of aging precipitation in a SiC(p)/ 6061 composites was investigated. Hardness testing.differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were employed. Theresults show that...The process of aging precipitation in a SiC(p)/ 6061 composites was investigated. Hardness testing.differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were employed. Theresults show that the main precipitation phase at the peak hardness is p' phase, and solution treatment at530℃ . followed by aging at 160℃ for 7 h, is a proper technique.展开更多
The electrical conductivity of Cu-10Ag in situ filamentary composite was studied during the deformation and annealing processes. The dependence of electrical resistivity of the deformed composites on the true strain p...The electrical conductivity of Cu-10Ag in situ filamentary composite was studied during the deformation and annealing processes. The dependence of electrical resistivity of the deformed composites on the true strain presents a two-stage change with increase of the true strain. The intermediate heat treatment and the stabilized annealing treatment to the deformed composite promote the separation of Ag precipitate, and increase the electrical conductivity. The maximum conductivity of the composite experienced the stabilizing heat treatment can reach about 97% IACS with σb≥400 MPa at 550 ℃ annealing, and reach about 70% IACS with σb≥1 250 MPa at 300 ℃ annealing. The corresponded strength of the composite was reported. The microstructure reason for the changes of the conductivity was discussed.展开更多
New powder metallurgy processing routes were designed to manufacture Ag ZnO electrical contact composites. Their physical properties, electrical contact properties and microstructures were investigated. By modelling ...New powder metallurgy processing routes were designed to manufacture Ag ZnO electrical contact composites. Their physical properties, electrical contact properties and microstructures were investigated. By modelling tests, it is shown that the requirements of commercial use were met. It is proved that Ag ZnO composites could be used to substitute toxic Ag CdO on large load electrical contactors.展开更多
The process of aging precipitation in SiC<sub>p</sub>/6061 and Al<sub>2</sub>O<sub>3</sub>/6061 composites were investigated. Hardness testing, differential scanning calorimetry(DS...The process of aging precipitation in SiC<sub>p</sub>/6061 and Al<sub>2</sub>O<sub>3</sub>/6061 composites were investigated. Hardness testing, differential scanning calorimetry(DSC) and transmission electron microscopy were employed. Results showed that the precipitation phase form directly along dislocation lines in the composites because the particles produce high densities of dislocations which makes vacancy densities in the composites decrease, and the main precipitation phase at peak hardness was β′ phase.展开更多
The in situ filamentary composites based on the Cu-10Ag and Cu-10Ag-Ce alloys were prepared. The microstructure and properties of the composites were studied. The effects of Ce addition on the microstructure as cast, ...The in situ filamentary composites based on the Cu-10Ag and Cu-10Ag-Ce alloys were prepared. The microstructure and properties of the composites were studied. The effects of Ce addition on the microstructure as cast, including refining Cu grains and the Ag filaments, increasing the proportion of (Cu+Ag) eutectic and decreasing the proportion of the Ag precipitate, were researched. The average size of the Ag filaments in the composites could be approached by a formula: d=C·exp(-0.228η), here C is a coefficient related to the size of the original grains and 1500 nm for Cu-10Ag and 800 nm for Cu-10Ag-Ce. A two-stage strain strengthening effect was found for the deformed composites, that is the dislocation strengthening at low strain stage and the ultra-fine Ag filaments or interface strengthening at the high strain stage. The intermediate heat treatment at lower temperature further refined the Ag filaments and therefore improved the properties. The high strengthening rate of Ce addition on Cu-10Ag alloy attributed the refining effect to Cu grains and Ag filaments. The typical properties of the heavy deformed composites with 1 IHT reached to UTS=1500 MPa with conductivity 62% IACS for the Cu-10Ag alloy and UTS=1550 MPa with conductivity 65% IACS for the Cu-10Ag-Ce alloy, respectively.展开更多
Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subsequently annealing method. Effects of annealing duration on the optical nonlinearity and ultrafast dynamics of Ag nanoparti...Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subsequently annealing method. Effects of annealing duration on the optical nonlinearity and ultrafast dynamics of Ag nanoparticles in glass were investigated by z-scan technique and pump-probe technique. The results indicate that the third-order optical nonlinearity increases with extending the annealing time, the fast decay process with lifetime of a few picoseconds is attributed to thermal equilibrium process of hot electrons and the energy transfer to lattices by interaction with phonons in the formed Ag nanoparticles, while the slow decay in more than one hundred picoseconds corresponds to the subsequent cooling process by a thermal diffusion from the Ag nanoparticle to the host matrix via the phonon-medium interaction. The fast decay process is accelerated with extending the annealing time.展开更多
文摘In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.
基金Project(2011CB605502)supported by the National Basic Research Program of ChinaProject(51001086)supported by the National Natural Science Foundation of China
文摘Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃ for 24 h after being heat treated at 1400 ℃ for 0.5 h. The in-situ composites consist of γ+α2 lamellar colonies, equiaxed y grains and Ti2AlN reinforcements. Matrix with nearly fully lamellar structure formed after solution and subsequently aging treatment. With the increase of Ti2AlN content, the nearly fully lamellar structure becomes instable for the aged composites. According to TEM study, fine Ti2AlN precipitates are found to distribute at the grain boundaries of lamellar colony. Needle-like Ti3AlN precipitates arrange in line with growing axis parallel to [001] direction of the γ-TiAl matrix and another needle-like Ti3AlN precipitates with lager size distribute at the dislocations. Key words:
基金supported by the National Natural Science Foundation of China(5147807051108487)the Science and Technology Project from Chongqing Education Commission(KJ1400617)~~
文摘Ternary Ag/AgC l/BiO IO3 composite photocatalysts are prepared by a facile method. Enhanced visible-light absorption and charge carrier separation are achieved after the introduction of Ag/AgC l particles into BiO IO3 systems,as revealed by ultraviolet-visible diffuse-reflectance spectrometry,photocurrent response and electrochemical impedance spectroscopy. The Ag/AgC l/BiO IO3 composites are applied to the visible-light photocatalytic oxidization of NO in air and exhibit an enhanced activity for NO removal in comparison with Ag/AgC l and pure BiO IO3. A possible photocatalytic mechanism for Ag/AgC l/BiO IO3 is proposed,which is related to the surface plasmon resonance effects of Ag metal and the effective carrier separation ability of BiO IO3. This work provides insight into the design and preparation of BiO IO3-based materials with enhanced visible-light photocatalysis ability.
基金supported by the National Natural Science Foundation of China(51572103 and 51502106)the Distinguished Young Scholar of Anhui Province(1808085J14)+2 种基金the Foundation for Young Talents in College of Anhui Province(gxyqZD2017051)the Key Foundation of Educational Commission of Anhui Province(KJ2016SD53)the Innovation Team of Design and Application of Advanced Energetic Materials(KJ2015TD003)~~
文摘Ag3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corrosion resistance of Ag3PO4. Herein, the Z-scheme WO3(H2O)0.333/Ag3PO4 composites are successfully prepared through microwave hydrothermal and simple stirring. The WO3(H2O)0.333/Ag3PO4 composites are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. In the degradation of organic pollutants, WO3(H2O)0.333/Ag3PO4 composites exhibit excellent performance under visible light. This is mainly attributed to the synergy of WO3(H2O)0.333 and Ag3PO4. Especially, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is the highest, and the methylene blue can be completely degraded in 4 min. In addition, the stability of the composites is also greatly enhanced. After five cycles of testing, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is not obviously decreased. However, the degradation efficiency of Ag3PO4 was only 20.2%. This indicates that adding WO3(H2O)0.333 can significantly improve the photoetching resistance of Ag3PO4. Finally, Z-scheme photocatalytic mechanism is investigated.
基金funding support of Babol Noshirvani University of Technology,Iran,through Grant Program No.BNUT/370167/99。
文摘The effects of Ag on the microstructure, mechanical properties, and electrical conductivity of AA2024 aluminum alloy coating were investigated. It was fabricated by friction surfacing as an additive manufacturing process. To carry out this investigation, Ag was added by 5.3, 10.6, and 16.0 wt.% to an AA2024 consumable rod by inserting holes in it. It was found that due to the strengthening by solid solution and the formation of precipitates and intermetallic containing Ag, the driving force for grain growth is reduced and consequently the grain size of the coating is decreased. After artificial aging heat treatment, the electrical conductivities of the coatings containing 0 and 16.0 wt.% Ag are increased by 4.15%(IACS) and decreased by 2.15%(IACS), respectively. While considering a linear relationship, it can be proposed that for a 1 wt.% Ag increase, the strength and hardness of the coating will be increased by 1.8% and 1.0%, respectively. It was established that the effect of Al6(Cu,Ag)Mg4 precipitate formation on strengthening is greater than that of Ag-rich intermetallic.
基金support for this research by the National Natural Science Foundation of China(Grant Nos.52071268,51771151)Key Laboratory of Interface Science and Engineering in Advanced Materials,Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China(Grant No.KLISEAM201603)+1 种基金State Key Laboratory of Advanced Metals and Materials(Grant No.2019-Z06)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(Grant No.CX201905).
文摘Microstructure evolution and mechanical properties of the aging treated AlN/AZ91 composites were systematically investigated by optical microscopy(OM),high resolution scanning electron microscopy(HRSEM)with an energy dispersive spectrum(EDS),and high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM).The results show that the higher fracture elongation(14±1%)and ultimate tensile strength(275±6 MPa)were simultaneously obtained in the peak-aged AlN/AZ91 composites.Comparied with AZ91 matrix alloy,the strength was increased by about 44%and the elongation was approximately five times higher,which mainly attributed to the precipitation of nano-sizedγ-Mg_(17)Al_(12)phase and the activation of non-basal slip systems induced by in-situ AlN particles at room temperature.However,the in-situ formation of AlN reinforcements consumed part of Al element in the matrix alloy,which resulted into the volume fraction decreasing ofγ-Mg_(17)Al_(12)precipitates,and then the age hardening and strengthening efficiency were reduced in the AlN/AZ91 composites.On the other hand,the mismatch of thermal expansion coefficient between AlN particles and AZ91 matrix generated high density dislocations around AlN particles,which promoted the precipitation ofγ-Mg_(17)Al_(12)phase,and then the peak aging time and temperature were decreased.
基金financially supported by the National Natural Science Foundation of China(Grant No.50765005)supported by the Innovative Group of Science and Technology of Colleges,Jiangxi Province,China(00008713)
文摘The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic method, an investigation has been undertaken by means of Vickers hardness measurement, scanning electron microscopy (SEM) and energy spectrum analyzing apparatus. The box-type heat treatment furnace was used in the study. The results showed that no discontinuous cellular precipitation is observed at the grain boundaries in the magnesium matrix of the composite while the MglTAI12 preferentially precipitates in the matrix. The time to reach the peak hardness for AZ61 alloy or SiCp/AZ61 magnesium matrix composites is reduced with the increase of aging temperature. At the same temperature, the composite exhibit an accelerated aging manner but lower aging efficiency, compared with the unreinforced matrix alloy. The microhardness of the composite is higher than that of the unreinforced matrix alloy, because that the SiC particles distributes homogeneously in the matrix alloy under the ultrasonic processing condition.
基金supported by National Natural Science Foundation of China (Nos. 11475039, 11705020, 11605023)Liaoning Provincial Natural Science Foundation of China (No. 20170540153)
文摘The complex nature of laser-material interaction causes non-stoichiometric ablation of alloy samples.This is attributed to matrix effect, which reduces analyzing capability. To address this issue, the analytical performance of three different normalization methods, namely normalization with background, internal normalization and three point smoothing techniques at different parameter settings is studied for quantification of Ag and Zn by Laser induced breakdown spectroscopy(LIBS).The LIBS spectra of five known concentration of silver zinc binary composites have been investigated at various laser irradiances(LIs). Calibration curves for both Ag(I) line(4d^(10)5s^2S_(1/2)→4d^(10)5p^2P_(1/2) at 338.28 nm) and Zn(I) line(4s5s^3S_1→4s4p^3P_2 at 481.053 nm) have been determined at LI of 5.86?×?10^(10)W cm^(-2). Slopes of these calibration curves provide the valuation of matrix effect in the Ag–Zn composites. With careful sample preparation and normalization after smoothing at optimum parameter setting(OPS), the minimization of sample matrix effect has been successfully achieved. A good linearity has been obtained in Ag and Zn calibration curve at OPS when normalized the whole area of spectrum after smoothing and the obtained coefficients of determination values were R^2?=?0.995 and 0.998 closer to 1. The results of matrix effect have been further verified by analysis of plasma parameters. Both plasma parameters showed no change with varying concentration at OPS. However, at high concentration of Ag, the observed significant changes in both plasma parameters at common parameter setting PS-1 and PS-2 were the gesture of matrix effect. In our case, the better analytical results were obtained at smoothing function with optimized parameter setting that indicates it is more efficient than normalization with background and internal normalization method.
基金Project(2006CB605203-3) supported by the National Basic Research Program of China
文摘Al2O3 short fiber reinforced Al-Cu composites containing 1%, 3%, 5% and 7% Cu were fabricated by a squeeze casting technique. The as-cast Al2O3/Al-Cu composites were solution treated at 535 ℃ and then aged at 170, 190 and 210 ℃, respectively. Age hardening behavior of the Al2O3/Al-Cu composites was analyzed by measuring the hardness of the samples at different aging temperatures and aging time. Microstructures of the composites were observed by transmission electron microscope(TEM). The results indicate that the hardness of the Al2O3/Al-Cu composites containing 7% Cu is much higher than that containing 1%-5% Cu because of the large amount of CuAl2 precipitant in the Al2O3/Al-Cu composite. With the increase of Cu content from 1% to 7%, the time needed for the appearance of peak hardness shortened, indicating that the addition of Cu can accelerate the kinetic of CuAl2 precipitation in the Al2O3/Al-Cu composites. The Al2O3/Al-Cu composite containing 7% Cu shows the highest increment of hardness by aging treatment. Therefore, in order to get a higher peak hardness, the Al2O3/Al-Cu composites need more Cu addition as compared with the un-reinforced Al-Cu alloys.
文摘The process of aging precipitation in a SiC(p)/ 6061 composites was investigated. Hardness testing.differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were employed. Theresults show that the main precipitation phase at the peak hardness is p' phase, and solution treatment at530℃ . followed by aging at 160℃ for 7 h, is a proper technique.
基金Project(50371031) supported by the National Natural Science Foundation of China
文摘The electrical conductivity of Cu-10Ag in situ filamentary composite was studied during the deformation and annealing processes. The dependence of electrical resistivity of the deformed composites on the true strain presents a two-stage change with increase of the true strain. The intermediate heat treatment and the stabilized annealing treatment to the deformed composite promote the separation of Ag precipitate, and increase the electrical conductivity. The maximum conductivity of the composite experienced the stabilizing heat treatment can reach about 97% IACS with σb≥400 MPa at 550 ℃ annealing, and reach about 70% IACS with σb≥1 250 MPa at 300 ℃ annealing. The corresponded strength of the composite was reported. The microstructure reason for the changes of the conductivity was discussed.
文摘New powder metallurgy processing routes were designed to manufacture Ag ZnO electrical contact composites. Their physical properties, electrical contact properties and microstructures were investigated. By modelling tests, it is shown that the requirements of commercial use were met. It is proved that Ag ZnO composites could be used to substitute toxic Ag CdO on large load electrical contactors.
文摘The process of aging precipitation in SiC<sub>p</sub>/6061 and Al<sub>2</sub>O<sub>3</sub>/6061 composites were investigated. Hardness testing, differential scanning calorimetry(DSC) and transmission electron microscopy were employed. Results showed that the precipitation phase form directly along dislocation lines in the composites because the particles produce high densities of dislocations which makes vacancy densities in the composites decrease, and the main precipitation phase at peak hardness was β′ phase.
文摘The in situ filamentary composites based on the Cu-10Ag and Cu-10Ag-Ce alloys were prepared. The microstructure and properties of the composites were studied. The effects of Ce addition on the microstructure as cast, including refining Cu grains and the Ag filaments, increasing the proportion of (Cu+Ag) eutectic and decreasing the proportion of the Ag precipitate, were researched. The average size of the Ag filaments in the composites could be approached by a formula: d=C·exp(-0.228η), here C is a coefficient related to the size of the original grains and 1500 nm for Cu-10Ag and 800 nm for Cu-10Ag-Ce. A two-stage strain strengthening effect was found for the deformed composites, that is the dislocation strengthening at low strain stage and the ultra-fine Ag filaments or interface strengthening at the high strain stage. The intermediate heat treatment at lower temperature further refined the Ag filaments and therefore improved the properties. The high strengthening rate of Ce addition on Cu-10Ag alloy attributed the refining effect to Cu grains and Ag filaments. The typical properties of the heavy deformed composites with 1 IHT reached to UTS=1500 MPa with conductivity 62% IACS for the Cu-10Ag alloy and UTS=1550 MPa with conductivity 65% IACS for the Cu-10Ag-Ce alloy, respectively.
基金Funded by the National Natural Science Foundation of China (No.50672069)Key Item for Basic Research of Shanghai (No.05JC14058)
文摘Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subsequently annealing method. Effects of annealing duration on the optical nonlinearity and ultrafast dynamics of Ag nanoparticles in glass were investigated by z-scan technique and pump-probe technique. The results indicate that the third-order optical nonlinearity increases with extending the annealing time, the fast decay process with lifetime of a few picoseconds is attributed to thermal equilibrium process of hot electrons and the energy transfer to lattices by interaction with phonons in the formed Ag nanoparticles, while the slow decay in more than one hundred picoseconds corresponds to the subsequent cooling process by a thermal diffusion from the Ag nanoparticle to the host matrix via the phonon-medium interaction. The fast decay process is accelerated with extending the annealing time.