A heat resistant aluminum alloy pipe blank with dimensions of d 700/300 mm×1 200 mm was prepared by the multi layer spray deposition technology. Optical microscopy, X ray diffractometry and transmission electron ...A heat resistant aluminum alloy pipe blank with dimensions of d 700/300 mm×1 200 mm was prepared by the multi layer spray deposition technology. Optical microscopy, X ray diffractometry and transmission electron microscopy were used to analyze its morphologies and microstructures. The results show that the microstructures of the pipe blank are homogeneous and the precipitates are uniformly distributed d 25~70 nm spherical or sphere like Al 12 (Fe,V) 3Si particles, its mechanical properties at room temperature and 350 ℃ after densification by extrusion are σ b=412 MPa, δ =7.6% and σ b=187 MPa, δ =7.6%, respectively. The analyses indicate that the proper match of the motion rates of atomizer and substrate can produce deposited blanks with uniform thickness and relatively high cooling rate.展开更多
Two thixoforming technologies of 6066 aluminum alloy (Al 1.37Si 1.37Mg 0.77Cu 0.07Mn ) produced by multi layer spray deposition process were studied. The spray formed materials are of equiaxed and very fine grain (10...Two thixoforming technologies of 6066 aluminum alloy (Al 1.37Si 1.37Mg 0.77Cu 0.07Mn ) produced by multi layer spray deposition process were studied. The spray formed materials are of equiaxed and very fine grain (10~20 μm). And the grain size coarsens slower than that of conventional casting materials at temperature below the liquidus, which may relate to high temperature particles distributed along the grain boundaries. Extrusion and hot pressing were used as the thixoforming processes respectively. After extrusion the materials show a microstructure of mean grain size below 20 μm without obvious recrystallization. The mechanical properties achieved via extrusion and pressing in semi solid state attain that of common wrought materials with shorter peak aging time of 4~5 h, about half of that in conventional condition. [展开更多
Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl_3-NaCl melts were studied by cyclic voltammetry,chronopotentiometry and chronoamperometry.Cyclic voltammetry and chronopo- tentiome...Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl_3-NaCl melts were studied by cyclic voltammetry,chronopotentiometry and chronoamperometry.Cyclic voltammetry and chronopo- tentiometry analyses showed that Al(Ⅲ) was reduced at 200℃in two consecutive steps in an electrolyte of molten AlCl_3-NaCl system with a composition 52:48 molar ratio.The current-time characteristics of nucle- ation aluminum on tungsten showed a strong dependence on overpotentials.Chronoamperometry showed that the deposition process of aluminum on tungsten was controlled by an instantaneous nucleation with a hemispherical diffusion-controlled growth mechanism.The results could lead to a better understanding of the AlCl_3-NaCl melt system that has technological importance in electrodeposition of metals as well as in rechargeable batteries.展开更多
Metal aluminum (Al) thin films are prepared by 2450 MHz electron cyclotron resonance plasma-assisted atomic layer deposition on glass and p-Si substrates using trimethylaluminum as the precursor and hydrogen as the re...Metal aluminum (Al) thin films are prepared by 2450 MHz electron cyclotron resonance plasma-assisted atomic layer deposition on glass and p-Si substrates using trimethylaluminum as the precursor and hydrogen as the reductive gas. We focus our attention on the plasma source for the thin-film preparation and annealing of the as-deposited films relative to the surface square resistivity. The square resistivity of as-deposited Al films is greatly reduced after annealing and almost reaches the value of bulk metal. Through chemical and structural analysis, we conclude that the square resistivity is determined by neither the contaminant concentration nor the surface morphology, but by both the crystallinity and crystal size in this process.展开更多
The parameters for the electro-deposition of Cu were optimized in order to increase the compressive properties of close cell aluminum. Different values of deposition voltages and times were considered to vary the amou...The parameters for the electro-deposition of Cu were optimized in order to increase the compressive properties of close cell aluminum. Different values of deposition voltages and times were considered to vary the amount of deposited Cu. The surface morphology of the coating was observed by SEM and the compressive properties were evaluated by MTS. The results show that the coating is more homogeneous and compact with increasing voltage in a certain range, and beyond which, the coating quality decreases apparently. The reason is dedicated to the discharge rate of Cu2+ and nucleus formed in unit time. The compression results show three experienced stages: elastic deformation stage, collapse deformation stage and densification stage. After the electro-deposition of Cu, the elasticity modulus is increased obviously and the platform stress is also increased. Under the same strain, the stress of the aluminum foam with coating is reinforced comparing with the aluminum foam without coating. Furthermore, the platform area is widened apparently. In addition, Cu-SiC nanocomposite coatings are electrodeposited in alumium foams for further improving the mechanical characterization.展开更多
Cristobalite aluminum phosphate (C-AlPO_4) coatings were prepared by a hydrothermal electrophoretic deposition process on SiC-coated C/C composites. Phase compositions and microstructures of the as-prepared coatings w...Cristobalite aluminum phosphate (C-AlPO_4) coatings were prepared by a hydrothermal electrophoretic deposition process on SiC-coated C/C composites. Phase compositions and microstructures of the as-prepared coatings were characterized by XRD and SEM analyses. The influence of deposition voltage on the phase, microstructure and antioxidation property of the cristobalite aluminum phosphate coatings was investigated. Results show that the as-prepared coatings are composed of cristobalite aluminum phosphate crystallites. The thickness and density of cristobalite aluminum phosphate coatings are improved with the increase of deposition voltage. The deposition amount and bonding strength of the cristobalite aluminum phosphate coatings also increase with the increase of deposition voltage. The deposition mass per unit area of the coatings and the square root of the deposition time at different hydrothermal voltages satisfy linear relationship. The antioxidation property of the coated C/C composites is improved with the increase of deposition voltage. Compared with SiC coatings prepared by pack cementation, the multilayer coatings prepared by pack cementation with a later hydrothermal electrophoretic deposition process exhibit better antioxidation property. The as-prepared multi-coatings can effectively protect C/C composites from oxidation in air at 1 773 K for 37 h with a mass loss rate of 0.53%.展开更多
A novel ceramic rolling technique was developed to improve the formability of spray deposited porous aluminum alloy sheets,in which the sheet preform was canned and ceramic particulates were adopted as the medium for ...A novel ceramic rolling technique was developed to improve the formability of spray deposited porous aluminum alloy sheets,in which the sheet preform was canned and ceramic particulates were adopted as the medium for transferring pressure to make a homogenous hydrostatic stress field. The fractional thickness deformation,fractional longitudinal elongation,and fractional lateral spreading were calculated from the dimensions of samples before and after ceramic rolling. The results show that the flowing of metals in the longitudinal and transverse directions can be restrained during rolling. So ceramic rolling can effectively improve the density of the spray deposited performs. When the thickness reduction ratio is up to about 60%,the full density preforms can be obtained. The effect of the kinds of ceramic particulates,including Al2O3,SiO2 and graphite on the densification behavior of the preforms during rolling was investigated. The results imply that the Al2O3 particles with the size of about 74 μm are most effective.展开更多
Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ...Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ability of surface coating technology under technical and economic considerations to meet the increased demands for heavy tribological applications of aluminum alloys. Microplasma oxidation (MPO) technology has recently been studied as a novel and effective means to provide thick and hard ceramic coating with improved properties such as excellent load-bearing and wear resistance properties on aluminum alloys. The present work covers the evaluation of the performances of current single and duplex coatings combining MPO, physical vapor deposition (PVD), and plasma assisted chemical vapor deposition (PACVD) coatings on aluminum alloys. It suggests that the MPO coating is a promising candidate for design engineers to apply aluminum alloys to heavy load-bearing applications. The prospective future for the research on MPO coatings is introduced as well.展开更多
In this investigation, protective layers were formed on aluminum substrate by Plasma Electrolytic Deposition (PED) using sodium silicate solution. The relation between the thickness of the layer and process time were ...In this investigation, protective layers were formed on aluminum substrate by Plasma Electrolytic Deposition (PED) using sodium silicate solution. The relation between the thickness of the layer and process time were studied. XRD, SEM, EDS were used to study the layer’s structure, composition and micrograph. The results show that the deposited layers are amorphous and contain mainly oxygen, silicon, and aluminum. The possible formation mechanism of amorphous [Al-Si-O] layer was proposed: During discharge periods, A12O3 phase of the passive film and SiO32"near the substrate surface are sintered into xSiO2(l - x)Al2O, and then transformed into amorphous [Al-Si-O] phase.展开更多
The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the alu...The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the aluminum toxicity on pine seedlings, and the long-term soil acidification model(LTSAM) and a terrestrial biogeochemistry model(CENTURY) are used to simulate the influences of acid deposition on pine forest ecosystems. The indoor experiment results of aluminum toxicity show that aluminum ions in solution limit plant growth and acid deposition enhances this effect by facilitating the release of aluminum ions from the soil. Pine seedling biomass and root elongation decrease as the aluminum concentration increases. The results of model simulations show that the soil chemistry varies significantly with different changes in acid deposition. When the acid deposition increases, the pH value in the soil solution decreases and the soil Al^(3+) concentration increases. The increased acid deposition also has negative impacts on the forest ecosystem, i.e., decreases plant biomass, net primary productivity(NPP) and net CO_2 uptake. As a result, the soil organic carbon(SOC) decreases because of the limited supply of decomposition material. Thus acid deposition need be reduced to help protect the forest ecosystems.展开更多
This manuscript deals with the electro-deposition of Cu on aluminum foams. Metallic foams are highly porous materials which present complex structure of three-dimensional open cells. This aspect causes strong limitati...This manuscript deals with the electro-deposition of Cu on aluminum foams. Metallic foams are highly porous materials which present complex structure of three-dimensional open cells. This aspect causes strong limitations in mass transport due to electro-deposition technology. Experimental tests were performed to study the influence of the operational parameters on the overall performance of the coated aluminum foams. The experimental findings revealed that the manufactured metal foams were characterized by a high thermal conductivity and low process costs, making these materials very promising in many technological fields. On the basis of the experimental results, analytical models are proposed to predict the quantity and the quality characteristics of the coating.展开更多
A novel Al-based composite material (Al63Cu25Fe12)p/A356 was prepared by spray co-deposition. It is revealed that the reinforcement of Al63Cu25Fe12 quasicrystalline particles disperses uniformly in the composite with ...A novel Al-based composite material (Al63Cu25Fe12)p/A356 was prepared by spray co-deposition. It is revealed that the reinforcement of Al63Cu25Fe12 quasicrystalline particles disperses uniformly in the composite with small crystalline grain structure of about 10μm. The reaction between the Al63Cu25Fe12 quasicrystalline particle and the matrix metal is constrained or depressed because of the high cooling velocity in the process of spray co-deposition. Compared with the composite reinforced by non-continuous ceramics particle, the aging harden behavior of the composites of (Al63Cu25Fe12)p/A356 has outstanding characteristics with less time on aging peak happening and with higher hardening rate. The mechanical properties of the composites evidently enhance except plastic strain.展开更多
在冷金属过渡(cold metal transfer,CMT)电弧增材制造过程中,熔池的流动行为极易受到电弧和熔滴的影响,从而严重影响堆积层的稳定性和成形件质量.该文利用高速摄影结果及电信号参数波形图,引入热输入量计算公式,从特征电信号、熔滴过渡...在冷金属过渡(cold metal transfer,CMT)电弧增材制造过程中,熔池的流动行为极易受到电弧和熔滴的影响,从而严重影响堆积层的稳定性和成形件质量.该文利用高速摄影结果及电信号参数波形图,引入热输入量计算公式,从特征电信号、熔滴过渡特征量、热输入量等方面定量分析了CMT+P模式下送丝速度及脉冲修正系数对熔滴过渡过程及单道成形形貌的影响,同时分析了脉冲变极性冷金属过渡(Advanced CMT,CMT+PA)模式下送丝速度及控制面板上的EP/EN修正系数η对熔滴过渡过程及单道成形形貌的影响,为后续工艺优化提供参考和指导.展开更多
The weld appearance,deposition rate,welding efficiency,stability of arc,laser keyhole characteristic,and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum alloy...The weld appearance,deposition rate,welding efficiency,stability of arc,laser keyhole characteristic,and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum alloy. The results were also compared with those by conventional laser-MIG hybrid welding process. It was found that with the suitable process parameters this novel welding process for aluminum alloy was stable and final weld bead had fine appearance. Compared to conventional laser-MIG hybrid welding process,during this novel welding process the stability of arc,the laser keyhole characteristic and the weld property were similar,while the keyhole cycle frequency and keyhole opening area had differences of 1. 23% and 15. 34%,respectively,and the welding efficiency increased by about 31% without increasing heat input.展开更多
Despite the great achievements made in improvement of wear resistance properties of aluminum alloys, their applications in heavy surface load-bearing are limited. Single coating is insufficient to produce the desired ...Despite the great achievements made in improvement of wear resistance properties of aluminum alloys, their applications in heavy surface load-bearing are limited. Single coating is insufficient to produce the desired combination of surface properties. These problems can be solved through the duplex coatings. The aim of the present study is to overview the research advances on processes of duplex coatings on (aluminum) alloys combined with micro plasma oxidation process and with other modern processes such as physical vapour deposition and plasma assisted chemical vapour deposition and also to evaluate the performance of micro plasma oxidation coatings in improving the load-bearing, friction and wear resistance properties of aluminum alloys in comparison with other coatings. Wherein, a more detailed presentation of the processes and their performances and disadvantages are given as well.展开更多
文摘A heat resistant aluminum alloy pipe blank with dimensions of d 700/300 mm×1 200 mm was prepared by the multi layer spray deposition technology. Optical microscopy, X ray diffractometry and transmission electron microscopy were used to analyze its morphologies and microstructures. The results show that the microstructures of the pipe blank are homogeneous and the precipitates are uniformly distributed d 25~70 nm spherical or sphere like Al 12 (Fe,V) 3Si particles, its mechanical properties at room temperature and 350 ℃ after densification by extrusion are σ b=412 MPa, δ =7.6% and σ b=187 MPa, δ =7.6%, respectively. The analyses indicate that the proper match of the motion rates of atomizer and substrate can produce deposited blanks with uniform thickness and relatively high cooling rate.
文摘Two thixoforming technologies of 6066 aluminum alloy (Al 1.37Si 1.37Mg 0.77Cu 0.07Mn ) produced by multi layer spray deposition process were studied. The spray formed materials are of equiaxed and very fine grain (10~20 μm). And the grain size coarsens slower than that of conventional casting materials at temperature below the liquidus, which may relate to high temperature particles distributed along the grain boundaries. Extrusion and hot pressing were used as the thixoforming processes respectively. After extrusion the materials show a microstructure of mean grain size below 20 μm without obvious recrystallization. The mechanical properties achieved via extrusion and pressing in semi solid state attain that of common wrought materials with shorter peak aging time of 4~5 h, about half of that in conventional condition. [
基金supported by the National Basic Research Program of China (No.2007CB210305)the National Natural Science Foundation of China (Grant No.50674031).
文摘Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl_3-NaCl melts were studied by cyclic voltammetry,chronopotentiometry and chronoamperometry.Cyclic voltammetry and chronopo- tentiometry analyses showed that Al(Ⅲ) was reduced at 200℃in two consecutive steps in an electrolyte of molten AlCl_3-NaCl system with a composition 52:48 molar ratio.The current-time characteristics of nucle- ation aluminum on tungsten showed a strong dependence on overpotentials.Chronoamperometry showed that the deposition process of aluminum on tungsten was controlled by an instantaneous nucleation with a hemispherical diffusion-controlled growth mechanism.The results could lead to a better understanding of the AlCl_3-NaCl melt system that has technological importance in electrodeposition of metals as well as in rechargeable batteries.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11175024)the Beijing Natural Science Foundation, China (Grant No. 1112012)+1 种基金the Science and Technology on Surface Engineering Laboratorythe Beijing Education Committee, China (Grant Nos. BM201002, 2011BAD24B01, KM201110015008, KM201010015005, and PHR20110516)
文摘Metal aluminum (Al) thin films are prepared by 2450 MHz electron cyclotron resonance plasma-assisted atomic layer deposition on glass and p-Si substrates using trimethylaluminum as the precursor and hydrogen as the reductive gas. We focus our attention on the plasma source for the thin-film preparation and annealing of the as-deposited films relative to the surface square resistivity. The square resistivity of as-deposited Al films is greatly reduced after annealing and almost reaches the value of bulk metal. Through chemical and structural analysis, we conclude that the square resistivity is determined by neither the contaminant concentration nor the surface morphology, but by both the crystallinity and crystal size in this process.
基金Funded in Part by the Fundamental Research Funds for the Central Universities(Nos.300102318205,310831161020,310831163401)the National Natural Science Foundation of China(No.51301021)+2 种基金the China Postdoctoral Science Foundation(No.2016M592730)the Innovation and Entrepreneurship Training Program of Chang’an University(No.201610710084)the Fund of the State Key Laboratory of Solidification and Processing in Northwestern Polytechnical University(No.SKLSP201302)
文摘The parameters for the electro-deposition of Cu were optimized in order to increase the compressive properties of close cell aluminum. Different values of deposition voltages and times were considered to vary the amount of deposited Cu. The surface morphology of the coating was observed by SEM and the compressive properties were evaluated by MTS. The results show that the coating is more homogeneous and compact with increasing voltage in a certain range, and beyond which, the coating quality decreases apparently. The reason is dedicated to the discharge rate of Cu2+ and nucleus formed in unit time. The compression results show three experienced stages: elastic deformation stage, collapse deformation stage and densification stage. After the electro-deposition of Cu, the elasticity modulus is increased obviously and the platform stress is also increased. Under the same strain, the stress of the aluminum foam with coating is reinforced comparing with the aluminum foam without coating. Furthermore, the platform area is widened apparently. In addition, Cu-SiC nanocomposite coatings are electrodeposited in alumium foams for further improving the mechanical characterization.
基金Project(50772063) supported by the National Natural Science Foundation of China Project(NCET-06-0893) supported by the Foundation of New Century Excellent Talent in University of China+2 种基金 Project(20070708001) supported by the Doctorate Foundation of Ministry of Education of China Project(SJ08-ZT05) supported by the Natural Science Foundation of Shaanxi Province, ChinaProject supported by the Graduate Innovation Fund of Shaanxi University of Science and Technology, China
文摘Cristobalite aluminum phosphate (C-AlPO_4) coatings were prepared by a hydrothermal electrophoretic deposition process on SiC-coated C/C composites. Phase compositions and microstructures of the as-prepared coatings were characterized by XRD and SEM analyses. The influence of deposition voltage on the phase, microstructure and antioxidation property of the cristobalite aluminum phosphate coatings was investigated. Results show that the as-prepared coatings are composed of cristobalite aluminum phosphate crystallites. The thickness and density of cristobalite aluminum phosphate coatings are improved with the increase of deposition voltage. The deposition amount and bonding strength of the cristobalite aluminum phosphate coatings also increase with the increase of deposition voltage. The deposition mass per unit area of the coatings and the square root of the deposition time at different hydrothermal voltages satisfy linear relationship. The antioxidation property of the coated C/C composites is improved with the increase of deposition voltage. Compared with SiC coatings prepared by pack cementation, the multilayer coatings prepared by pack cementation with a later hydrothermal electrophoretic deposition process exhibit better antioxidation property. The as-prepared multi-coatings can effectively protect C/C composites from oxidation in air at 1 773 K for 37 h with a mass loss rate of 0.53%.
基金Project(06FJ3041) supported by Science and Technology Bureau of Hunan Province, China
文摘A novel ceramic rolling technique was developed to improve the formability of spray deposited porous aluminum alloy sheets,in which the sheet preform was canned and ceramic particulates were adopted as the medium for transferring pressure to make a homogenous hydrostatic stress field. The fractional thickness deformation,fractional longitudinal elongation,and fractional lateral spreading were calculated from the dimensions of samples before and after ceramic rolling. The results show that the flowing of metals in the longitudinal and transverse directions can be restrained during rolling. So ceramic rolling can effectively improve the density of the spray deposited performs. When the thickness reduction ratio is up to about 60%,the full density preforms can be obtained. The effect of the kinds of ceramic particulates,including Al2O3,SiO2 and graphite on the densification behavior of the preforms during rolling was investigated. The results imply that the Al2O3 particles with the size of about 74 μm are most effective.
文摘Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ability of surface coating technology under technical and economic considerations to meet the increased demands for heavy tribological applications of aluminum alloys. Microplasma oxidation (MPO) technology has recently been studied as a novel and effective means to provide thick and hard ceramic coating with improved properties such as excellent load-bearing and wear resistance properties on aluminum alloys. The present work covers the evaluation of the performances of current single and duplex coatings combining MPO, physical vapor deposition (PVD), and plasma assisted chemical vapor deposition (PACVD) coatings on aluminum alloys. It suggests that the MPO coating is a promising candidate for design engineers to apply aluminum alloys to heavy load-bearing applications. The prospective future for the research on MPO coatings is introduced as well.
基金supported by the National Natural Sciences Foundation of China(50071066)
文摘In this investigation, protective layers were formed on aluminum substrate by Plasma Electrolytic Deposition (PED) using sodium silicate solution. The relation between the thickness of the layer and process time were studied. XRD, SEM, EDS were used to study the layer’s structure, composition and micrograph. The results show that the deposited layers are amorphous and contain mainly oxygen, silicon, and aluminum. The possible formation mechanism of amorphous [Al-Si-O] layer was proposed: During discharge periods, A12O3 phase of the passive film and SiO32"near the substrate surface are sintered into xSiO2(l - x)Al2O, and then transformed into amorphous [Al-Si-O] phase.
基金Under the auspices of National Basic Research Program of China(No.2010CB951802,2005CB422207)Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-219)National High Technology Research and Development Program of China(No.2009AA122104)
文摘The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the aluminum toxicity on pine seedlings, and the long-term soil acidification model(LTSAM) and a terrestrial biogeochemistry model(CENTURY) are used to simulate the influences of acid deposition on pine forest ecosystems. The indoor experiment results of aluminum toxicity show that aluminum ions in solution limit plant growth and acid deposition enhances this effect by facilitating the release of aluminum ions from the soil. Pine seedling biomass and root elongation decrease as the aluminum concentration increases. The results of model simulations show that the soil chemistry varies significantly with different changes in acid deposition. When the acid deposition increases, the pH value in the soil solution decreases and the soil Al^(3+) concentration increases. The increased acid deposition also has negative impacts on the forest ecosystem, i.e., decreases plant biomass, net primary productivity(NPP) and net CO_2 uptake. As a result, the soil organic carbon(SOC) decreases because of the limited supply of decomposition material. Thus acid deposition need be reduced to help protect the forest ecosystems.
文摘This manuscript deals with the electro-deposition of Cu on aluminum foams. Metallic foams are highly porous materials which present complex structure of three-dimensional open cells. This aspect causes strong limitations in mass transport due to electro-deposition technology. Experimental tests were performed to study the influence of the operational parameters on the overall performance of the coated aluminum foams. The experimental findings revealed that the manufactured metal foams were characterized by a high thermal conductivity and low process costs, making these materials very promising in many technological fields. On the basis of the experimental results, analytical models are proposed to predict the quantity and the quality characteristics of the coating.
基金Project(50071030) supported by the National Natural Science Foundation of China
文摘A novel Al-based composite material (Al63Cu25Fe12)p/A356 was prepared by spray co-deposition. It is revealed that the reinforcement of Al63Cu25Fe12 quasicrystalline particles disperses uniformly in the composite with small crystalline grain structure of about 10μm. The reaction between the Al63Cu25Fe12 quasicrystalline particle and the matrix metal is constrained or depressed because of the high cooling velocity in the process of spray co-deposition. Compared with the composite reinforced by non-continuous ceramics particle, the aging harden behavior of the composites of (Al63Cu25Fe12)p/A356 has outstanding characteristics with less time on aging peak happening and with higher hardening rate. The mechanical properties of the composites evidently enhance except plastic strain.
文摘在冷金属过渡(cold metal transfer,CMT)电弧增材制造过程中,熔池的流动行为极易受到电弧和熔滴的影响,从而严重影响堆积层的稳定性和成形件质量.该文利用高速摄影结果及电信号参数波形图,引入热输入量计算公式,从特征电信号、熔滴过渡特征量、热输入量等方面定量分析了CMT+P模式下送丝速度及脉冲修正系数对熔滴过渡过程及单道成形形貌的影响,同时分析了脉冲变极性冷金属过渡(Advanced CMT,CMT+PA)模式下送丝速度及控制面板上的EP/EN修正系数η对熔滴过渡过程及单道成形形貌的影响,为后续工艺优化提供参考和指导.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX22_1311)the Natural Science Foundation of Jiangsu Province,China(No.BK20190684)the Natural Science Research of the Jiangsu Higher Education Institutions of China(No.18KJB460016)。
基金supported by the Key Science and Technology of Jilin Province(Grant No.20140204070GX)
文摘The weld appearance,deposition rate,welding efficiency,stability of arc,laser keyhole characteristic,and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum alloy. The results were also compared with those by conventional laser-MIG hybrid welding process. It was found that with the suitable process parameters this novel welding process for aluminum alloy was stable and final weld bead had fine appearance. Compared to conventional laser-MIG hybrid welding process,during this novel welding process the stability of arc,the laser keyhole characteristic and the weld property were similar,while the keyhole cycle frequency and keyhole opening area had differences of 1. 23% and 15. 34%,respectively,and the welding efficiency increased by about 31% without increasing heat input.
文摘Despite the great achievements made in improvement of wear resistance properties of aluminum alloys, their applications in heavy surface load-bearing are limited. Single coating is insufficient to produce the desired combination of surface properties. These problems can be solved through the duplex coatings. The aim of the present study is to overview the research advances on processes of duplex coatings on (aluminum) alloys combined with micro plasma oxidation process and with other modern processes such as physical vapour deposition and plasma assisted chemical vapour deposition and also to evaluate the performance of micro plasma oxidation coatings in improving the load-bearing, friction and wear resistance properties of aluminum alloys in comparison with other coatings. Wherein, a more detailed presentation of the processes and their performances and disadvantages are given as well.