Multi-walled carbon nanotubes （MWNTs） were wet-milled in the presence of ammonia and cationic surfactant and then used as reinforcements to prepare Ni-P-MWNTs composite coatings by electroless plating. The tribologi...Multi-walled carbon nanotubes （MWNTs） were wet-milled in the presence of ammonia and cationic surfactant and then used as reinforcements to prepare Ni-P-MWNTs composite coatings by electroless plating. The tribological performances of the composite coatings under dry condition were investigated in comparison with 45 steel and conventional Ni-P coating, Micrographs show that short MWNTs with uniform length and open tips were obtained through the wet-milling process. The results of wear test reveal that the Ni-P-MWNTs composite coatings posses much better friction reduction and anti-wear performances when compared with 45 steel and Ni-P coating. Within the MWNTs content range of 0.74%-1.97%, the friction coefficient and the volume wear rate of the composite coatings decrease gradually and reach the minimum values of 0.08 and 6.22x10-15 m3/（N.m）, respectively. The excellent tribological performances of the composite coatings can be attributed to the introduction of MWNTs, which play both roles of reinforcements and solid lubricant during the wear process.展开更多
Carbon nanotubes （CNTs） reinforced aluminum matrix composites were fabricated by mechanical milling followed by hot extrusion. The commercial Al-2024 alloy with 1% CNTs was milled under various ball milling conditio...Carbon nanotubes （CNTs） reinforced aluminum matrix composites were fabricated by mechanical milling followed by hot extrusion. The commercial Al-2024 alloy with 1% CNTs was milled under various ball milling conditions. Microstructure evolution and mechanical properties of the milled powder and consolidated bulk materials were examined by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and mechanical test. The effect of CNTs concentration and milling time on the microstructure of the CNTs/Al-2024 composites was studied. Based on the structural observation, the formation behavior of nanostructure in ball milled powder was discussed. The results show that the increment in the milling time and ration speed, for a fixed amount of CNTs, causes a reduction of the particle size of powders resulting from MM. The finest particle size was obtained after 15 h of milling. Moreover, the composite had an increase in tensile strength due to the small amount of CNTs addition.展开更多
FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated...FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated.The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5,milling time of 2 h,ball-to-material mass ratio of 15:1 and milling with stainless steel ball.Then,the composites were characterized by XRD,SEM,FTIR,etc.The physicochemical properties of FeS2/Fe mixture change dramatically,which is responsible for its excellent performance.Finally,the stabilization process of FAS was optimized.When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min,the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.展开更多
The strengthening effect of fullerenes in aluminum matrix composites was investigated. The composites are produced using a two-step ball-milling technique combined with a hot rolling process. First, fullerene aggregat...The strengthening effect of fullerenes in aluminum matrix composites was investigated. The composites are produced using a two-step ball-milling technique combined with a hot rolling process. First, fullerene aggregates, where fullerene molecules initially come together to form giant particles(~200 μm in diameter) via van der Waals bonding, are shattered into smaller particles(~1 μm in diameter) by planetary milling. Second, primarily ball-milled fullerenes are dispersed in aluminum powder via attrition milling. Finally, aluminum/fullerene composite powder is consolidated by hot-rolling at 480 °C. For the composite sheet, grain refinement strengthening and dispersion hardening by fullerenes are accomplished at the same time, thereby exhibiting HV ~222 of Vickers hardness(e.g., ~740 MPa of yield strength) with only 2%(volume fraction) of fullerenes.展开更多
The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nan...The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.展开更多
The potential of powder metallurgy processing for the manufacture of Al?SrB6 composites was explored. Al4Sr particles fractured extensively during the ball milling of Al?15Sr/Al?4B powder mixtures. There was no intera...The potential of powder metallurgy processing for the manufacture of Al?SrB6 composites was explored. Al4Sr particles fractured extensively during the ball milling of Al?15Sr/Al?4B powder mixtures. There was no interaction between the Al4Sr and AlB2 compounds across the section of the aluminium grains in the as-milled state. SrB6 formed, when the ball milled powder blends were subsequently annealed at sufficiently high temperatures. Ball milling for 1 h was sufficient for SrB6 to become the major constituent in powder blends annealed at 700 °C while it took 2 h of ball milling for powder blends annealed at 600 °C. Higher annealing temperatures and longer ball milling time encouraged the formation of the SrB6 compound while the latter made a great impact on the microstructural features of the Al?SrB6 composite. The SrB6 compound particles were much smaller and more uniformly distributed across the aluminium matrix grains in powder grains ball milled for 2 h before the annealing treatments at 600 °C and 700 °C.展开更多
Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indica...Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indicating high crystalline and phase purity.The SEM and TEM images reveal that diameter of the spherical-like Na2FePO4F/C particles ranges from 50 to 300 nm,and HRTEM image shows that the surface of Na2FePO4F/C composite is uniformly coated by carbon layer with a average thickness of about 3.6 nm.The carbon coating constrains the growth of the particles and effectively reduces the agglomeration of nanoparticles.Using lithium metal as anode,the composite delivers a discharge capacities of 102.8,96.4 and 90.3 mA·h/g at rates of 0.5C,1C and 2C,respectively.After 100 cycles at 0.5C,a discharge capacity of 98.9 mA·h/g is maintained with capacity retention of 96.2%.The Li+diffusion coefficient(D)of Na2FePO4F/C composite is calculated as 1.71×10^–9 cm^2/s.This study reveals that the simple solid state reaction could be a practical and effective synthetic route for the industrial production of Na2FePO4F/C material.展开更多
Mg-x(Ti0.9 Zr0.2 Mn1.5 Cr0.3)(x=20%,30%,40%) (mass fraction) composite powders were prepared by reactive ball milling with hydrogen and their hydrogen storage properties and microstructure were investigated by XRD,SEM...Mg-x(Ti0.9 Zr0.2 Mn1.5 Cr0.3)(x=20%,30%,40%) (mass fraction) composite powders were prepared by reactive ball milling with hydrogen and their hydrogen storage properties and microstructure were investigated by XRD,SEM and pressure-composition-temperature measurement.The results show that the composites have 3.83%-5.07%hydrogen capacity at 553 K and good hydrogenation kinetics,even at room temperature.Among them,the milled Mg-30%(Ti0.9Zr0.2Mn1.5Cr0.3)composite has the highest hydrogenation kinetics as it can quickly absorb 2.1%hydrogen at 373 K,3.5%in 2 000 s at 473 K,even 3.26%in 60 s at 553 K under 3 MPa hydrogen pressure.The improved hydrogenation properties come from the catalytic effect of Ti0.9 Zr0.2 Mn1.5 Cr0.3 particles dispersed uniformly on the surface of Mg particles.展开更多
基金Project (JPPT-115-5-1759) supported by the National Defense Science and Technology Industry Committee of China Project (20090162120080) supported by Research Fund for the Doctoral Program of Higher Education of ChinaProject (2010FJ3012) supported by the Program of Science and Technology of Hunan Province, China
文摘Multi-walled carbon nanotubes （MWNTs） were wet-milled in the presence of ammonia and cationic surfactant and then used as reinforcements to prepare Ni-P-MWNTs composite coatings by electroless plating. The tribological performances of the composite coatings under dry condition were investigated in comparison with 45 steel and conventional Ni-P coating, Micrographs show that short MWNTs with uniform length and open tips were obtained through the wet-milling process. The results of wear test reveal that the Ni-P-MWNTs composite coatings posses much better friction reduction and anti-wear performances when compared with 45 steel and Ni-P coating. Within the MWNTs content range of 0.74%-1.97%, the friction coefficient and the volume wear rate of the composite coatings decrease gradually and reach the minimum values of 0.08 and 6.22x10-15 m3/（N.m）, respectively. The excellent tribological performances of the composite coatings can be attributed to the introduction of MWNTs, which play both roles of reinforcements and solid lubricant during the wear process.
基金Project(2012CB619503)supported by the National Basic Research Program of ChinaProject(2013AA031001)supported by the National High-tech Research and Development Program of ChinaProject(2012DFA50630)supported by the International Science&Technology Cooperation Program of China
文摘Carbon nanotubes （CNTs） reinforced aluminum matrix composites were fabricated by mechanical milling followed by hot extrusion. The commercial Al-2024 alloy with 1% CNTs was milled under various ball milling conditions. Microstructure evolution and mechanical properties of the milled powder and consolidated bulk materials were examined by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and mechanical test. The effect of CNTs concentration and milling time on the microstructure of the CNTs/Al-2024 composites was studied. Based on the structural observation, the formation behavior of nanostructure in ball milled powder was discussed. The results show that the increment in the milling time and ration speed, for a fixed amount of CNTs, causes a reduction of the particle size of powders resulting from MM. The finest particle size was obtained after 15 h of milling. Moreover, the composite had an increase in tensile strength due to the small amount of CNTs addition.
基金Projects(2018YFC1900305,2018YFC1903301)supported by the National Key R&D Program of ChinaProject(51825403)supported by the National Natural Science Foundation for Distinguished Young Scholars of China+1 种基金Project(51634010)supported by the National Natural Science Foundation of ChinaProject(2017RS3010)supported by the Science and Technology Program of Hunan Province,China
文摘FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated.The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5,milling time of 2 h,ball-to-material mass ratio of 15:1 and milling with stainless steel ball.Then,the composites were characterized by XRD,SEM,FTIR,etc.The physicochemical properties of FeS2/Fe mixture change dramatically,which is responsible for its excellent performance.Finally,the stabilization process of FAS was optimized.When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min,the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.
基金supported in part by the New Faculty Research Program 2012 of Kookmin University in Koreathe support from the Priority Research Centers Program (2012-0006680)the Korea-Belarus Joint Research Program (2012-057348) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology
文摘The strengthening effect of fullerenes in aluminum matrix composites was investigated. The composites are produced using a two-step ball-milling technique combined with a hot rolling process. First, fullerene aggregates, where fullerene molecules initially come together to form giant particles(~200 μm in diameter) via van der Waals bonding, are shattered into smaller particles(~1 μm in diameter) by planetary milling. Second, primarily ball-milled fullerenes are dispersed in aluminum powder via attrition milling. Finally, aluminum/fullerene composite powder is consolidated by hot-rolling at 480 °C. For the composite sheet, grain refinement strengthening and dispersion hardening by fullerenes are accomplished at the same time, thereby exhibiting HV ~222 of Vickers hardness(e.g., ~740 MPa of yield strength) with only 2%(volume fraction) of fullerenes.
基金Iranian Nanotechnology Initiative (INI) for finical support of the research work
文摘The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.
文摘The potential of powder metallurgy processing for the manufacture of Al?SrB6 composites was explored. Al4Sr particles fractured extensively during the ball milling of Al?15Sr/Al?4B powder mixtures. There was no interaction between the Al4Sr and AlB2 compounds across the section of the aluminium grains in the as-milled state. SrB6 formed, when the ball milled powder blends were subsequently annealed at sufficiently high temperatures. Ball milling for 1 h was sufficient for SrB6 to become the major constituent in powder blends annealed at 700 °C while it took 2 h of ball milling for powder blends annealed at 600 °C. Higher annealing temperatures and longer ball milling time encouraged the formation of the SrB6 compound while the latter made a great impact on the microstructural features of the Al?SrB6 composite. The SrB6 compound particles were much smaller and more uniformly distributed across the aluminium matrix grains in powder grains ball milled for 2 h before the annealing treatments at 600 °C and 700 °C.
基金Projects(51472211,51502256)supported by the National Natural Science Foundation of ChinaProjects(2016GK4005,2016GK4030)supported by the Strategic New Industry of Hunan Province,ChinaProject(13C925)supported by the Research Foundation of Education Bureau of Hunan Province,China
文摘Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indicating high crystalline and phase purity.The SEM and TEM images reveal that diameter of the spherical-like Na2FePO4F/C particles ranges from 50 to 300 nm,and HRTEM image shows that the surface of Na2FePO4F/C composite is uniformly coated by carbon layer with a average thickness of about 3.6 nm.The carbon coating constrains the growth of the particles and effectively reduces the agglomeration of nanoparticles.Using lithium metal as anode,the composite delivers a discharge capacities of 102.8,96.4 and 90.3 mA·h/g at rates of 0.5C,1C and 2C,respectively.After 100 cycles at 0.5C,a discharge capacity of 98.9 mA·h/g is maintained with capacity retention of 96.2%.The Li+diffusion coefficient(D)of Na2FePO4F/C composite is calculated as 1.71×10^–9 cm^2/s.This study reveals that the simple solid state reaction could be a practical and effective synthetic route for the industrial production of Na2FePO4F/C material.
基金Projects(20833009,20873148,U0734005) supported by the National Natural Science Foundation of ChinaProject(2010CB631303) supported by the National Basic Research Program of China+2 种基金Project(2009A11GX052) supported by Dalian Science and Technology Foundation,ChinaProject(KFJJ10-1Z) supported by the State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,ChinaProject(Y4090507) supported by the Zhejiang Basic Research Program of China
文摘Mg-x(Ti0.9 Zr0.2 Mn1.5 Cr0.3)(x=20%,30%,40%) (mass fraction) composite powders were prepared by reactive ball milling with hydrogen and their hydrogen storage properties and microstructure were investigated by XRD,SEM and pressure-composition-temperature measurement.The results show that the composites have 3.83%-5.07%hydrogen capacity at 553 K and good hydrogenation kinetics,even at room temperature.Among them,the milled Mg-30%(Ti0.9Zr0.2Mn1.5Cr0.3)composite has the highest hydrogenation kinetics as it can quickly absorb 2.1%hydrogen at 373 K,3.5%in 2 000 s at 473 K,even 3.26%in 60 s at 553 K under 3 MPa hydrogen pressure.The improved hydrogenation properties come from the catalytic effect of Ti0.9 Zr0.2 Mn1.5 Cr0.3 particles dispersed uniformly on the surface of Mg particles.
