The influence of grain size or grain refinement on the corrosion of Zr alloy is clarified by employing a series of electrochemical analyses and characterization techniques.The corrosion resistance,as a function of exp...The influence of grain size or grain refinement on the corrosion of Zr alloy is clarified by employing a series of electrochemical analyses and characterization techniques.The corrosion resistance,as a function of exposure time,F−concentration,and solution temperatures,of Zr alloys with different grain sizes is ascertained.The results confirm that refining the grain size can effectively enhance the short-time corrosion properties of Zr alloy in HNO_(3) with F−.The fine grained Zr alloy(~10μm in diameter)consistently exhibits a lower corrosion current density,ranging from 18%to 46%lower than that of the coarse-grained Zr alloy(~44μm).The enhanced corrosion resistance is attributed to the high density grain boundaries,which promote oxide stability,and accelerate the creation of the protective layer.The high corrosion rate and pseudo-passivation behavior of Zr alloys in fluorinated nitric acid originate from the accelerated“dissolution-passivation”of the oxide film.However,the grain refinement does not provide enduring anti-corrosion for Zr alloys.To meet the operation of spent fuel reprocessing,additional systematic efforts are required to evaluate the long term effect of grain refinement.展开更多
A numerical approach for process optimization and microstructure evolution of lager-sized forging of aluminium alloy 7050 was proposed, which combined a commercial FEM code Deform 3D with empirical models. To obtain t...A numerical approach for process optimization and microstructure evolution of lager-sized forging of aluminium alloy 7050 was proposed, which combined a commercial FEM code Deform 3D with empirical models. To obtain the parameters of empirical constitutive equation and dynamic recrystallization models for aluminium alloy 7050, the isothermal compression tests of 7050 samples were performed on Gleeble-1500 thermo-simulation machine in the temperature range of 250-450 ℃ and strain rate of 0.01-10 s-1, and the metallograph analysis of the samples were carried out on a Leica DMIRM image analyzer. The simulation results show that the dynamic recrystallization in the central area of the billet occurs more easily than that on the edge. Repetitious upsetting and stretching processes make the billet deform adequately. Among several forging processes e.g. upsetting, stretching, rounding and flatting, the stretching process is the most effective way to increase the effective strain and refine the microstructure of the billet. As the forging steps increase, the effective strain rises significantly and the average grain size reduces sharply. Recrystallized volume fractions in most parts of the final forging piece reach 100% and the average grain size reduces to 10 μm from initial value of 90 μm.展开更多
The prediction of microstructure evolution plays an important role in the design of forging process. In the present work, the cellular automaton (CA) program was developed to simulate the process of dynamic recrystall...The prediction of microstructure evolution plays an important role in the design of forging process. In the present work, the cellular automaton (CA) program was developed to simulate the process of dynamic recrystallization (DRX) for aluminium alloy 7050. The material constants in CA models, including dislocation density, nucleation rate and grain growth, were determined by the isothermal compress tests on Gleeble 1500 machine. The model of dislocation density was obtained by linear regression method based on the experimental results. The influences of the deformation parameters on the percentage of DRX and the mean grain size for aluminium alloy 7050 were investigated in details by means of CA simulation. The simulation results show that, as temperature increases from 350 to 450 ℃ at a strain rate of 0.01 s?1, the percentage of DRX also increases greatly and the mean grain size decreases from 50 to 39.3 μm. The mean size of the recrystallied grains (R-grains) mainly depends on the Zener-Hollomon parameter. To obtain fine grain, the desired deformation temperature is determined from 400 to 450 ℃.展开更多
The influence of casting parameters on stray grain formation of a unidirectionally solidified superalloy IN738LC casting with three platforms was investigated by using a 3D cellular automaton-finite element （CAFE） m...The influence of casting parameters on stray grain formation of a unidirectionally solidified superalloy IN738LC casting with three platforms was investigated by using a 3D cellular automaton-finite element （CAFE） model in CALCOSOFT package. The model was first validated by comparison of the reported grain structure of AI-7%Si （mass fraction） alloy. Then, the influence of pouring temperature, heat flux of the lateral surface, convection heat coefficient of the cooled chill and mean undercooling of the bulk nucleation on the stray grain formation was studied during the unidirectional solidification. The predictions show that the stray grain formation is obviously sensitive to the pouring temperature, heat flux and mean undercooling of the bulk nucleation. However, increasing the heat convection coefficient has little influence on the stray grain formation.展开更多
The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test,optical microscopy,scanning electron ...The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test,optical microscopy,scanning electron microscopy and transmission electron microscopy.For the Zr-free alloy,the strength increases to the highest value at 20 s with transfer time,and then decreases slightly.The elongation decreases slowly with transfer time within 20 s,and more rapidly after 20 s.For the Zr-containing alloy,prolonging transfer time within 20 s results in slight decrease in the strength and elongation,and rapid drop of which is observed after 20 s.For the Zr-free alloy,prolonging transfer time can increase the percentage of intergranular fracture,which is mainly caused by wide grain boundary precipitate free zone.The failure mode of the Zr-containing alloy is modified from the predominant transgranular void growth and intergranular fracture to transgranular shear and intergranular fracture with increase in the transfer time,which is attributed to the wider grain boundary precipitate free zone and coarse equilibrium η phases in the matrix.展开更多
The effects of heat treatment and strontium(Sr) addition on the microstructure and mechanical properties of ADC1_(2) alloys were investigated,and two-stage solution treatment was introduced.The results indicated that ...The effects of heat treatment and strontium(Sr) addition on the microstructure and mechanical properties of ADC1_(2) alloys were investigated,and two-stage solution treatment was introduced.The results indicated that the addition of Sr obviously refined the microstructure of ADC12 alloys.When 0.05 wt%Sr was added into the alloy,the eutectic Si phase was fully modified into fine fibrous structure;a-A1 andβ-A1_(5)FeSi phases were best refined;and the eutectic AlzCu phase was modified into block-like AlzCu phase that continuously distributed at the grain boundary.The ultimate tensile strength(UTS)(270.63 MPa)and elongation(3.19%)were increased by 51.2%and 73.4%respectively compared with unmodified alloys.After the two-stage solution treatment(500℃,6 h+520℃,4 h),for 0.05 wt%Sr modified ADC12 alloys,the Si phases transformed into fine particle structure and Al_(2)Cu phases were fully dissolved.The peak hardness value of the alloys processed by the two-stage solution treatment was increased by 8.3%and 6.8%respectively compared to solution treatment at 500℃and 520℃.After the aging treatment(175℃,7 h),the hardness and UTS were increased by 38.73%and 13.96%respectively when compared with the unmodified alloy.展开更多
A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis ...A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （Co3W3C or Co6W6C） during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.展开更多
Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the comp...Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the composites were examined by XRD,SEM and EDS.The results show that no other intermetallic compounds beside Al3Ti can be in-situ synthesized.Around the titanium fibers,the reaction zones and diffusion zones can be obviously found.Due to the stirring of the electromagnetic function,the formation of the micro-cracks inside the reaction zone was conducive to the peeling off of the Al3Ti particles,and ensures the continuous reaction between liquid aluminum and titanium fibers,as well as the diffusion of Al3Ti particles.At the same time,there were secondary splits of Al3Ti particles located in diffusion zones.Two-body abrasion test shows that with the increase of induction heating power,the wear rates of the composites reduced and the number of grooves decreased.展开更多
Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and ind...Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors.Regardless of the superior features in Ti-MMC,however,referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part,the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability.Furthermore,adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied.Therefore,adequate knowledge of this regard is strongly demanded.Among machinability attributes,ultrafine particles(UFPs)and fine particles(FPs)have been selected as the main machinability attributes and the factors leading to minimized emission have been studied.According to experimental observations,despite the type of coating used,the use of higher levels of flow rate led to less UFPs,while no significant effects were observed on UFPs.Under similar cutting conditions,higher levels of FPs were recorded under the use of uncoated inserts.Moreover,cutting speed had no significant influence on UFPs;nevertheless,it significantly affects the FPs despite the type of insert used.展开更多
Due to the biological risks of using the conventional lubricants,the vegetable oils have been considered nowadays.Besides,to improve the tribological properties of the vegetable oils in various applications like metal...Due to the biological risks of using the conventional lubricants,the vegetable oils have been considered nowadays.Besides,to improve the tribological properties of the vegetable oils in various applications like metal forming processes,nanoparticles have been used as additives.This research evaluated the lubrication performance of the Al2O3 and TiO2 nanoparticles dispersed in rapeseed oil during the parallel tubular channel angular pressing (PTCAP) process.The experimental PTCAP tests have been fulfilled under three lubrication conditions and the comparison between the PTCAP processed tubes has been performed in terms of the maximum forming force,surface roughness,and microhardness.The experimental results indicate that adding the mentioned nanoparticles has caused at least a 50% reduction in the maximum deformation load.Moreover,a remarkable decrement in the surface roughness of the formed tubes has been obtained.展开更多
A reliable method for detecting nanoparticles is necessary for the wide application of nanomaterials. Single particle-inductively coupled plasma mass spectrometry(SP-ICP-MS) was investigated to detect the size of gold...A reliable method for detecting nanoparticles is necessary for the wide application of nanomaterials. Single particle-inductively coupled plasma mass spectrometry(SP-ICP-MS) was investigated to detect the size of gold nanoparticles(Au NPs) in this work. Discrimination of particle signal and iterative algorithm were used to calculate the baseline of particle signal. Influence of dwell time was discussed and 3 ms was selected as dwell time for size detection. Different Au NPs standards(30, 60, 80 and 100 nm) and mixed samples(60 and 100 nm) were determined by SP-ICP-MS and the accuracy was confirmed with reference values. The particle size detection limit was 19 nm in ultrapure water(UP water) and 31 nm in 0.1 μg/L Au^(3+) solution. Stability of Au NPs in ultrapure water and natural water samples was investigated by detecting size variation of AuN Ps. The result shows that Au NPs are stable in aqueous environment for 6 d but degraded after 30 d.展开更多
Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) ...Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.展开更多
基金Project(U2067217)supported by the National Natural Science Foundation of ChinaProject(SASTIND)supported by the State Administration of Science,Technology and Industry for National Defense,ChinaProject(2020M683572)supported by China Postdoctoral Science Foundation。
文摘The influence of grain size or grain refinement on the corrosion of Zr alloy is clarified by employing a series of electrochemical analyses and characterization techniques.The corrosion resistance,as a function of exposure time,F−concentration,and solution temperatures,of Zr alloys with different grain sizes is ascertained.The results confirm that refining the grain size can effectively enhance the short-time corrosion properties of Zr alloy in HNO_(3) with F−.The fine grained Zr alloy(~10μm in diameter)consistently exhibits a lower corrosion current density,ranging from 18%to 46%lower than that of the coarse-grained Zr alloy(~44μm).The enhanced corrosion resistance is attributed to the high density grain boundaries,which promote oxide stability,and accelerate the creation of the protective layer.The high corrosion rate and pseudo-passivation behavior of Zr alloys in fluorinated nitric acid originate from the accelerated“dissolution-passivation”of the oxide film.However,the grain refinement does not provide enduring anti-corrosion for Zr alloys.To meet the operation of spent fuel reprocessing,additional systematic efforts are required to evaluate the long term effect of grain refinement.
基金Project(2005CB724105) supported by the National Basic Research Program of ChinaProject (IRT0549) supported by the Program for Changjiang Scholars and Innovative Research Team in University
文摘A numerical approach for process optimization and microstructure evolution of lager-sized forging of aluminium alloy 7050 was proposed, which combined a commercial FEM code Deform 3D with empirical models. To obtain the parameters of empirical constitutive equation and dynamic recrystallization models for aluminium alloy 7050, the isothermal compression tests of 7050 samples were performed on Gleeble-1500 thermo-simulation machine in the temperature range of 250-450 ℃ and strain rate of 0.01-10 s-1, and the metallograph analysis of the samples were carried out on a Leica DMIRM image analyzer. The simulation results show that the dynamic recrystallization in the central area of the billet occurs more easily than that on the edge. Repetitious upsetting and stretching processes make the billet deform adequately. Among several forging processes e.g. upsetting, stretching, rounding and flatting, the stretching process is the most effective way to increase the effective strain and refine the microstructure of the billet. As the forging steps increase, the effective strain rises significantly and the average grain size reduces sharply. Recrystallized volume fractions in most parts of the final forging piece reach 100% and the average grain size reduces to 10 μm from initial value of 90 μm.
基金Project(2005CB724105) supported by the Major State Basic Research Program of ChinaProject(IRT0549) supported by Program for Changjiang Scholars and Innovative Research Team in University
文摘The prediction of microstructure evolution plays an important role in the design of forging process. In the present work, the cellular automaton (CA) program was developed to simulate the process of dynamic recrystallization (DRX) for aluminium alloy 7050. The material constants in CA models, including dislocation density, nucleation rate and grain growth, were determined by the isothermal compress tests on Gleeble 1500 machine. The model of dislocation density was obtained by linear regression method based on the experimental results. The influences of the deformation parameters on the percentage of DRX and the mean grain size for aluminium alloy 7050 were investigated in details by means of CA simulation. The simulation results show that, as temperature increases from 350 to 450 ℃ at a strain rate of 0.01 s?1, the percentage of DRX also increases greatly and the mean grain size decreases from 50 to 39.3 μm. The mean size of the recrystallied grains (R-grains) mainly depends on the Zener-Hollomon parameter. To obtain fine grain, the desired deformation temperature is determined from 400 to 450 ℃.
基金Project(08BZ1130100) supported by the Science and Technology Committee of Shanghai,ChinaProject(SHUCX102251) supported by the Innovation Fund for Graduate Student of Shanghai University,China
文摘The influence of casting parameters on stray grain formation of a unidirectionally solidified superalloy IN738LC casting with three platforms was investigated by using a 3D cellular automaton-finite element （CAFE） model in CALCOSOFT package. The model was first validated by comparison of the reported grain structure of AI-7%Si （mass fraction） alloy. Then, the influence of pouring temperature, heat flux of the lateral surface, convection heat coefficient of the cooled chill and mean undercooling of the bulk nucleation on the stray grain formation was studied during the unidirectional solidification. The predictions show that the stray grain formation is obviously sensitive to the pouring temperature, heat flux and mean undercooling of the bulk nucleation. However, increasing the heat convection coefficient has little influence on the stray grain formation.
基金Project(2005CB623706) supported by the Major State Basic Research Development Program of ChinaProject(50230310) supported by the National Natural Science Foundation of China
文摘The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test,optical microscopy,scanning electron microscopy and transmission electron microscopy.For the Zr-free alloy,the strength increases to the highest value at 20 s with transfer time,and then decreases slightly.The elongation decreases slowly with transfer time within 20 s,and more rapidly after 20 s.For the Zr-containing alloy,prolonging transfer time within 20 s results in slight decrease in the strength and elongation,and rapid drop of which is observed after 20 s.For the Zr-free alloy,prolonging transfer time can increase the percentage of intergranular fracture,which is mainly caused by wide grain boundary precipitate free zone.The failure mode of the Zr-containing alloy is modified from the predominant transgranular void growth and intergranular fracture to transgranular shear and intergranular fracture with increase in the transfer time,which is attributed to the wider grain boundary precipitate free zone and coarse equilibrium η phases in the matrix.
基金Project(51364035)supported by the National Natural Science Foundation of ChinaProject(20133601110001)supported by the Ministry of Education Tied up with the Special Research Fund for the Doctoral Program for Higher School,China+1 种基金Project(KJLD14003)supported by the Loading Program of Science and Technology of College of Jiangxi Province,ChinaProject(2012-CYH-DW-XCL-002)supported by the Production and Teaching and Research Cooperation Plan of Naaachaaag Non-party Experts and Doctor,China
文摘The effects of heat treatment and strontium(Sr) addition on the microstructure and mechanical properties of ADC1_(2) alloys were investigated,and two-stage solution treatment was introduced.The results indicated that the addition of Sr obviously refined the microstructure of ADC12 alloys.When 0.05 wt%Sr was added into the alloy,the eutectic Si phase was fully modified into fine fibrous structure;a-A1 andβ-A1_(5)FeSi phases were best refined;and the eutectic AlzCu phase was modified into block-like AlzCu phase that continuously distributed at the grain boundary.The ultimate tensile strength(UTS)(270.63 MPa)and elongation(3.19%)were increased by 51.2%and 73.4%respectively compared with unmodified alloys.After the two-stage solution treatment(500℃,6 h+520℃,4 h),for 0.05 wt%Sr modified ADC12 alloys,the Si phases transformed into fine particle structure and Al_(2)Cu phases were fully dissolved.The peak hardness value of the alloys processed by the two-stage solution treatment was increased by 8.3%and 6.8%respectively compared to solution treatment at 500℃and 520℃.After the aging treatment(175℃,7 h),the hardness and UTS were increased by 38.73%and 13.96%respectively when compared with the unmodified alloy.
基金Project (50474049) supported by the National Natural Science Foundation of China
文摘A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （Co3W3C or Co6W6C） during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.
基金Project(2015DFR50990-01)supported by International Cooperation Project of Ministry of Science and Technology of ChinaProjects(18JS060,18JS075)supported by the Shaanxi Key Laboratory of Nano-materials and Technology,China。
文摘Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the composites were examined by XRD,SEM and EDS.The results show that no other intermetallic compounds beside Al3Ti can be in-situ synthesized.Around the titanium fibers,the reaction zones and diffusion zones can be obviously found.Due to the stirring of the electromagnetic function,the formation of the micro-cracks inside the reaction zone was conducive to the peeling off of the Al3Ti particles,and ensures the continuous reaction between liquid aluminum and titanium fibers,as well as the diffusion of Al3Ti particles.At the same time,there were secondary splits of Al3Ti particles located in diffusion zones.Two-body abrasion test shows that with the increase of induction heating power,the wear rates of the composites reduced and the number of grooves decreased.
基金financial support received from Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT)
文摘Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors.Regardless of the superior features in Ti-MMC,however,referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part,the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability.Furthermore,adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied.Therefore,adequate knowledge of this regard is strongly demanded.Among machinability attributes,ultrafine particles(UFPs)and fine particles(FPs)have been selected as the main machinability attributes and the factors leading to minimized emission have been studied.According to experimental observations,despite the type of coating used,the use of higher levels of flow rate led to less UFPs,while no significant effects were observed on UFPs.Under similar cutting conditions,higher levels of FPs were recorded under the use of uncoated inserts.Moreover,cutting speed had no significant influence on UFPs;nevertheless,it significantly affects the FPs despite the type of insert used.
文摘Due to the biological risks of using the conventional lubricants,the vegetable oils have been considered nowadays.Besides,to improve the tribological properties of the vegetable oils in various applications like metal forming processes,nanoparticles have been used as additives.This research evaluated the lubrication performance of the Al2O3 and TiO2 nanoparticles dispersed in rapeseed oil during the parallel tubular channel angular pressing (PTCAP) process.The experimental PTCAP tests have been fulfilled under three lubrication conditions and the comparison between the PTCAP processed tubes has been performed in terms of the maximum forming force,surface roughness,and microhardness.The experimental results indicate that adding the mentioned nanoparticles has caused at least a 50% reduction in the maximum deformation load.Moreover,a remarkable decrement in the surface roughness of the formed tubes has been obtained.
基金Projects(21407182,21277175)supported by the National Natural Science Foundation of ChinaProject(20120162110019)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘A reliable method for detecting nanoparticles is necessary for the wide application of nanomaterials. Single particle-inductively coupled plasma mass spectrometry(SP-ICP-MS) was investigated to detect the size of gold nanoparticles(Au NPs) in this work. Discrimination of particle signal and iterative algorithm were used to calculate the baseline of particle signal. Influence of dwell time was discussed and 3 ms was selected as dwell time for size detection. Different Au NPs standards(30, 60, 80 and 100 nm) and mixed samples(60 and 100 nm) were determined by SP-ICP-MS and the accuracy was confirmed with reference values. The particle size detection limit was 19 nm in ultrapure water(UP water) and 31 nm in 0.1 μg/L Au^(3+) solution. Stability of Au NPs in ultrapure water and natural water samples was investigated by detecting size variation of AuN Ps. The result shows that Au NPs are stable in aqueous environment for 6 d but degraded after 30 d.
基金Project(51271012)supported by the National Natural Science Foundation of China
文摘Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.
