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
Titanium alloy is a kind of typical hard-to-cut material due to its low thermal conductivity and high strength at elevated temperatures, this contributes to the fast tool wear in the milling of titanium alloys. The in...Titanium alloy is a kind of typical hard-to-cut material due to its low thermal conductivity and high strength at elevated temperatures, this contributes to the fast tool wear in the milling of titanium alloys. The influence of cutting conditions on tool wear has been focused on the turning process, and their influence on tool wear in milling process as well as the influence of tool wear on cutting force coefficients has not been investigated comprehensively. To fully understand the tool wear behavior in milling process with inserts, the influence of cutting parameters on tool wear in the milling of titanium alloys Ti6A14V by using indexable cutters is investigated. The tool wear rate and trends under different feed per tooth, cutting speed, axial depth of cut and radial depth of cut are analyzed. The results show that the feed rate per tooth and the radial depth of cut have a large influence on tool wear in milling Ti6A14V with coated insert. To reduce tool wear, cutting parameters for coated inserts under experimental cutting conditions are set as： feed rate per tooth less than 0.07 mm, radial depth of cut less than 1.0 mm, and cutting speed sets between 60 and 150 m/min. Investigation on the relationship between tool wear and cutting force coefficients shows that tangential edge constant increases with tool wear and cutter edge chipping can lead to a great variety of tangential cutting force coefficient. The proposed research provides the basic data for evaluating the machinability of milling Ti6A14V alloy with coated inserts, and the recommend cutting parameters can be immediately applied in practical production.展开更多
Ti6Al4V powder compaction was performed by using magnetic pulse compaction in air at 200℃.Effects of process parameters such as voltage,capacitance,discharge times on the microstructure,compressive strength,hardness ...Ti6Al4V powder compaction was performed by using magnetic pulse compaction in air at 200℃.Effects of process parameters such as voltage,capacitance,discharge times on the microstructure,compressive strength,hardness and relative density of compacts were investigated.The experimental results show that the relative density,hardness and compressive strength of compacted specimens increase with increasing voltage.In addition,the relative density and compressive strength of compacted specimens increase with the augmentation of capacitance in the range investigated.The relative density increases,the hardness firstly increases and then tends to be a fixed value;and the compressive strength firstly increases and then decreases from one to five times compaction.Both values of the hardness and compressive strength reach the maxima of HRA 69.1 and 1 062.31 MPa,at three times compaction,respectively.There are pores in and between particles.展开更多
The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased i...The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased implantation time(dose),and more like a parabola at the low implantation pulse voltage.When implantation pulse voltage is increased,the implantation depth increased with the nitrogen distribution peak being deepened,widened and lowered somewhat.TiN,TiN+Ti 2N,or Ti 2N second phases were formed in the implanted layer.The relative percentage of nitrogen content in the form of TiN increases when going deeper into the implanted(TiN formed) layer.The increase of implantation pulse width and/or time is favourable for the formation of TiN rather than Ti 2N.It is unfavourable for formation of any nitrides when implantation pulse voltage is decreased to 30kV or less.Tiny crystalline particles (made mainly of Ti 2N and a smaller percentage of TiO 2 phases) of regular shapes such as triangle and tetragon, etc .(about 20 nm) are found distrbuted dispersively in the near surface region of samples implanted at the high implantation pulse voltage (75kV).展开更多
The grindability of alloy Ti6AI4V with zireonia alumina and silicon carbide flap wheels, and the effect of process parameters on grinding forces, grinding temperature and surface integrity are studied. The grinding fo...The grindability of alloy Ti6AI4V with zireonia alumina and silicon carbide flap wheels, and the effect of process parameters on grinding forces, grinding temperature and surface integrity are studied. The grinding forces are measured by KISTLER 9265B dynamometer. The grinding temperature response is obtained by NI USB-621X signal collection system. Ground surface morphology and the metallographic structure are observed by the Hirox KN-7700 stereoscopic microcope and the Quanta200 scanning electron microscope （SEM）. Surface roughnesses are measured by Mahr Perthometer M1 instrument. The surface microhardnesses are detected by HXS-1000 microhardness tester.展开更多
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.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2013CB035802)National Natural Science Foundation of China(Grant No.51575453)+1 种基金Fundamental Research Funds for the Central Universities(Grant No.3102015JCS05002)the 111 Project,China(Grant No.B13044)
文摘Titanium alloy is a kind of typical hard-to-cut material due to its low thermal conductivity and high strength at elevated temperatures, this contributes to the fast tool wear in the milling of titanium alloys. The influence of cutting conditions on tool wear has been focused on the turning process, and their influence on tool wear in milling process as well as the influence of tool wear on cutting force coefficients has not been investigated comprehensively. To fully understand the tool wear behavior in milling process with inserts, the influence of cutting parameters on tool wear in the milling of titanium alloys Ti6A14V by using indexable cutters is investigated. The tool wear rate and trends under different feed per tooth, cutting speed, axial depth of cut and radial depth of cut are analyzed. The results show that the feed rate per tooth and the radial depth of cut have a large influence on tool wear in milling Ti6A14V with coated insert. To reduce tool wear, cutting parameters for coated inserts under experimental cutting conditions are set as： feed rate per tooth less than 0.07 mm, radial depth of cut less than 1.0 mm, and cutting speed sets between 60 and 150 m/min. Investigation on the relationship between tool wear and cutting force coefficients shows that tangential edge constant increases with tool wear and cutter edge chipping can lead to a great variety of tangential cutting force coefficient. The proposed research provides the basic data for evaluating the machinability of milling Ti6A14V alloy with coated inserts, and the recommend cutting parameters can be immediately applied in practical production.
文摘Ti6Al4V powder compaction was performed by using magnetic pulse compaction in air at 200℃.Effects of process parameters such as voltage,capacitance,discharge times on the microstructure,compressive strength,hardness and relative density of compacts were investigated.The experimental results show that the relative density,hardness and compressive strength of compacted specimens increase with increasing voltage.In addition,the relative density and compressive strength of compacted specimens increase with the augmentation of capacitance in the range investigated.The relative density increases,the hardness firstly increases and then tends to be a fixed value;and the compressive strength firstly increases and then decreases from one to five times compaction.Both values of the hardness and compressive strength reach the maxima of HRA 69.1 and 1 062.31 MPa,at three times compaction,respectively.There are pores in and between particles.
文摘The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased implantation time(dose),and more like a parabola at the low implantation pulse voltage.When implantation pulse voltage is increased,the implantation depth increased with the nitrogen distribution peak being deepened,widened and lowered somewhat.TiN,TiN+Ti 2N,or Ti 2N second phases were formed in the implanted layer.The relative percentage of nitrogen content in the form of TiN increases when going deeper into the implanted(TiN formed) layer.The increase of implantation pulse width and/or time is favourable for the formation of TiN rather than Ti 2N.It is unfavourable for formation of any nitrides when implantation pulse voltage is decreased to 30kV or less.Tiny crystalline particles (made mainly of Ti 2N and a smaller percentage of TiO 2 phases) of regular shapes such as triangle and tetragon, etc .(about 20 nm) are found distrbuted dispersively in the near surface region of samples implanted at the high implantation pulse voltage (75kV).
基金Supported by the Natural Science Foundation of Jiangsu Province (BK2006723)New Century Ex-cellent Talents in University from Ministry of Education of China (NCET-07-0435)~~
文摘The grindability of alloy Ti6AI4V with zireonia alumina and silicon carbide flap wheels, and the effect of process parameters on grinding forces, grinding temperature and surface integrity are studied. The grinding forces are measured by KISTLER 9265B dynamometer. The grinding temperature response is obtained by NI USB-621X signal collection system. Ground surface morphology and the metallographic structure are observed by the Hirox KN-7700 stereoscopic microcope and the Quanta200 scanning electron microscope （SEM）. Surface roughnesses are measured by Mahr Perthometer M1 instrument. The surface microhardnesses are detected by HXS-1000 microhardness tester.
