Sodium chloride(NaCl)was added as a space holder in synthesis of porous titanium by using metal injection molding(MIM)method.The microstructure and mechanical properties of porous titanium were analyzed by mercury por...Sodium chloride(NaCl)was added as a space holder in synthesis of porous titanium by using metal injection molding(MIM)method.The microstructure and mechanical properties of porous titanium were analyzed by mercury porosimeter, scanning electron microscope(SEM)and compression tester.The results show that the content of NaCl influences the porosity of porous titanium significantly.Porous titanium powders with porosity in the range of 42.4%-71.6%and pore size up to 300μm were fabricated.The mechanical test shows that with increasing NaCl content,the compressive strength decreases from 316.6 to 17.5 MPa and the elastic modulus decreases from 3.03 to 0.28 GPa.展开更多
Titanium alloy (Ti-Al-V alloy) substrate was brazed with stainless steel (STS304) using filler metal.At an optimized brazing condition,various filler metals were used.Microstructures were observed at each condition.Fi...Titanium alloy (Ti-Al-V alloy) substrate was brazed with stainless steel (STS304) using filler metal.At an optimized brazing condition,various filler metals were used.Microstructures were observed at each condition.Filler metals were titanium based 40Ti-20Zr-20Cu-20Ni,silver based Ag 5Pd,and nickel based Ni-7Cr-3.1B-4.5Si-3Fe-0.06C (BNi2) and Ni-14Cr-10P-0.06C (BNi7).To select a good filler metal for brazing process,wetting test was performed at 880-1050 °C.It was not brazed using silver based filler metals,but at the conditions using titanium and nickel based filler metals had brazed zone between titanium alloy and stainless steel.However,titanium alloy was eroded during brazing using titanium based filler metals.Nickel based filler metal has a good brazed zone between titanium alloy and stainless steel among the filler metals.展开更多
A set of metal nanoparticle-decorated titanium dioxide(Mx/TiO_(2);where x is the percent by mass,%)photocatalysts was prepared via the sol-immobilization in order to enhance the simultaneous hydrogen(H_(2))production ...A set of metal nanoparticle-decorated titanium dioxide(Mx/TiO_(2);where x is the percent by mass,%)photocatalysts was prepared via the sol-immobilization in order to enhance the simultaneous hydrogen(H_(2))production and pollutant reduction from real biodiesel wastewater.Effect of the metal nanoparticle(NP)type(M=Ni,Au,Pt or Pd)and,for Pd,the amount(1%–4%)decorated on the surface of thermal treated commercial TiO_(2)(T_(400))was evaluated.The obtained results demonstrated that both the type and amount of decorated metal NPs did not significantly affect the pollutant reduction,measured in terms of the reduction of chemical oxygen demand(COD),biological oxygen demand(BOD)and oil&grease levels,but they affected the H_(2) production rate from both deionized water and biodiesel wastewater,which can be ranked in the order of Pt_(1)/T_(400)>Pd_(1)/T_(400)>Au_(1)/T_(400)>Ni_(1)/T_(400).This was attributed to the high difference in work function between Pt and the parent T400.However,the difference between Pt1/T400 and Pd1/T400 was not great and so from an economic consideration,Pd/TiO_(2) was selected as appropriate for further evaluation.Among the four different Pdx/TiO_(2) photocatalysts,the Pd3/TiO_(2) demonstrated the highest activity and gave a high rate of H_(2) production(up to 135 mmol·h−1)with a COD,BOD and oil&grease reduction of 30.3%,73.7%and 58.0%,respectively.展开更多
It＇ s well known welding takes the leading role in development of titanium structures. However, in number of cases technological processes of brazing are more appropriate and, sometimes, being the single possible, in...It＇ s well known welding takes the leading role in development of titanium structures. However, in number of cases technological processes of brazing are more appropriate and, sometimes, being the single possible, in particular, during production of multilayer thin-wall structures. It should be noted that brazing filler metals of Ti-Cu-Ni, Ti-Zr-Cu-Ni, Zr-Ti-Ni and Cu-Zr-Ti systems in a form of plastic foils, as well as in powder form are mainly used in world practice for brazing of titanium alloys. Present work provides the results of complex investigations of brazing filler metals of Ti-Zr-Fe, Ti-Zr-Mn and Ti-Zr-Co systems using differential thermal analysis, light and scanning microscopy, X-ray microspectrum analysis. Data on melting ranges of pilot alloys were obtained, and liquidas su^Caces of given systems using simplex-lattice method were build. Brazing filler metals covering brazing temperature range of current structural titanium materials based on solid solutions as well as intermetallics were proposed. Structure, chemical inhomogeniety and strength characteristics of brazed joints were studied. It is determined that brazing of solid solution based alloys （OT4, VT6 ） using indicated brazing fiUer metals ensures strength characteristics of joints, which are not inferior to that obtained with application of known brazing filler metals even if they are received at lower brazing temperature.展开更多
This study presents the first stage of a multi-scale numerical framework designed to predict the non-linear constitutive behavior of metal-composite interfaces in titanium-graphite fiber metal laminates. Scanning elec...This study presents the first stage of a multi-scale numerical framework designed to predict the non-linear constitutive behavior of metal-composite interfaces in titanium-graphite fiber metal laminates. Scanning electron microscopy and x-ray diffraction techniques are used to characterize the baseline physical and chemical state of the interface. The physics of adhesion between the metal and polymer matrix composite components are then evaluated on the atomistic scale using molecular dynamics simulations. Interfacial mechanical properties are subsequently derived from these simulations using classical mechanics and thermodynamics. These molecular-level property predictions are used in a companion study to parameterize a continuum-level finite element model of the interface by means of a traction-separation constitutive law. Extension of the proposed approach to other dissimilar metal- or metal oxide-polymer interfaces is also discussed.展开更多
基金Project(30770576)supported by the National Natural Science Foundation of ChinaProject(2007AA03Z114)supported by Hi-tech Research and Development Program of China
文摘Sodium chloride(NaCl)was added as a space holder in synthesis of porous titanium by using metal injection molding(MIM)method.The microstructure and mechanical properties of porous titanium were analyzed by mercury porosimeter, scanning electron microscope(SEM)and compression tester.The results show that the content of NaCl influences the porosity of porous titanium significantly.Porous titanium powders with porosity in the range of 42.4%-71.6%and pore size up to 300μm were fabricated.The mechanical test shows that with increasing NaCl content,the compressive strength decreases from 316.6 to 17.5 MPa and the elastic modulus decreases from 3.03 to 0.28 GPa.
文摘Titanium alloy (Ti-Al-V alloy) substrate was brazed with stainless steel (STS304) using filler metal.At an optimized brazing condition,various filler metals were used.Microstructures were observed at each condition.Filler metals were titanium based 40Ti-20Zr-20Cu-20Ni,silver based Ag 5Pd,and nickel based Ni-7Cr-3.1B-4.5Si-3Fe-0.06C (BNi2) and Ni-14Cr-10P-0.06C (BNi7).To select a good filler metal for brazing process,wetting test was performed at 880-1050 °C.It was not brazed using silver based filler metals,but at the conditions using titanium and nickel based filler metals had brazed zone between titanium alloy and stainless steel.However,titanium alloy was eroded during brazing using titanium based filler metals.Nickel based filler metal has a good brazed zone between titanium alloy and stainless steel among the filler metals.
文摘A set of metal nanoparticle-decorated titanium dioxide(Mx/TiO_(2);where x is the percent by mass,%)photocatalysts was prepared via the sol-immobilization in order to enhance the simultaneous hydrogen(H_(2))production and pollutant reduction from real biodiesel wastewater.Effect of the metal nanoparticle(NP)type(M=Ni,Au,Pt or Pd)and,for Pd,the amount(1%–4%)decorated on the surface of thermal treated commercial TiO_(2)(T_(400))was evaluated.The obtained results demonstrated that both the type and amount of decorated metal NPs did not significantly affect the pollutant reduction,measured in terms of the reduction of chemical oxygen demand(COD),biological oxygen demand(BOD)and oil&grease levels,but they affected the H_(2) production rate from both deionized water and biodiesel wastewater,which can be ranked in the order of Pt_(1)/T_(400)>Pd_(1)/T_(400)>Au_(1)/T_(400)>Ni_(1)/T_(400).This was attributed to the high difference in work function between Pt and the parent T400.However,the difference between Pt1/T400 and Pd1/T400 was not great and so from an economic consideration,Pd/TiO_(2) was selected as appropriate for further evaluation.Among the four different Pdx/TiO_(2) photocatalysts,the Pd3/TiO_(2) demonstrated the highest activity and gave a high rate of H_(2) production(up to 135 mmol·h−1)with a COD,BOD and oil&grease reduction of 30.3%,73.7%and 58.0%,respectively.
文摘It＇ s well known welding takes the leading role in development of titanium structures. However, in number of cases technological processes of brazing are more appropriate and, sometimes, being the single possible, in particular, during production of multilayer thin-wall structures. It should be noted that brazing filler metals of Ti-Cu-Ni, Ti-Zr-Cu-Ni, Zr-Ti-Ni and Cu-Zr-Ti systems in a form of plastic foils, as well as in powder form are mainly used in world practice for brazing of titanium alloys. Present work provides the results of complex investigations of brazing filler metals of Ti-Zr-Fe, Ti-Zr-Mn and Ti-Zr-Co systems using differential thermal analysis, light and scanning microscopy, X-ray microspectrum analysis. Data on melting ranges of pilot alloys were obtained, and liquidas su^Caces of given systems using simplex-lattice method were build. Brazing filler metals covering brazing temperature range of current structural titanium materials based on solid solutions as well as intermetallics were proposed. Structure, chemical inhomogeniety and strength characteristics of brazed joints were studied. It is determined that brazing of solid solution based alloys （OT4, VT6 ） using indicated brazing fiUer metals ensures strength characteristics of joints, which are not inferior to that obtained with application of known brazing filler metals even if they are received at lower brazing temperature.
文摘This study presents the first stage of a multi-scale numerical framework designed to predict the non-linear constitutive behavior of metal-composite interfaces in titanium-graphite fiber metal laminates. Scanning electron microscopy and x-ray diffraction techniques are used to characterize the baseline physical and chemical state of the interface. The physics of adhesion between the metal and polymer matrix composite components are then evaluated on the atomistic scale using molecular dynamics simulations. Interfacial mechanical properties are subsequently derived from these simulations using classical mechanics and thermodynamics. These molecular-level property predictions are used in a companion study to parameterize a continuum-level finite element model of the interface by means of a traction-separation constitutive law. Extension of the proposed approach to other dissimilar metal- or metal oxide-polymer interfaces is also discussed.
