The Ni-TiN nanocomposite film was successfully electrodeposited on brass copper substrates.The microstructures of the Ni-TiN nanocomposite film were investigated using scanning electron microscopy（SEM） and transmiss...The Ni-TiN nanocomposite film was successfully electrodeposited on brass copper substrates.The microstructures of the Ni-TiN nanocomposite film were investigated using scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.Its average grain size was analyzed through X-ray diffraction（XRD）,and its anti-corrosion property was studied through potentiodynamic scanning curves and electrochemical impedance spectroscopy（EIS）.The results show that the morphology of Ni-TiN composite film is sensitively dependent on the electroplating current density,TiN nanoparticle concentration,solution stirring speed,bath temperature and pH value of solution.The average grain size of the optimized nanocomposite film is about 50 nm.Meanwhile,the Ni-TiN nanocomposite films are much more resistant to corrosion than pure Ni coatings.展开更多
After Sn/Pd activating, the SiCp/Al composite with 65% SiC (volume fraction) was coated by electroless Ni?P alloy plating. Surface morphology of the composite and its effect on the Ni?P alloy depositing process and bo...After Sn/Pd activating, the SiCp/Al composite with 65% SiC (volume fraction) was coated by electroless Ni?P alloy plating. Surface morphology of the composite and its effect on the Ni?P alloy depositing process and bonding action of Ni and P atoms in the Ni?P alloy were studied. The results show that inhomogeneous distribution of the Sn/Pd activating points results in preferential deposition of the Ni?P alloy particles on the Al alloy and rough SiC particle surfaces and in the etched caves. The Ni?P alloy film has an amorphous structure where chemical bonding between Ni and P atoms exists. After a continuous Ni?P alloy film formed, electroless Ni?P alloy plating is not affected by surface morphology and characteristics of the SiCp/Al composite any longer, but by the electroless plating process itself. The Ni?P alloy film follows linear growth kinetics with an activation energy of 68.44 kJ/mol.展开更多
Pourbaix diagrams are calculated to describe electrochemical processes for alloys in aqueous solution.With the multi-component differentiation of alloy systems,the construction of Pourbaix diagrams is fac-ing challeng...Pourbaix diagrams are calculated to describe electrochemical processes for alloys in aqueous solution.With the multi-component differentiation of alloy systems,the construction of Pourbaix diagrams is fac-ing challenges,especially for non-single-phase alloy systems.In this study,the simultaneous construction of phase diagrams and Pourbaix diagrams were implemented for predicting the evolution of the phases in the immune and passive regions.The CALPHAD(CALculation of PHAse Diagram)approach was used to quickly access the Gibbs free energies of various phases and the chemical potential of the elements in the phases from the thermodynamic database of the Ni-Si-Al-Y system.The corrosion behavior of two typical Ni-Al-Si and Ni-Al-Y systems was investigated.Si and Y were added to Ni-based alloys to produce the solid solutions L12-Ni_(3)(Al,Si)and L12-Ni_(3)Al+Ni_(5)Y,respectively.Calculations showed that NiO and Al_(2)O_(3)make up the passive area of the Ni_(3)Al 1 alloy.The introduction of SiO_(2)and Y(OH)3 in the passive region separately helped to minimize the alloys’susceptibility to corrosion.However,Si reduced the thermody-namical possibility of NiO for mation in the passive film,and the addition of Y caused extreme galvanic corrosion.Experiments on Ni-based alloys validated the results through electrochemical corrosion.It was also discovered that the presence of Ni_(5)Y produced galvanic corrosion and that Si reduced the oxide in the passive film,causing pitting corrosion.The corrosion prediction of the quaternary alloys indicates that the solid solution of Si in Ni_(5)Y reduces the galvanic corrosion effect and the dissolution of passive film.The current work demonstrates that phase diagrams and Pourbaix diagrams may be efficiently and accurately predicted using a well-constructed thermodynamic database,which has major implications for future studies on the corrosion behavior of multi-component alloys.展开更多
To understand the corrosion performance of additive-manufactured Ni-based in various corrosion media during the actual engineering application environment,the corrosion properties of NiFeCrMo alloys were investigated ...To understand the corrosion performance of additive-manufactured Ni-based in various corrosion media during the actual engineering application environment,the corrosion properties of NiFeCrMo alloys were investigated in 3.5 wt.%NaCl solution,1 mol/L H2SO_(4) solution,and 1 mol/L KOH solution,using potentiodynamic polarization and electrochemical impedance spectroscopy.The electrochemical measurement results revealed that the additive-manufactured NiFeCrMo alloys have higher corrosion resistance in all three solutions,compared with the as-cast samples.The results of the scanning electron microscope confirmed that the degree of additive-manufactured NiFeCrMo alloys after potentiostatic polarization in all three solutions is less serious.X-ray photoelectron spectroscopy analysis revealed that the enhancement of the corrosion resistance for the additive-manufactured NiFeCrMo alloys is attributed to the modification of the composition of the passive films.Additive manufactured processing promotes the enrichment of the element of Cr or Mo in the passive film and it suppresses the formation of the oxidation of the element of Fe,leading to higher stability of the passive films.The reason for the higher corrosion resistance of the additive-manufactured NiFeCrMo alloys was related to the enrichment of the element of Cr,as well as the lower content of the elements of Ni and Fe near the grain boundaries,which are beneficial to forming a more compact passive film.The combined results are essential for the applications of high-strength Ni-based as structural materials in a corrosion environment.展开更多
Nanomultilayered TiN/Ni thin films with different bilayer periods(57.8-99.7 nm) and Ni single-layer thickness(3.9-19.2 nm) were prepared by alternatively sputtering Ti and Ni targets in N2 gas atmosphere.The micros tr...Nanomultilayered TiN/Ni thin films with different bilayer periods(57.8-99.7 nm) and Ni single-layer thickness(3.9-19.2 nm) were prepared by alternatively sputtering Ti and Ni targets in N2 gas atmosphere.The micros tructure,mechanical and corrosion properties of the multilayer films were investigated by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),X-ray photoelectron spectroscopy(XPS),nanoindenter and electrochemical technologies.The multilayer films are fine with a mean grain size of ~8-9 nm independent of the bilayer period.However,the smoothness and compactness seem to decrease with the bilayer period increasing.The hardness(H) and elastic modulus(E) of the multilayer films gradually decrease as the bilayer period increases,and the multilayer film with bilayer period of 57.8 nm exhibits higher H,ratios of(H/E^*and H^3/E^*2)(E^*is effective Young’s modulus)than the monolithic TiN film and the other multilayers.The multilayer films exhibit an obvious passivation phenomenon in 10% H2SO4 solution,and the passive current and corrosion current densities decrease,whereas the corrosion potential increases when the bilayer period or Ni single-layer thickness decreases.It is found that the passivating behavior and corrosion potential of the multilayers are more sensitive to Ni single-layer thickness than the bilayer period.More corrosion pits and lamellar flaking could be found on the films with larger bilayer period or Ni single-layer thickness.展开更多
基金Projects(50771092,21073162) supported by the National Natural Science Foundation of ChinaProject(2005DKA10400-Z15) supported by the Ministry of Science and Technology of China
文摘The Ni-TiN nanocomposite film was successfully electrodeposited on brass copper substrates.The microstructures of the Ni-TiN nanocomposite film were investigated using scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.Its average grain size was analyzed through X-ray diffraction（XRD）,and its anti-corrosion property was studied through potentiodynamic scanning curves and electrochemical impedance spectroscopy（EIS）.The results show that the morphology of Ni-TiN composite film is sensitively dependent on the electroplating current density,TiN nanoparticle concentration,solution stirring speed,bath temperature and pH value of solution.The average grain size of the optimized nanocomposite film is about 50 nm.Meanwhile,the Ni-TiN nanocomposite films are much more resistant to corrosion than pure Ni coatings.
基金Project(2014DFA50860)supported by International Science&Technology Cooperation Program of China
文摘After Sn/Pd activating, the SiCp/Al composite with 65% SiC (volume fraction) was coated by electroless Ni?P alloy plating. Surface morphology of the composite and its effect on the Ni?P alloy depositing process and bonding action of Ni and P atoms in the Ni?P alloy were studied. The results show that inhomogeneous distribution of the Sn/Pd activating points results in preferential deposition of the Ni?P alloy particles on the Al alloy and rough SiC particle surfaces and in the etched caves. The Ni?P alloy film has an amorphous structure where chemical bonding between Ni and P atoms exists. After a continuous Ni?P alloy film formed, electroless Ni?P alloy plating is not affected by surface morphology and characteristics of the SiCp/Al composite any longer, but by the electroless plating process itself. The Ni?P alloy film follows linear growth kinetics with an activation energy of 68.44 kJ/mol.
基金financially supported by the National Natural Science Foundation of China(No.U21A20127)Excellent Young Scientists Fund of National Natural Science Foundation of China(NSFC),No.52222507)the Natural Science Foundation of Ningbo City(No.2022J304).
文摘Pourbaix diagrams are calculated to describe electrochemical processes for alloys in aqueous solution.With the multi-component differentiation of alloy systems,the construction of Pourbaix diagrams is fac-ing challenges,especially for non-single-phase alloy systems.In this study,the simultaneous construction of phase diagrams and Pourbaix diagrams were implemented for predicting the evolution of the phases in the immune and passive regions.The CALPHAD(CALculation of PHAse Diagram)approach was used to quickly access the Gibbs free energies of various phases and the chemical potential of the elements in the phases from the thermodynamic database of the Ni-Si-Al-Y system.The corrosion behavior of two typical Ni-Al-Si and Ni-Al-Y systems was investigated.Si and Y were added to Ni-based alloys to produce the solid solutions L12-Ni_(3)(Al,Si)and L12-Ni_(3)Al+Ni_(5)Y,respectively.Calculations showed that NiO and Al_(2)O_(3)make up the passive area of the Ni_(3)Al 1 alloy.The introduction of SiO_(2)and Y(OH)3 in the passive region separately helped to minimize the alloys’susceptibility to corrosion.However,Si reduced the thermody-namical possibility of NiO for mation in the passive film,and the addition of Y caused extreme galvanic corrosion.Experiments on Ni-based alloys validated the results through electrochemical corrosion.It was also discovered that the presence of Ni_(5)Y produced galvanic corrosion and that Si reduced the oxide in the passive film,causing pitting corrosion.The corrosion prediction of the quaternary alloys indicates that the solid solution of Si in Ni_(5)Y reduces the galvanic corrosion effect and the dissolution of passive film.The current work demonstrates that phase diagrams and Pourbaix diagrams may be efficiently and accurately predicted using a well-constructed thermodynamic database,which has major implications for future studies on the corrosion behavior of multi-component alloys.
基金supported by the National Natural Science Foundation of China(51901086).
文摘To understand the corrosion performance of additive-manufactured Ni-based in various corrosion media during the actual engineering application environment,the corrosion properties of NiFeCrMo alloys were investigated in 3.5 wt.%NaCl solution,1 mol/L H2SO_(4) solution,and 1 mol/L KOH solution,using potentiodynamic polarization and electrochemical impedance spectroscopy.The electrochemical measurement results revealed that the additive-manufactured NiFeCrMo alloys have higher corrosion resistance in all three solutions,compared with the as-cast samples.The results of the scanning electron microscope confirmed that the degree of additive-manufactured NiFeCrMo alloys after potentiostatic polarization in all three solutions is less serious.X-ray photoelectron spectroscopy analysis revealed that the enhancement of the corrosion resistance for the additive-manufactured NiFeCrMo alloys is attributed to the modification of the composition of the passive films.Additive manufactured processing promotes the enrichment of the element of Cr or Mo in the passive film and it suppresses the formation of the oxidation of the element of Fe,leading to higher stability of the passive films.The reason for the higher corrosion resistance of the additive-manufactured NiFeCrMo alloys was related to the enrichment of the element of Cr,as well as the lower content of the elements of Ni and Fe near the grain boundaries,which are beneficial to forming a more compact passive film.The combined results are essential for the applications of high-strength Ni-based as structural materials in a corrosion environment.
基金financially supported by the National Natural Science Foundation of China (No.51171118)
文摘Nanomultilayered TiN/Ni thin films with different bilayer periods(57.8-99.7 nm) and Ni single-layer thickness(3.9-19.2 nm) were prepared by alternatively sputtering Ti and Ni targets in N2 gas atmosphere.The micros tructure,mechanical and corrosion properties of the multilayer films were investigated by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),X-ray photoelectron spectroscopy(XPS),nanoindenter and electrochemical technologies.The multilayer films are fine with a mean grain size of ~8-9 nm independent of the bilayer period.However,the smoothness and compactness seem to decrease with the bilayer period increasing.The hardness(H) and elastic modulus(E) of the multilayer films gradually decrease as the bilayer period increases,and the multilayer film with bilayer period of 57.8 nm exhibits higher H,ratios of(H/E^*and H^3/E^*2)(E^*is effective Young’s modulus)than the monolithic TiN film and the other multilayers.The multilayer films exhibit an obvious passivation phenomenon in 10% H2SO4 solution,and the passive current and corrosion current densities decrease,whereas the corrosion potential increases when the bilayer period or Ni single-layer thickness decreases.It is found that the passivating behavior and corrosion potential of the multilayers are more sensitive to Ni single-layer thickness than the bilayer period.More corrosion pits and lamellar flaking could be found on the films with larger bilayer period or Ni single-layer thickness.
