The La-Mg-Ni-based A2B7-type La0.5Mg0.2Ni3.3Co0.2Six （x=0-0.2） electrode alloys were prepared by casting and annealing. The influences of the additional silicon and the annealing treatment on the structure and elect...The La-Mg-Ni-based A2B7-type La0.5Mg0.2Ni3.3Co0.2Six （x=0-0.2） electrode alloys were prepared by casting and annealing. The influences of the additional silicon and the annealing treatment on the structure and electrochemical performances of the alloys were investigated systemically. Both of the analyses of XRD and SEM reveal that the as-cast and annealed alloys are of a multiphase structure, involving two main phases （La, Mg）2Ni7 and LaNi5 as well as one minor phase LaNi3. The addition of Si and annealing treatment bring on an evident change in the phase abundances and cell parameters of （La, Mg）2Ni7 and LaNi5 phase for the alloy without altering its phase structure. The phase abundances decrease from 74.3% （x=0） to 57.8% （x=0.2） for the （La, Mg）2Ni7 phase, and those of LaNi5 phase increase from 20.2% （x^0） to 37.3% （x=0.2）. As for the electrochemical measurements, adding Si and performing annealing treatment have engendered obvious impacts. The cycle stability of the alloys is improved dramatically, being enhanced from 80.3% to 93.7% for the as-annealed （950 ℃） alloys with Si content increasing from 0 to 0.2. However, the discharge capacity is reduced by adding Si, from 399.4 to 345.3 mA.h/g as the Si content increases from 0 to 0.2. Furthermore, such addition makes the electrochemical kinetic properties of the alloy electrodes first increase and then decrease. Also, it is found that the overall electrochemical properties of the alloys first augment and then fall with the annealing temperature rising.展开更多
A comparative study of amorphous electroless Ni-W-P coatings on mild steel substrate treated by a high power diode laser and furnace annealing was presented.Effects of different laser operating parameters and furnace-...A comparative study of amorphous electroless Ni-W-P coatings on mild steel substrate treated by a high power diode laser and furnace annealing was presented.Effects of different laser operating parameters and furnace-annealing conditions on microstructures,in terms of crystallisation,pores formation and grain growth,were investigated using SEM/EDX and XRD. Corrosion behaviours of these coatings before and after various treatments were evaluated with anodic polarisation in 0.5 mol/L H2SO4 solution.The results show that the furnace-annealing produces either a mixture of nanocrystallined Ni and amorphous phases or precipitated Ni3P phase distributed in nanocrystallined Ni-based matrix,depending on annealing temperatures,whilst the laser treatment under the operating conditions only produces nanocrystallined Ni-based matrix with Ni3P precipitates.Corrosion performance of the coatings treated by both the laser and the furnace-annealing is dependent on the annealing temperature and laser operating conditions.Corrosion mechanisms of various treated-coatings were discussed in the consideration of phase constitutes and proportion,grain sizes of both Ni and Ni3P phases,pores formation and residual stresses.展开更多
The aim of present work was to produce pure nickel aluminate （NiAl2O4） nanoceramic compound by high energy millingof nickel carbonate （NiCO3） and aluminum （Al） powders followed by annealing. Phase composition, t...The aim of present work was to produce pure nickel aluminate （NiAl2O4） nanoceramic compound by high energy millingof nickel carbonate （NiCO3） and aluminum （Al） powders followed by annealing. Phase composition, thermal behavior, morphologyand microstructure of powder samples were characterized by means of X-ray diffraction, differential scanning calorimeter,thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results showed that formationof NiAl2O4 spinel compound from NiCO3 and Al powders took place in three steps： oxidation of Al to Al2O3, decomposition ofNiCO3 to NiO and CO2, and finally the solid state reaction between Al2O3 and NiO. It was also demonstrated that single phaseNiAl2O4 spinel compound can be produced by 5 h of mechanical milling with subsequent annealing of NiCO3/Al mixture at 900 Cfor 2 h, which is 冾 500 C lower than the temperatures used in the traditional solid state methods. The particle diameter of theproduced NiAl2O4 spinel compound was found to be less than 100 nm as measured by transmission electron microscopy.展开更多
基金Projects(51371094,51161015)supported by the National Natural Science Foundations of ChinaProject(2011ZD10)supported by Natural Science Foundation of Inner Mongolia,China
文摘The La-Mg-Ni-based A2B7-type La0.5Mg0.2Ni3.3Co0.2Six （x=0-0.2） electrode alloys were prepared by casting and annealing. The influences of the additional silicon and the annealing treatment on the structure and electrochemical performances of the alloys were investigated systemically. Both of the analyses of XRD and SEM reveal that the as-cast and annealed alloys are of a multiphase structure, involving two main phases （La, Mg）2Ni7 and LaNi5 as well as one minor phase LaNi3. The addition of Si and annealing treatment bring on an evident change in the phase abundances and cell parameters of （La, Mg）2Ni7 and LaNi5 phase for the alloy without altering its phase structure. The phase abundances decrease from 74.3% （x=0） to 57.8% （x=0.2） for the （La, Mg）2Ni7 phase, and those of LaNi5 phase increase from 20.2% （x^0） to 37.3% （x=0.2）. As for the electrochemical measurements, adding Si and performing annealing treatment have engendered obvious impacts. The cycle stability of the alloys is improved dramatically, being enhanced from 80.3% to 93.7% for the as-annealed （950 ℃） alloys with Si content increasing from 0 to 0.2. However, the discharge capacity is reduced by adding Si, from 399.4 to 345.3 mA.h/g as the Si content increases from 0 to 0.2. Furthermore, such addition makes the electrochemical kinetic properties of the alloy electrodes first increase and then decrease. Also, it is found that the overall electrochemical properties of the alloys first augment and then fall with the annealing temperature rising.
基金Project(Y2006F40) supported by the Natural Science Foundation of Shandong Province, ChinaProject(N00003) supported by UK Northwest Science Council through Northwest Laser Engineering Consortium (NWLEC)
文摘A comparative study of amorphous electroless Ni-W-P coatings on mild steel substrate treated by a high power diode laser and furnace annealing was presented.Effects of different laser operating parameters and furnace-annealing conditions on microstructures,in terms of crystallisation,pores formation and grain growth,were investigated using SEM/EDX and XRD. Corrosion behaviours of these coatings before and after various treatments were evaluated with anodic polarisation in 0.5 mol/L H2SO4 solution.The results show that the furnace-annealing produces either a mixture of nanocrystallined Ni and amorphous phases or precipitated Ni3P phase distributed in nanocrystallined Ni-based matrix,depending on annealing temperatures,whilst the laser treatment under the operating conditions only produces nanocrystallined Ni-based matrix with Ni3P precipitates.Corrosion performance of the coatings treated by both the laser and the furnace-annealing is dependent on the annealing temperature and laser operating conditions.Corrosion mechanisms of various treated-coatings were discussed in the consideration of phase constitutes and proportion,grain sizes of both Ni and Ni3P phases,pores formation and residual stresses.
文摘The aim of present work was to produce pure nickel aluminate （NiAl2O4） nanoceramic compound by high energy millingof nickel carbonate （NiCO3） and aluminum （Al） powders followed by annealing. Phase composition, thermal behavior, morphologyand microstructure of powder samples were characterized by means of X-ray diffraction, differential scanning calorimeter,thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results showed that formationof NiAl2O4 spinel compound from NiCO3 and Al powders took place in three steps： oxidation of Al to Al2O3, decomposition ofNiCO3 to NiO and CO2, and finally the solid state reaction between Al2O3 and NiO. It was also demonstrated that single phaseNiAl2O4 spinel compound can be produced by 5 h of mechanical milling with subsequent annealing of NiCO3/Al mixture at 900 Cfor 2 h, which is 冾 500 C lower than the temperatures used in the traditional solid state methods. The particle diameter of theproduced NiAl2O4 spinel compound was found to be less than 100 nm as measured by transmission electron microscopy.
