An investigation was carried out to assess the applicability of transient liquid phase bonding of two dissimilar super-alloys with different interlayers. The effect of using three types of interlayer such as BNi-2, BN...An investigation was carried out to assess the applicability of transient liquid phase bonding of two dissimilar super-alloys with different interlayers. The effect of using three types of interlayer such as BNi-2, BNi-3, and BNi-9 on microstructure and mechanical properties was studied in the GTD-111/IN-718 system at 1100 ℃ for different bonding time. To determine the compositional changes and microstructure in the joint region, field emission scanning electron microscopy equipped with energy dispersive spectroscopy was utilized. The formation of Ni_(3)B in the athermally solidified zone(ASZ) is controlled by the B content and, accordingly, the morphology of Ni_(3)Si is governed by the Si content. The Cr content might impede the relocation of B from the interlayer into the base metal and the formation of CrB inside the ASZ is dominated by the Cr content. The high micro-hardness of the eutectic compounds is originated from the formation of boride matrixes such as Ni or Cr boride. The shear strength of the joint using BNi-9 after the completion of isothermal solidification is lower compared that that using BNi-3 and BNi-2, which could be related to the absence of Si in the filler metals constituent and the significant presence of Cr in BNi-9.展开更多
A series of Ce-doped Ni-B amorphous alloy catalysts were prepared by a KBH_4 reduction method, characterized by ICP, BET, XRD, H_2-chemisorption, H_2-TPD, etc., and tested in the hydrogenation of 2-ethylanthraquinone....A series of Ce-doped Ni-B amorphous alloy catalysts were prepared by a KBH_4 reduction method, characterized by ICP, BET, XRD, H_2-chemisorption, H_2-TPD, etc., and tested in the hydrogenation of 2-ethylanthraquinone. The results of characterization show that with the addition of Ce the amount of H_2-chemisorption and H_2-TPD areas first increases markedly and then decreases with the maximum appears at the atomic ratio of Ce to Ni of 0.036. The hydrogenation activity also shows the same trend. The effects of Ce are attributed to its dispersion of Ni particles, resulting in the formation of more surface Ni centers. However, much higher Ce contents may result in the decrease of the surface Ni contents. After heat treatment at higher temperatures, the amorphous structure of Ni-B is destroyed.展开更多
The search for active,stable,and cost-effective electrocatalysts for hydrogen evolution reaction(HER)is desirable,but it remains a great challenge in the overall water splitting.Here,we report the synthesis of nickel ...The search for active,stable,and cost-effective electrocatalysts for hydrogen evolution reaction(HER)is desirable,but it remains a great challenge in the overall water splitting.Here,we report the synthesis of nickel boron nanoparticles supported on Vulcan carbon(Ni-B)via a simple,yet scalable,two-step chemical reduction–annealing strategy.The results of the electrochemical measurements suggest that the overpotentials of Ni-B-400 are 114 and 215 mV(in 1 mol L^–1 KOH)at current densities of 10 and 40 mA cm^?2,respectively,indicating an exceedingly good electrocatalytic activity in the HER.More importantly,Ni-B maintains a current density of 7.6 mA cm^-2 at an overpotential of 0.15 V for 20 h in the durability test.The excellent HER activity of Ni-B-400 is derived from the small particle size and the expanded lattice of Ni,which can optimize the hydrogen absorption energy and enhance the electrocatalytic properties.展开更多
The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride, ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treat...The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride, ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treatments on micro-diamond particle, and the optimized parameters were obtained. Both the morphology and the composition of original diamond and the diamond with Ni-B coating were analyzed by SEM and XRD respectively. The SEM image shows that the spherical Ni-B particle is coated upon diamond. XRD pattern shows that the coating compositions are Ni and Ni2B.展开更多
Some parameters of liquid binary alloy were investigated , and the calculation formulae were proposed.According to the formulae for calculating coordination number, the accordination numbers of Cu-Zr , Fe-B, Ni-B, Co-...Some parameters of liquid binary alloy were investigated , and the calculation formulae were proposed.According to the formulae for calculating coordination number, the accordination numbers of Cu-Zr , Fe-B, Ni-B, Co-P, Fe-P systems were calculated, the results agree well with those in literature and in experiments ofthis study.展开更多
Uniform Ni-B amorphous alloys about 14 nm have been prepared on CNTs-A support,named Ni-B/CNTs-A. In comparison with the Ni-B/CNTs amorphous catalyst, Ni-B/CNTs-A showed higher nickel loading, determined by ICP and be...Uniform Ni-B amorphous alloys about 14 nm have been prepared on CNTs-A support,named Ni-B/CNTs-A. In comparison with the Ni-B/CNTs amorphous catalyst, Ni-B/CNTs-A showed higher nickel loading, determined by ICP and better catalytic activity and ethylene selectivity in the acetylene hydrogenation reaction.展开更多
Annealing crystallization of ultrafine NiB amorphous alloy prepared by the chemical reduction method was studied by DTA, XRD and XAFS techniques. The XRD and XAFS results have revealed that the crystallization process...Annealing crystallization of ultrafine NiB amorphous alloy prepared by the chemical reduction method was studied by DTA, XRD and XAFS techniques. The XRD and XAFS results have revealed that the crystallization process of ultrafine NiB amorphous alloy proceeds in two steps. First, ultrafine NiB amorphous alloy is crystallized to form metastable nanocrystalline Ni3B at an annealing temperature of 325℃. Second, the nanocrystalline Ni3B is further decomposed into crystalline Ni at 380CCC or higher tempera ture, the local structure around Ni atoms in resultant product is similar to that in Ni foil. It was found that the catalytic activity of nanocrystalline Ni3B for benzene hydro-genation is much higher than that of ultrafine NiB amorphous alloy or crystalline Ni. The result indicates that the active sites of nanocrystalline Ni3B for benzene hydrogena-tion are composed of both Ni and B with proper geometry configuration.展开更多
Electroless nickel coatings are very popular for their corrosion resistant actions. The present article attempts to study the corrosion behaviour of electroless Ni-B coatings by varying the coating parameters viz. bat...Electroless nickel coatings are very popular for their corrosion resistant actions. The present article attempts to study the corrosion behaviour of electroless Ni-B coatings by varying the coating parameters viz. bath temperature, reducing agent concentration and nickel source concentration together with the annealing temperature. The electrochemical parameters viz., corrosion potential and corrosion current density are evaluated with the help of potentiodynamic polarization experimentation. Taguchi based Grey analysis is employed in order to optimize this multiple response problem and the optimal combination of parameters for maximum corrosion resistance for Ni-B coatings is presented. Moreover, analysis of variance reveals that bath temperature and concentration of nickel source have significant influence on the corrosion performance of the coating. The microstructure characterization of the coating is also conducted with the help of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis. The Ni-B coating in general exhibits a nodular structure and turns crystalline with heat treatment. The corroded surface exhibits cracks and black spots which imply the occurrence of localized corrosion.展开更多
文摘An investigation was carried out to assess the applicability of transient liquid phase bonding of two dissimilar super-alloys with different interlayers. The effect of using three types of interlayer such as BNi-2, BNi-3, and BNi-9 on microstructure and mechanical properties was studied in the GTD-111/IN-718 system at 1100 ℃ for different bonding time. To determine the compositional changes and microstructure in the joint region, field emission scanning electron microscopy equipped with energy dispersive spectroscopy was utilized. The formation of Ni_(3)B in the athermally solidified zone(ASZ) is controlled by the B content and, accordingly, the morphology of Ni_(3)Si is governed by the Si content. The Cr content might impede the relocation of B from the interlayer into the base metal and the formation of CrB inside the ASZ is dominated by the Cr content. The high micro-hardness of the eutectic compounds is originated from the formation of boride matrixes such as Ni or Cr boride. The shear strength of the joint using BNi-9 after the completion of isothermal solidification is lower compared that that using BNi-3 and BNi-2, which could be related to the absence of Si in the filler metals constituent and the significant presence of Cr in BNi-9.
文摘A series of Ce-doped Ni-B amorphous alloy catalysts were prepared by a KBH_4 reduction method, characterized by ICP, BET, XRD, H_2-chemisorption, H_2-TPD, etc., and tested in the hydrogenation of 2-ethylanthraquinone. The results of characterization show that with the addition of Ce the amount of H_2-chemisorption and H_2-TPD areas first increases markedly and then decreases with the maximum appears at the atomic ratio of Ce to Ni of 0.036. The hydrogenation activity also shows the same trend. The effects of Ce are attributed to its dispersion of Ni particles, resulting in the formation of more surface Ni centers. However, much higher Ce contents may result in the decrease of the surface Ni contents. After heat treatment at higher temperatures, the amorphous structure of Ni-B is destroyed.
基金supported by the National Natural Science Foundation of China(21573083)the 1000 Young Talent(to Deli Wang)initiatory financial support from Huazhong University of Science and Technology(HUST)~~
文摘The search for active,stable,and cost-effective electrocatalysts for hydrogen evolution reaction(HER)is desirable,but it remains a great challenge in the overall water splitting.Here,we report the synthesis of nickel boron nanoparticles supported on Vulcan carbon(Ni-B)via a simple,yet scalable,two-step chemical reduction–annealing strategy.The results of the electrochemical measurements suggest that the overpotentials of Ni-B-400 are 114 and 215 mV(in 1 mol L^–1 KOH)at current densities of 10 and 40 mA cm^?2,respectively,indicating an exceedingly good electrocatalytic activity in the HER.More importantly,Ni-B maintains a current density of 7.6 mA cm^-2 at an overpotential of 0.15 V for 20 h in the durability test.The excellent HER activity of Ni-B-400 is derived from the small particle size and the expanded lattice of Ni,which can optimize the hydrogen absorption energy and enhance the electrocatalytic properties.
基金the National Key Technology R & D Program of MOST(No.2003BA328C)Chinese Nature Science Foundation Committee(No.50472043)+2 种基金Program for New Century Excellent Talents in University(No.NCET-06-0658)the Excellent Young Teachers Program of MOE(No.EYTP 2003-355)Science and Technology Key Project of MOE(No:Key 104136).
文摘The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride, ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treatments on micro-diamond particle, and the optimized parameters were obtained. Both the morphology and the composition of original diamond and the diamond with Ni-B coating were analyzed by SEM and XRD respectively. The SEM image shows that the spherical Ni-B particle is coated upon diamond. XRD pattern shows that the coating compositions are Ni and Ni2B.
文摘Some parameters of liquid binary alloy were investigated , and the calculation formulae were proposed.According to the formulae for calculating coordination number, the accordination numbers of Cu-Zr , Fe-B, Ni-B, Co-P, Fe-P systems were calculated, the results agree well with those in literature and in experiments ofthis study.
基金The National Natural Science Foundation of China(No.20263003)supported this work.
文摘Uniform Ni-B amorphous alloys about 14 nm have been prepared on CNTs-A support,named Ni-B/CNTs-A. In comparison with the Ni-B/CNTs amorphous catalyst, Ni-B/CNTs-A showed higher nickel loading, determined by ICP and better catalytic activity and ethylene selectivity in the acetylene hydrogenation reaction.
基金the National NaturalScience Foundation of China (Grant No. 29673038) and "the One-hundred People Plan" of the Chinese Academy of Sciences.
文摘Annealing crystallization of ultrafine NiB amorphous alloy prepared by the chemical reduction method was studied by DTA, XRD and XAFS techniques. The XRD and XAFS results have revealed that the crystallization process of ultrafine NiB amorphous alloy proceeds in two steps. First, ultrafine NiB amorphous alloy is crystallized to form metastable nanocrystalline Ni3B at an annealing temperature of 325℃. Second, the nanocrystalline Ni3B is further decomposed into crystalline Ni at 380CCC or higher tempera ture, the local structure around Ni atoms in resultant product is similar to that in Ni foil. It was found that the catalytic activity of nanocrystalline Ni3B for benzene hydro-genation is much higher than that of ultrafine NiB amorphous alloy or crystalline Ni. The result indicates that the active sites of nanocrystalline Ni3B for benzene hydrogena-tion are composed of both Ni and B with proper geometry configuration.
文摘Electroless nickel coatings are very popular for their corrosion resistant actions. The present article attempts to study the corrosion behaviour of electroless Ni-B coatings by varying the coating parameters viz. bath temperature, reducing agent concentration and nickel source concentration together with the annealing temperature. The electrochemical parameters viz., corrosion potential and corrosion current density are evaluated with the help of potentiodynamic polarization experimentation. Taguchi based Grey analysis is employed in order to optimize this multiple response problem and the optimal combination of parameters for maximum corrosion resistance for Ni-B coatings is presented. Moreover, analysis of variance reveals that bath temperature and concentration of nickel source have significant influence on the corrosion performance of the coating. The microstructure characterization of the coating is also conducted with the help of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis. The Ni-B coating in general exhibits a nodular structure and turns crystalline with heat treatment. The corroded surface exhibits cracks and black spots which imply the occurrence of localized corrosion.
