Rapid Quenching

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Yanghuan Zhang - One of the best experts on this subject based on the ideXlab platform.

  • mechanism of distinct high rate dischargeability of la4mgni19 electrode alloys prepared by casting and Rapid Quenching followed by annealing treatment
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Yanghuan Zhang, Huiping Ren, Zhuocheng Liu, Hao Sun
    Abstract:

    Abstract Microstructure and hydrogen storage properties of La4MgNi19 alloys prepared by casting and Rapid Quenching, and followed by annealing were investigated in the present work. These alloys have analogical gaseous capabilities, however they exhibit distinct electrochemical performances. High-rate dischargeabilities (HRD) of the alloys with different phase constitution and grain size due to various prepared routes were mainly focused. The as-quenched (RQ) alloy with the most fine microstructure possesses excellent cycling stability, but poor discharge capacity and HRD. Annealing on the as-quenched alloy (the QA alloy) suppresses the electrochemical cycling stability, but dramatically elevates HRD. However, the converse trend is observed in the as-cast alloy that HRD becomes even worse after annealing. Mechanism of HRD is considered based on the electrochemical kinetics and synergetic effects of the multiphase microstructure. Fine microstructure is favorable to the hydrogen diffusion ability, but contributes to higher charge-transfer resistance. Furthermore, fine grains lead to transition of the hydrogen storage mechanism from funneling mode to synergetic mode which promotes the catalytic effects of LaNi5. Thus, the excellent HRD of the as-cast alloy results from the fast electrochemical kinetics. High HRD of the QA alloy is caused by the advantageous synergetic mode, while the sluggish HRD of the RQ alloy is due to the large electrochemical impedance which is strongly more than the other alloys.

  • gaseous and electrochemical hydrogen storage kinetics of nanocrystalline mg2ni type alloy prepared by Rapid Quenching
    Journal of Alloys and Compounds, 2011
    Co-Authors: Yanghuan Zhang, Huiping Ren, Guofang Zhang, Shihai Guo
    Abstract:

    Abstract The nanocrystalline Mg2Ni-type Mg2Ni1−xCux (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were synthesized by direct melt Quenching technique. The structures of the as-cast and quenched alloys were investigated by XRD, SEM and HRTEM. The gaseous hydrogen storage kinetics of the alloys was measured using an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the alloys was tested by using constant current to charge and discharge the electrode. The results indicate that the substitution of Cu notably rendered the grain refinement of the as-cast alloys without altering the major phase Mg2Ni. All the as-quenched alloys exhibit a nanocrystalline structure without the presence of any amorphous phase. It is found that the substitution of Cu for Ni and Rapid Quenching significantly ameliorated the gaseous and electrochemical hydrogen storage kinetics of the nanocrystalline Mg2Ni1−xCux (x = 0–0.4) alloys. Furthermore, both the Rapid Quenching treatment and the Cu substitution results in a notable increase in the hydrogen diffusion coefficient (D) as well as the limiting current density (IL) but an obvious decline in the electrochemical impedance.

  • cycle stabilities of the la0 7mg0 3ni2 55 xco0 45mx m fe mn al x 0 0 1 electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2008
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Huiping Ren, Ying Cai, Xin-lin Wang
    Abstract:

    Abstract In order to improve the cycle stability of La–Mg–Ni system (PuNi 3 -type) hydrogen storage alloy, Ni in the alloy was partly substituted by Fe, Mn and Al, and the electrode alloys La 0.7 Mg 0.3 Ni 2.55− x Co 0.45 M x (M = Fe, Mn, Al; x  = 0, 0.1) were prepared by casting and Rapid Quenching. The effects of the substitution of Fe, Mn and Al for Ni and Rapid Quenching on the microstructures and electrochemical properties of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM indicate that element substitution has no influence on the phase compositions of the alloys, but it changes the phase abundances of the alloys. Particularly, the substitution of Al and Mn obviously raises the amount of the LaNi 2 phase. The substitution of Al and Fe leads to a significant refinement of the as-quenched alloy's grains. The substitution of Al strongly restrains the formation of an amorphous in the as-quenched alloy, but the substitution of Fe is quite helpful for the formation of an amorphous phase. The effects of the substitution of Fe, Mn and Al on the cycle stabilities of the as-cast and quenched alloys are different. The positive influence of the substitution elements on the cycle stabilities of the as-cast alloys is in proper order Al > Fe > Mn, and for as-quenched alloys, the order is Fe > Al > Mn. Rapid Quenching engenders an inappreciable influence on the phase composition, but it markedly enhances the cycle stabilities of the alloys.

  • effects of Rapid Quenching on microstructures and electrochemical properties of la0 7mg0 3ni2 55co0 45bx x 0 0 2 hydrogen storage alloy
    Transactions of Nonferrous Metals Society of China, 2006
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Jiangyuan Ren, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45(x=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and Rapid Quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of Rapid Quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after Rapid Quenching. Rapid Quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of Rapid Quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing Quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the Quenching rate. The Rapid Quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of Rapid Quenching on the activation capabilities of the alloys was complicated.

  • effects of Rapid Quenching on the electrochemical performances and microstructures of the mm nimnsial 4 3co0 6 xfex x 0 0 6 electrode alloys
    Journal of Power Sources, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performance of rare-earth-based AB 5 -type electrode alloy, the AB 5 -type Mm(NiMnSiAl) 4.3 Co 0.6− x Fe x ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) electrode alloys were quenched by melt-spinning. The phase structures and microstructure morphologies of the as-cast and quenched alloys were analyzed by XRD, SEM and TEM. The effects of the Rapid Quenching on the microstructures and electrochemical performances of the alloys were investigated in detail. The obtained results show that the as-quenched alloys have an excellent activation performance and can be completely activated through two to five charge–discharge cycles. The effect of the Rapid Quenching on the capacities of the alloys with Fe content x ≤ 0.2 is minor, and the capacities and high rate discharge abilities of the alloys with Fe content x > 0.2 decrease significantly with the increase of Quenching rate. The cycle lives of the alloys increase greatly with the increase of the Quenching rate.

Xin-lin Wang - One of the best experts on this subject based on the ideXlab platform.

  • cycle stabilities of the la0 7mg0 3ni2 55 xco0 45mx m fe mn al x 0 0 1 electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2008
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Huiping Ren, Ying Cai, Xin-lin Wang
    Abstract:

    Abstract In order to improve the cycle stability of La–Mg–Ni system (PuNi 3 -type) hydrogen storage alloy, Ni in the alloy was partly substituted by Fe, Mn and Al, and the electrode alloys La 0.7 Mg 0.3 Ni 2.55− x Co 0.45 M x (M = Fe, Mn, Al; x  = 0, 0.1) were prepared by casting and Rapid Quenching. The effects of the substitution of Fe, Mn and Al for Ni and Rapid Quenching on the microstructures and electrochemical properties of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM indicate that element substitution has no influence on the phase compositions of the alloys, but it changes the phase abundances of the alloys. Particularly, the substitution of Al and Mn obviously raises the amount of the LaNi 2 phase. The substitution of Al and Fe leads to a significant refinement of the as-quenched alloy's grains. The substitution of Al strongly restrains the formation of an amorphous in the as-quenched alloy, but the substitution of Fe is quite helpful for the formation of an amorphous phase. The effects of the substitution of Fe, Mn and Al on the cycle stabilities of the as-cast and quenched alloys are different. The positive influence of the substitution elements on the cycle stabilities of the as-cast alloys is in proper order Al > Fe > Mn, and for as-quenched alloys, the order is Fe > Al > Mn. Rapid Quenching engenders an inappreciable influence on the phase composition, but it markedly enhances the cycle stabilities of the alloys.

  • effects of Rapid Quenching on microstructures and electrochemical properties of la0 7mg0 3ni2 55co0 45bx x 0 0 2 hydrogen storage alloy
    Transactions of Nonferrous Metals Society of China, 2006
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Jiangyuan Ren, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45(x=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and Rapid Quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of Rapid Quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after Rapid Quenching. Rapid Quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of Rapid Quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing Quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the Quenching rate. The Rapid Quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of Rapid Quenching on the activation capabilities of the alloys was complicated.

  • effects of Rapid Quenching on the electrochemical performances and microstructures of the mm nimnsial 4 3co0 6 xfex x 0 0 6 electrode alloys
    Journal of Power Sources, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performance of rare-earth-based AB 5 -type electrode alloy, the AB 5 -type Mm(NiMnSiAl) 4.3 Co 0.6− x Fe x ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) electrode alloys were quenched by melt-spinning. The phase structures and microstructure morphologies of the as-cast and quenched alloys were analyzed by XRD, SEM and TEM. The effects of the Rapid Quenching on the microstructures and electrochemical performances of the alloys were investigated in detail. The obtained results show that the as-quenched alloys have an excellent activation performance and can be completely activated through two to five charge–discharge cycles. The effect of the Rapid Quenching on the capacities of the alloys with Fe content x ≤ 0.2 is minor, and the capacities and high rate discharge abilities of the alloys with Fe content x > 0.2 decrease significantly with the increase of Quenching rate. The cycle lives of the alloys increase greatly with the increase of the Quenching rate.

  • Investigation on the microstructure and electrochemical performances of La2Mg(Ni0.85Co0.15)9Bx (x=0–0.2) hydrogen storage electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract The rare-earth Mg-based La 2 Mg(Ni 0.85 Co 0.15 ) 9 B x ( x =0–0.2) hydrogen storage electrode alloys were prepared by casting and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were determined and measured systematically. The effects of boron content and Quenching rate on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni 3 phase (PuNi 3 -type structure), the LaNi 5 phase as well as of the LaNi 2 phase. A trace of the Ni 2 B phase exists in the as-cast alloys containing boron, and when the Quenching rate is larger than 15 m/s, the Ni 2 B phase in the alloys nearly disappears. The relative amount of each phase in the alloys depends on the composition of the alloys and the Quenching rate. The addition of boron enhances the cycle stability of the as-cast and Quenching alloys, but decreases the discharge capacity of the alloys. The capacity of the alloys without boron monotonously decreases with increasing Quenching rate, but for the alloys containing boron, the capacities have a maximum value when varying the Quenching rate. The cycle lives of the as-quenched alloys increase with increasing Quenching rate. The as-cast and quenched alloys have an excellent activation performance.

  • microstructure and electrochemical characteristics of mm ni co mn al 5bx x 0 0 4 hydrogen storage alloys prepared by cast and Rapid Quenching
    Electrochimica Acta, 2004
    Co-Authors: Yanghuan Zhang, Xin-lin Wang, Guoqing Wang, Meiyan Chen, Xiaoping Dong
    Abstract:

    Abstract Low Co AB 5 -type MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by cast and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were analysed and measured. The effects of boron additive and Rapid Quenching technique on the microstructures and electrochemical properties of as-cast and quenched alloys were investigated comprehensively. The experimental results showed that the microstructure of as-cast MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) alloys was composed of CaCu 5 -type main phase and a small amount of CeCo 4 B-type secondary phase. The abundance of the secondary phase increases with the increase of boron context x . The Rapid Quenching techniques were used in the preparation of the alloys. The amount of secondary phase in the alloys decreased with the increase of Quenching rate. Rapid Quenching made lattice constants increase slightly. The effects of Rapid Quenching on the electrochemical performances of the alloys are very significant. The discharge capacity of the alloys decreased obviously and the cycle stability increased dramatically with the increase of Quenching rate. Rapid Quenching made the activation capability of the alloys lowered. However, the activate performance and high rate discharge capability as well as discharge voltage characteristic of the alloys were modified obviously with the increase of boron content x .

Xiaoping Dong - One of the best experts on this subject based on the ideXlab platform.

  • cycle stabilities of the la0 7mg0 3ni2 55 xco0 45mx m fe mn al x 0 0 1 electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2008
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Huiping Ren, Ying Cai, Xin-lin Wang
    Abstract:

    Abstract In order to improve the cycle stability of La–Mg–Ni system (PuNi 3 -type) hydrogen storage alloy, Ni in the alloy was partly substituted by Fe, Mn and Al, and the electrode alloys La 0.7 Mg 0.3 Ni 2.55− x Co 0.45 M x (M = Fe, Mn, Al; x  = 0, 0.1) were prepared by casting and Rapid Quenching. The effects of the substitution of Fe, Mn and Al for Ni and Rapid Quenching on the microstructures and electrochemical properties of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM indicate that element substitution has no influence on the phase compositions of the alloys, but it changes the phase abundances of the alloys. Particularly, the substitution of Al and Mn obviously raises the amount of the LaNi 2 phase. The substitution of Al and Fe leads to a significant refinement of the as-quenched alloy's grains. The substitution of Al strongly restrains the formation of an amorphous in the as-quenched alloy, but the substitution of Fe is quite helpful for the formation of an amorphous phase. The effects of the substitution of Fe, Mn and Al on the cycle stabilities of the as-cast and quenched alloys are different. The positive influence of the substitution elements on the cycle stabilities of the as-cast alloys is in proper order Al > Fe > Mn, and for as-quenched alloys, the order is Fe > Al > Mn. Rapid Quenching engenders an inappreciable influence on the phase composition, but it markedly enhances the cycle stabilities of the alloys.

  • effects of Rapid Quenching on microstructures and electrochemical properties of la0 7mg0 3ni2 55co0 45bx x 0 0 2 hydrogen storage alloy
    Transactions of Nonferrous Metals Society of China, 2006
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Jiangyuan Ren, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45(x=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and Rapid Quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of Rapid Quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after Rapid Quenching. Rapid Quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of Rapid Quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing Quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the Quenching rate. The Rapid Quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of Rapid Quenching on the activation capabilities of the alloys was complicated.

  • effects of Rapid Quenching on the electrochemical performances and microstructures of the mm nimnsial 4 3co0 6 xfex x 0 0 6 electrode alloys
    Journal of Power Sources, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performance of rare-earth-based AB 5 -type electrode alloy, the AB 5 -type Mm(NiMnSiAl) 4.3 Co 0.6− x Fe x ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) electrode alloys were quenched by melt-spinning. The phase structures and microstructure morphologies of the as-cast and quenched alloys were analyzed by XRD, SEM and TEM. The effects of the Rapid Quenching on the microstructures and electrochemical performances of the alloys were investigated in detail. The obtained results show that the as-quenched alloys have an excellent activation performance and can be completely activated through two to five charge–discharge cycles. The effect of the Rapid Quenching on the capacities of the alloys with Fe content x ≤ 0.2 is minor, and the capacities and high rate discharge abilities of the alloys with Fe content x > 0.2 decrease significantly with the increase of Quenching rate. The cycle lives of the alloys increase greatly with the increase of the Quenching rate.

  • Investigation on the microstructure and electrochemical performances of La2Mg(Ni0.85Co0.15)9Bx (x=0–0.2) hydrogen storage electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract The rare-earth Mg-based La 2 Mg(Ni 0.85 Co 0.15 ) 9 B x ( x =0–0.2) hydrogen storage electrode alloys were prepared by casting and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were determined and measured systematically. The effects of boron content and Quenching rate on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni 3 phase (PuNi 3 -type structure), the LaNi 5 phase as well as of the LaNi 2 phase. A trace of the Ni 2 B phase exists in the as-cast alloys containing boron, and when the Quenching rate is larger than 15 m/s, the Ni 2 B phase in the alloys nearly disappears. The relative amount of each phase in the alloys depends on the composition of the alloys and the Quenching rate. The addition of boron enhances the cycle stability of the as-cast and Quenching alloys, but decreases the discharge capacity of the alloys. The capacity of the alloys without boron monotonously decreases with increasing Quenching rate, but for the alloys containing boron, the capacities have a maximum value when varying the Quenching rate. The cycle lives of the as-quenched alloys increase with increasing Quenching rate. The as-cast and quenched alloys have an excellent activation performance.

  • microstructure and electrochemical characteristics of mm ni co mn al 5bx x 0 0 4 hydrogen storage alloys prepared by cast and Rapid Quenching
    Electrochimica Acta, 2004
    Co-Authors: Yanghuan Zhang, Xin-lin Wang, Guoqing Wang, Meiyan Chen, Xiaoping Dong
    Abstract:

    Abstract Low Co AB 5 -type MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by cast and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were analysed and measured. The effects of boron additive and Rapid Quenching technique on the microstructures and electrochemical properties of as-cast and quenched alloys were investigated comprehensively. The experimental results showed that the microstructure of as-cast MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) alloys was composed of CaCu 5 -type main phase and a small amount of CeCo 4 B-type secondary phase. The abundance of the secondary phase increases with the increase of boron context x . The Rapid Quenching techniques were used in the preparation of the alloys. The amount of secondary phase in the alloys decreased with the increase of Quenching rate. Rapid Quenching made lattice constants increase slightly. The effects of Rapid Quenching on the electrochemical performances of the alloys are very significant. The discharge capacity of the alloys decreased obviously and the cycle stability increased dramatically with the increase of Quenching rate. Rapid Quenching made the activation capability of the alloys lowered. However, the activate performance and high rate discharge capability as well as discharge voltage characteristic of the alloys were modified obviously with the increase of boron content x .

Guoqing Wang - One of the best experts on this subject based on the ideXlab platform.

  • effects of Rapid Quenching on microstructures and electrochemical properties of la0 7mg0 3ni2 55co0 45bx x 0 0 2 hydrogen storage alloy
    Transactions of Nonferrous Metals Society of China, 2006
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Jiangyuan Ren, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45(x=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and Rapid Quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of Rapid Quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after Rapid Quenching. Rapid Quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of Rapid Quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing Quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the Quenching rate. The Rapid Quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of Rapid Quenching on the activation capabilities of the alloys was complicated.

  • effects of Rapid Quenching on the electrochemical performances and microstructures of the mm nimnsial 4 3co0 6 xfex x 0 0 6 electrode alloys
    Journal of Power Sources, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performance of rare-earth-based AB 5 -type electrode alloy, the AB 5 -type Mm(NiMnSiAl) 4.3 Co 0.6− x Fe x ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) electrode alloys were quenched by melt-spinning. The phase structures and microstructure morphologies of the as-cast and quenched alloys were analyzed by XRD, SEM and TEM. The effects of the Rapid Quenching on the microstructures and electrochemical performances of the alloys were investigated in detail. The obtained results show that the as-quenched alloys have an excellent activation performance and can be completely activated through two to five charge–discharge cycles. The effect of the Rapid Quenching on the capacities of the alloys with Fe content x ≤ 0.2 is minor, and the capacities and high rate discharge abilities of the alloys with Fe content x > 0.2 decrease significantly with the increase of Quenching rate. The cycle lives of the alloys increase greatly with the increase of the Quenching rate.

  • Investigation on the microstructure and electrochemical performances of La2Mg(Ni0.85Co0.15)9Bx (x=0–0.2) hydrogen storage electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract The rare-earth Mg-based La 2 Mg(Ni 0.85 Co 0.15 ) 9 B x ( x =0–0.2) hydrogen storage electrode alloys were prepared by casting and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were determined and measured systematically. The effects of boron content and Quenching rate on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni 3 phase (PuNi 3 -type structure), the LaNi 5 phase as well as of the LaNi 2 phase. A trace of the Ni 2 B phase exists in the as-cast alloys containing boron, and when the Quenching rate is larger than 15 m/s, the Ni 2 B phase in the alloys nearly disappears. The relative amount of each phase in the alloys depends on the composition of the alloys and the Quenching rate. The addition of boron enhances the cycle stability of the as-cast and Quenching alloys, but decreases the discharge capacity of the alloys. The capacity of the alloys without boron monotonously decreases with increasing Quenching rate, but for the alloys containing boron, the capacities have a maximum value when varying the Quenching rate. The cycle lives of the as-quenched alloys increase with increasing Quenching rate. The as-cast and quenched alloys have an excellent activation performance.

  • microstructure and electrochemical characteristics of mm ni co mn al 5bx x 0 0 4 hydrogen storage alloys prepared by cast and Rapid Quenching
    Electrochimica Acta, 2004
    Co-Authors: Yanghuan Zhang, Xin-lin Wang, Guoqing Wang, Meiyan Chen, Xiaoping Dong
    Abstract:

    Abstract Low Co AB 5 -type MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by cast and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were analysed and measured. The effects of boron additive and Rapid Quenching technique on the microstructures and electrochemical properties of as-cast and quenched alloys were investigated comprehensively. The experimental results showed that the microstructure of as-cast MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) alloys was composed of CaCu 5 -type main phase and a small amount of CeCo 4 B-type secondary phase. The abundance of the secondary phase increases with the increase of boron context x . The Rapid Quenching techniques were used in the preparation of the alloys. The amount of secondary phase in the alloys decreased with the increase of Quenching rate. Rapid Quenching made lattice constants increase slightly. The effects of Rapid Quenching on the electrochemical performances of the alloys are very significant. The discharge capacity of the alloys decreased obviously and the cycle stability increased dramatically with the increase of Quenching rate. Rapid Quenching made the activation capability of the alloys lowered. However, the activate performance and high rate discharge capability as well as discharge voltage characteristic of the alloys were modified obviously with the increase of boron content x .

  • Effect of boron additive on the cycle life of low-Co AB5-type electrode consisting of alloy prepared by cast and Rapid Quenching
    Journal of Power Sources, 2004
    Co-Authors: Yanghuan Zhang, Xin-lin Wang, Guoqing Wang, Meiyan Chen, Yu-fang Lin
    Abstract:

    Abstract In order to modify the cycle stability of low-Co AB 5 -type alloy, a trace of boron was added in MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 hydrogen storage alloy. The low-Co AB 5 -type alloys MmNi 3.8 Co 0.4 Mn 0.6 Al 0.2 B x ( x =0, 0.1, 0.2, 0.3, 0.4) were prepared by cast and Rapid Quenching. The cycle lives and microstructures of the as-cast and quenched alloys were measured and analyzed. The effects of boron additive on the microstructures and cycle lives of as-cast and quenched alloys were investigated comprehensively. The obtained results showed that the addition of boron could dramatically enhance the cycle lives of the as-cast and quenched alloys. When boron content x increases from 0 to 0.4, the cycle lives of the as-cast alloys were increased from 118 to 183 cycles, and for as-quenched alloys with Quenching rate of 38 m/s from 310 to 566 cycles.

Shihai Guo - One of the best experts on this subject based on the ideXlab platform.

  • gaseous and electrochemical hydrogen storage kinetics of nanocrystalline mg2ni type alloy prepared by Rapid Quenching
    Journal of Alloys and Compounds, 2011
    Co-Authors: Yanghuan Zhang, Huiping Ren, Guofang Zhang, Shihai Guo
    Abstract:

    Abstract The nanocrystalline Mg2Ni-type Mg2Ni1−xCux (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were synthesized by direct melt Quenching technique. The structures of the as-cast and quenched alloys were investigated by XRD, SEM and HRTEM. The gaseous hydrogen storage kinetics of the alloys was measured using an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the alloys was tested by using constant current to charge and discharge the electrode. The results indicate that the substitution of Cu notably rendered the grain refinement of the as-cast alloys without altering the major phase Mg2Ni. All the as-quenched alloys exhibit a nanocrystalline structure without the presence of any amorphous phase. It is found that the substitution of Cu for Ni and Rapid Quenching significantly ameliorated the gaseous and electrochemical hydrogen storage kinetics of the nanocrystalline Mg2Ni1−xCux (x = 0–0.4) alloys. Furthermore, both the Rapid Quenching treatment and the Cu substitution results in a notable increase in the hydrogen diffusion coefficient (D) as well as the limiting current density (IL) but an obvious decline in the electrochemical impedance.

  • effects of Rapid Quenching on microstructures and electrochemical properties of la0 7mg0 3ni2 55co0 45bx x 0 0 2 hydrogen storage alloy
    Transactions of Nonferrous Metals Society of China, 2006
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Jiangyuan Ren, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45(x=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and Rapid Quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of Rapid Quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after Rapid Quenching. Rapid Quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of Rapid Quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing Quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the Quenching rate. The Rapid Quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of Rapid Quenching on the activation capabilities of the alloys was complicated.

  • effects of Rapid Quenching on the electrochemical performances and microstructures of the mm nimnsial 4 3co0 6 xfex x 0 0 6 electrode alloys
    Journal of Power Sources, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract In order to improve the electrochemical performance of rare-earth-based AB 5 -type electrode alloy, the AB 5 -type Mm(NiMnSiAl) 4.3 Co 0.6− x Fe x ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) electrode alloys were quenched by melt-spinning. The phase structures and microstructure morphologies of the as-cast and quenched alloys were analyzed by XRD, SEM and TEM. The effects of the Rapid Quenching on the microstructures and electrochemical performances of the alloys were investigated in detail. The obtained results show that the as-quenched alloys have an excellent activation performance and can be completely activated through two to five charge–discharge cycles. The effect of the Rapid Quenching on the capacities of the alloys with Fe content x ≤ 0.2 is minor, and the capacities and high rate discharge abilities of the alloys with Fe content x > 0.2 decrease significantly with the increase of Quenching rate. The cycle lives of the alloys increase greatly with the increase of the Quenching rate.

  • Investigation on the microstructure and electrochemical performances of La2Mg(Ni0.85Co0.15)9Bx (x=0–0.2) hydrogen storage electrode alloys prepared by casting and Rapid Quenching
    Journal of Alloys and Compounds, 2004
    Co-Authors: Yanghuan Zhang, Xiaoping Dong, Guoqing Wang, Shihai Guo, Xin-lin Wang
    Abstract:

    Abstract The rare-earth Mg-based La 2 Mg(Ni 0.85 Co 0.15 ) 9 B x ( x =0–0.2) hydrogen storage electrode alloys were prepared by casting and Rapid Quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were determined and measured systematically. The effects of boron content and Quenching rate on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni 3 phase (PuNi 3 -type structure), the LaNi 5 phase as well as of the LaNi 2 phase. A trace of the Ni 2 B phase exists in the as-cast alloys containing boron, and when the Quenching rate is larger than 15 m/s, the Ni 2 B phase in the alloys nearly disappears. The relative amount of each phase in the alloys depends on the composition of the alloys and the Quenching rate. The addition of boron enhances the cycle stability of the as-cast and Quenching alloys, but decreases the discharge capacity of the alloys. The capacity of the alloys without boron monotonously decreases with increasing Quenching rate, but for the alloys containing boron, the capacities have a maximum value when varying the Quenching rate. The cycle lives of the as-quenched alloys increase with increasing Quenching rate. The as-cast and quenched alloys have an excellent activation performance.