There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of beta -NiAl and cx-Cr. After air and furnace cooling solution treatments, far 1400 degreesC, 2 h ...There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of beta -NiAl and cx-Cr. After air and furnace cooling solution treatments, far 1400 degreesC, 2 h and 1450 degreesC, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. During solution treatment at 1450 degreesC, bulk and 'fish bone' shape Zr-rich phases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2AlZr phase forms after 1450 C for 1h F.C. and 850 degreesC for 12 h, F.C.. The alloy has less pure Zr and Ni2AlZr phase after 1400 degreesC with both air and furnace cooling followed by 850 C and 950 C for 12 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAlZr and a phase enriched Zr and Cr forms at the edge of the eutectic of beta -NiAl and alpha -Cr in the alloy treated at 1400 degreesC, 2 h, F.C. and 950 degreesC, 12 h, F.C.展开更多
Phases of Cu-（0.4%-2.0%） Cr-（0.05%-0.16%） Zr alloys were analyzed in both as cast and deformed state. Solute-rich clusters of Cr, which was supposed to form during aging treatment, were observed in as cast state; ...Phases of Cu-（0.4%-2.0%） Cr-（0.05%-0.16%） Zr alloys were analyzed in both as cast and deformed state. Solute-rich clusters of Cr, which was supposed to form during aging treatment, were observed in as cast state; along with the morphology character, corresponding preferential orientation of Cr phase in as cast state was also investigated. Precipitates were observed to distribute in the matrix with a bimodal distribution, viz. coarse precipitates with dimension larger than several hundred nanometers and fine precipitates with size of 2- 10 nm. Three types of intermetallics, the common compound of Cu51Zr14, correspondingly infrequent Cu5Zr and rare Cu5Zr3, were characterized in different samples.展开更多
LiNiCoAlO（NCA） with Zr（OH）coating is demonstrated as high performance cathode material for lithium ion batteries（LIBs）. The coated materials are synthesized via a simple dry coating method of NCA with Zr（OH）po...LiNiCoAlO（NCA） with Zr（OH）coating is demonstrated as high performance cathode material for lithium ion batteries（LIBs）. The coated materials are synthesized via a simple dry coating method of NCA with Zr（OH）powders, and then characterized with scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and X-ray photoelectron spectroscopy（XPS）. Experimental results show that amorphous Zr（OH）powders have been successfully coated on the surface of spherical NCA particles, exhibiting improved electrochemical performance. 0.50 wt% Zr（OH）coated NCA delivers a capacity of 197.6 mAh/g at the first cycle and 154.3 mAh/g after 100 cycles with a capacity retention of 78.1% at 1 C rate. In comparison, the pure NCA shows a capacity of 194.6 mAh/g at the first cycle and 142.5 mAh/g after 100 cycles with a capacity retention of 73.2% at 1 C rate. Electrochemical impedance spectroscopy（EIS） results show that the coated material exhibits a lower resistance, indicating that the coating layer can efficiently suppress transition metals dissolution and decrease the side reactions at the surface between the electrode and electrolyte. Therefore, surface coating with amorphous Zr（OH）is a simple and useful method to enhance the electrochemical performance of NCA-based materials for the cathode of LIBs.展开更多
Binary Ce-Zr（CZ）,Pr-Zr（PZ） and ternary Ce-Zr-Pr（CZP） mixed oxides were prepared by an ammonia-aided co-precipitation method,and were aged in a steam/air flow at 1050 °C.X-ray diffraction（XRD）,Raman spectr...Binary Ce-Zr（CZ）,Pr-Zr（PZ） and ternary Ce-Zr-Pr（CZP） mixed oxides were prepared by an ammonia-aided co-precipitation method,and were aged in a steam/air flow at 1050 °C.X-ray diffraction（XRD）,Raman spectra,X-photon spectra（XPS） and CO temperature programmed reduction（TPR） were carried out to characterize the micro-structure and reducibility of catalysts.The oxygen storage capacity（OSC） was evaluated with CO serving as probe gas.The results showed that a pseudo cubic structure was formed for the Zr-rich ceria-zirconia mixed oxides with Pr doping.The insertion of Pr prevented the phase segregation of the mixed oxides during the hydrothermal ageing.The Pr doped samples showed better redox performances in comparison with CZ,and the sample doped with 5 wt.% Pr showed the most remarkably promoted dynamic oxygen storage capacity.This phenomenon was closely related to both the reducibility and oxygen mobility of the mixed oxides.The introduction of praseodymium into ceria-zirconia could accelerate the oxygen migration by increasing the amount of oxygen vacancies,although it was difficult for Pr3＋ ions themselves to participate in the oxygen exchange process.展开更多
基金The work was supported by the National Advanced Materials Connittee of China(Grant No.970321016)the National Natural Science Foundation of Chind(No.59895152).
文摘There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of beta -NiAl and cx-Cr. After air and furnace cooling solution treatments, far 1400 degreesC, 2 h and 1450 degreesC, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. During solution treatment at 1450 degreesC, bulk and 'fish bone' shape Zr-rich phases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2AlZr phase forms after 1450 C for 1h F.C. and 850 degreesC for 12 h, F.C.. The alloy has less pure Zr and Ni2AlZr phase after 1400 degreesC with both air and furnace cooling followed by 850 C and 950 C for 12 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAlZr and a phase enriched Zr and Cr forms at the edge of the eutectic of beta -NiAl and alpha -Cr in the alloy treated at 1400 degreesC, 2 h, F.C. and 950 degreesC, 12 h, F.C.
文摘Phases of Cu-（0.4%-2.0%） Cr-（0.05%-0.16%） Zr alloys were analyzed in both as cast and deformed state. Solute-rich clusters of Cr, which was supposed to form during aging treatment, were observed in as cast state; along with the morphology character, corresponding preferential orientation of Cr phase in as cast state was also investigated. Precipitates were observed to distribute in the matrix with a bimodal distribution, viz. coarse precipitates with dimension larger than several hundred nanometers and fine precipitates with size of 2- 10 nm. Three types of intermetallics, the common compound of Cu51Zr14, correspondingly infrequent Cu5Zr and rare Cu5Zr3, were characterized in different samples.
基金supported by the National Projects of NSFC(21322101 and 21231005)MOE(B12015 and IRT13R30)
文摘LiNiCoAlO（NCA） with Zr（OH）coating is demonstrated as high performance cathode material for lithium ion batteries（LIBs）. The coated materials are synthesized via a simple dry coating method of NCA with Zr（OH）powders, and then characterized with scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and X-ray photoelectron spectroscopy（XPS）. Experimental results show that amorphous Zr（OH）powders have been successfully coated on the surface of spherical NCA particles, exhibiting improved electrochemical performance. 0.50 wt% Zr（OH）coated NCA delivers a capacity of 197.6 mAh/g at the first cycle and 154.3 mAh/g after 100 cycles with a capacity retention of 78.1% at 1 C rate. In comparison, the pure NCA shows a capacity of 194.6 mAh/g at the first cycle and 142.5 mAh/g after 100 cycles with a capacity retention of 73.2% at 1 C rate. Electrochemical impedance spectroscopy（EIS） results show that the coated material exhibits a lower resistance, indicating that the coating layer can efficiently suppress transition metals dissolution and decrease the side reactions at the surface between the electrode and electrolyte. Therefore, surface coating with amorphous Zr（OH）is a simple and useful method to enhance the electrochemical performance of NCA-based materials for the cathode of LIBs.
基金Project supported by the National Natural Science Foundation of China (50972069)the Ministry of Science and Technology, China (2009AA064803)the Chinese Ministry of Industry and Information Technology
文摘Binary Ce-Zr（CZ）,Pr-Zr（PZ） and ternary Ce-Zr-Pr（CZP） mixed oxides were prepared by an ammonia-aided co-precipitation method,and were aged in a steam/air flow at 1050 °C.X-ray diffraction（XRD）,Raman spectra,X-photon spectra（XPS） and CO temperature programmed reduction（TPR） were carried out to characterize the micro-structure and reducibility of catalysts.The oxygen storage capacity（OSC） was evaluated with CO serving as probe gas.The results showed that a pseudo cubic structure was formed for the Zr-rich ceria-zirconia mixed oxides with Pr doping.The insertion of Pr prevented the phase segregation of the mixed oxides during the hydrothermal ageing.The Pr doped samples showed better redox performances in comparison with CZ,and the sample doped with 5 wt.% Pr showed the most remarkably promoted dynamic oxygen storage capacity.This phenomenon was closely related to both the reducibility and oxygen mobility of the mixed oxides.The introduction of praseodymium into ceria-zirconia could accelerate the oxygen migration by increasing the amount of oxygen vacancies,although it was difficult for Pr3＋ ions themselves to participate in the oxygen exchange process.
