A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rate...A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.展开更多
The oxidation kinetics,surface morphology and phase structure of oxide films grown on 25Cr20Ni alloy in air-H2O and H2-H2O atmospheres at 900 ℃ for 20 h were investigated.The anti-coking performance and resistance to...The oxidation kinetics,surface morphology and phase structure of oxide films grown on 25Cr20Ni alloy in air-H2O and H2-H2O atmospheres at 900 ℃ for 20 h were investigated.The anti-coking performance and resistance to carburization of the two oxide films were compared using 25Cr20Ni alloy tubes with an inner diameter of 10 mm and a length of 850 mm in a bench scale naphtha steam pyrolysis unit.The oxidation kinetics followed a parabolic law in an air-H2O atmosphere and a logarithm law in a H2-H2O atmosphere in the steady-state stage.The oxide film grown in the air-H2O atmosphere had cracks where the elements Fe and Ni were enriched and the un-cracked area was covered with octahedral-shaped MnCr2O4 spinels and Cr1.3Fe0.7O3 oxide clusters,while the oxide film grown in the H2-H2O atmosphere was intact and completely covered with dense standing blade MnCr2O4 spinels.In the pyrolysis tests,the anti-coking performance and resistance to carburization of the oxide film grown in the H2-H2O atmosphere were far better than that in the air-H2O atmosphere.The mass of coke formed in the oxide film grown in the H2-H2O atmosphere was less than 10％ of that in the air-H2O atmosphere.The Cr1.3Fe0.7O3 oxide clusters converted into Cr23C6 carbides and the cracks were filled with carbon in the oxide film grown in the air-H2O atmosphere after repeated coking and decoking tests,while the dense standing blade MnCr2O4 spinels remained unchanged in the oxide film grown in the H2-H2O atmosphere.The ethylene,propylene and butadiene yields in the pyrolysis tests were almost the same for the two oxide films.展开更多
Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be ...Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10-5, 2×10-4 and 2×10-3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of Ni Fe2O4 and Ni O. With increasing oxygen content, Ni Fe2O4 content in the ceramic increases, while Ni O content appears a contrary trend. In vacuum, Ni Fe2O4 ceramic has average grain size of 3.94 μm, and bending strength of85.12 MPa. The changes of the phase composition and mechanical properties of Ni Fe2O4 based cermets are mainly caused by the alteration of their properties of Ni Fe2O4 ceramic.展开更多
Changes of CO 2/H 2O exchange parameters were continually measured in winter wheat under different water stress stages.The results showed that photosynthesis rate and transpiration rate of winter wheat in water stress...Changes of CO 2/H 2O exchange parameters were continually measured in winter wheat under different water stress stages.The results showed that photosynthesis rate and transpiration rate of winter wheat in water stress conditions were obviously lower than that in non stress conditions.After water stress,both of them slowly increased and even overtook that on sufficient irrigation treatment. Responses of winter wheat to water stress in different growth stages were different.To some extent, water stress can improve crop water use efficiency,speed up the process of milking.Under water stress condition,stomatal conductance limited diurnal changes of photosynthesis and transpiration in the morning but not in the afternoon.Transpiration is more sensitive to water stress than photosynthesis.展开更多
Department of Chemistry&Biology,Hechi Teacher’s College,Yizhou546300)abstract:The new complex formulated[Co（DPC）abstract: 2 ]-Co（H 2 O）abstract: 5 ]·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract...Department of Chemistry&Biology,Hechi Teacher’s College,Yizhou546300)abstract:The new complex formulated[Co（DPC）abstract: 2 ]-Co（H 2 O）abstract: 5 ]·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of[Co（DPC）abstract: 2 ]possess an approximate D 2d symmetry,while the part of[OCo （2）OH 2 5 ]has an approximate C2symmetry.展开更多
基金Project(51474238)supported by the National Natural Science Foundation of China
文摘A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.
基金financially supported by the scientific research project of China Petroleum and Chemical Corporation(No.409075)
文摘The oxidation kinetics,surface morphology and phase structure of oxide films grown on 25Cr20Ni alloy in air-H2O and H2-H2O atmospheres at 900 ℃ for 20 h were investigated.The anti-coking performance and resistance to carburization of the two oxide films were compared using 25Cr20Ni alloy tubes with an inner diameter of 10 mm and a length of 850 mm in a bench scale naphtha steam pyrolysis unit.The oxidation kinetics followed a parabolic law in an air-H2O atmosphere and a logarithm law in a H2-H2O atmosphere in the steady-state stage.The oxide film grown in the air-H2O atmosphere had cracks where the elements Fe and Ni were enriched and the un-cracked area was covered with octahedral-shaped MnCr2O4 spinels and Cr1.3Fe0.7O3 oxide clusters,while the oxide film grown in the H2-H2O atmosphere was intact and completely covered with dense standing blade MnCr2O4 spinels.In the pyrolysis tests,the anti-coking performance and resistance to carburization of the oxide film grown in the H2-H2O atmosphere were far better than that in the air-H2O atmosphere.The mass of coke formed in the oxide film grown in the H2-H2O atmosphere was less than 10％ of that in the air-H2O atmosphere.The Cr1.3Fe0.7O3 oxide clusters converted into Cr23C6 carbides and the cracks were filled with carbon in the oxide film grown in the air-H2O atmosphere after repeated coking and decoking tests,while the dense standing blade MnCr2O4 spinels remained unchanged in the oxide film grown in the H2-H2O atmosphere.The ethylene,propylene and butadiene yields in the pyrolysis tests were almost the same for the two oxide films.
基金Project(2008AA030503)supported by the National High Technology Research and Development Program of ChinaProject(51474238)supported by the National Natural Science Foundation of China
文摘Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10-5, 2×10-4 and 2×10-3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of Ni Fe2O4 and Ni O. With increasing oxygen content, Ni Fe2O4 content in the ceramic increases, while Ni O content appears a contrary trend. In vacuum, Ni Fe2O4 ceramic has average grain size of 3.94 μm, and bending strength of85.12 MPa. The changes of the phase composition and mechanical properties of Ni Fe2O4 based cermets are mainly caused by the alteration of their properties of Ni Fe2O4 ceramic.
文摘Changes of CO 2/H 2O exchange parameters were continually measured in winter wheat under different water stress stages.The results showed that photosynthesis rate and transpiration rate of winter wheat in water stress conditions were obviously lower than that in non stress conditions.After water stress,both of them slowly increased and even overtook that on sufficient irrigation treatment. Responses of winter wheat to water stress in different growth stages were different.To some extent, water stress can improve crop water use efficiency,speed up the process of milking.Under water stress condition,stomatal conductance limited diurnal changes of photosynthesis and transpiration in the morning but not in the afternoon.Transpiration is more sensitive to water stress than photosynthesis.
文摘Department of Chemistry&Biology,Hechi Teacher’s College,Yizhou546300)abstract:The new complex formulated[Co（DPC）abstract: 2 ]-Co（H 2 O）abstract: 5 ]·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of[Co（DPC）abstract: 2 ]possess an approximate D 2d symmetry,while the part of[OCo （2）OH 2 5 ]has an approximate C2symmetry.
