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
Ni80Fe20/Ni48Fe12Cr40 bilayer films and Ni80Fe20 monolayer films were deposited at room temperature on SiO2/Si（100） substrates by electron beam evaporation. The influence of the thickness of the Ni48Fe12Cr40 underla...Ni80Fe20/Ni48Fe12Cr40 bilayer films and Ni80Fe20 monolayer films were deposited at room temperature on SiO2/Si（100） substrates by electron beam evaporation. The influence of the thickness of the Ni48Fe12Cr40 underlayer on the structure, magnetization, and magnetoresistance of the Ni80Fe20/Ni48Fe12Cr40 bilayer film was investigated. The thickness of the Ni48Fe12Cr40 layer varied from about 1 nm to 18 nm while the Ni80Fe20 layer thickness was fixed at 45 nm. For the as-deposited bilayer films the introducing of the Ni48Fe12Cr40 underlayer promotes both the （111） texture and grain growth in the Ni80Fe20 layer. The Ni48Fe12Cr40 underlayer has no significant influence on the magnetic moment of the Ni80Fe20/Ni48Fe12Cr40 bilayer film. However, the coercivity of the bilayer film changes with the thickness of the Ni48Fe12Cr40 undedayer. The optimum thickness of the Ni48Fe12Cr40 underlayer for improving the anisotropic magnetoresistance effect of the Ni80Fe20/Ni48Fe12Cr40 bilayer film is about 5 nm. With a decrease in temperature from 300 K to 81 K, the anisotropic magnetoresistance ratio of the Ni80Fe20 （45 nm）/Ni48Fe12Cr40 （5 nm） bilayer film increases linearly from 2.1% to 4.8% compared with that of the Ni80Fe20 monolayer film from 1.7% to 4.0%.展开更多
NiCr micron-resistor was designed and prepared by magnetron sputtering and lithography on the substrate of silicon with different powers. It is found that there exists a big gap in the TCR between the annealed group a...NiCr micron-resistor was designed and prepared by magnetron sputtering and lithography on the substrate of silicon with different powers. It is found that there exists a big gap in the TCR between the annealed group and the un-annealed group. A series of tests were made to figure out the reasons lying behind the gap in the TCR between the annealed group and the un-annealed group. UV reflection results show that there is no increase in the concentration of free electrons after annealing. However, the data obtained from XRD reveal that the annealing does not have an obvious influence on the strain of thin films, but really increases the grain size of thin films. Therefore, the grain boundary scattering plays a dominant role in explaining the obvious difference in the TCR. Finally through appropriate methods, a micron-resistor for heating-up with a low TCR value was obtained.展开更多
Sm22Co78/Fe65Co35/Sm22Co78/Fe65Co35 multilayer films were prepared by magnetron sputtering. The temperature dependence of coercivity (Hc), remanence (Mr) and reduced remanence (Mr/Ms) has been measured. The coercivit...Sm22Co78/Fe65Co35/Sm22Co78/Fe65Co35 multilayer films were prepared by magnetron sputtering. The temperature dependence of coercivity (Hc), remanence (Mr) and reduced remanence (Mr/Ms) has been measured. The coercivity decreases with increasing of temperature. The remanence decreases with increasing the temperature from 26 to 100℃, and then increases with continuously increasing the temperature from 100 to 150℃. The reduced remanence increases with increasing the temperature.展开更多
The effect of surface roughness of aluminum oxide (95%) substrate on the properties of Ni-Cr alloy thin film is studied.The thin films are prepared on the substrates with different roughness by using magnetron sputter...The effect of surface roughness of aluminum oxide (95%) substrate on the properties of Ni-Cr alloy thin film is studied.The thin films are prepared on the substrates with different roughness by using magnetron sputtering.The micro-structure,adhesive and electrical properties of the thin films were investigated by using scanning electron microscopy,scratch method and four-probe method.The burst voltage and current of the thin film transducers with different substrates were measured according to D-optimization method.The results show that the particle size,structural defect,resistivity and adhesion strength of the thin film increase with the increase of the substrate roughness.The difference among the burst time of the samples with difference substrate roughness gradually decreases with the increase of stimulation amount.The burst time is approximate to 20 μs in the charging voltage of 37 V.展开更多
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.
文摘Ni80Fe20/Ni48Fe12Cr40 bilayer films and Ni80Fe20 monolayer films were deposited at room temperature on SiO2/Si（100） substrates by electron beam evaporation. The influence of the thickness of the Ni48Fe12Cr40 underlayer on the structure, magnetization, and magnetoresistance of the Ni80Fe20/Ni48Fe12Cr40 bilayer film was investigated. The thickness of the Ni48Fe12Cr40 layer varied from about 1 nm to 18 nm while the Ni80Fe20 layer thickness was fixed at 45 nm. For the as-deposited bilayer films the introducing of the Ni48Fe12Cr40 underlayer promotes both the （111） texture and grain growth in the Ni80Fe20 layer. The Ni48Fe12Cr40 underlayer has no significant influence on the magnetic moment of the Ni80Fe20/Ni48Fe12Cr40 bilayer film. However, the coercivity of the bilayer film changes with the thickness of the Ni48Fe12Cr40 undedayer. The optimum thickness of the Ni48Fe12Cr40 underlayer for improving the anisotropic magnetoresistance effect of the Ni80Fe20/Ni48Fe12Cr40 bilayer film is about 5 nm. With a decrease in temperature from 300 K to 81 K, the anisotropic magnetoresistance ratio of the Ni80Fe20 （45 nm）/Ni48Fe12Cr40 （5 nm） bilayer film increases linearly from 2.1% to 4.8% compared with that of the Ni80Fe20 monolayer film from 1.7% to 4.0%.
文摘NiCr micron-resistor was designed and prepared by magnetron sputtering and lithography on the substrate of silicon with different powers. It is found that there exists a big gap in the TCR between the annealed group and the un-annealed group. A series of tests were made to figure out the reasons lying behind the gap in the TCR between the annealed group and the un-annealed group. UV reflection results show that there is no increase in the concentration of free electrons after annealing. However, the data obtained from XRD reveal that the annealing does not have an obvious influence on the strain of thin films, but really increases the grain size of thin films. Therefore, the grain boundary scattering plays a dominant role in explaining the obvious difference in the TCR. Finally through appropriate methods, a micron-resistor for heating-up with a low TCR value was obtained.
文摘Sm22Co78/Fe65Co35/Sm22Co78/Fe65Co35 multilayer films were prepared by magnetron sputtering. The temperature dependence of coercivity (Hc), remanence (Mr) and reduced remanence (Mr/Ms) has been measured. The coercivity decreases with increasing of temperature. The remanence decreases with increasing the temperature from 26 to 100℃, and then increases with continuously increasing the temperature from 100 to 150℃. The reduced remanence increases with increasing the temperature.
文摘The effect of surface roughness of aluminum oxide (95%) substrate on the properties of Ni-Cr alloy thin film is studied.The thin films are prepared on the substrates with different roughness by using magnetron sputtering.The micro-structure,adhesive and electrical properties of the thin films were investigated by using scanning electron microscopy,scratch method and four-probe method.The burst voltage and current of the thin film transducers with different substrates were measured according to D-optimization method.The results show that the particle size,structural defect,resistivity and adhesion strength of the thin film increase with the increase of the substrate roughness.The difference among the burst time of the samples with difference substrate roughness gradually decreases with the increase of stimulation amount.The burst time is approximate to 20 μs in the charging voltage of 37 V.
