To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization ...To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization hysteresis loops and the Mossbauer spectra. Furthermore, the shape anisotropy was used to explain the origin of composite microwave performance, and the calculated results agree with the experiment. It is believed that the shape anisotropy dominates microwave complex permeability, and the natural resonance plays main role in flake.展开更多
Mossbauer spectroscopy has been used to study the morphology of iron oxides formed during the oxidation of superalloys, such as SS-304L （1.4306S）, Incoloy-800H, Incoloy-825, UBHA-25L, Sanicro-28 and Inconel-690, at ...Mossbauer spectroscopy has been used to study the morphology of iron oxides formed during the oxidation of superalloys, such as SS-304L （1.4306S）, Incoloy-800H, Incoloy-825, UBHA-25L, Sanicro-28 and Inconel-690, at 1200℃ exposed in air and steam environments for 400 h. The basic aim was to identify and compare the iron oxides qualitatively and quantitatively, formed during the oxidation of these alloys in two environments. The behaviour of alloy UBHA-25L in high temperature oxidation in both environments indicates that it has good oxidation resistance especially in steam, whereas Sanicro-28 has excellent corrosion resistance in steam environment. In air oxidation of Inconel-690 no iron oxide, with established Mossbauer parameters, was detected.展开更多
Physical and chemical properties of the magnetic nanoparticles coated with oleate have been investigated by means of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Mossbauer spectroscopy, su...Physical and chemical properties of the magnetic nanoparticles coated with oleate have been investigated by means of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Mossbauer spectroscopy, superconducting quantum interference device (SQUID) magnetometry, infrared spectra (IR) and the contact angle device. The results show that doped Al ions in Fe3O4 nanoparticles are located on the octahedral sites of the spinel structure. Oleate is coated on the magnetic nanoparticles with two layers by chemical absorbing, the outer layer can be washed away. The wetting of the surface of magnetic nanoparticles coated with monolayer has been changed from hydrophilicity to hydrophobicity, and the nanoparticles can be dispersed very well in some organic solutions.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 90505007 and 10774061)
文摘To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization hysteresis loops and the Mossbauer spectra. Furthermore, the shape anisotropy was used to explain the origin of composite microwave performance, and the calculated results agree with the experiment. It is believed that the shape anisotropy dominates microwave complex permeability, and the natural resonance plays main role in flake.
文摘Mossbauer spectroscopy has been used to study the morphology of iron oxides formed during the oxidation of superalloys, such as SS-304L （1.4306S）, Incoloy-800H, Incoloy-825, UBHA-25L, Sanicro-28 and Inconel-690, at 1200℃ exposed in air and steam environments for 400 h. The basic aim was to identify and compare the iron oxides qualitatively and quantitatively, formed during the oxidation of these alloys in two environments. The behaviour of alloy UBHA-25L in high temperature oxidation in both environments indicates that it has good oxidation resistance especially in steam, whereas Sanicro-28 has excellent corrosion resistance in steam environment. In air oxidation of Inconel-690 no iron oxide, with established Mossbauer parameters, was detected.
基金Hi-Tech Research and Develop-ment Program of China under the grant No.2002AA302202 the National Natural Scicnce Foundation of China through grant No.20490210.
文摘Physical and chemical properties of the magnetic nanoparticles coated with oleate have been investigated by means of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Mossbauer spectroscopy, superconducting quantum interference device (SQUID) magnetometry, infrared spectra (IR) and the contact angle device. The results show that doped Al ions in Fe3O4 nanoparticles are located on the octahedral sites of the spinel structure. Oleate is coated on the magnetic nanoparticles with two layers by chemical absorbing, the outer layer can be washed away. The wetting of the surface of magnetic nanoparticles coated with monolayer has been changed from hydrophilicity to hydrophobicity, and the nanoparticles can be dispersed very well in some organic solutions.
