NaCl aqueous solution（15 wt%） was used as the quenching medium to prepare amorphous Lithium-Zinc ferrite hollow microspheres（LiZn FHMs） based on self-reactive quenching technology. Investigations by scanning elect...NaCl aqueous solution（15 wt%） was used as the quenching medium to prepare amorphous Lithium-Zinc ferrite hollow microspheres（LiZn FHMs） based on self-reactive quenching technology. Investigations by scanning electro microscope, X-ray diffraction, electron diffraction of transmission electron microscope, and differential scanning calorimetry prove that LiZn FHMs are susceptible to amorphization. It is indicated that NaCl aqueous solution（15 wt%） has ultra-fast quenching speed, and the growth rate of crystals on LiZn FHMs is so large that the formation and growth of the crystal nucleus are significantly restrained. This is the main reason for the formation of amorphous LiZn FHMs.展开更多
In order to obtain high comprehensive performance hollow ceramic microspheres (HCMs), used Al-Cr2O3 as the main reaction system, HCMs were prepared by Self-reactive flame quenching technology in Ar2 and N2 atmosphere ...In order to obtain high comprehensive performance hollow ceramic microspheres (HCMs), used Al-Cr2O3 as the main reaction system, HCMs were prepared by Self-reactive flame quenching technology in Ar2 and N2 atmosphere respectively. Effects of the two different atmospheres on synthesizing HCMs were studied. Results show that in Ar2 atmosphere, because of incomplete reaction of agglomerate powders, porous particles with hollow structure and smooth-faced HCMs constitute the products. However in N2 atmosphere, because agglomerate powders react completely, all of them become smooth-faced HCMs. Results above show that experiment atmosphere is a important parameter to synthesize HCMs and to a great extent influences reaction process of agglomerate powders in the flame field.展开更多
A1 ＋ BaO2 ＋ Fe2O3 ＋ sucrose and O2 as reaction system and feeding gas, respectively, are used to prepare hollow multiphase ceramic microspheres （HMCMs） absorbent based on self-reactive quenching technology. The m...A1 ＋ BaO2 ＋ Fe2O3 ＋ sucrose and O2 as reaction system and feeding gas, respectively, are used to prepare hollow multiphase ceramic microspheres （HMCMs） absorbent based on self-reactive quenching technology. The morphologies, particle size distribution, hollow structure and phase compositions were characterized by scanning electron microscope （SEM）, X-ray diffraction （XRD） and size analysis. The results show that the quenching products possess high sphere-forming rate, and most of them are hollow structures. Owing to the self-burst, the particle size is between 40 and 70 μm. The phase compositions contain Al2O3, Fe3O4, Fe2O3, Ba2Fe14O22, BaO2 and BaFe4O7. The microwave absorbing tests show that the lowest reflectivity of HMCMs is -19 dB. The frequency bands less than -10 dB are from 13.0 to 15.8 GHz. The reasons for HMCMs possessing good microwave absorbing properties may be their magnetic and electrical properties as well as special hollow structure.展开更多
基金Funded by the National Natural Science Foundation of China(No.51172282)the Hebei Natural Science Foundation of China(E2015506011)
文摘NaCl aqueous solution（15 wt%） was used as the quenching medium to prepare amorphous Lithium-Zinc ferrite hollow microspheres（LiZn FHMs） based on self-reactive quenching technology. Investigations by scanning electro microscope, X-ray diffraction, electron diffraction of transmission electron microscope, and differential scanning calorimetry prove that LiZn FHMs are susceptible to amorphization. It is indicated that NaCl aqueous solution（15 wt%） has ultra-fast quenching speed, and the growth rate of crystals on LiZn FHMs is so large that the formation and growth of the crystal nucleus are significantly restrained. This is the main reason for the formation of amorphous LiZn FHMs.
基金National Nature Science Foundation of China (50672130)
文摘In order to obtain high comprehensive performance hollow ceramic microspheres (HCMs), used Al-Cr2O3 as the main reaction system, HCMs were prepared by Self-reactive flame quenching technology in Ar2 and N2 atmosphere respectively. Effects of the two different atmospheres on synthesizing HCMs were studied. Results show that in Ar2 atmosphere, because of incomplete reaction of agglomerate powders, porous particles with hollow structure and smooth-faced HCMs constitute the products. However in N2 atmosphere, because agglomerate powders react completely, all of them become smooth-faced HCMs. Results above show that experiment atmosphere is a important parameter to synthesize HCMs and to a great extent influences reaction process of agglomerate powders in the flame field.
基金financially supported by the National Natural Science Foundation of China(No.51172282)
文摘A1 ＋ BaO2 ＋ Fe2O3 ＋ sucrose and O2 as reaction system and feeding gas, respectively, are used to prepare hollow multiphase ceramic microspheres （HMCMs） absorbent based on self-reactive quenching technology. The morphologies, particle size distribution, hollow structure and phase compositions were characterized by scanning electron microscope （SEM）, X-ray diffraction （XRD） and size analysis. The results show that the quenching products possess high sphere-forming rate, and most of them are hollow structures. Owing to the self-burst, the particle size is between 40 and 70 μm. The phase compositions contain Al2O3, Fe3O4, Fe2O3, Ba2Fe14O22, BaO2 and BaFe4O7. The microwave absorbing tests show that the lowest reflectivity of HMCMs is -19 dB. The frequency bands less than -10 dB are from 13.0 to 15.8 GHz. The reasons for HMCMs possessing good microwave absorbing properties may be their magnetic and electrical properties as well as special hollow structure.
