Preparation of Amorphous LiZn Ferrites Hollow Microspheres by Self-reactive Quenching Technology

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.

Development and application of titanium alloy casting technology in China

The development and research of titanium cast alloy and its casting technology, especially its application in aeronautical industry in China are presented. The technology of molding, melting and casting of titanium alloy, casting quality control are introduced. The existing problems and development trend in titanium alloy casting technology are also discussed.

Effect of Atmosphere on Synthesizing Hollow Ceramic Microspheres by Self-reactive Flame Quenching Technology

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.

Preparation of hollow ceramic microspheres absorbent based on self-reactive quenching technology

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.

储氢合金/AP/HTPB推进剂的燃烧现象分析

利用单幅照相、微热电偶测温、扫描电镜(SEM)、俄歇电子能谱(EDS)以及X射线衍射(XRD)研究了Al/AP/HTPB推进剂(P-A0)、Al/储氢合金/AP/HTPB推进剂(P-A10)和储氢合金/AP/HTPB推进剂(P-A17)的火焰结构、燃烧表面温度、熄火表面形貌、熄火表面残留元素以及熄火表面残留化合物。结果表明,相对于P-A0,P-A10和P-A17燃面上方有更加猛烈的喷射现象;P-A10和P-A17的燃面温度分别提高了5.92℃和7.45℃,凝聚相反应区域分别扩大了13.13%和47.30%;P-A17熄火表面相对平整,突起的合金团表面大部分被氧化;P-A10和P-A17熄火表面残碳量相对P-A0分别减少了15.81%和27.61%,说明储氢合金可以提高AP/HTPB推进剂有机组分在燃面处的燃烧效率;P-A0,P-A10和P-A17熄火表面Al含量依次减少,而Al2O3含量依次增多,说明储氢合金的燃烧效率高于Al。储氢合金替代Al作为燃烧剂,可以明显改善AP/HTPB推进剂的燃烧性能。

基于Al-SiO_2-蔗糖体系制备空心陶瓷微珠

以Al-SiO2-蔗糖为反应体系,利用自反应淬熄法合成了Al2O3-Si复相空心陶瓷微珠,研究了其形成机制。结果表明,熔射产物由球形、类球形和不规则粉状物三类颗粒组成,球形颗粒和类球形颗粒为内部空心结构,由Al2O3-Si复相以及可能含有的少量未反应SiO2组成,粉状物由SiC、C与可能含有的SiO2和发生反应但未成球的颗粒组成。高的反应放热量与快的反应速率有利于陶瓷熔滴的形成,C氧化产生的大量气体是形成内部空心结构的关键,3个因素共同决定着空心陶瓷微珠的形成。