A novel two-step processing method for fabrication of in situ Al2O3np/Al-Al11Ce3 nanocomposite

In situ Al2O3np/Al-Al11Ce3 nanocomposite was successfully synthesized from Al-CeO2 system using a novel two-step processing method that combines liquid-state mechanical mixing(step-I) and sonochemistry melt reaction(step-II). The microstructural evolution and mechanical properties were investigated by optical microscopy(OM), scanning electron microscopy(SEM), transmission electron spectroscopy(TEM) and tensile tests, respectively. A good spatial distribution of CeO2 particles in the Al melt was achieved due to reactive wetting during step-I, and the following formation of Al2O3 np during step-II was attributed to the cavitation-accelerated interfacial reaction. The solidified microstructure comprised uniformly dispersed Al2O3 np in the matrix and ultrafine lamellar Al-Al11Ce3 at the grain boundaries. Such unique microstructure endowed Al2O3np/Al-Al11Ce3 nanocomposite with a good balance between tensile strength(175 MPa) and ductility(18.5%). The strengthening mechanisms of the nanocomposite included grain refinement, Orowan strengthening and quench strengthening, among which Orowan strengthening contributed the most to the yield strength of the nanocomposite.     

The interaction between molten gallium and the hydrocarbon medium induced by ultrasonic energy—can gallium carbide be formed?

Ultrasonic irradiation of molten gallium in organic liquids (decane, dodecane, etc.) results in dispersion of the gallium into nanometric spheres. These were examined by several analytical methods XRD, DSC, Raman and IR spectroscopy) as well as electron microscopy (SEM, TEM) and found to be composed of Ga and C. The DSC analysis indicates that the Ga has possibly reacted with carbon, while the Raman spectrum of the product demonstrates a strong additional peak that could not be identified. This work explores the possibility that the product is gallium carbide or another gallium‐carbon complex. To investigate the nature of the product, we performed detailed extended X‐ray absorption fine structure (EXAFS) and X‐ray absorption near‐edge structure (XANES) analyses. On the basis of DSC, IR, and Raman it appear to be formation of GaC, whereas the analysis by EXAFS and XANES demonstrated that the gallium is found to be in a higher reduced state (almost metallic), supported by carbon. The question that remains open in addition to the one related to the formation of galium carbide is whether a complex structure, including oxygen contamination is involved in the layers surrounding the Ga as indicated by the EXAFS results.     

一种适用于声化学的新型复合超声变幅杆

提出一种新型复合超声变幅杆,该变幅杆总长为一个波长,由五段组成,其中三段为等截面圆柱杆,两段为变截面圆柱杆。给出了该类复合变幅杆的设计方法,并计算了两个实例。结果表明,和普通使用的半波长复合变幅杆相比,该类复合变幅杆具有在不减少甚至增大辐射面积的情况下放大振幅的特点,这对提高整个超声系统的辐射声功率和辐射效率具有积极意义。此类复合变幅杆特别适合在声化学等超声液体处理领域使用。     

超声波在粉体材料制备中的应用

介绍超声化学的基本原理及其在粉体材料制备中的。评述了超声波应用于金属及合金粉末、陶瓷粉体、复合粉体、稀土材料、磁性材料、高分子纳米材料制备方面的研究工作和取得的成绩。展望了其应用前景，指出了超声波与所作用物之间的定量关系和定量规律研究的重要性。     

声化学效应在矿物化学处理中的应用

综述了声化学强化矿物化学浸出过程的研究成果及其作用机理。     

超声辐射溶胶-凝胶法制备纳米In2O3气敏材料

以无机盐为原料,采用溶胶-凝胶法与超声技术相结合的手段制备颗粒均匀的纳米氧化铟.运用XRD和TEM等分析手段对合成产品的结构、形貌等进行了表征,用静态配气法初步测试了合成材料的气敏性能.结果表明,溶胶-凝胶法与超声技术相结合是合成高性能纳米材料较有前途的一种方法,并且该法制备的纳米氧化铟材料有较好的气敏性能.     

B4 用染色法记录液体中大功率超声场的分布

利用染料在纸上染色可以方便，快速地记录液体中大功率超声场的分布，本文给出这一套验研究的结果，表明该方法在声化学和超声清洗等大功率超声液体处理应用中，对于测量空化强度的空间分布是一种实用，可取的方法。     

C2 用于声化学研究的大功率超声系统的研制

根据声化学反应的特殊要求，我们研制了上前用于声化学研究的大功率超声系统，由参数可调节的超声发生器配合不同频率的换能器工作，并用它组合成杯式幅杆结构声化学反应器，解决了有关声化学设备的一些技术问题。为声化学技术从实验室规模向工业应用过渡做了必要的准备。