金属铁在硫酸根自由基反应中的催化应用

基于SO_(4)-·的高级氧化技术处理有机污染物在国内外受到广泛关注,铁作为廉价、环境友好、自然富足的活化剂,有望成为应用于高级氧化技术的新代绿色催化剂。本文综述了近几年国内外关于各种铁材料在活化过硫酸盐氧化技术中的研究进展,包括亚铁离子活化、纳米铁活化、铁矿活化、金属铁改性活化、金属铁负载活化以及其他技术耦合活化过硫酸盐降解有机污染物的研究现状,最后提出了该技术目前面临的问题及未来发展方向,期望为促进炭质材料活化过硫酸盐高级氧化技术的进一步推广和应用提供参考。

A review on in vitro corrosion performance test of biodegradable metallic materials

Extensive in vitro corrosion test systems have been carried out to simulate the in vivo corrosion behavior of biodegradable metallic materials. Various methods have their own unique benefits and limitations. The corrosion mechanism of biodegradable alloys and in vitro corrosion test systems on biodegradable metallic materials are reviewed, to build a reasonable simulated in vitro test system for mimicking the in vivo animal test from the aspects of electrolyte solution selection, surface roughness influence, test methods and evaluation methodology of corrosion rate. Buffered simulated body fluid containing similar components to human blood plasma should be applied as electrolyte solution, such as simulated body fluid （SBF） and culture medium with serum. Surface roughness of samples and ratio of solution volume to sample surface area should be adopted based on the real implant situation, and the dynamic corrosion is preferred. As to the evaluation methodology of corrosion rate, different methods may complement one another.

Fabrication of amino-functionalized Fe_3O_4@Cu_3(BTC)_2 for heterogeneous Knoevenagel condensation

Metal organic frameworks（MOFs） are an important platform for heterogeneous catalysts.Although MOFs with a smaller particle size exhibit better catalytic performance because of less diffusion limitations,their separation and recycling after catalytic reactions are difficult.The integration of MOFs with magnetic nanoparticles could facilitate their recovery and separation.Especially,the shell thickness of the core-shell structured composites is controllable.In this study,amino-functionalized Fe3O4@Cu3（BTC）2 was fabricated by a stepwise assembly method and its catalytic performance in Knoevenagel condensation was investigated.The results demonstrated that the magnetic hybrid material exhibited a core-shell structure,with a shell thickness of about 2 00 nm.Furthermore,it not only exhibited high catalytic activity,but remarkably,it could also be easily recovered magnetically and recycled without obvious loss of catalytic efficiency after three cycles.

Combustion synthesis of FeAl−Al2O3 composites with TiB2 and TiC additions via metallothermic reduction of Fe2O3 and TiO2

Combustion synthesis involving metallothermic reduction of Fe2O3 and TiO2 was conducted in the mode of self-propagating high-temperature synthesis(SHS)to fabricate FeAl-based composites with dual ceramic phases,TiB2/Al2O3 and TiC/Al2O3.The reactant mixture included thermite reagents of 0.6Fe2O3+0.6TiO2+2Al,and elemental Fe,Al,boron,and carbon powders.The formation of xFeAl−0.6TiB2−Al2O3 composites with x=2.0−3.6 and yFeAl−0.6TiC−Al2O3 composites with y=1.8−2.75 was studied.The increase of FeAl causes a decrease in the reaction exothermicity,thus resulting in the existence of flammability limits of x=3.6 and y=2.75 for the SHS reactions.Based on combustion wave kinetics,the activation energies of Ea=97.1 and 101.1 kJ/mol are deduced for the metallothermic SHS reactions.XRD analyses confirm in situ formation of FeAl/TiB2/Al2O3 and FeAl/TiC/Al2O3 composites.SEM micrographs exhibit that FeAl is formed with a dense polycrystalline structure,and the ceramic phases,TiB2,TiC,and Al2O3,are micro-sized discrete particles.The synthesized FeAl−TiB2−Al2O3 and FeAl−TiC−Al2O3 composites exhibit the hardness ranging from 12.8 to 16.6 GPa and fracture toughness from 7.93 to 9.84 MPa·m1/2.

Dynamic mechanical behaviour of AZ31 magnesium alloy

To investigate the dynamic mechanical behavior of AZ31 Mg alloy, dynamic compression was carried out using a split Hopkinson pressure bar （5HPB） apparatus at strain rates up to 2.0 × 10^3 s^-1, and dynamic hardness was tested employ- ing a dynamic hardness device at room temperature. Microstructural characteristic was analysed by optical microscopy. The dynamic compression results demonstrate that AZ31 Mg alloy exhibits obvious yield phenomena and strain hardening behav- ior at high strain rates. The basically same curvature of stress-strain curves shows a similar strain hardening rate. The dy- namic yield strength changes little, and the peak stress increases with the strain rates. The dynamic hardness test results indi- cate that the dynamic mechanical properties of AZ31 alloy sheet are anisotropic. The dynamic hardness increases slowly with average strain for the 0° and 45° oriented samples. For the 90° oriented sample, dynamic hardness with strain increases rapidly first and then decreases when the strain is more than 0.14. An examination by optical microscopy after high strain rate deformation reveals the occurrence of twinning, and the twin area percentage escalates with the strain rate increasing.