Advanced technology for fabrication of reaction-bonded SiC with controlled composition and properties

An advanced fabrication technology of reaction-bonded SiC is developed, which includes the preparation of a C/SiC preform by repeated cycles of phenolic resin impregnation and pyrolysis, followed by infiltration with silicon melt. The use of different number of impregnation stages provides control of carbon content in the preform and the corresponding SiC content in final ceramics. The effect of the impregnation number on the preform characteristics and ceramics composition, thermal and mechanical properties are investigated comprehensively. With an increase of impregnation number up to four, SiC fraction in the ceramics enlarges to 93 vol%, thermal conductivity and Young’s modulus increase to 186 W/(m?K) and 427 GPa respectively, which are superior to most reaction-bonded SiC. Flexural strength (225 MPa) and thermal expansion coefficient (2?10^?6 K^-1) are not dependent on the impregnation number. The obtained results provide an opportunity to design and fabricate reaction-bonded SiC ceramics with a given set of properties.     

Microfluidic fabrication of ceramic microspheres with controlled morphologies

In this study, the diffusion‐induced external gelation is combined with a microfluidic technique to prepare monodisperse ZrO₂ ceramic microspheres. The gelation of sol droplets is traced by fluorescence visualization of the local pH, and it illustrates the effect of the external concentration of triggering agent (tetramethylethylenediamine, TMEDA) on the formation of the gel network, which results in 3 kinds of deformation of the gel particles. The deformation mechanism mainly lies in the imbalanced Laplace pressure exerted on the gel network during the competition between the gelation and the drying processes. By regulating the concentration of TMEDA, the monodisperse ZrO₂ ceramic microspheres with high sphericity can be readily fabricated.     

Special issue on progress in advanced energy technologies and materials

正This special issue of the Chinese Journal of Chemical Engineering(CJCh E) concerns with the current progress in advanced energy technologies and materials related to chemical science and technology, especially the work in the field of renewable energy,energy storage, clean and efficient utilization of energy, aligning well to the scope of this Journal.The world is moving towards a sustainable, clean and low-carbon future via ‘Energy Transition', i.e.,     

农药控释技术研究进展

论述了缓释农药的发展概况及其相对于传统药剂的优越性。详细介绍了几种常见的缓控释剂型的特点，并列举了研究实例。对该技术的应用前景和发展方向作了分析和预测。