Effect of thickness of SiC films on compression and thermal properties of SiC/CF composites

Commonly, carbon foam derived from commercially available melamine foam showed brittle characteristics. In this paper, the carbon foam was prepared via the direct carbonization of the melamine foam, and chemical vapor deposition was employed to deposit ultra-thin SiC films on the CF skeleton. The evolution, microstructure, mechanical strength, and thermal properties of the as-prepared SiC/CF composites were investigated. Test results showed that a novel SiC skeleton with a three-dimensional interconnected network was prepared successfully. The thickness of the SiC filmes had a significant influence on the compression and thermal properties of the composites. The SiC/CF-II possessed a higher compression performance than that of SiC/CF-I, while the thermal insulation was relatively much poorer. This present work had some reference meaning to the correlation studies of the thermal insulation material for the potential applications while bearing live loads.     

Overview no. 96 evolution of f.c.c. deformation structures in polyslip

The microstructural evolution during polyslip in f.c.c. metals in investigated by the examples of Al, Ni, NiCo alloys and an AlMg alloy, deformed at room temperature either by rolling or by torsion. The principles governing this evolution appears to be the following: (a) There are differences in the number and selection of simultaneously acting slip systems among neighboring volume elements of individual grains. In any one volume element (called a cell block), the number of slip systems falls short of that required for homogeneous (Taylor) deformation, but groups of neighboring cell blocks fulfil the Taylor criterion collectively. (b) The dislocations are trapped into low-energy dislocation structures in which neigboring dislocations mutually screen their stresses. The microstructural evolution at small strains progresses by the subdivision of grains into cell blocks delineated by dislocation boundaries. These boundaries accomodate the lattice misorientations, which result from glide on different slip system combinations in neighbouring cell blocks. The cell blocks are subdivided into ordinary cells and both cell blocks and cells shrink with increasing strain. All observations appear to be in good accord with the theoretical interpretation. However, some problems remain to be solved quantitatively.     

Amorphous CoFeP/NC hybrids as highly efficient electrocatalysts for water oxidation

The rational design and regulate structure and composition are pivotal for the development of highly efficient oxygen evolution reaction (OER) catalysts for water splitting. In this study, amorphous CoFeP/NC hybrid electrocatalyst has been synthesized by a simple and effective phosphorization of a CoFe-based coordination polymer under N₂ atmosphere. The synergistic effects between the CoFeP and N-doped carbon has led to high electronic conductivity attributed to the optimal Fe contents with N-doped carbon and enlarged electrocatalytic active surface area aroused by the nanostructure of CoFeP/NC, as well as the surface structural evolution of oxyhydroxide/phosphate during OER process. The resulting Co_0.35Fe_0.17P_0.48/NC electrocatalyst can attain a current density of 10 mA/cm² at an overpotential of 275 mV with a Tafel slope of 31 mV/dec on glassy carbon electrode and 228 mV on Ni foam electrode in 1 M KOH solution, long-term OER stability of this Co_0.35Fe_0.17P_0.48/NC under the applied potential of 1.53 V vs. RHE demonstrates no obvious decline in current densities of 110 mA/cm² within 17 h, which outperforms those of the contrast electrocatalysts in this work and also comparable to that of many of the reported electrocatalysts in the literatures. This Co_0.35Fe_0.17P_0.48/NC electrocatalyst highlights the rational modulation of optimal composition and electronic structure with homogeneous incorporation of the foreign metal-doped and N-doped carbon for the synthesis of highly efficient electrocatalysts toward to the water oxidation reactions.     

GPU 加速的路径依赖数字图像相关法

对于数字图像相关法(digital image correlation, DIC)计算效率的需求日益增长,提出了一种图形处理器(GPU)加速的路 径依赖 DIC 方法。 该算法利用基于快捷傅里叶变换的互相关算法(FFT-CC)计算初始种子点,利用反向组合高斯牛顿法( IC-GN)进行亚像素匹配,然后通过初值传递策略快速产生多个新种子点参与亚像素匹配的并行计算,从而使其快速扩散,直至完 成整个感兴趣区域的计算。 利用公开的实验图例进行测试,结果表明方法精度良好,能得到清晰的表面变形云图,并且能在子 区大小 17×17 pixels 时获得 6. 5×10 5 点/ s 的计算速度,相对于典型的高速 DIC 算法速度提升超过 50%,为高速 DIC 算法的设计 提供了参考。