The influence of heat treatment on the microstructure and mechanical properties of isotropic pyrolytic carbon prepared by chemical vapor deposition was studied by TEM, SEM, XRD, polarized light metallography, laser Raman spectroscopy, microhardness and three-point bend tests. Results show that the interlayer spacing of the pyrolytic carbon decreases and the crystal size increases with the increase of heat treatment temperature. At the same time, the microhardness and the elastic modulus decrease with the increase of heat treatment temperature. Heat treatment below 2400°C has no effect on the flexural strength of the isotropic pyrolytic carbon, but its flexural strength increases after graphitization at 2600°C. It is observed that the high temperature heat treatment has changed the pore structure, which consequently influences the mechanical properties.

Jun Feng Wu;Shuo Bai;会明 成

Xinxing Tan Cailiao/New Carbon Materials

2006-9

The catalyst with high activity and durability plays a crucial role in the hydrogen generation systems for the portable fuel cell generators. In the present study, a ruthenium supported on graphite catalyst (Ru/G) for hydrogen generation from sodium borohydride (NaBH₄) solution is prepared by a modified impregnation method. This is done by surface pretreatment with NH₂ functionalization via silanization, followed by adsorption of Ru (III) ion onto the surface, and then reduced by a reducing agent. The obtained catalyst is characterized by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Very uniform Ru nanoparticles with sizes of about 10 nm are chemically bonded on the graphite surface. The hydrolysis kinetics measurements show that the concentrations of NaBH₄ and NaOH all exert considerable influence on the catalytic activity of Ru/G catalyst towards the hydrolysis reaction of NaBH₄. A hydrogen generation rate of 32.3 L min^-1 g^-1 (Ru) in a 10 wt.% NaBH₄ + 5 wt.% NaOH solution has been achieved, which is comparable to other noble catalysts that have been reported.

Yan Liang;Hong Bin Dai;Lai Peng Ma;Ping Wang;会明 成

International Journal of Hydrogen Energy

2010-4

Hua Zhang;会明 成;Peide Ye

Chemical Society Reviews

2018-8-21

An investigation was carried out on the fabrication of carbon fibre-reinforced aluminium matrix composites with hybridization of particulates or whiskers of silicon carbide by pressure casting. A small amount of particulates or whiskers was uniformly distributed among carbon fibres and the preforms prepared from the treated fibres were directly infiltrated by molten aluminium under applied stress. It was found that the longitudinal tensile strengths of hybrid composites were greatly improved, although their fibre volume fractions were very low compared to those of conventional composites. With this hybridization method, it is also practical to tailor the fibre volume fraction of composites from 60 to 25 vol %, which is not possible in direct infiltration of fibre preforms by pressure casting. The results obtained lead to the conclusion that particulate or whisker additions act not directly as reinforcements but as promoters to improve the infiltration performances of fibre preforms, and consequently to increase the strength-transfer efficiency of carbon fibres. The addition of particulates or whiskers can also improve other properties of the composites, such as hardness and wear resistance.

会明 成;A. Kitahara;S. Akiyama;K. Kobayashi;B. L. Zhou

Journal of Materials Science

1992-7

会明 成;A. Kitahara;K. Kobayashi;B. L. Zhou

Journal of Materials Science Letters

1991-1

To explore potential applications of nanocomposites for microelectronic packaging, the thermal properties were investigated on newly developed nanocrystalline Al composites reinforced by AIN nanoparticles. It was found that the thermal conductivity (TC) is reduced with increasing AIN volume fraction (V_p), since connectivity of Al matrix is decreased by introduction of the nanoparticles. Although AIN nanoparticles introduce thermal resistance, they still have significant contribution to the TC of the composite as high-TC inclusion. Particularly, a percolation behavior of AIN nanoparticles is thought to occur with the threshold at 23-30%. Measurements at elevated temperatures (∼500 °C) show almost no distinct degradation of TC relative to room temperature. Moreover, the coefficient of thermal expansion (CTE) is remarkably lowered as V_p increases, e.g., from 26 × 10^-6 to 13.9 × 10^-6 K^-1, by raising V_p to 39%. Therefore, the nanocomposites may be applicable as electronic packaging material, due to the combination of acceptable TC and low CTE.

Y. Q. Liu;H. T. Cong;会明 成

Journal of Materials Research

2009-1

Single-crystalline mushroom-like AlN nanorod array has been synthesized. The AlN nanorods, with diameters of 50-200 nm and lengths of several micrometers, are distributed uniformly with density of 107 - 108 rods cm2. The field emission measurements show that the turn-on field is 8.8 Vμm at a field emission current density (J) of 10 μA cm2, and the J (10.31 mA cm2) fluctuation is as small as 2% within an hour. The relationship between the nanostructure and field emission properties is discussed. The low turn-on field and high current stability demonstrate that the mushroom-like AlN nanorod array is a promising field emission material.

Y. B. Tang;H. T. Cong;Z. G. Zhao;会明 成

Applied Physics Letters

2005

With the rapid development and technological breakthroughs in the synthesis of graphene on a large scale at low cost, the commercial application of graphene materials has been arousing great interest from both academic and industrial fields. We review the latest research progress on graphene/polymer composites, focusing on their mechanical reinforcement, improvement of electrical and thermal conductivity, corrosion resistance, and flame-retardance. The current situation regarding commercial graphene products is summarized, and the main problems and future development of graphene/polymer composites are discussed.

You Zeng;Han Wang;会明 成

Xinxing Tan Cailiao/New Carbon Materials

2016-12-1

Lithium-sulfur (Li-S) batteries are one of the most promising next generation battery systems owing to their high energy density and low cost, but they suffer from the low conductivity of sulfur, polysulfide shuttling and lithium dendrite growth, which limit their practical applications. Porous graphene networks (PGNs) not only have the advantages of graphene as a multifunctional host, but also exhibit unique properties derived from their porous structures, which enable PGNs to have a variety of positive effects in Li-S batteries. Here, we provide an overview of the roles and functions of PGNs in Li-S batteries, including increasing sulfur utilization, confining sulfur species, accommodating the volume change of sulfur, improving the conversion kinetics of polysulfides, reducing the consumption of lithium, preventing the dendrite growth, and acting as flexible hosts. The systematic summary of the recent progress in the use of PGNs in different components of Li-S batteries provides guidance for designing materials with diversity that meet different requirements. By mechanism analysis and a recent achievement summary of PGNs in Li-S batteries, we hope to inspire further developments of PGNs in Li-S batteries one step closer to industrialization.

Chongbo Sun;Yingqi Liu;Jinzhi Sheng;Qikai Huang;Wei Lv;Guangmin Zhou;会明 成

Materials Horizons

2020

会明 成

Kexue Tongbao/Chinese Science Bulletin

2020-6-25