The properties and microstructures of several high-strength and high-modulus carbon fibrereinforced aluminium or aluminium alloy matrix composites (abbreviated as HSCF/Al and HMCF/Al, respectively, for the two types of fibre) have been characterized. The composites evaluated were fabricated by pressure casting based on a hybridization method. It was found that the strength degradation of high-modulus carbon fibres after infiltration of aluminium matrices was not marked and depended upon the type of aluminium matrix. However, the strength of high-strength carbon fibres was greatly degraded by aluminium infiltration and the degradation seemed to be independent of the type of aluminium matrix. The longitudinal tensile strength (LTS) of CF/Al composites was very different between HMCF/Al and HSCF/Al composites. The HMCF/Al composites had LTS values above 800 MPa, but the HSCF/Al composites had only about 400 MPa. In contrast, the transverse tensile strength of the HSCF/Al composites, above 60 MPa, was much higher than that of the HMCF/Al composites, about 16 MPa. Chemical reactions were evident to the interface of high-strength carbon fibres and aluminium matrices. There was no evidence of chemical products arising between high-modulus carbon fibres and Al-Si alloy and 6061 alloy matrices. However, it was considered that some interfacial reactions took place in pure aluminium matrix composites. Fracture morphology observation indicated that the good LTS of CF/Al composites corresponded to an intermediate fibre pull-out, whereas a planar fracture pattern related to a very poor LTS and fibre strength transfer. The results obtained suggested that interfacial bonding between carbon fibres and aluminium matrices had an important bearing on the mechanical properties of CF/Al composites. An intermediate interfacial bonding is expected to achieve good longitudinal and transverse tensile strengths of CF/Al composites.

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

Journal of Materials Science

1994-1

Identification of effective catalyst has been a subject of great interest and challenge in developing metal-N-H systems as potential hydrogen storage media. Motivated by the mechanistic understanding of the essential amide/imide conversion, we experimentally examined the possibility of N-H bond activation by using metal catalyst. We prepared the graphite-supported Ru nanoparticles (Ru/C catalyst) and evaluated their effect on the hydrogen storage properties of Mg(NH₂)₂ + 2LiH material. Our studies show that the Ru/C catalyst is catalytically active toward both dehydrogenation and rehydrogenation reactions of Mg(NH₂)₂ + 2LiH. Moreover, the catalytically enhanced hydrogen sorption kinetics persists well over 10 de/rehydrogenation cycles. Careful examination of the isothermal dehydrogenation behaviors suggests that the enhanced dehydrogenation kinetics may result from the Ru-catalyzed interface reaction between amide and imide solid phases. This is consistent with the Fourier transform infrared results, which show clearly the promoting effect of Ru catalyst on the N-H bond reconstruction. Finally, the catalytic mechanism of Ru catalyst on the reversible dehydrogenation reactions of Mg(NH ₂)₂ + 2LiH material is discussed.

Lai Peng Ma;Hong Bin Dai;Yan Liang;Xiang Dong Kang;Zhan Zhao Fang;Pei Jun Wang;Ping Wang;会明 成

Journal of Physical Chemistry C

2008-11-20

Multi-walled carbon nanotube/epoxy resin composites have been fabricated. By choosing an over-aged hardener, relatively soft and ductile matrix, a rubbery epoxy resin, has been obtained. This made possible to evaluate the effect of nanotube addition on the whole stress-strain curve up to high strain level. The mechanical and electrical properties of the composite with different weight percentages of nanotubes have been investigated. The Young's modulus and the yield strength have been doubled and quadrupled for composites with respectively 1 and 4 wt.% nanotubes, compared to the pure resin matrix samples. Conductivity measurements on the composite samples showed that the insulator-to-conductor transition took place for nanotube concentration between 0.5% and 1 wt.%.

A. Allaoui;S. Bai;会明 成;J. B. Bai

Composites Science and Technology

2002-11

Common solar-driven photoelectrochemical (PEC) cells for water splitting were designed by using semiconducting photoactive materials as working photoelectrodes to capture sunlight. Due to the thermodynamic requirement of 1.23 eV and kinetic energy loss of about 0.6 eV, a photo-voltage of 1.8 V produced by PEC cells is generally required for spontaneous water splitting. Therefore, the minimum bandgap of 1.8 eV is demanded for photoactive materials in single-photoelectrode PEC cells, and the bandgap of about 1 eV for back photoactive materials is appropriate in tandem PEC cells. All these PEC cells cannot effectively utilize the infrared light from 1250 to 2500 nm. In order to realize the full spectrum utilization of solar light, here, we develop a solar-driven PEC water splitting system integrated with a thermoelectric device. The key feature of this system is that the thermoelectric device produces a voltage as an additional bias for the PEC system by using the temperature difference between the incident infrared-light heated aqueous electrolyte in the PEC cell as the hot source and unirradiated external water as the cold source. Compared to a reference PEC system without the thermoelectric device, this system has a significantly improved overall water splitting activity of 1.6 times and may provide a strategy for accelerating the application of full spectrum solar light-driven PEC cells for hydrogen production.

Yuyang Kang;Runze Chen;Chao Zhen;Lianzhou Wang;Gang Liu;会明 成

Science Bulletin

2020-7-30

In order to fabricate highly-conductive glass fibers using graphene as multi-functional coatings, we reported the preparation of graphene-coated glass fibers with high electrical conductivity through sol-gel and dip-coating technique in a simple way. Graphene oxide (GO) was partially reduced to graphene hydrosol, and then glass fibers were dipped and coated with the reduced GO (rGO). After repeated sol-gel and dip-coating treatment, the glass fibers were fully covered with rGO coatings, and consequently exhibited increased hydrophobicity and high electrical conductivity. The graphene-coated fibers exhibited good electrical conductivity of 24.9 S/cm, being higher than that of other nanocarbon-coated fibers and commercial carbon fibers, which is mainly attributed to the high intrinsic electrical conductivity of rGO and full coverage of fiber surfaces. The wettability and electrical conductivity of the coated fibers strongly depended on the dip-coating times and coating thickness, which is closely associated with coverage degree and compact structure of the graphene coatings. By virtue of high conductivity and easy operation, the graphene-coated glass fibers have great potential to be used as flexible conductive wires, highly-sensitive sensors, and multi-functional fibers in many fields.

Minghe Fang;Xuhai Xiong;Yabin Hao;Tengxin Zhang;Han Wang;会明 成;You Zeng

Journal of Materials Science and Technology

2019-9

A hydrogen storage material was prepared by mechanical milling of LiNH₂ / MgH₂ (2:1) mixture. Phase identification and structural investigation indicated that the initial dehydrogenation leads to the formation of a novel Li-Mg-N-H phase. The reversible reaction between the novel phase and Mg ( NH₂ )₂ / LiH mixture in the following de-/rehydrogenation cycles at 200 ^{{ring operator}} C leads to a stable hydrogen uptake capacity of ∼ 4.3 wt %. The dehydrogenation of the material can be performed at lower temperatures, but with markedly slow kinetics and lowered hydrogen uptake capacity.

Yong Chen;Cheng Zhang Wu;Ping Wang;会明 成

International Journal of Hydrogen Energy

2006-8

It's elemental! β-Rhombohedral boron was investigated as an elemental photocatalyst. Boron crystals were found to be photocatalytically active in the generation of ^.OH radicals under irradiation with visible light (see picture); however, the presence of an amorphous oxide layer on the surface of the crystals impaired their photocatalytic activity.

Gang Liu;Li Chang Yin;Ping Niu;Wei Jiao;会明 成

Angewandte Chemie - International Edition

2013-6-10

The behaviour of high modulus carbon fibre reinforced Al–Si composites after thermal exposure at 773 K for various times has been investigated. The composites were fabricated via hybridisation of a small volume fraction of SiC particles using a pressure casting process. The longitudinal tensile strength (LTS) of the composites increased to a maximum of 899 MN m⁻² when exposed for 216 h, then decreased as the exposure continued. The transverse tensile strength (TTS) of the composites increased monotonically with increasing treatment time, suggesting that interfacial bond strength was improved by the thermal exposure. It was found that fibre pull-out played an important role in the LTS of the composites and that moderate fibre pull-out resulted in higher values of LTS. The results of single fibre tensile tests show that long term thermal exposure at 773 K only slightly degraded the fibres compared with the fibres in the as cast composites. The fibre pull-out behaviour and the microstructural observations of the fibre surfaces gave some evidence that chemical interactions occurred in the fibre/matrix interfaces.

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

Materials Science and Technology

1992-3

Large-scale implementation of electrochemical hydrogen production requires several fundamental issues to be solved, including understanding the mechanism and developing inexpensive electrocatalysts that work well at high current densities. Here we address these challenges by exploring the roles of morphology and surface chemistry, and develop inexpensive and efficient electrocatalysts for hydrogen evolution. Three model electrocatalysts are flat platinum foil, molybdenum disulfide microspheres, and molybdenum disulfide microspheres modified by molybdenum carbide nanoparticles. The last catalyst is highly active for hydrogen evolution independent of pH, with low overpotentials of 227 mV in acidic medium and 220 mV in alkaline medium at a high current density of 1000 mA cm ⁻² , because of enhanced transfer of mass (reactants and hydrogen bubbles) and fast reaction kinetics due to surface oxygen groups formed on molybdenum carbide during hydrogen evolution. Our work may guide rational design of electrocatalysts that work well at high current densities.

Yuting Luo;Lei Tang;Usman Khan;Qiangmin Yu;会明 成;Xiaolong Zou;Bilu Liu

Nature Communications

2019-12-1

The issue of the sustainability of energy supply has attracted worldwide concern given the rapid depletion of fossil energy sources amid increasingly worsening environmental pollution and the drive to develop alternative, environment-friendly, renewable energy sources and energy carriers to secure our energy supply and sustainable development. Hydrogen is considered to be among the best solutions available, although technical barriers, in particular effective hydrogen storage, need to be dealt with. Quasi-one-dimensional carbon nanotubes (CNTs) with rich nanosized pore structures are considered to be a potential hydrogen storage medium; however, controversy over and discrepancies in both the experimental and theoretical results do exist. Therefore, the latest research progress in and the current situation pertaining to hydrogen storage in CNTs are reviewed and discussed in detail. Moreover, CNTs can have wide applications as alternative energy storage media, utilizing fully their unique structural characteristics. We summarize and analyse the advantages as well as the research progress made in using CNTs as electrode materials in lithium-ion batteries and supercapacitors. Further, future applications of CNTs in the energy storage field are explored.

Chang Liu;会明 成

Journal Physics D: Applied Physics

2005-7-21