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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
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    Electrical Conductivity and Micro Hardness of Synthetic and Natural Graphite Epoxy Composite

    Hendra SuhermanJaafar SahariAbu Bakar Sulong
    P.614-618页
    查看更多>>摘要：This study investigates the electrical conductivity and micro hardness of synthetic and natural graphite epoxy composite. Graphite used on this study is synthetic graphite (SG) and natural graphite (NG) with particle size 44μm and 30μm, respectively. Different graphite concentrations (50 ～ 80 wt.%) were added into the epoxy resin. The dispersion of graphite in epoxy resin was conducted by high speed mixer through mechanical shearing mechanism, its graphite epoxy suspension was poured into the mold and compression molding was conducted for fabrication of graphite epoxy composites. Electrical conductivity was measured by the four point probe. Microscopic analyses conducted on fracture surface use scanning electron microscopic. Results reveal that non conductive epoxy polymer becomes conductor as addition of graphite. Electrical conductivity of NG higher than SG at the same weight percentage (Wt. %) of conducting filler loading. The highest loading concentration, it exhibited values 12.6 S/cm and 7 S/cm at (80 Wt. %). Hardness property of epoxy composites of both type of graphite increase continuously and reached peak at 60 wt% for NG and 70 wt % for SG, while more addition decreased it.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effects of Molecular Weight and Annealing on Electrical Conductivity of Multi-walled Carbon Nanotube/Polypropylene Composites

    Yongzheng PanLin LiSiew Hwa ChanJianhong Zhao...
    P.619-623页
    查看更多>>摘要：Composites of polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs) were prepared by a micro melt mixing process. The molecular weight of PP was varied from 190,000 to 340,000 to examine its effects on the electrical conductivity. It has been discovered that a significant enhancement of electrical conductivity could be achieved by a thermal post annealing process above the melting temperature of PP. Factors such as annealing time, temperature, viscosity of PP, and content of MWCNTs all affected the enhancement of electrical conductivity. Re-aggregation of MWCNTs and the subsequent formation of MWCNT networks during annealing are considered to be the main reasons for the quick enhancement of electrical conductivity. The observed effect of molecular weight of PP on the enhancement of electrical conductivity suggested that the enhancement process could be controlled by diffusion of MWCNTs.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Drilling of Titanium/CFRP/Aluminium Stacks

    Islam ShyhaSein Leung SooDavid K. AspinwallSam Bradley...
    P.624-633页
    查看更多>>摘要：Following a review on the machinability of CFRP composites and multilayer stacks typically comprising metallic and composite material elements, the paper details experimental results when drilling 30 mm thick titanium/CFRP/aluminium workpiece stacks. Testing utilised a modified fractional factorial design based on an L18 Taguchi orthogonal array. This comprised four factors, three of which were at three levels and one at two levels and involved tool coating, cutting speed, feed rate and machining environment. Tools evaluated involved hardmetal and diamond coated carbide in addition to uncoated tungsten carbide drills. Response variables were principally tool wear and cutting force/torque with an end of test criteria of 300μm flank wear. Peeling of the CVD diamond coating occurred within the first several holes drilled however this was not a limiting factor in terms of tool life. Principal damage occurred when drilling through the titanium (Ti-6A1-4V) rather than the aluminium (Al 7050) or CFRP (unidirectional "UD" laminates) sections. Best tool life/performance (310 drilled holes) was obtained with the more conventional uncoated carbide drills at lower cutting speed and feed rate. Typically thrust forces increased from 300 N for the first hole to ～2200 N for last hole drilled while torque values were generally below 600 N.cm for worn tools.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Molecular Interactions in PA6, LCP and Their Blend Incorporated with Functionalized Carbon Nanotubes

    Henry Kuo Feng ChengNanda Gopal SahooLin LiSiew Hwa Chan...
    P.634-638页
    查看更多>>摘要：Multi-walled carbon nanotubes (MWCNTs) were functionalized with a carboxyl group (-COOH) to improve their dispersion in a nylon6 (PA6) matrix, a liquid crystal polymer (LCP) and their blend. This functionalized MWCNTs also achieved better interfacial adhesions with both polymer matrices and with both phases in the blend. The dispersion of MWCNT-COOH in the polymer matrices and their interfacial interactions with polymer molecules were found to be the most important factors affecting the properties of composites. Moreover, studies on morphological, rheological, and mechanical properties confirmed that a better miscibility between PA6 and LCP had been constituted in the presence of MWCNT-COOH. Therefore, it is observed that the functionalized MWCNTs not only played the traditional role as reinforcing fillers in the polymer matrices, but also performed a novel role as compatibilizers for their blend.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fiber- complected and Reeled Microstructure of Insect Cuticle and Biomimetic Fabrication

    Bin ChenQuan YuanJi Luo
    P.639-642页
    查看更多>>摘要：A scanning electron microscope (SEM) was used for the observation of the microstructures of a chafer cuticle. It showed that the cuticle is a kind of biocomposite consisting of complected chitin-fiber plies and sclerous protein matrix. The observation also showed that there are many holes in the cuticle and the complected fibers continuously reel these holes forming a kind of fiber-complected and reeled microstructure. Based on the SEM observation, a kind of biomimetic composite laminate with complected and reeled structure was fabricated with a special mould and process. The ultimate strength of the obtained biomimetic composite laminate was experimentally investigated and compared with that of the conventional drilling-hole composite laminate. It showed that the ultimate strength of the biomimetic composite laminate is markedly larger than that of the drilling-hole composite laminate.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Electrical Conductivity and Flexural Strength of Graphite/Carbon Nanotubes/Epoxy Nanocomposites

    Hendra SuhermanJaafar SahariAbu Bakar SulongNishata Royan...
    P.643-647页
    查看更多>>摘要：Carbon nanotubes (CNTs) have excellent mechanical and electrical properties. CNTs reported have excellent properties that can replace conventional conductive filler in advanced engineering applications. The polymer matrix was epoxy resin (EP).Conductive fillers were MWCNTs and synthetic graphite (G). Different variation of CNTs (0～10 wt. %) and graphite (60 ~ 67.5 wt. %) loading concentration were added into the epoxy resin. Dispersion of CNTs and G in epoxy resin were conducted by internal mixer with a Haake torque rheometer. The mixture of G/CNTs/EP was poured into the steel mold, and G/CNTs/EP nanocomposites had been fabricated through compression molding. The electrical conductivity of nanocomposites in term of variation of G and CNTs concentration were measured by the four point probe for in plane electrical conductivity. The results revealed that addition of G/CNTs and increasing curing temperature are an effective ways to produce high electrical conductive nanocomposites. Dispersion quality of CNTs and G in epoxy matrix were observed on the fractured surface by scanning electron microscopic.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fiber-intersected Microstructure of Cockle Shell and Biomimetic Fabrication

    Bin ChenQuan YuanJi Luo
    P.648-651页
    查看更多>>摘要：A scanning electronic microscope (SEM) was used for observing the microstructures of a Cockle shell. It showed that the shell is a kind of natural bioceramic composite consisting of aragonite sheets and organic collagen matrix. The aragonite sheets are further composed of aragonite fibers. The aragonite fibers are of long and thin shape and compose various reinforced microstructures, which include a kind of fiber-intersected reinforced one. The fiber-intersected reinforced microstructure was employed as the design example for the structure of man-made fiber-reinforced composite, a kind of fiber-reinforced composite with the fiber-intersected reinforced structure was biomimetically fabricated. The fracture toughness of the biomimetical composite was tested and compared with that of the conventional composite with fiber-parallel structure. It indicated that the fracture toughness of the biomimetical composite is markedly larger than that of the fiber-parallel composite.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Mixture of Plasticizer on the Thermoplastics Formability of Polyvinyl Alcohol (PVA)

    Liu BinQiu DieZhao Chunzhen
    P.652-656页
    查看更多>>摘要：In this paper, PVA was modified by mixture of plasticizer with glycerol and caprolactam. DSC and FTIR were used to test the thermoplastics formability of modified PVA. The results showed that the melt temperature of modified PVA with plasticizer was decreased significantly. With the same content of mixture of plasticizer (20%), the melt temperature of modified PVA is 207° C when the mass ratio of glycerol and caprolactam is 3:2. Under the same content of plasticizer, plasticized effect of mixture of plasticizer was enhanced more than the plasticizer of glycerine or caprolactam alone, so the melt temperature of modified PVA with mixture of plasticizer was lowest relatively.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fiber-spiral Microstructures of Bamboo and Biomimetic Research

    Bin ChenQuan YuanJi Luo
    P.657-660页
    查看更多>>摘要：The microstructures of a whangee (a kind of bamboo) were observed with a scanning electron microscope (SEM). It showed that the whangee is a kind of natural cellular biocomposite consisting of countless bamboo cells. The bamboo cells are columnar and all of them are parallel with the surface of the bamboo. The observation also showed that the walls of the bamboo cell are a kind of fiber-reinforced biocomposite with bamboo fiber-spiral mcirstructure. Based on the SEM observation, a kind of biomimetic composite with the fiber-spiral structure was fabricated. The fracture toughness of the composite was investigated and compared with that of the conventional composite with parallel-fiber structure. It showed that the fracture toughness of the biomimetic composite is markedly larger than that of the conventional composite.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Combinatorial Searching for Ni-Nb-Zr Amorphous Alloys as Glass Lens Molding Die Materials

    Junpei SakuraiMitsuhiro AbeMasayuki AndoSeiichi Hata...
    P.661-665页
    查看更多>>摘要：This paper presents a search for Ni-Nb-Zr amorphous alloys for application as glass lens molding die materials. To efficiently screen candidate materials, we employed the combinatorial method partially to evaluate thermal stability. First, compositionally spread Ni-Nb-Zr libraries were fabricated by combinatorial arc plasma deposition (CAPD). In order to evaluate the high thermal stability, Ni-Nb-Zr amorphous samples in the libraries were annealed at 723K, the molding temperature for glass lens, for various times in vacuum. Phases in the annealed samples were identified by X-ray diffraction. From XRD identification, candidate amorphous samples with high thermal stabilities were screened. Sputtered samples with the same compositions as the candidate amorphous samples were then fabricated. Other desired properties for glass lens molding die materials, such as mechanical strength, machinability and anti-sticking properties, were evaluated. These investigations revealed Ni_(36)Nb_(39)Zr_(25) to be a suitable material for a new glass lens molding die. This material exhibited a high fracture stress σ_f of 1.3 GPa, good heat resistance, good machinability, and excellent anti-sticking properties to molten glass.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd