Papers by Keyword: Graphite

Abstract: In 2009, ASME incorporated the construction specifications of graphite pressure vessels (GPV) in BPV construction codes (BPV VIII-1 part UIG). It is the first time that the non-metallic pressure vessel was incorporated. For the raw materials of GPV, a special property was specified in the codes, i.e. the permeability. As the porous microstructure of impregnated graphite, the permeability becomes a key property for the construction of the GPV especially in the high toxicity applications. In this paper, the whole test technique about the permeability of graphite was discussed, including the computational derivations, design of the test equipment, the test procedure and the result data processing.

Abstract: The combination of different carbon-based fillers (commercial plate graphite (GR) and rod carbon fiber (CF)) were added as conductive fillers to improve the thermal conductivity of polypropylene (PP). The effect of different ratio of carbon-based fillers on the thermal and mechanical properties of GR/CF/PP composites was investigated in detail. A remarkable synergistic effect between GR and CF in improving thermal conductivity of PP composites has been achieved. The results show that the in-plane thermal conductivity rises to 2.8 W·(m·k)^-1 at a GR/CF ratio of 5:1 (the total mass fraction of carbon-based fillers to 40wt%), which is 14 times as the thermal conductivity of pure PP (0.2 W·(m·k)^-1) and also much higher than that of single filler composites.

Abstract: Polyaniline and graphite composites at different graphite loading were synthesized via solution method by using N-Methyl pyrrolidone (NMP) as a solvent. The structural and electrical properties of the composites were analyzed by using XRD, FT-IR and four-point probe method. The increment in the graphite content improved the conductivity of polyaniline (PANI) from 0.017 to 0.050 S/cm. The improvement in conductivity were also being observed through peak shifted in XRD pattern and FT-IR spectra.

Abstract: Aluminium composites are widely used in a variety of applications including aerospace, automotive, defence, thermal as well as in sports and avocation. Technological and industrial demands often account to inculcating special properties to materials to achieve its target that may not be achieved by conventional materials. This phenomenon was widely observed in the recent decades in fields of aerospace and transport where high performance materials with low densities are required. The primary objective of this work is to develop an Aluminium Metal Matrix Composite (AMMC) by in-situ stir casting for naval applications and successfully bring about self-lubrication properties, thereby lowering wear rate and improving corrosion resistance. This is done by adding graphite at various weight fractions to the base metal. The fabricated composites are subjected to various mechanical tests and corrosion test. It was found that ,increase in graphite addition improves the Microhardness of the material, improves the wear resistance and enhances its corrosion resistance. The materials were further observed and found that , there will be lower tensile strengths compared to the base metal with increase in addition of graphite particles.

Abstract: Graphite has attracted both academia and researchers due to its outstanding properties such as having strength 200 times stronger than steel, great efficiency of heat and electricity conduction, low cost and also facile fabrication. In this study, two facile approaches of producing nanosize graphite were performed; thermal expansion and sonication. Graphite that was produced are used as reinforcement in epoxy composite for adhesive applications. In order to determine the mechanical properties of the composite, tensile test was performed using Dumbbell shape of sample. The outcome of the test shows that 1 wt% of expanded graphite produce the highest value of Young Modulus which is 18 MPa. It was also found that adding more expanded graphite increased the ductility of composite by lowering epoxy brittleness. As for adhesive testing, double cantilever beam was used using Universal Testing Machine where the result shows that 1 wt% of expanded graphite demonstrates the highest value of adhesive toughness which is 9398 J/m2. The result of porosity-density indicates that porosity of composites will affect the mechanical properties. From the overall results, it is conclude that smaller weight percentage of expanded graphite produces better composite while for sonication process shows no difference at all. Thus demonstrates that time of dispersion does not give significant effect on the maximum load and stress of the composites.

Abstract: We investigated the effect of poly (vinylidene fluoride) (PVdF) binder content on graphite negative electrodes for lithium secondary batteries. The negative electrode was prepared by artificial graphite powder and poly (vinylidene fluoride) binder. Scanning electron microscopy, charge/discharge test, and electrochemical impedance microscopy were conducted. As a result of electrochemical analysis, we confirmed that the electrochemical behavior varied according to the PVdF content (5, 10, 15, 50, and 90 wt%). In addition, charge/discharge test and electrochemical impedance microscopy results showed the high irreversible capacities and resistances, observed for electrodes containing PVdF contents of 50 and 90 wt%. This demonstrated that decomposition of the binder was generated during electrochemical analysis.

Abstract: Applied research tries to offer new materials from the slag mortars. Basic research tries to explore these engineered materials from the perspective of all the possible test methods. Modern vector analyzer R&S ZNC with a coaxial probe DAK-12 from Speag company was used to determine permittivity and dielectric loss factor of the beams and interesting spectrums of electric resistance were measured for samples with varying content of carbon powder. Carbon contributes from the viewpoint of electrical properties, for example it improved antistatic properties of the floor. In addition to the vector analyzer – the simpler measuring unit was also used. In a frequency range of 40 Hz to 1 MHz values of electrical resistance and permittivity values of the beams with different content of graphite powder, labeled Cond 896 were determined. The higher content of graphite powder increases the electrical conductivity; building materials based on cement are becoming more measurable using electromagnetic measuring methods. The most striking change in the relative conductivity was observed at excitation frequency of the external electric field of 1 kHz. At high frequencies of electrical excitation field from 10 MHz to 3 GHz values of the real part of permittivity were determined by vector analyzer. These measurements are among the building materials used rarely and they open new possibilities of diagnostics.

Abstract: Using three types of yarns with metal filaments, textile samples with various arrangements of yarns were made and additionally coated with polyurethane and graphite layer. The aim of the study is to identify the metal filaments fabrics with the highest shielding effectiveness (SE) and influence of graphite layer on it, using a waveguide method and network analyzer with radiated frequency from 2.6 – 3.6 GHz. Layer of graphite improves the SE properties, although, some uncoated samples have higher SE for definite frequencies.

Abstract: Both conductivity and thermal resistivity measurements of commercial graphite dispersions in non-aqueous polar fluids and non-polar fluids were carried out. Fluids exhibiting different densities as: mineral oil, ethylene glycol, glycerin bidistilled and liquid vaseline were used. Dispersions of commercial graphite containing 5, 10, 20, 40, 60 and 80 weight percent were prepared by sonication technique. The thermal conductivity of each fluid increases as a function of the increasing of the volumetric density of fluid and of the fraction of graphite. Values of thermal conductivity of graphite dispersion were at around ten times higher than that value of the base-fluid. Effects of processing parameters of graphite dispersions on the magnitude of its thermal conductivity are discussed.

Abstract: As auto manufacturers strive to meet imposed fuel economy and emissions regulations while producing vehicles with the quality and features that consumer expect, the industry needs to rely on advancements made in the field of metal matrix composites. The efforts of combining or replacing metals with the use of advanced metal matrix composites (MMCs) not only reduce weight, but can also improve safety, reliability and efficiency. A hybrid MMC was developed for the cylinder liner of advanced diesel engines. Composites of Al-6063 aluminium alloy reinforced with, fly ash particulate containing 10% and graphite particulate containing 5, 10 and 15 % were produced by stir casting. The wear and frictional properties of the casted hybrid metal matrix composites were investigated by performing dry sliding wear test using a pin-on-disc wear tester. The investigation was done to find the influence of applied load, sliding speed and sliding distance on wear rate, as well as the coefficient of friction during wearing process. From the investigation, it is evident that wear resistance of Al-6063 is increased while adding the fly ash and graphite reinforcement content. The results were compared with the existing liner material. From this comparative study the Al-6063/fly ash/graphite hybrid metal matrix composite can be the considered as an alternative material for existing cylinder material.