Papers by Keyword: Graphite

Abstract: A new tubular cathode support for Direct Ethanol Fuel Cell (DEFC) was prepared by the gelcasting process using mesocarbon microbead(MCMB) and graphite as the main raw materials. The effects of different graphite doping ratios on tensile strength, bending strength, crushing strength, volume resistivity and shrinkage rate for the prepared tubular cathode support were studied by experimental test. The result showed that the prepared tubular cathode support had very good comprehensive performance. The tubular cathode support with 10% graphite exhibits the best performance such as bending strength 25MPa and resistivity30µΩ•m, and it satisfied the DEFC cathode working conditions and performance requirements.

Abstract: Graphite powders are important pore former, and widely used in the preparation of many kinds of porous ceramics. The dispersion of pore former controls the homogenous pore structure of porous ceramics, and deeply influences its properties. The dispersion and its influence factors of graphite powders in water and alcohol were systematically studied. The dispersion of graphite powders in water and alcohol were investigated by sedimentation method. It was found that alcohol as dispersion media can improve the dispersibility of graphite powders. In addition, the influence of different surfactants on the disperisibility was also studies. It can be confirmed that surfactant can prompt the dispersion of graphite powders in water. The zeta potential and particle size of graphite powders in different pH value were tested to understand its dispersion.

Abstract: Short carbon fiber is used to reinforce phenol formaldehyde (PF) resin/graphite composite. With carbon fiber by thick nitric acid liquid-phase oxidative surface treatment (TNALPOST) and its content 3.wt%~ 4.wt%, the composite flexural strength is increased highly and electrical conductivity is also increased on some degree. To PF resin/graphite matrix material without carbon fiber added, if PF resin content is 15.wt%, its flexural strength is 49.0MPa and electrical conductivity is 111S/cm. But with adding carbon fiber by TNALPOST and the same PF resin content , the composite flexural strength and electrical conductivity approach 68MPa、122S/cm respectively, both mechanical property and electrical property satisfy the requirement of USA Department of Energy on carbon filler/polymer composite bipolar plate. The PF resin/graphite composite without carbon fiber added presents brittle fracture mode, but with carbon fiber added, it presents ductile fracture mode. According to the fracture morphology by scanning electron microscopy, carbon fiber and matrix is on relatively weak boundary bonding state accompanied by fiber de-bounding、sliding、pulling-out and bridge-making to crack, they are main factors contributed to improving composite toughness.

Abstract: The tetracycline (TC) adsorption on the graphite was investigated by method of static experiments. Related properties of the adsorbate and adsorbent were studied to support the adsorption mechanisms exploration. The results indicate the close relationship existing among the adsorption capacity variation, TC K_ow and TC species (+,-,0) distribution on pH. And the hydrophobic force drives TC adsorption on the graphite.

Abstract: Si/C composites were synthesized by using graphite and glucose as carbon source. The samples were characterized by X-ray diffractometer (XRD) and field emission scanning electron microscope(SEM). The electrochemical charge/discharge test was used to evaluate capacity and cycling stability of the composites. The first discharge and charge capacity of SGC composite using graphite and glucose as carbon source were 1661mAh/g and 1259.1 mAh/g, and the first coulombic efficiency was 75.8%. After 20 cycles, the capacity of SGC composite was 380 mAh/g and the coulombic efficiency remained over 98%.

Abstract: This paper gives an assessment on the electrical conductivity of different additive fillers (graphite, multi-walled carbon nanotubes) into carbon fiber-cement based composites (CFRC). Results show that cement matrix containing 0.4% carbon fiber (CF) and 0.5% multi-walled carbon nanotubes (MWCNTs) exhibits an excellent electrical conductivity of 33.65Ω·cm. When the content of CF is below the percolation threshold (0.4% CF), adding graphite is beneficial to the electrical conduction of CFRC, which has a tremendous drift from 3991.44Ω·cm to 524.33Ω·cm as the content of graphite varies from 0% to 30%. However, when the content of CF is above the percolation threshold, adding graphite makes no advantages in the electrical conductivity of CFRC because of leading to a porosity rising. MWCNTs are useful conductive constituents for CFRC and can increase electrical conductivity by two orders of magnitude. However, excessive adding MWCNTs into CFRC will have a rapid increase of electrical resistivity on the contrary.

Abstract: Thin diamond films are deposited on commercial tungsten carbide micro ball end mill by using hot filament chemical vapour deposition (HFCVD) technique. Raman spectrum results confirm the high purity of sp³-carbon bond diamond of as-deposited films. The scanning electron microscope (SEM) investigation exhibits continuous fine grained diamond films are uniformly deposited on micro ball end mill. Milling of graphite is chosen to check the cutting performance of fabricated diamond coated micro ball end mill. For the sake of comparison, milling test is also carried out using uncoated micro ball end mill under the same cutting parameters. The milling test results show that the tool life of diamond coated micro ball end mill is about 10 times than that of uncoated one, which may attribute to high hardness, wear resistance, low sticking to graphite of deposited diamond films and strong adhesive strength between them and substrate surfaces.

Abstract: In this investigation, conventional microcrystalline diamond (MCD) and boron doped diamond (BDD) films are deposited onto commercially available cemented tungsten carbide (WC-Co) Ball-nose endmills by using hot filament chemical vapour deposition (HFCVD). The quality and properties of the as-deposited diamond film are characterized by field emission scanning electron microscope (FESEM) and Raman spectroscopy. Milling tests of graphite materials using MCD, BDD coated and uncoated tool are carried out. Experiment results reveal that BDD films possess higher adhesive strength to the substrate than that of MCD films, and the BDD coated mills allow to be given smaller flank wear and longer tool life, when compared with MCD coated and uncoated WC-Co tools. Cutting performances of WC-Co mills in graphite milling are greatly improved by BDD coating, and typically more than 10 times the tool life is obtained. The research results are of great significance for high efficiency and quality machining of graphite materials.

Abstract: Soil moisture detective probe is an important part of automatic irrigation system. Soil moisture probe is usually made of metal material which is easy to be corroded and passivated as long-term working in the damp soil, especially containing acid, alkali and salt. We developed a new soil moisture probe material - the graphite-based cementitious material. The mechanical properties and the conductive properties of the material were tested and we found the graphite-based cementitious material which contains 30% to 50% of graphite could be an applicable material for the soil moisture probe.

Abstract: Combining with productive practice, production of intermediate castings in high-strength turbochargers under the condition of intermediate frequency furnaces is analysed in this paper. By adopting measures of compound inoculation and increasing Sulfur, 95% type A graphite and high-strength intermediate castings whose tensile strength is 300 MPa are acquired. Furthermore, moderate amounts of S and Mn as well as CE values are determined according to test results. As for thin-wall gray cast iron with high strength and complicate structure, when w _S is low and w _C is high, castings with good graphite form can be produced. But it is not stable and the strength is low. Adding inoculants like Calballoy and Si-Ca-Ba can significantly improve the graphite form on the edge of thin-walls. When w _C is stabilized at about 4.1, stable and continuous production of high strength gray cast iron with good graphite form can be guaranteed by adding sulfur and controlling the amount of Mn. The proportion of A type graphite and that of pearlite are both more than 90%.When high-strength gray cast iron is produced in intermediate frequency furnaces, w _S should be controlled between 0.1% and 0.12% and w _Mn should be controlled between 0.5% and 0.55%.