The Characterization of Fibrous Material in CVI Graphite Cylinder Wall

By isothermal chemical vapor infiltration (ICVI) preparation of carbon/carbon composites, We found fibrous materials with silver metallic luster in CVI furnace graphite cylinder outer wall, fiber diameter is 1 ~ 2 mm, length is 4 ~ 15 mm. The characterization of fibrous material have been systematically studied by scanning electron microscopy (SEM),element analysis, energy dispersive X-rays spectroscopy (EDS).After 2300 degrees heat treatment, the fibrous material were characterized by ultra-violet laser Raman spectroscopy. The SEM examination shows that these fibrous materials have a spherical top, the cross-section reveals a unique structure in which layers like growth rings lie concentrically on top of each other. The EDS analysis show the main element of fibrous material is carbon and a small amount of metallic element. Raman spectra show after 2300°C high temperature treatment ,the carbon fibrous material transformed from layer structure to graphite structure.

Electrochemical pilot scale study for reduction of 2,4-DNT

An electrochemical pilot scale reactor was used to treat simulated munitions wastewater containing 100 mg/L of 2,4-dinitrotoluene (DNT). Experiments were conducted by using a glassy carbon (zero porosity) coated graphite cylinder as the cathode and a platinum wire as the anode. All experiments were conducted under dissolved oxygen concentration of less than 1.5 mg/L. Initially, experiments simulating batch conditions were conducted to obtain the optimum operating conditions for the reactor. During this batch-mode study, the effects of various parameters such as applied current, electrolyte concentration, and type of electrolyte on the reduction of DNT were evaluated. Results obtained showed that the rates of reduction of DNT increased with an increase in current or concentration of electrolyte. Based on the results obtained from the batch simulation experiments, continuous flow experiments were conducted at three different currents. The ionic strength of the feed solution was maintained at 0.027 M. A current of 200 mA was found to provide a stable reduction of DNT at the 80% level for a period of 14 days after which reactor cleaning is necessary for removal of solids that were formed within the reactor. End products determined for the continuous flow experiments showed 100% molar balance conversion.