Effects of the Time of Combined Vibration Grinding and the Compacting Pressure on the Density and Shrinkage of Graphite MPG-7 Workpieces

摘要

A technique for the manufacturing of graphite MPG-7 was developed on a laboratory scale with the use of the following new raw materials: uncalcined isotropic shale tar coke and three high-temperature pitches. The caking capacity and density of the test samples of MPG-7 after molding, burning, and graphi-tizing were determined. It was found that the optimum concentration of a binding agent determined from the caking capacity decreased from 40 to 28% as the volatile matter content of coke increased from 4.5 to 9.5% and the softening temperature of pitch decreased from 148 to 135°C. In this case, the total shrinkages of the test samples decreased from 60 to 54%, and their densities decreased from 1.98 to 1.76 g/cm3. The optimum time of combined vibration grinding was determined, and the range of compacting pressures was chosen. The relationships between the densities of the test samples burned under laboratory and production conditions, as well as between the densities of burned and graphitized samples, were obtained. These relationships make it possible to predict the density level of MPG-7 material reached under plant conditions.