无粘结剂冷压成型天然鳞片石墨样品力学性能和微观结构的研究

采用天然鳞片石墨粉无粘结剂冷压成型为天然鳞片石墨样品，分别研究了成型压力、保压时间的变化对样品密度、孔隙度和抗折强度的影响，用三点弯曲法测试了样品的室温弯曲力学性能，并利用扫描电镜分析了样品的表面形貌以及断面形貌。结果表明，对样品的成型压力越大，样品的密度和抗折强度越大，而样品的孔隙率越小；保压时间对样品的密度影响不大，在5分钟以上样品的成型性较好；样品的抗折强度与样品成型时的取向有关。定性的分析了天然鳞片石墨样品的微观结构和抗折强度之间的关系。

A STUDY ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF SAMPLES MADE OF NATURAL FLAKES GRAPHITE POWDER WITHOUT BINDING BY COLD PRESSING

The samples were prepared using natural flakes graphite powder without binding by cold pressing. The effects of variation of shaped press and pressing time on the density, pore degree, and bending strength of samples were studied. Flexural strength was measured at room temperature by three--point bending with a 20--mm span. And surface morphology and fracture surface morphology were detected by SEM. It showed that the density and bending strength of samples increased with the increasing of shaped press of samples. But pore degree of samples decreased. The time of maintained press have a little influence on density of samples,which have good shaped properties beyond 5 minutes. Bending strength of samples is related with the orientation of shaped sample. A qualitative model is proposed to account for the correlation between bending strength and microstructure of samples of natural flakes graphite.