隐晶质石墨含量与粒径对复合材料导热性能的影响

摘要

以天然隐晶质石墨为导热填料,聚乙烯醇(PVA)为粘结剂,采用热压法制备了隐晶质石墨/PVA 导热复合材料,研究了纯化前后隐晶质石墨含量与粒径对复合材料导热性能的影响.结果表明,随着石墨含量增加,复合材料的热扩散率上升.隐晶质石墨含量分别为89％和99％时,原矿隐晶质石墨制备的复合材料热扩散率分别为5．224和7．459 mm2/s,纯化后隐晶质石墨制备的复合材料热扩散率则为7．839和9．458 mm2/s,纯化后复合材料热扩散率较原矿提高；纯化前后隐晶质石墨在未球磨和以300~600 r/min球磨时,随着平均粒径的减小,复合材料的热扩散率下降.原矿球磨后隐晶质石墨/PVA 复合材料热扩散率从5．224 mm2/s 减小到4．682 mm2/s,纯化后球磨隐晶质石墨/PVA 复合材料热扩散率从7．839 mm2/s 下降到6．019 mm2/s.研究表明,隐晶质石墨/PVA 复合材料导热性能随着石墨含量的提高而增强,随着石墨粒径的减小而减弱.%Regarding natural aphanitic graphite and PVA as thermal conducting fillers and binder respectively, the research adopts the hot pressing method to prepare the thermal conductive composite of aphanitic graphite/PVA.Meanwhile,the influence of the content and particle of aphanitic graphite before and after purification on the composites’thermal conductivity was studied.The indications of the results were as follows:on the one hand,along with the increase of graphite content,the thermal diffusivity of composites rises,namely when the content of aphanitic graphite was 89% and 99% respectively,the thermal diffusivity of composites was 5.224 and 7.459 mm2/s respectively by the preparation of raw ore,and the thermal diffusivity of composites was 7.839 and 9.458 mm2/s respectively by the preparation of aphanitic graphite after purification,which suggest that the thermal diffusivity of composites through the purification was better improved than raw ore.On the other hand, when the aphanitic graphite before and after purification without milling and the milling with the speed of 300-600 r/min,the thermal diffusivity of composites declines along with the reduce of average particle size,namely the thermal diffusivity of composites including the aphanitic graphite by the milling of raw ore and PVA drops to 4.682 from 5.224 mm2/s,and the thermal diffusivity of composites covering the aphanitic graphite by the milling of purification and PVA falls to 6.01 9 from 7.839 mm2/s.According to the above results,it was turned out that the thermal conductivity of composites from the effect of the content and particle of aphanitic graphite increases with the improvement of graphite content and decreases with the diminution of graphite content.