高强高导热多孔石墨骨架的快速制备工艺

Rapid preparation process of high strength and high thermal conductivity porous graphite skeleton

利用选择性激光烧结成形技术制备的石墨件内部疏松多孔、力学性能和导热性能不佳,难以作为功能结构件使用,因此需要对制备工艺进行优化。研究了中间相碳微球(MCMB)的加入量对多孔石墨预制体初始密度、力学性能和导热性能的影响,在比较液态酚醛树脂和中温沥青两种浸渍剂的浸渍效果基础上,对比研究了不同的浸渍工艺组合方案对多孔石墨预制体的性能影响。结果表明:当MCMB加入量为20 mass%时,其挥发性β树脂对孔隙填充效果最好,此时预制体的密度、抗压强度和导热系数达到最高,分别为0.54 g/cm^(3)、2.57 MPa和2.32 W·m^(-1)·K^(-1);组合浸渍工艺方案中,先浸渍一次液态酚醛树脂,再浸渍两次中温沥青对预制体的性能改善效果最好,密度由0.54 g/cm^(3)增加至1.46 g/cm^(3),抗压强度由2.57 MPa上升到了14.81 MPa。经石墨化处理后,多孔石墨骨架导热系数达到214 W·m^(-1)·K^(-1),相比石墨化前(11 W·m^(-1)·K^(-1))大幅提高。

The graphite parts prepared by selective laser sintering technology are porous,poor in mechanical properties and thermal conductivity,and difficult to be used as functional structural parts.Therefore,the preparation process needs to be optimized.The effect of the addition amount of mesocarbon microbead(MCMB)on the initial density,mechanical properties and thermal conductivity of porous graphite preforms was studied.Based on the comparison of the impregnation effects of liquid phenolic resin and medium-temperature asphalt,the effects of different impregnation process combinations on the properties of porous graphite preforms were compared.The results show that when the addition amount of MCMB is 20 mass%,its volatileβresin has the best filling effect on pores,and the density,compressive strength and thermal conductivity of the preform are the highest,which are 0.54 g/cm^(3),2.57 MPa and 2.32 W·m^(-1)·K^(-1),respectively.In the combined impregnation process scheme,first impregnating liquid phenolic resin once,and then impregnating mediumtemperature asphalt twice has the best effect on improving the properties of the preform,the density increases from 0.54 g/cm^(3) to 1.46 g/cm^(3),and the compressive strength increases from 2.57 MPa to 14.81 MPa.After graphitization,the thermal conductivity of the porous graphite skeleton reaches 214 W·m^(-1)·K^(-1),which is significantly higher than before graphitization(11 W·m^(-1)·K^(-1)).