粉体石墨烯对铝基复合材料微观结构和性能的影响

Effect of the graphene content on the microstructures and properties of graphene/aluminum composites

  • 摘要: 采用机械合金化与电场压力激活辅助烧结工艺相结合的方式,分别制备纯Al和GNPs/Al复合材料,探究粉体石墨烯对铝基复合材料微观结构和性能的影响。结果表明:通过优化烧结工艺有效地抑制化合物Al4C3在GNPs/Al复合材料中的形成,提高石墨烯与Al基体的界面结合强度。石墨烯添加量为0.5wt.%时,在Al基体晶界处能够均匀的分散,由于石墨烯与Al基体有良好的界面润湿性,促进声子在基体材料中的移动,降低材料的界面热阻,在GNPs/Al复合材料表面形成导电网络,提高电子的迁移率和平均自由程,使GNPs/Al复合材料的热导率和电导率分别提升7.1%和4%;添加石墨烯能改变Al基体材料的晶体结构,在石墨烯周围形成晶格畸变的应力场,该应力场与位错应力场产生交互作用,使位错运动受阻,GNPs/Al复合材料的强度和硬度分别提升30.6%和44%;石墨烯能降低基体材料界面电容的介电损耗,在Al基体材料表面形成致密平整的膜层,提高GNPs/Al复合材料的电荷传递电阻,降低材料表面在电化学腐蚀过程中的弥散效应,使GNPs/Al复合材料耐腐蚀性能提高31%。石墨烯含量超过0.5 wt.%时,团聚在基体晶界的石墨烯,降低复合材料的界面结合强度,使GNPs/Al复合材料导带中的能带宽度变窄,电子的局域性增强,导致GNPs/Al复合材料的性能下降。综上所述,粉体石墨烯的最佳添加量为0.5wt.%。

     

    Abstract: A graphite mold was filled with a mixed powder of aluminum and graphene. It was evacuated to 2×10-1 Pa, pre-pressed under 10 MPa, heated to 450℃ where it was kept for 5 min, pressed again under 40 MPa, heated to 600℃ where it was kept for another 5 min to prepare graphene/aluminum (G/Al) composites. The effect of the graphene content on the microstructure, and thermal, electrical, mechanical and anticorrosive properties of the composites was investigated. Results indicate that when the graphene content is 0.5 wt.%, it is uniformly dispersed at grain boundaries in the Al matrix. Compared to pure Al the resulting composite has thermal and electrical conductivities that are respectively 7.1% and 4% higher, tensile strength and hardness that are 30.6% and 44% higher, and a corrosion resistance that is 31% higher. When the graphene content exceeds 0.5 wt.%, it agglomerates at grain boundaries in the Al matrix, leading to a decrease of all the above-mentioned properties.

     

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