粉体石墨烯对铝基复合材料微观结构和性能的影响

摘要

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 agglom-erates at grain boundaries in the Al matrix, leading to a decrease of all the above-mentioned properties.%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Al4 C3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. % .