The iron-based friction material was prepared directly from vanadium-bearing titanomagnetite concentrates by in situ selective carbothermal reactions and vacuum sintering. In this study, drawing on the extraordinary properties of graphene, experiments were conducted to evaluate the effects of graphene additives with a range of 0.2 to 1.0 wt pct on the microstructure and properties of iron-based materials sintered at 1050 \(^\circ \)C for 3 hours. The graphene was added in the form of copper-coated graphene to solve the weak bonding between matrix and graphene. The results show that the microstructure and properties of iron-based friction materials with graphene are significantly improved, especially the iron-based material containing 0.8 wt pct graphene. The graphene reduces the lamellar spacing of pearlite and contributes a more uniform growth of the grain due to its considerable high thermal conductivity. In addition, graphene could also facilitate the austenite transformation to refine the grain. As a result, with the increasing of the graphene content, the hardness is enhanced while the wear rate and friction coefficient are decreased. Particularly, the oxide films on the worn surface are accumulated and transform from FeO to Fe₃O₄ and Fe₂O₃, together with the improved wear resistance, leading the wear behavior turns from severe abrasive and adhesive wear to mild abrasive wear. However, when the graphene content reaches to 1.0 wt pct, both the microstructure and tribological properties of the materials deteriorate again due to the aggregation of graphene.

Graphical Abstract

中文翻译：

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添加石墨烯对含钒钛磁铁矿直接制备铁基摩擦材料的影响

铁基摩擦材料由含钒钛磁铁精矿通过原位选择性碳热反应和真空烧结直接制备而成。在这项研究中，利用石墨烯的非凡性能，进行了实验，以评估石墨烯添加剂在 0.2 至 1.0 wt pct 范围内对 1050 \(^\circ\ )C 3 小时。石墨烯以镀铜石墨烯的形式加入，解决了基体与石墨烯之间的弱结合。结果表明，含石墨烯的铁基摩擦材料的微观结构和性能得到显着改善，尤其是含0.8 wt pct石墨烯的铁基材料。石墨烯减少了珠光体的层状间距，并且由于其相当高的导热性而有助于晶粒更均匀的生长。此外，石墨烯还可以促进奥氏体转变以细化晶粒。结果，随着石墨烯含量的增加，硬度提高，而磨损率和摩擦系数降低。特别是磨损表面的氧化膜堆积并由FeO转变为Fe ₃ O₄和Fe ₂ O ₃，以及提高的耐磨性，导致磨损行为从严重的磨粒和粘着磨损转变为轻度磨粒磨损。然而，当石墨烯含量达到 1.0 wt pct 时，由于石墨烯的聚集，材料的微观结构和摩擦学性能再次恶化。

图形概要