3D-Cf/Al复合材料低成本制备及界面调控机制研究

During the preparation of conventional 3D-Cf/Al composite, poor wettability and interfacial reaction will have severe impact on the preparation efficiency and properties of the as-fabricated composites. Sol-gel method is utilized to prepare SiO2 coating on the surface of 3D-Cf, and then SiC coating can be obtained by the in situ reduction reaction between the reducing carbon produced by the pyrolysis carbonization of sucrose and SiO2 coating. This improves the wettability between aluminum melt and carbon fiber, and simultaneously restrains the interface reaction, effectively reducing the damage of carbon fiber. In addition, nano Si particles is used to induce efficient infilitration of aluminum melt into 3D-Cf preform, thus to prepare light-weight, conductive and wear resistant 3D-Cf/Al composite with high efficiency at a low cost. This study focus on some key issues associated with the low-cost preparation of 3D-Cf/Al composite, such as interfacial wetting and interface reaction control mechanism, and obtains the mechanisms of interface control by nano carbon fiber coating, high-efficient spontaneous infiltration of Al melt induced by Si nanoparticles, and effect laws of composite interface evolution on its microstructure and performance. This study will not only enrich the research field of low-cost preparation of 3D fiber reinforced composites, but also have a great significance for promoting their widely use.

在传统三维碳纤维(3D-Cf)增强铝基复合材料制备过程中，因较差的润湿性和严重的界面反应，复合材料的制备效率和性能受到严重影响。本申请提出采用溶胶-凝胶法在3D-Cf表面涂覆SiO2涂层，并利用蔗糖裂解碳化生成的还原性碳与该氧化物涂层发生原位还原反应制备SiC涂层，在改善铝熔体与碳纤维润湿性的同时，抑制其界面反应，有效降低对碳纤维的损伤。另外，利用纳米Si颗粒诱发铝熔体高效浸渗3D-Cf预制块，从而实现3D-Cf/Al复合材料的高效、低成本制备，最终获得轻质、导电、耐磨的铝基复合材料。项目重点解决与低成本制备3D-Cf/Al复合材料过程有关的界面润湿及界面反应控制机制等关键问题，获得碳纤维纳米涂层界面调控机理和Si颗粒诱发高效自发浸渗机理以及复合材料界面演变对其微观组织及性能的影响规律。项目研究不仅丰富三维编织体增强金属基复合材料低成本制备领域的研究内容，而且对于促进其广泛应用有重要意义。

碳纤维增强铝基复合材料(Cf/Al)具有较高的比强度和比刚度，优异的摩擦磨损性能等，在航空航天领域有着巨大的应用潜力，受到了研究者们的广泛关注。然而，铝熔体易与碳纤维发生严重的界面反应以及较差的润湿性严重影响了其广泛推广应用。针对以上关键问题，本项目提出一种改善碳纤维与铝熔体界面反应性与润湿性的方法，即溶胶-凝胶技术与金属诱发压力浸渗技术相结合，用以制备碳纤维增强铝基复合材料。主要采用溶胶-凝胶技术，以蔗糖为碳热还原剂，在碳纤维表面涂覆纳米碳化物涂层抑制碳纤维与铝熔体的界面反应，并用Si/Ti颗粒作为诱发浸渗剂，改善铝熔体与碳纤维的润湿性，采用压力浸渗技术实现碳纤维增强铝基复合材料的成功制备。结果发现，溶胶-凝胶技术可以在碳纤维表面形成致密完全的纳米涂层；单向碳纤维增强铝基复合材料界面结合较好，而双向和编织碳纤维则由于纤维交错缠结问题而存在铝熔体无法浸渗而产生的孔隙缺陷，这也直接影响了复合材料的力学性能；单向、双向和编织碳纤维增强铝基复合材料的抗弯性能依次下降，纤维脱粘、基体开裂和孔洞则是复合材料脆性断裂的主要原因。本研究通过采取有效措施以控制界面反应并改善界面润湿性，制得具有良好机械性能的Cf/Al复合材料，对该材料的推广应用具有重要的意义，对纤维增强金属基复合材料的制备具有理论和实践参考意义。