基于界面调控的石墨烯强韧化复相陶瓷刀具研究

With very high hardness/ wear resistance, chemical stability, ceramic tools are advantageous in the high speed machining of some hard to cut materials such as hardened steels and ultra high strength steels. But their intrinsic brittleness restricts their wide applications. Being a two-dimensional crystal tightly packed by Carbon atoms, graphene is currently the thinnest and the hardest nano material with ultra high specific surface area, ultra high strength and toughness, providing new approach and new principle for the strengthening/ toughneing of ceramic tool materials. Aiming at the high speed machining of hardened steels and ultra high strength steels, this proposal introduces graphene nano sheets as reinforcing phase for ceramic tool materials. By designing and constructing graphene-composite ceramic interfaces, and by means of interface physical control based on surface functional modification of graphene, and interface stress control based on interlace of strong/ weak interfaces, multiple strengthening/ toughneing mechanisms will be introduced to greatly improve the mechanical properties of ceramic tool materials. Investigations are performed on the surface functional modification of graphene, and the dispersion, mixing and sintering processes of raw materials, and the processing parameters are optimized. Subsequently the interface control theory of tool materials is verified. Graphene reinforced ceramic tools suitable for the high speed machining of hardened steels and ultra high strength steels will be developed successfully. This proposal is theoretically and practically significant for the enrichment of tool design theories, as well as the improvements in machining efficiency and machining quality.

陶瓷刀具具有很高的硬度/耐磨性、化学稳定性，在淬硬钢、超高强度钢等难加工材料的高速加工领域具有特有的优势，但其固有的脆性制约了其广泛应用。石墨烯是一种由碳原子紧密堆积构成的二维晶体，是目前最薄也是最坚硬的纳米材料，具有超大的比表面积、超高的强度和韧性，为陶瓷刀具的强韧化提供了新途径和新原理。本项目针对淬硬钢、超高强度钢等难加工材料的高速加工，将石墨烯纳米片作为陶瓷刀具材料的强韧化相，设计并构筑石墨烯/复相陶瓷界面，通过基于石墨烯表面功能化改性的界面物理调控，和基于强弱界面交错分布的界面应力调控，引入多种强韧化机制，从而显著提高陶瓷刀具材料的力学性能。研究石墨烯功能化改性、刀具原材料分散、混料及烧结制备工艺，并优化工艺参数，验证刀具材料界面调控理论，研制成功分别适于高速加工淬硬钢和超高强度钢的石墨烯强韧化陶瓷刀具。对于丰富刀具设计理论，提高切削加工效率及加工质量，具有重要的理论和实际意义。

陶瓷刀具具有很高的硬度/耐磨性、化学稳定性，在淬硬钢、超高强度钢等难加工材料的高速加工领域具有特有的优势，但其固有脆性制约了其广泛应用。石墨烯是一种由碳原子紧密堆积构成的二维晶体，是目前最薄也是最坚硬的纳米材料，具有超大的比表面积、超高的强度和韧性，为陶瓷刀具的强韧化提供了新途径和新原理。本项目针对淬硬钢、镍基高温合金等难加工材料的高速加工，将石墨烯纳米片作为陶瓷刀具材料的强韧化相。基于断裂力学和能量守恒定律，建立了石墨烯增韧模型，定量分析了石墨烯引入的不同强韧化机制对复相陶瓷刀具材料增韧的贡献，结果表明石墨烯片拔出是主导增韧机制，为石墨烯/陶瓷复相刀具材料的设计与制备提供了理论指导。通过基于石墨烯表面功能化修饰的界面物理调控和基于强、弱界面交错分布的界面应力调控，在复合陶瓷刀具材料中引入了载荷转移、晶粒细化等强化机理以及裂纹偏转、裂纹分叉、裂纹桥接、石墨烯拔出等韧化机理。研究了石墨烯功能化改性、刀具原材料分散、混料及烧结制备工艺，并优化了工艺参数，验证了刀具材料界面调控理论，研制成功分别适于高速加工淬硬钢和镍基高温合金的石墨烯强韧化Al2O3-WC-TiC、Al2O3-Ti(C, N)陶瓷刀具，显著提高了复合陶瓷刀具的力学性能和刀具寿命。石墨烯对陶瓷刀具的强韧化作用以及石墨烯良好的润滑性能和导热性能，是石墨烯强韧化陶瓷刀具切削性能提高的主要原因。该项目对于丰富刀具材料设计理论，提高难加工材料的加工效率及加工质量，具有重要的理论和实际意义。