基于核-壳自润滑与增强复合效应的干切削刀具基础研究

Dry machining, one of the significant development trends in the metal cutting field, requires the tool performance ever increasingly. The fabrication of self-lubrication cutting tool with the addition of solid lubricants is an effective method to improve the tool performance. However, the incorporation of solid lubricants will inevitably decrease the mechanical properties of tool materials. How to balance the mechanical property and lubrication characteristic of tool materials to develop a new cutting tool with both good self-lubrication and high tool life is a key problem to be urgently solved in the dry machining field. Facing to the requirements of dry machining of adhesive difficult-to-cut materials such as nickel based alloy and stainless steel, a design method for dry machining tools is proposed in the present study based on the combined effect of self-lubrication and strengthening with core-shell approach. Microstructural model for the tool design will be established. The forming condition and mechanism of intragranular structure with the incorporation of nano lubricants inside the tool material through the core-shell way will be explored. The combined effect of self-lubrication and strengthening with core-shell approach will be investigated as well as its improving mechanism of mechanical property and cutting performance. The tool failure characteristic and self-lubrication mechanism in high speed dry machining will then be revealed. A series of new self-lubrication cutting tools for dry machining will finally be developed with the unification of both high mechanical property and good lubrication performance. The research will provide a new design thought for the development of dry cutting tools. It is of both scientific and engineering application significance for the progress and advancement of dry machining technology.

干切削是当前金属切削加工领域的重要发展方向之一，对刀具性能的要求不断提高。通过引入固体润滑剂制备自润滑刀具，是改善刀具性能的有效途径，但固体润滑剂的添加同时导致刀具材料的力学性能显著降低。如何兼顾刀具材料力学性能和润滑特性之间的平衡，使之兼具良好的自润滑效果与高的刀具寿命，是当前干切削刀具研究亟待解决的理论与技术难题。本研究面向镍基合金、不锈钢等易粘结的难加工工件材料干切削加工需要，提出基于核-壳自润滑与增强复合效应的干切削刀具设计方法，建立刀具设计的微观结构模型，探索在刀具材料中以核-壳方式引入纳米固体润滑剂形成晶内型结构的条件和机理，阐明核-壳自润滑与增强复合效应及其对刀具力学性能与切削性能的改善机制，揭示干切削时的刀具失效特性及自润滑机理，研制力学性能与润滑性能相统一的新型自润滑干切削刀具。该研究为干切削刀具研制提供了新的设计思路，对干切削技术的发展具有重要的科学意义和工程应用价值。

如何兼顾刀具材料力学性能和润滑特性之间的平衡，使之兼具良好的自润滑效果与高的刀具寿命，是当前干切削刀具研究亟待解决的理论与技术难题。本项目建立了纳/微米固体润滑剂晶内型/晶间型结构的增强效应模型，阐明了核-壳自润滑与增强复合效应的理论基础。采用纳米和微米固体润滑剂时，固体润滑剂分别形成晶内型和晶间型结构，分别利用Voigt模型和Reuss模型计算了材料的弹性模量，实验值与理论计算结果的基本一致。采用非均匀成核、超声波化学镀、改进的Stöber等方法，将Al2O3、SiC、Ni-B、Ni和GO等包覆在CaF2、h-BN等固体润滑剂颗粒表面，制备了多种包覆效果良好的核-壳型固体润滑剂复合粉体。采用真空热压烧结工艺，制备了Al2O3/TiC、Al2O3/Ti(C,N)、Al2O3/WB2、Al2O3/TiB2等多种基体、添加不同包覆型固体润滑剂的多系列自润滑干切削包覆型刀具材料，均具有良好的力学性能和切削性能。与添加未包覆的固体润滑剂的刀具材料相比，其抗弯强度、断裂韧性和维氏硬度分别提高8.9-22.2%，14.5-36.9%和12.3-27%。在切削球墨铸铁、调质和淬火后的40Cr钢、45钢时，刀具寿命提高了约19.7-37.5%。特别是高速切削时，所研制的包覆型刀具可在多种切削参数下实现良好的加工表面质量。研究了包覆型刀具材料在干摩擦和干切削时的摩擦磨损特性，系统研究了法向载荷、滑动速度与时间等实验条件以及不同组分含量对摩擦学特性的影响规律，分析了刀具前刀面润滑膜的分布和组成成分，揭示了包覆型刀具材料的自润滑与减磨耐磨机理。 .该项目解决了自润滑陶瓷刀具材料的设计难题，取得了具有自主知识产权的研究成果。作为一种高效、洁净的绿色切削刀具，在现代切削加工中具有广阔的应用前景，可满足干切削、硬切削等对刀具的要求，同时对于促进先进制造技术及相关行业领域的科学发展与技术进步具有重要意义。