基于激光微细加工的WC-Ni3Al-Si3N4刀具表面微织构原位强化机制及缺陷抑制策略研究

Based on the requirement of the durability of the micro-textured cutting tool and the characteristic of the laser micro-texturing, the WC-Ni3Al-Si3N4 is proposed to be the matrix material of the micro-textured cutting tool. The composition and proportion of the additive in WC-Ni3Al-Si3N4 is optimally designed through the analysis of the phase transformation mechanism and necessary requisite under the high temperature rise rate. A combination of the spark plasma sintering technology and the laser micro-texturing technology is utilized to fabricate the WC-Ni3Al-Si3N4 cutting tool with micro-textured surface. The microstructure evolution of WC grain and β-Si3N4 whisker under sintering and laser machining process are revealed, and the theoretical basis and technical strategy of micro-texturing toughening and laser machining defect reduction are proposed. Furthermore, the relationship between the design and performance of the WC-Ni3Al-Si3N4 cutting tool with micro-textured surface and the physical parameters in machining of titanium alloy is investigated. Finally, the preparation theory, preparation method and the machining processing technology are obtained for the micro-textured WC-Ni3Al-Si3N4 cutting tool with high chemical stability, high wear resistance, less defect on the texturing surface and β-Si3N4 whisker with large ratio of length to diameter in the laser machining heat affected zone.

基于微织构表面刀具对织构耐用度的要求，结合微织构激光加工技术的特点，提出以WC-Ni3Al-Si3N4作为微织构表面刀具的基体材料。通过分析高升温率下α-Si3N4→β-Si3N4的相变机制及必要条件，优化设计WC-Ni3Al-Si3N4中添加剂的成分及比例；综合利用放电等离子烧结技术及激光微细加工技术，制备具有微织构表面的WC-Ni3Al-Si3N4刀具，揭示材料烧结及微织构加工过程中WC晶粒及β-Si3N4晶须的生长规律，提出增韧强化微织构并抑制激光加工缺陷的理论依据和技术策略；研究车削钛合金时，具有微织构表面WC-Ni3Al-Si3N4刀具的设计和性能与加工过程中各特征量的相关关系；获得在微织构激光加工热影响区内原位生成大长径比的β-Si3N4晶须、织构内少缺陷、并具有良好高温化学稳定性及耐磨性的微织构表面WC-Ni3Al-Si3N4刀具的制备理论、制备方法和加工工艺技术。

本项目以提高硬质合金刀具表面微织构耐用度为目的，以无Co硬质合金材料制备及激光微织构加工工艺为主要研究对象，开展了WC-Ni3Al-Si3N4制备、纳米脉冲激光加工工艺优化、微织构表面硬质合金抗磨损性能测试等方面的基础工作，建立微织构表面硬质合金刀具的制备和应用为一体的研究体系。创新性地提出了采用微织构刀具基体材料制备以及激光微细加工相结合的策略以增韧强化刀具表面微织构并抑制微织构加工缺陷；开发出兼顾高温硬度、强度和化学稳定性，并可在激光微细加工条件下原位增韧强化微织构的WC-Ni3Al-Si3N4刀具材料；揭示激光微细加工过程中局部极高热流密度条件下，WC-Ni3Al-Si3N4硬质合金材料表面微结构原位强化机理；获得激光微细加工WC-Ni3Al-Si3N4硬质合金材料表面微结构加工缺陷控制策略；揭示具有微织构表面的WC-Ni3Al-Si3N4硬质合金刀具在车削Ti6Al4V时的磨损及失效机理；获得具有微织构表面的WC-Ni3Al-Si3N4硬质合金刀具的制备理论、制备方法和加工工艺技术。进而解决微织构表面刀具织构耐用度较低的难题。实现了微织构表面硬质合金在摩擦副以及塑性金属切削过程中的实际应用。项目的研究成果在Opt. Lett.、Opt. Express、Opt. Laser Eng.、Int. J. Adv. Manuf. Tech.、Surf. Coat. Tech.、Int. J. Refract. Met. Hard Mater.、等上发表发表SCI学术论文18篇，申请发明专利12项，实用新型专利2项。研究成果有望在无Co硬质合金增韧强化、纳米脉冲激光加工工艺优化及微织构表面硬质合金刀具切削性能优化等方面得到推广应用。