基于多尺度动静态性能预报的高抗热-机械冲击陶瓷刀具的研究

The application and development of ceramic cutting tools are limited by their spalling and fracture in the cutting process and the key point to develop ceramic tool materials is to improve their thermal-mechanical shock resistance and use the initiative design technique. In the project, ceramic cutting tools with high thermal-mechanical shock resistance for iron-based superalloys cutting are studied using the multiscale dynamic and static properties prediction method. The macro and micro structure models of ceramic tool materials would be built and theoretical calculation and numerical simulation are used to predict their static mechanical properties and thermal and mechanical shock resistance. The effect of macro and micro structural parameters on the above properties would be analyzed and their matching relation would be revealed. Then, the design method of ceramic cutting tool materials with high thermal-mechanical shock resistance would be established. The crack initiation and propagation mechanisms and the evolution of damage under thermal and mechanical shock would be revealed. The transmission and consumption of stress waves under mechanical shock would be clarified as well. The material would be fabricated by the hot press sintering technique and the fabrication technologies would be optimized. Their mechanical properties would be tested to verify and improve the properties prediction models. A kind of macro and micro heterogeneous ceramic tool with high thermal-mechanical shock resistance for high speed cutting iron based alloys would be developed. The research achievements of the project have important theoretical significance and practical application value on improving thermal-mechanical shock resistance of ceramic cutting tools, enriching their developing methods as well as improving machining efficiency of high temperature iron-based superalloys.

陶瓷刀具在切削中的剥落和断裂限制了其应用与发展，提高抗热-机械冲击性能并进行主动设计是陶瓷刀具研发的重点。本项目针对铁基高温合金的加工，利用多尺度动静态性能预报手段进行高抗热-机械冲击陶瓷刀具的研制。分别建立陶瓷刀具材料的宏微观尺度结构模型，应用理论计算与数值模拟，预报其静态力学性能和抗热冲击以及抗机械冲击性能，分析宏微观结构参数的影响规律，确定其匹配关系，建立高抗-热机械冲击性能陶瓷刀具的设计方法。揭示热冲击和机械冲击载荷下，裂纹的萌生与扩展以及损伤演变规律；阐明机械冲击载荷下应力波的传导与损耗机制。热压烧结制备陶瓷刀具材料，研究优化制备工艺，进行性能试验，验证并优化性能预报模型。开发一种具有高抗热-机械冲击性能，适用于高速加工铁基高温合金的宏微观非均质陶瓷刀具。研究成果对于提高陶瓷刀具的抗热-机械冲击性能，丰富其设计方法，提高铁基高温合金的加工效率，具有重要的理论和实际意义。

提高陶瓷刀具的强度、韧性以及抗热-机械冲击性能是陶瓷刀具材料研发的重点。本课题针对铁基高温合金的加工，结合计算机模拟与实验，进行了高抗冲击性能陶瓷刀具材料的设计。首先应用多种刀具切削铁基高温合金GH2132，研究其切削性能。为了保证较长的刀具寿命，硬质合金、CBN和陶瓷刀具的适宜加工速度应分别不高于50、150和200m/min。涂层且刀具基体较硬的硬质合金刀具、CBN含量较高且结合剂为Co-W-Al陶瓷的PCBN刀具、综合性能较好的陶瓷刀具拥有更好的切削性能。陶瓷刀具硬度较低时，容易被磨钝，韧性较低时，会出现沟槽磨损。建立并改进了GH2132高温高应变率下的Johnson-Cook本构模型。其次进行了陶瓷刀具材料的宏微观结构建模。基于Python二次开发，利用Voronoi算法，建立了双相氧化铝基和双相氮化硅基陶瓷材料的微观结构模型，利用层数和层厚比建立了陶瓷刀具的宏观结构模型。利用有限元仿真手段，对梯度结构陶瓷刀具材料进行了静态和动态性能的预报，优化了梯度结构。之后利用热压烧结工艺制备了Si3N4/(W, Ti)C/Co和Al2O3/TiN/Graphene系列陶瓷刀具。其中Si3N4基梯度陶瓷刀具在切削GH2132时，切削性能优良。Al2O3基陶瓷刀具石墨烯的最优添加量为0.5vol%，石墨烯的添加有效提高了刀具材料的抗热冲击性能，且该刀具在切削27SiMn钢时，切削性能优良。最后探索了激光熔覆技术在制备金属陶瓷刀具方面的应用潜力。以45钢为基体，以金属陶瓷作为表面熔覆层，进行刀具材料的制备。在保证熔覆层表面质量良好的前提下，钴基粉末最高WC添加量为25%，镍基粉末最高WC添加量为45%，其熔覆层硬度可以达到1000HV0.3左右，而梯度熔覆层的硬度在1100HV0.3以上，与硬质合金刀具相当，满足刀具材料的硬度要求。研究成果对于提高陶瓷刀具材料的抗冲击性能，丰富其设计方法与手段，以及提高铁基高温合金和27SiMn钢的加工效率，具有一定的理论和实际意义。