硬质合金粉末挤出打印中增材制造工艺及其显微结构

粉末挤出打印(PEP)是基于传统金属注塑成型和3D打印相结合的新型增材制造技术，具有打印材料范围广、打印成本低等巨大优势。以WC-13Co硬质合金的PEP增材制造为核心，以热塑性打印材料为重点研究对象，开发打印原料的材料体系，研究打印原料的均匀性、流变性能、成形性能、黏结剂的脱除工艺以及烧结工艺对打印件显微结构及力学性能的影响机制。独立开发了硬质合金PEP打印专用的有机黏结剂材料体系，通过EDS分析黏结剂在打印坯体中分散均匀性。采用两步法脱脂工艺可以完全脱除打印坯体中的黏结剂，并结合真空烧结，在1450 ℃下保温60 min，成功制备高性能硬质合金打印件。研究结果发现打印件线收缩率为17.8%，WC晶粒尺寸分布均匀，维氏硬度1410HV₃₀。本研究采用PEP增材制造技术制备了高性能、打印件尺寸可控的硬质合金材料，为硬质合金的增材制造探索出一条有效的技术路线。

Additive manufacturing process and microstructure during powder extrusion printing of cemented carbides

Powder extrusion printing (PEP) is an additive manufacturing (AM) technology based on the combination of traditional metal injection molding and 3D printing, which has the advantages of wide range of printable materials and low cost. The PEP process of WC-13Co cemented carbide was studied, including the development and properties of thermoplastic printing materials, such as the dispersity, rheology and formability. The effects of debinding and sintering process on the microstructure and mechanical properties of the final parts were also investigated. The results show that the specialized binder for PEP of cemented carbides has been prepared successfully. EDS analysis demonstrates that the binder is uniformly dispersed in the green body. The binder can be effectively and totally removed from the green body by two-step debinding process. In combination with vacuum sintering at 1450 ℃ for 60 min, high performance of cemented carbide sample with the shrinkage rate of 17.8%, uniform distribution of WC grain size, and Vickers hardness of 1410HV₃₀ is successfully fabricated. The result confirms that the PEP technology can be applied to prepare cemented carbide materials with high performance and controllable print size, which provides an effective technical route for additive manufacturing of cemented carbide.