SBIR Phase I: Functionally Graded Cemented Tungsten Carbide -- Process and Properties

该小型企业创新研究（SBIR）第一阶段项目旨在开发一种创新工艺，通过利用高温渗碳工艺显著提高功能梯度硬质合金（FGM WC-Co）的可制造性。该技术基于对烧结过程中液相平衡和迁移的热力学和动力学的理解。该方法是利用液态Co相和其他相之间的热力学平衡以及平衡对温度和碳含量的依赖性。在常规液相烧结WC-Co的渗碳热处理过程中，通过迫使液态Co从表面区域向内部区域流动，在该过程中形成Co梯度。该项目的更广泛/商业影响将是开发功能梯度WC-Co的高可制造性工艺的潜力。硬质合金WC-Co是金属加工、采矿、石油、冶金、石油、冶金天然气、地热能勘探和其他需要极高耐磨性的工业应用。 FGM WC-Co材料由从材料表面到内部具有不同钴成分的WC-Co复合材料制成。与传统的均质WC-Co相比，FGM WC-Co提供了上级耐磨性、断裂韧性和强度的组合，从而提供了更理想的工程性能。 然而，制造FGM WC-Co提出了一个困难的挑战，因为当今大多数WC-Co产品的液相烧结产生均匀的材料。该项目的目标是开发一种新的工艺，可以用于以经济可行的方式制造FGM WC-Co。

This Small Business Innovation Research (SBIR) Phase I project aims to develop an innovative process to significantly enhance the manufacturability of functionally graded cemented tungsten carbide (FGM WC-Co) by utilizing a high temperature carburization process. This technology is based on the understanding of the thermodynamics and kinetics of liquid phase equilibrium and migration during sintering. The approach is to exploit the thermodynamic equilibriums among liquid Co phase and other phases and the dependence of the equilibrium on temperature and carbon content. Co gradient is formed in this process by forcing liquid Co to flow from the surface region towards the interior region during carburizing heat treatment of conventional liquid-phase-sintered WC-Co. The broader/commercial impact of this project will be the potential to develop a high-manufacturability process for FGM WC-Co. Cemented tungsten carbide, WC-Co, is one of the most widely used tool materials in metal machining, mining, oil, gas, geothermal energy explorations, and other industrial applications where extreme wear resistance is required. FGM WC-Co materials are made of WC-Co composites with varying cobalt compositions from surface to the interior of the material. Compared to conventional homogeneous WC-Co, FGM WC-Co offers a combination of superior wear resistance, fracture toughness, and strength, thus provides much more desired engineering performance. However, manufacturing FGM WC-Co presents a difficult challenge because liquid phase sintering, by which most WC-Co products are made today, produces homogeneous materials. This project targets on the development of a new process that can be used to manufacture FGM WC-Co in an economically viable manner.