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。这项技术是建立在对烧结过程中液相平衡和迁移的热力学和动力学的理解基础上的。方法是利用液态钴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关系。在传统的液态烧结WC-Co渗碳热处理过程中，通过迫使液态Co从表面区向内层流动，从而形成了Co梯度。该项目的更广泛/商业影响将是为女性生殖器切割WC-Co开发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、天然气、地热能勘探和其他对耐磨性要求极高的工业应用中使用最广泛的刀具材料之一。功能梯度材料WC-Co材料是由WC-Co复合材料制成的，从材料表面到材料内部的钴成分各不相同。与传统的均匀WC-Co相比，功能梯度材料WC-Co具有优异的耐磨性、断裂韧性和强度，从而提供了更理想的工程性能。然而，制造功能梯度材料WC-Co是一项艰巨的挑战，因为目前大多数WC-Co产品都是通过液态烧结生产的，所产生的材料是均匀的。该项目的目标是开发一种可用于以经济可行的方式生产女性生殖器切割WC-Co的新工艺。

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.