Develop new carbides for high-performance high-Cr cast irons (HCCIs) with optimized combination of fracture toughness and hardness

高铬铸铁（HCCIs）广泛应用于油砂，采矿和制造业，以抵抗磨损和腐蚀磨损。HCCIs的优异性能源于硬质碳化物（如M7C3）和铁基的结合。商用hcci的Cr和C含量分别在23-30 wt%Cr和2-3wt%C之间。近年来，油砂行业做出了巨大的努力，将Cr和C含量提高到更高的水平，为在恶劣条件下的应用提供了更多的选择。然而，提高%C和%Cr提高了材料的强度，但由于促进了粗原生碳化物的形成，降低了断裂韧性，导致在遇到涉及冲击力和很大波动磨损力的磨损时性能不那么令人印象深刻。虽然hcci的性能可以通过微观结构工程来优化，但由于工业规模铸造的微观结构不均匀、设计指南模糊以及制造成本高，这种改进是有限的。在hcci中直接改性碳化物是提高性能和简化微观结构控制的另一种方法。然而，由于实验和理论工具的限制，相关研究相当有限。多模原子力显微镜和计算材料科学的发展使研究成为可能。本项目提出了在HCCIs中定制碳化物的几种有前途的方法，包括在碳化物中添加第三元素、开发复杂的MC碳化物、促进核-壳结构碳化物以及定制碳化物与基体之间的界面键。拟议的研究是基于我们成功的初步研究，并将与我们在加拿大Weir Minerals的工业合作伙伴合作进行。发达的知识和数据库不仅有利于加拿大油砂工业，也有利于采矿和制造业等其他技术部门。此外，在这个项目中培养的hqp将为加拿大带来长期的利益。

High Chromium Cast Irons (HCCIs) are widely used in oil sands, mining, and manufacturing industries to resist wear and corrosive wear. The excellent performance of HCCIs results from the combination of hard carbides, e.g., M7C3, and a ferrous matrix. Commercially used HCCIs have their Cr and C contents in the range of 23-30 wt%Cr and 2-3wt%C, respectively. In recent years, the oil sands industry has made great efforts to push Cr and C contents to higher levels with more options for applications under aggressive and harsh conditions. However, raising %C and %Cr increases the material strength but lowers the fracture toughness due to promoted formation of coarse primary carbides, resulting in less impressive performance when encounter wear involving impact force and largely fluctuated wearing forces. Although the performance of HCCIs can be optimized through microstructure engineering, the improvement is limited due to the microstructure inhomogeneity in industrial-scale casting, vague design guidelines, and high costs in manufacturing. Direct modification of carbides in HCCIs is an alternative approach for improved performance and simplified microstructure control. However, relevant research is rather limited due to the limitation of experimental and theoretical tools. The development of multimode atomic force microscope and computational materials science has made the research possible. This project is proposed to tailor carbides in HCCIs with a few promising approaches, including adding 3rd element to carbides, developing complex MC carbides, promoting core-shell structured carbides, and tailoring interfacial bonding between carbides and matrix. The proposed research is based on our successful preliminary studies, and will be conducted in collaboration with our industrial partners in Weir Minerals Canada. Developed knowledge and database will not only benefit the Canadian oil sands industry but also other technical sectors such as mining and manufacturing. Furthermore, the HQPs trained in this project will bring long-term benefits to Canada.