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

高铬铸铁（HCCI）广泛用于油砂、采矿和制造业以抵抗磨损和腐蚀磨损。HCCI的优异性能来自于硬质碳化物的组合，例如，M7 C3和含铁基质。商业上使用的HCCI的Cr和C含量分别在2 - 3 -30重量%Cr和2- 3重量%C的范围内。近年来，油砂行业一直在努力将Cr和C含量提高到更高的水平，以便在侵蚀性和恶劣条件下提供更多的应用选择。然而，提高%C和%Cr增加了材料强度，但由于促进了粗一次碳化物的形成而降低了断裂韧性，从而在遇到涉及冲击力和大幅波动的磨损力的磨损时导致不太令人印象深刻的性能。虽然可以通过微观结构工程优化HCCI的性能，但由于工业规模铸造中的微观结构不均匀性、模糊的设计指导方针和高制造成本，这种改进是有限的。 直接对HCCI中的碳化物进行改性是改善性能和简化微观结构控制的替代方法。然而，由于实验和理论工具的限制，相关的研究相当有限。多模原子力显微镜和计算材料科学的发展使这一研究成为可能。本课题提出了几种有前景的方法来定制HCCI中的碳化物，包括向碳化物中添加第三元素，开发复杂的MC碳化物，促进核-壳结构的碳化物，以及定制碳化物与基体之间的界面结合。拟议的研究基于我们成功的初步研究，并将与我们在加拿大伟尔矿业的工业合作伙伴合作进行。开发的知识和数据库不仅有利于加拿大油砂行业，也有利于采矿和制造业等其他技术部门。此外，在该项目中培训的HQP将为加拿大带来长期利益。

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.