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

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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.