Tribological Improvement of Titanium Alloys by Surface Engineering without Sacrificing their Fatigue Resistance

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Titanium alloys despite their high strength-to-mass ratios and good fatigue and corrosion resistance exhibit poor tribological performance that preclude their use in aerospace and automotive components subjected to sliding contact. Compared to other materials of similar static and dynamic strength, titanium alloys have higher wear rates, higher coefficients of friction, and they are prone to galling and seizure. Various surface treatment methods have been employed to improve the wear and frictional behaviour of titanium alloys. However, they cause unacceptable changes in mechanical properties including decreases in fracture toughness and fatigue strength. The proposed research in the next five years will be aimed at improving microstructures and properties of low temperature ion nitrided alloys developed as a part of the applicant's previous NSERC Discovery program. New methods are proposed to control compositions and morphologies of the compound layer to increase ductility, toughness and wear resistance Accordingly, the main themes of the proposed research are: (A) Enhancement of low temperature ion nitriding treatment by following pre-treatment i) plastic deformation induced strain, ii) deposition of Vanadium on surface followed by thermal diffusion. (B) Development of a duplex surface treatment by deposition of DLC coatings on ion nitrided surfaces The experimental work will elucidate relationships between microstructures and wear and fatigue resistance by developing wear mechanism maps and identifying fatigue crack growth mechanisms. These investigations will provide insight into the micromechanisms of wear and fatigueensuring that the relationship between the microstructure and the mechanisms are established, which will help with the development of durable and practical surface treatments. Overall, the research will provide the scientific and engineering knowledge needed to produce energy efficient engineering components and technologies and train two Ph.D., one MASc and one undergraduate student.The unique training, knowledge, and skills obtained in this program will make these HQP very attractive to many Canadian manufacturers. These professionals will be equipped with valuable skill sets that can meet Canada's future requirements in technology and the automotive, and aerospace sectors as well as other industrial applications where they will be in high demand in this industry.