Preparation of highly dense Ti-based coatings with enhanced corrosion protection performance via cold spray

In the current study, relatively large TC4 powder (D50: 35.1 μm) were blended with Ti powder (D50: 24.2 μm) in different mixing fractions (0, 10, 30, 50, 100 vol%) to prepare corrosion protection Ti-based coatings on 1045 steel substrates via cold spray under moderate ‘intensity’ deposition condition. The idea is to utilize the strong hammering effect of hard TC4 particles to significantly densify the originally loose Ti layer, while the inclusion of TC4 particles after deposition will not cause severe galvanic problem with Ti due to similar free potential in corrosive medium, which avoids the deterioration of the corrosion resistance of Ti-based coating. Results show that cold sprayed Ti-based coating with high density (99.8 %) was achieved when the mixed powder contains 30 vol% TC4 particles. Moreover, only a slight decrease trend in deposition efficiency of the mixed powder is shown with the increase of TC4 content. Electrochemical tests and cross-sectional microstructural observations indicate that this coating is not permeable during the entire 24 h immersion in 10 wt% HCl solution, thus provided excellent corrosion protection for the substrate. The present method of cold spraying Ti and TC4 mixed powders exhibits great potential for economical and effective preparations of Ti-based corrosion protection coatings.