Inhibiting low-dimensional defects of titanium diboride coatings by Si incorporation: Toward enhanced corrosion resistance and mechanical properties

Hard and anti-corrosive coatings can provide effective protection for marine components, but low-dimensional defects (LDDs) in the coatings would reduce the performance thus limit the application of the coatings. This work attempts to reduce the LDDs by Si doping to improve the corrosion resistance and mechanical properties of magnetron sputtered titanium diboride coatings. Results reveal appropriate Si doping (5.4 at.%) can obviously enhance the quality of the coating and reduce the LDDs, but excessive Si doping (8.6 at.%) will lead to the formation of new LDDs because of the appearance of amorphous phase. The electrochemical measurements with 3 days and 30 days prove that the corrosion resistance of the coating can be significantly improved when the LDDs are reduced. Reducing LDDs can inhibit the corrosion of Cl- due to the reducing of penetrable sites, and even limit the growth of pinholes by inhibiting transverse corrosion interior of the coating. The hardness can be improved due to solid solution strengthening by Si doping, but decreases when forming a soft amorphous phase.