Effect of annealing and copper concentration on corrosion protection of sputtering-deposited Ti-Cu alloy coating on stainless steel

Abstract Considering the corrosion of steel and the irreparable damages caused by it, research in the field of corrosion control of steel is necessary. A practical approach used in this study involves the preparation of a corrosion-resistant nano-coating on steel surfaces, which can effectively prevent steel corrosion in a corrosive solution. In this study, Titanium (Ti), Copper (Cu), and Titanium-copper (Ti-Cu) thin films with different weight percentages of Cu were deposited on the stainless steel surface. After coating, the Ti-Cu thin films were annealed at temperatures of 200, 300, and 500 °C. This study aims to evaluate the impact of annealing temperature on the corrosion resistance and structural properties of Ti-Cu thin films deposited on stainless steel using the sputtering method for the first time. Prepared thin films were characterized by x-ray diffraction, energy-dispersive x-ray spectroscopy, field emission scanning electron microscopy, atomic force microscopy and their corrosion behavior were evaluated using linear sweep voltammetry and electrochemical impedance spectroscopy in a 3.5% NaCl solution. Results indicated that by increasing the concentration of Cu as a beta-stabilizing element in Ti-Cu thin films and applying the annealing temperature up to 300 °C, the surface roughness decreased from 36 nm to 4 nm due to the reduction of impurities and structural defects. The thin films had a remarkably protective effect in a 3.5% NaCl solution. The corrosion current density is reduced from 1.52 × 10 −5 to 8.98 × 10 −9 A·cm −2 which shows this coating has a good protective efficiency (99.9%) on stainless steel, and the charge transfer resistance was increased from 6.09 to 723.65 kΩ·cm 2 which exhibited a protective efficiency of (95.2%) on the used stainless steel 304 L. The results underline the potential of Ti-Cu coatings for practical applications in industries requiring long-term corrosion resistance, such as petrochemical equipment, marine engineering, and biomedical devices.