Corrosion and Wear Behavior of Nitrogen-Doped TiO2 Coatings on Stainless Steel Prepared by Plasma Surface Alloying Technique
A novel process has been developed to improve tribological and corrosion properties of austenitic stainless steel (S. S). Titanium nitride coatings were obtained by plasma surface alloying technique. Nitrogen-doped titanium dioxide was synthesized by oxidative annealing the resulted TiNx coatings in air. The microstructure of TiO2 coatings was characterized by SEM, GDOES, XPS and XRD, respectively. Simulated body solution (Hanks’ solution, 37°C) was used to characterize the electrochemical corrosion properties of the coatings and substrate. Ball-on-disc sliding wear was applied to test and compare the tribological behaviors of the coatings and substrate against Al2O3 ball. Results reveal that the resultant coatings have a layered structure, comprising of N-doped TiO2 layer at the top and a diffuse-type interface. Such a hybrid coatings system shows good adhesion with the substrate. Composition analysis shows that the coatings shield the substrate entirely. The N-doped TiO2 coatings are anatase in structure as characterized by X-ray diffraction. The electrochemical measurements show that the corrosion potential positively shifts from -0.267 V for bare S. S to -0.275 V for N-doped TiO2 coated S. S, and the corrosion current density decreases from 1.3 × 10-5 A/cm2 to 4.1 ×10-6 A/cm2. Under a load of 7.6 N, the coefficient of friction is in the range of 0.27～0.38 for the N-doped TiO2 and the wear rate of the coatings is only one-fourteenth of that for untreated 316L S. S. Duplex-treated N-doped TiO2 coatings display much better wear resistance and antifriction performance than that of S. S.
Chengming Li, Chengbao Jiang, Zhiyong Zhong and Yichun Zhou
H. F. Wang et al., "Corrosion and Wear Behavior of Nitrogen-Doped TiO2 Coatings on Stainless Steel Prepared by Plasma Surface Alloying Technique", Materials Science Forum, Vol. 687, pp. 602-609, 2011