Hydrogen Permeation Characteristic of Alumina Coatings Deposited on X65 Pipeline Steel by Magnetron Sputtering

Hydrogen embrittlement is a severe problem for the natural gas pipeline attributed to the hydrogen sulfide, and the hydrogen permeation barrier can prevent X65 pipeline steel from hydrogen damage. The alumina coating has attracted extensive attention due to its strong corrosion resistance and wear resistance, and it also can act as a barrier inhibiting hydrogen permeation. In order to solve the cracking and poor density of traditional alumina coatings, the high power impulse magnetron sputtering (HiPIMS) was chosen to deposit alumina on X65 pipeline steel. The inhibitory effects of alumina on hydrogen permeation were studied by electrochemical technique using the Devanathan-Stachurski (D-S) cells. The adhesion strength was measured by scratching method. Microstructure, composition and morphology were analyzed by SEM and XRD. The results showed that alumina coatings deposited by HiPIMS could effectively inhibit hydrogen permeation. The hydrogen diffusion coefficient and hydrogen permeation flux of alumina coatings were also obtained. Compared with traditional preparation methods, the adhesion strength of alumina coatings deposited by HiPIMS was enhanced. In addition, the mechanism of hydrogen permeation resistance for alumina coatings was discussed in detail.