Rapid synthesis of highly oriented hydrophobic silicalite-1 zeolite films on alloy steel at lower temperature for corrosion protection

Abstract

• Rapid growth of oriented zeolite film on diverse substrates at lower temperature was studied. • Thickness of as-prepared zeolite films under three conditions is all around 1 μm. • Lower temperature leads to longer synthesis time and worse hydrophobicity of films. • Films prepared at 373 K for 4 h show terrific hydrophobicity and corrosion resistance. A method to quickly prepare highly oriented silicalite-1 zeolite films on different substrates at lower temperature was provided in this work. Compared with the traditional hydrothermal synthesis, rubbing a layer of seed pastes on the pretreated substrate surface in advance and using (NH 4 ) 2 SiF 6 as silicon source for subsequent secondary growth process can effectively reduce the synthesis temperature and shorten the contact time between the substrate and the strong alkaline synthesis solution. The thickness of the zeolite films prepared under three optimal conditions is all around 1 μm and the best contact angle value of 142.5° was achieved for the film prepared at 373 K for 4 h, while this values of the film prepared at 363 K for 6 h and 353 K for 10 h were 97.8° and 41.7°, respectively. The results of SECM showed that the detected localized current value of the film prepared at 353 K for 10 h was similar to that on bare steel after immersion in 0.62 M NaCl solution for 24 h (around 0.4 nA). At the same time, the current value measured under the other two preparation conditions was much higher, suggesting that the corrosion resistance of the film prepared under 353 K was unsatisfactory. In addition, EIS results demonstrated that the corrosion resistance of the films prepared at 363 K for 6 h also decreased significantly after 72 h immersion, while the films prepared at 373 K for 4 h still maintained excellent corrosion resistance and no obvious corrosion products were detected even immersion time up to 720 h. This work provides a new strategy for the application of zeolite in the field of material protection.