D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:

A. A. Abrashov, Associate Professor at the Department of Innovative Materials and Corrosion Protection, Candidate of Technical Sciences, e-mail: abr-aleksey@yandex.ru
N. S. Grigoryan, Professor at the Department of Innovative Materials and Corrosion Protection, Associate Professor, Candidate of Chemical Sciences, e-mail: ngrig108@mail.ru
Ya. V. Tolmachev, Undergraduate Student at the Department of Innovative Materials and Corrosion Protection, e-mail: vetolmyan@gmail.com
A. N. Serov, Assistant Lecturer at the Department of Innovative Materials and Corrosion Protection, Candidate of Chemical Sciences, e-mail: serov@muctr.ru

Lately, one of the most sought-after methods of protecting metal surfaces in aggressive environments is the formation of continuous films with water-repellent properties and self-cleaning ability; the so-called superhydrophobic films. In the scientific and technical literature, the term “superhydrophobic” is used to refer to surfaces that possess the contact angle in water and water solutions of no less then 150^o, and the water droplet is able to roll of the surface with the tilt angle of no more then 10^o. A superhydrophobizing solution for 5556 aluminum alloy surface containing DMSO and water in the ration of 7:1, as well as stearic acid (SA) in the amount of 2–3 g/l has been developed. It has been established that the coating that forms in this solution, is characterized by the contact angle Θ_c = 151^o. The coating’s XPS survey spectra point to the presence of oxygen, aluminum, carbon and hydrogen in the coating. The analysis of the individual spectra of aluminum, oxygen and carbon has shown that oxygen and carbon are present in the form of carboxyl group COO^–, aluminum is present as Al³⁺, which is formed by the reaction of stearic acid with the aluminum surface. It has been established that the lightening stage lowers the surface roughness, which negatively effects the hydrophobic surface. The contact angle rises from 140^o to 151^o if the lightening stage is bypassed.
This research was funded by D. Mendeleev University of Chemical Technology of Russia. Project No.: Х-2020-028.

1. Lushina M. V., Parshin S. G. Innovative corrosion protection technology for aluminium alloy products. Morskoy Vestnik. 2011. No. 1. pp. 113–115.
2. Abrashov A. A., Grigoryan N. S., Vagramyan T. A., Zhilenko D. Yu. Titaniferous protective coatings on aluminum alloys. Non-ferrous Metals. 2016. No. 1. pp. 33–37.
3. Boynovich L. B., Emelianenko A. M. Hydrophobic materials and coatings: Production, properties and application. Uspekhi khimii. 2008. Vol. 77, No. 7. pp. 619–638.
4. Kuznetsov Yu. I., Semiletov A. M., Chirkunov A. A., Arkhipushkin I. A. et al. Surface hydrophobization of aluminium with stearic acid and trialkoxysilanes for corrosion protection. Zhurnal fizicheskoy khimii. 2018. Vol. 92, No. 4. pp. 512–521.
5. Dongmian Zang, Ruiwen Zhu, Wen Zhang, Jie Wu et al. Stearic acid modifed aluminum surfaces with controlled wetting properties and corrosion resistance. Corrosion Science. 2014. Vol. 83. pp. 86–93.
6. Feng L., Zhang Y. A., Xi J. M., Zhu Y. et al. Petal effect: a superhydrophobic state with high adhesive force. Langmuir. 2008. Vol. 24, No. 8. pp. 4114–4119.
7. Semiletov A. M., Kuznetsov Yu. I., Chirkunov A. A. On the use of higher carboxylates mixed with trialkoxysilanes for surface hydrophobization and corrosion protection of AMg6 alloy. Korroziya: materialy, zashchita. 2017. No. 6. pp. 24–30.
8. Semiletov A. M., Kuznetsov Yu. I., Chirkunov A. A. Surface hydrophobization of aluminium with stearic acid and trialkoxysilanes for corrosion protection. Korroziya: materialy, zashchita. 2018. No. 4. pp. 512–521.
9. Chambers L. D., Stokes K. R., Walsh F. C., Wood R. J. K. Modern approaches to marine antifouling coatings. Surface and Coatings Technology. 2006. Vol. 201. pp. 3642–3652.
10. Kako T., Nakajima A., Irie H., Kato Z. et al. Adhesion and sliding of wet snow on a super-hydrophobic surface with hydrophilic channels. Journal of Materials Science. 2004. Vol. 39. pp. 547–555.
11. Boinovich L. B., Emelyanenko A. M., Emelyanenko K. A., Maslakov K. I. Anti-icing properties of a superhydrophobic surface in a salt environment: an unexpected increase in freezing delay times for weak brine droplets. Physical Chemistry Chemical Physics. 2016. Vol. 18, No. 4. pp. 3131–3136.
12. Liu W., Xu Q., Han J., Chen X. et al. A novel combination approach for the preparation of superhydrophobic surface on copper and the consequent corrosion resistance. Corrosion Science. 2016. Vol. 110. pp. 105–113.
13. GOST 9.302–88. Metal and non-metal inorganic coatings. Control methods. Introduced: 01.01.1990. Moscow : Izdatelstvo standartov, 1988. 41 p.
14. Laha P., Schram T., Terry H. Use of spectroscopic ellipsometry to study Zr/Ti films on Al. Surface and Interface Analysis. 2002. Vol. 34. pp. 677–680.
15. Woicik J. C. Hard X-ray photoelectron spectroscopy (HAXPES). Springer International Publishing Switzerland, 2016. 571 p.