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

A. A. Abrashov, Cand. Eng., Assistant Professor, Dept. of Innovative Materials and Corrosion Protection, E-mail: abr-aleksey@yandex.ru
N. S. Grigoryan, Cand. Chem., Assistant Professor, Dept. of Innovative Materials and Corrosion Protection, E-mail: ngrig108@mail.ru
T. A. Vagramyan, Dr. Eng., Prof., Head of Dept. of Innovative Materials and Corrosion Protection, E-mail: vagramyan@muctr.ru
E. A. Shcherbina, Post-graduate, Dept. of Innovative Materials and Corrosion Protection, E-mail: katerina.sherbin@mail.ru

A black nickel plating process has been developed to install highly durable, adhesive and protective coatings on the following steel grades: 50A and 50RA, 09G2S, Steel 20, Steel 30, 08Kh17. Nickel sulphate electrolyte with the following composition was used as the base solution (g/L): NiSO₄·7H₂O — 100; (NH₄)₂SO₄ — 15; ZnSO₄·7H₂O — 40; NH₄CNS — 15; H₃BO₃ — 25, at рН = 4.5–5.5, temperature — 50 °С. The following process conditions are associated with the widest current density range (0.1 to 3.0 A/dm²) for black coatings: zinc sulphate concentration — 30–50 g/L, ammonium thiocyanide concentration — 15–20 g/L, pH — 4.5 to 5.5, temperature — 45 to 50 °С. However, such coatings are less protective or durable than black chromium coatings. A two-stage current mode has been selected to produce black coatings: Stage I — During the initial 10 minutes the current density is slowly increasing from i₁ = 0.02 A/dm² to i₂ = 0.2 A/dm², Stage II — the current density is drastically raised to i₃ = 1.5 A/dm², and the process continues for 10 more minutes. During Stage I, when the current densities are relatively low, an interlayer of light nickel is deposited ensuring good adhesion to the substrate. During Stage II, when the current densities are higher, a black coating is formed of up to 1 μm thick, which consists of metallic nickel and zinc, as well as nickel and zinc sulphides. It is demonstrated that black coatings form due to a drastic rise in zinc concentration in the coating, as well as to the development of roughness caused by current surge. It is shown that the resultant black nickel coatings are not only comparable with but they can also outperform black chromium coatings in terms of protective capacity and durability.

This research was funded by D. Mendeleev University of Chemical Technology of Russia. Project No. 016-2018.

1. Rudenko M. F., Kravtsov E. E., Idiatulin S. A. Effecient surfaces of solar receivers. Khimicheskoe i neftegazovoe mashinostroenie. 1998. No. 7. pp. 33–35.
2. Meshalkin V. P., Abrashov A. A., Vagramyan T. A., Grigoryan N. S., Utochkina D. S. New environmentally friendly, protective and decorative, molybdenum conversion coatings for galvanized surfaces: Development and performance studies. Doklady Akademii nauk. 2018. Vol. 480. No. 5. pp. 555–558.
3. Takadoum J. Black coatings: a review. European Physical Journal Applied Physics. 2010. No. 52. p. 30401. pp. 1–7.
4. Somasundaram S., Pillai A. M., Rajendra A., Sharma A. K. High emittance black nickel coating on copper substrate for space applications. Journal of Alloys and Compounds. 2015. Vol. 643. pp. 263–269.
5. Estrella-Gutiérrez M. A., Lizama-Tzec F. I., Arés-Muzio O., Oskam G. Influence of a metallic nickel interlayer on the performance of solar absorber coatings based on black nickel electrodeposited onto copper. Electrochimica Acta. 2016. Vol. 213. pp. 460–468.
6. Jeeva P. A., Karthikeyan S., Narayanan S. Performance characteristics of corrosion resistant black coatings. Procedia Engineering. 2013. Vol. 64. pp. 491–496.
7. Jeeva P. A., Karthikeyan S., Narayanan S. Optimization of black coatings by electro deposition and evaluation of optical properties. International Journal of ChemTech Research. 2013. Vol. 5. No. 5. pp. 2405–2409.
8. Nunes R. A. X., Costa V. C., Sade W., Araújo F. R., Silva G. M. Selective surfaces of black chromium for use in solar absorbers. Materials Research. 2018. Vol. 21. No. 1. p. e20170556.
9. Medeiros I. D. M., Gomes K. C. S elective solar surface solar based on black chromium: Influence of electrodeposition parameters in the absorption of surfaces. Materials Research. 2019. Vol. 22. No. 2. p. e20180625.
10. Jeeva P. A., Narayanan S., Karthikeyan S. A review on black coatings for solar energy storaging systems. International Journal of ChemTech Research. 2016. Vol. 9. No. 3. p. 589–596.
11. Smirnov K. N. Some recommendations on monitoring electroplating bath solution performance. Electroplating & Surface Treatment. 2005. Vol. ХIII. No. 2. pp. 6–9.
12. Grigoryan N. S., Abrashov A. A., Vagramyan T. A., Kostyuk A. G. Passivation of ferrous and non-ferrous metals in the solution made with esters of gallic acid. Khimiya i tekhnologiya organicheskikh veshchestv. 2017. No. 4. pp. 55–63.
13. Joseph C. Woicik Hard X-ray Photoelectron Spectroscopy (HAXPES). Springer International Publishing Switzerland. 2016. 571 p.
14. Sidelnikova S. P., Yushchenko S. P., Dikusar A. I. Morphology, structure and composition of coatings in Black Nickel electroplating. Elektronnaya obrabotka materialov. 2009. No. 4. pp. 93–101.
15. Karuppiah N., John S., Natarajan S., Sivan V. Characterization of electrodeposited Nickel-Cobalt selective black coatings — scanning electron microscopic studies. Bulletin of Electrochemistry. 2002. Vol. 18. No. 7. pp. 295–298.
16. Kaiser N., Pulker H. K. Optical interference coatings. Springer-Verlag Berlin Heidelberg. 2003. 503 p.