MECHANISM OF TRIVALENT CHROMIUM ELECTRODEPOSITION USING Cr(III)-CONTAINING BATH WITH AND WITHOUT INORGANIC ADDITIES

Nguyen Van Tai; Nguyen Van Cuong; Nguyen Hoai Tan; Huynh Thanh Thuong; Hoang Minh Thuan

Nguyen Van Tai Faculty of Mechanical Engineering, College of Engineering, Can Tho University
Nguyen Van Cuong Faculty of Mechanical Engineering, College of Engineering, Can Tho University
Nguyen Hoai Tan Faculty of Mechanical Engineering, College of Engineering, Can Tho University
Huynh Thanh Thuong Faculty of Mechanical Engineering, College of Engineering, Can Tho University
Hoang Minh Thuan Faculty of Mechanical Engineering, Hung Yen University of Technology and Education

Keywords: Electrodeposition, Cathodic polarization, Cr(III), Cation, Anion

Abstract

Cathodic polarization technique was used for different Cr(III)-containing baths to explore the effect of inorganic additives on the mechanism of trivalent chromium electrodeposition. The presence of cations in the Cr(III)-containing bath can support a good condition for the diffusion of Cr3+ complexes from the bulk electrolyte to the cathode surface, thus improving the reduction of the Cr-complex. On the contrary, effect of anions was more complicated due to the appearance of additional reactions or an increase of viscosity in the bath. Results show that the morphology of the coating depends significantly on the addition of cations and anions. Quality of the coating is much better from the baths with the addition of Na+ or Mg2+ than addition-free, and only SO42- was acceptable to obtain a smooth morphology. In addition, higher current efficiency can be obtained from the baths added with cations of Na+ or Mg2+, and anion of SO42- in comparison with the other baths.

References

R. Directive, “Directive 2002/95/EC of the European Parliament and of the Council of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment”. Official Journal of the European Union, 2003, Vol. 13, pp. L37.

N.V. Tài, P.H. Khoa, N.V. Cương, N.Q. Hiếu, H.T. Thưởng, H.M. Thuận, “Ảnh hưởng của pH và nồng độ các cation kim loại đến hiệu suất dòng điện và hình thái bề mặt lớp mạ crom thu được từ dung dịch mạ chứa Cr (III)”. Tạp chí Khoa học và Công nghệ-Đại học Đà Nẵng, 2022, Vol. 20, pp. 5-11.

V. Tài, Xi Mạ Crom Cứng Trục Khuỷu, truy cập tại trang https://ximavinhtai.com/gia-cong-xima-crom-cung-truc-khuyu, Ngày truy cập: 22/09/2022.

F. Danilov, V. Protsenko, T. Butyrina, “Chromium electrodeposition kinetics in solutions of Cr(III) complex ions”. Russian journal of electrochemistry, 2001, Vol. 37, pp. 704-709.

N. Van Phuong, S.-C. Kwon, J.-Y. Lee, J. Shin, B.T. Huy, Y.-I.J.M.J. Lee, “Mechanistic study on the effect of PEG molecules in a trivalent chromium electrodeposition process”. Microchemical Journal, 2011, Vol. 99, Number 1, pp. 7-14.

X. Li, T. Ogihara, M. Abe, Y. Nakamura, S. Yamago, “The effect of viscosity on the diffusion and termination reaction of organic radical pairs”. Chemistry–A European Journal, 2019, Vol. 25, Number 42, pp. 9846-9850.