Determination of Internal Stress of Ni Electroplated Samples in Sulphamate Solutions

Wednesday, 31 May 2017
Grand Ballroom (Hilton New Orleans Riverside)
B. Aykac (Middle East Technical University), M. Erdogan (Yildirim Beyazit University), and I. Karakaya (Middle East Technical University)
Electroplating is a surface modification process that does not alter the bulk properties of the substrate and is conducted for improving the surface appearance, generally increasing the corrosion and wear resistance of the material to be electroplated [1]. There are several metals that can be electroplated such as Ni, Cu, Au, Co, Cd, Zn, etc. or the alloys thereof. Among these metals, Ni is the most commonly preferred one. Through the last five decades, the technology of electroplating of nickel extensively developed into a broad range of industrial coatings for both decorative and functional applications. The annual commercially electroplated nickel is over 150,000 tones worldwide [2] due to the useful properties of Ni as a coating and its versatility.

There are several types of baths based on nickel chloride, nickel sulfate and nickel sulphamate [3] for Ni electroplating. Among these, the advantages of Ni electrodeposition from Ni sulphamate based solutions are low internal stress and high current efficiency (>90%). The functionalities of coatings are affected by internal stress which is a common problem of the electroplating process. The parameters of electrodeposition and additive particles which are insoluble in the bath, in the case of composite coatings [4], change the characteristics of the plating and affect the internal stress of the coatings. The influence of the electrodeposition parameters and their interaction effects on the internal stress of Ni deposits were studied by fractional factorial design. Self-interactions and cross correlations of temperature, pH, current density and bath composition on internal stress were determined by statistical analysis of results obtained from sulphamate baths. It was found that increasing temperature and deposit thickness and decreasing boric acid and chloride ion concentrations resulted in decreasing the internal stress within the parameter ranges covered in this study.

[1] Popov,K.I., Djokic,S.S., Grgur,B.N.(2002), Fundamental Aspects of Electrometallurgy, Kluwer Academic Publishers, pp.1-3

[2] Nickel Plating Handbook. (2014). June 28, 2016, retrieved from; https://www.nickelinstitute.org/~/media/Files/TechnicalLiterature/NPH_141015.ashx

[3] DuRose, A.H. (1997), Nickel Solution Buffers and Limiting Current Density, Surface Finishing, 48-52

[4] Saraloğlu Güler, E., Karakaya, İ. and Konca, E. (2014) Effects of current density, coating thickness, temperature, pH and particle concentration on internal stress during Ni-MoS2 electrocodeposition, Surface Engineering, 30, 109-114.