I am trying to deposit a pure nickel coating on a stainless steel substrate by means of a conventional electroplating process. But the deposited coatings are not adherent to the substrate.
Before the electrodeposition process the substrate was polished by different grade (P 400, P 800 and P 1200) silicon carbide paper and then with fine cloth, using 6 µm diamond paste as a polishing agent. After polishing these stubs were sonicated in sodium hydroxide (0.1 molar) and hydrochloric acid (0.01 molar) solutions for 10 and 5 min respectively in order to remove the acid-base soluble impurities and also to activate the surface. After acid base treatment, the steel substrates was then sonicated with doubly distilled water and ethanol for 5 and 10 min respectively in order to remove the diamond particles and other extraneous materials adhered during polishing with the surface.
what is the easiest and applicable way to make it adherent.
Hello,
I suggest to use HCl 1 M (30 s) just before Nikel electroplating. It should improve adhesion of the nickel layer. What kind of nickel bath do you use? For Nickel plating on stainless steel, the best way is to use a thin layer with nickel wood (NiCl2 + HCl) to improve the adhesion.
Hope it helps...
Best Regards
Thanks Dr Thomas Perrier for your valuable answer . i have already used 1M HCl for 30 s. it produces black spots on steel surface. i am using watt,s type bath.
Dear Dr. Zia Ullah Khan ,
Watts nickel plating solutions are commonly used for functional applications as will be discussed in a later section. Deposits from Watts solutions without additives are soft and ductile but dull in appearance. The appearance and properties can however be dramatically changed by the use of addition agents. The addition agents consist of organic and certain metallic compounds selected to brighten and level the deposits. As will be discussed further in the section on decorative plating, addition agents may be used to produce semi-bright, bright or satin nickel coatings.
For more details please see the source:
"Nickel Plating Handbook" by Nickel Institute (2014)
Available at: https://www.nickelinstitute.org/media/2323/nph_141015.pdf
Best regards, Pierluigi Traverso.
Thanks Dr. Pierluigi Traverso for you valuable answer. i am in interested in surfactant free coating. i will go through your suggested article.
best regard Zia Ullah Khan
Hello,
Completely agree with the above answers! As I sait before, try Zia Ullah Khan to use a nickel Woods bath to improve your adhesion between nickel and stainless steel.
Concerning the black spot you have, what bath do you use? I It could be an oxide or hydroxide nickel.
Best Regards
thank you Thomas Perrier . i am using Nickel sulphate + Nacl+boric acid. the black spot produced during activation of the surface with 1 M HCl.
Since the stainless steel consists of passive coating (Primarily due to the chromium content of the metal), a surface energy alteration occur on the metal surface , resulting low wettability.
You might consider a passivity breakdown mechanism before electroplating on the alloy. This passive coating can develop simultaneously when exposed to air. Thus the method should include a mechanism to prevent re-passivation. There are a few ways to do this task. Wood's nickel strike (Strike was originally developed by Donald Wood, who published the article, “A Simple Method of Plating Nickel on Stainless Steel,” in Metal Industry, July, 1938.) is considered a proper method among all the solutions for passivity breakdown and to prevent the re-passivation of the metal.
Refer to these articles for more information.
https://www.researchgate.net/publication/335495008_Lead_Free_Solder_Compatibility_Improvement_on_Nichrome_Alloy_Through_Contact_Angle_Modification
https://www.researchgate.net/publication/344174136_Surface_Wettability_Analysis_of_Nichrome_Alloy_Based_on_the_Measurements_of_Sessile_Droplet_Contact_Angles
Also , you might find useful information from "4 th edition of the Electroplating Engineering Handbook (1984), page 233"
Best Regards
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