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Standard test for adherence of products to electrode?

For my physics A-Level coursework I am investigating how current and time affect the adherence of a product to the electrode. I would like to know if there is a standard test for adherence, because I have as yet not been able to find one that I could feasibly use in my school lab.

Thanks,

Robert [last name deleted for privacy by Editor]
- England
2002

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There are several formal tests described in ASTM standards, and countless informal ad-hoc tests. The best test depends on the substrate and what you are plating it with, but a mandrel test might be appropriate if you are plating sheet metal test strips. In a mandrel test you bend the plated sheet around mandrels (cylinders) of various diameter. Your test might be, say, 100 percent adhesion and freedom from cracking after a 90 degree or 180 degree bend around a 1/4" diameter mandrel.

But your test is probably not going to work well, so you might want to change it early on. The problem is that adhesion in electroplating is far, far more dependent upon cleaning and activation conditions than upon plating conditions, and you may never get the cleaning and activation so repeatable and accurate that you can make any conclusions about the effect of plating conditions upon adhesion.Good luck!

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

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I am not sure what you mean by electrode coatings; in electroplating there can be coverings on both the anode and cathode and the electrochemistry of these is quite complex. However, in many cases relating to the anode, the coating is transient, often non-adherent and often disappears when the power is turned off. In the case of the cathode, the object of the exercise is to deposit metal onto the substrate. There are standard tests for this and these can include thermal cycling, scratch tests, slashed diamond and tape tests, etc. The best source of information would be the British Standards for the relevant metal deposits

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2002

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Thank you for your replies.

My electrolyte is copper sulphate ⇦this on eBay or Amazon [affil links] any my electrodes will be either graphite rods of sheets of copper, depending on which provide me with the best results. If I carry out an electrolysis in copper sulphate, the copper product would go to cathode, so the product should in theory remain after I have turned the power off.

I hope to discover whether time and current how much the coppers adheres to the cathode and by how much.

Could you please tell me where I could find information on the "British Standards for the relevant metal deposits" or the name of the book and author if it is not available online.

Robert W. [last name deleted for privacy by Editor]
- Birmingham, England
2002

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You will have probably have perfect copper-to-copper adhesion over a broad range of current densities, and if you don't it will be due to inconsistent cleaning or activation. You didn't mention why you chose this as an experiment, and I've already expressed my opinion twice that the experiment won't work and told you why I hold that opinion. That doesn't make me right, but it does make it time for me to punch out on this topic. So good luck. :-)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

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Firstly, Birmingham has an excellent city library where they almost certainly keep the British standards (BS); just ask a librarian. They are documents that prescribe a minimum quality or standard for thousands of products and services in the UK. They are also probably on line but you will have to pay for them. Secondly, now we have ascertained a bit more about what you are doing, perhaps we can give you some tips. Ted is dead right about the adhesion being dependent on the cleaning procedure of the cathode; it must be clean or no metal will adhere to it. Let us know how you cleaned your cathodes and what effect different ways had on the adhesion. I am certain that copper will adhere to copper better than it will to graphite, but it is up to you to tell us why - we will not do your experiment for you. Another factor that will affect adhesion is the stress in the deposit; if it has high tensile stress it will peel off the substrate (tell us what will happen if the deposit has high compressive stress?). Luckily copper doesn't suffer too badly from this problem. There are numerous other factors you have not appeared to consider in this work; how will the composition of the electrolyte affect the quality of the deposit? How will you maintain a steady state, or don't you intend to?! How will the pH of the solution affect the deposit? What happens if the temperature is altered and why? How and why does the current density affect the quality of the deposit. How does the current density affect the thickness and stress of the deposit? You have a very interesting project in front of you, so get on and do the practical work and then come back and tell us how it went and what you conclude.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2002

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2002

Thank you all for your replies. I began this experiment using copper sulphate solution and copper, and found it too difficult to maintain a constant "cleanliness" of the electrode. I decided it best if I tried a new project, that had slightly less variables and was possible to undertake under the conditions I had.

I have made a post on this (letter 18811)where you will see I have asked another question ;). It is regarding how temperature and concentration of a solution affect its resistance. My results appear to show a relationship, but I cannot be sure whether it is accurate and have not been able to find any official experiments carried out to confirm my findings.

I would greatly appreciate a reply to the question either here or in the topic when it is published.

Thanks again.

Robert W. [last name deleted for privacy by Editor]
- England, Birmingham