Anyone knows how many times the electroplating bath can be use to deposit a coating? I'm doing trivalent chromium bath contained 0.5M Cr2(SO4)3.6H2O. The working parameters: bath volume=125ml, working surface area=1cm2, current density= 40A/dm2, time=10mins. And the weight gain of chromium coating is around 0.015g.
You can calculate the change in the solution concentrations according to the weight gain and the reaction mechanism.
However, I think you should estimate this experimentally by characterizing the product of electroplating after n=1,2,3.... times of use. Only then you can know the limit for your parameters.
Hi Eydar
by default one would use a standard electroplating bath till the deposit of the electroplating no longer occurs on the sample. The standard electroplating bath can be made based on the concentration of the electroplating solution, i.e., dependent on the volume of the electroplating bath, the cathodic current density, the size of the sample.
Hi Eydar,
One indication that your electroplating bath is exhausted when its operating efficiency is dramatically reduced, i.e. there is no more deposit on your substrate even if you extend the deposition time. Another indication is the decomposition of your bath and the formation of suspension in your solution.
Hello Eydar,
Previous advices are to take into account. In addition, it depends of your system. Do you use a sacrificial anode or not ? What ever the case, you should carry out a dosage of your active species (e.g Cr) after each deposit to assess the losts.
Eyder
Unless you are in trade of electroplating, it is a trial and error. Just kept doing till you find that electroplated part has not enough Cr deposited, and then Cr salt is added to the bath to carry out plating. If it is done in he university lab for student demonstration, then, the bath would last, if, the samples are small. Also, if you are teaching, then, a question could be put to students on this. Hope this helps.
Dr.K
It depends also on what you are doing. For example, if you teach in an electrochemistry lab and the main goal is having some demonstration for learners/students, the bath can be used several times until you see those signs that Charif Dehchar mentioned, which show your electrolyte is almost already dead. However, once you are doing some research work, then you should be really meticulous about your electrolyte conditions. For such a case, experience and Avigail Landman advice should be really taken into account.
So, one more piece of advice can be your experimental condition; using the electrolyte for teaching, industrial depositions, or research work.
I have performed the electroplating of Ni from 0.1M NiSO4 +additives for 7-8 hours until the solution is almost colourless.
Mosaad
It all depends upon the size (surface area) of the article to be plated as well as the bath size with concentration of Ni - salt in the bath Once you get experience, then, it becomes a daily routine.
Dr. K
Hello Eydar,
in addition to the above advices...
If you count according to Faraday's law and the proposed parameters, it turns out that the current efficiency of your electrolyte is nearly 35%. I did not encounter electrolytes based on trivalent chromium, but in traditional electrolytes based on hexavalent chromium (even very dilute and with organic additives) the current efficiency does not exceed 22-25%. I can advise you to use a more accurate scale, not up to the 3rd (0.015 g), but to the 4th sign (0.015? g). This can help reduce the error.
To answer the question of how many times it is possible to use electrolyte with similar electrolysis parameters, it is necessary to know the minimum possible concentration of chromium sulphate at which the coating is still obtained. I agree that if it is unknown, if you are, for example, working on the development of such compounds, it can be established by experience.
Irina.
Why it is to go all these problems of calculating. Once the electrolyte is prepared, then plate to right thickness, once the coating thickness achieved and the time is known to get that coating thickness, then you just repeat the plating cycle and keep note of the cycles, and this way you will know when the solution depleted to energise the solution to the same strength level and repeat plating.
you can use it as many times till you get your desired plating. bath stability depends upon the replenishment of the active species and the impurities generated in the plating process.
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