I want to measure hardness of a polymer based coating using AFM. I have already used Micro-Vickers hardness test, but to substantiate the results and to ensure 'no substrate' effects I want to go for AFM based nano-indentation
Since I am a beginner to the use of AFM I have few doubts:
1) For Micro Vickers I used a flat metal (100*100 mm) sheet to which I coated the polymer using film applicator.
2) For AFM the specimen placement is on a small circular cylinder as I have observed in the lab. Now, I cannot coat on such a small specimen using film applicator. So, what are the alternate methods ?
Hi Murali,
Generally you should maintain an indentation depth of less than 1/10 of the film thickness to stay safe from substrate effects. Further you should try and vary the indentation load (still remain below 1/10) and see if you get deviations in your modulus. If the modulus is constant you can be quite certain that your substrate does not interfere.
Coating on the small cylinder is going to be tricky. Do you have the possibility to spray-coat your film? Otherwise you may have a chance coating on a larger substrate and cutting it down to the size of your specimen holder.
Good luck with your measurements,
Felix
Mr. Felix thank you for sharing your idea. I am going to do that, I have measured the Micro Vickers hardness of substrate and coated substrate separately and found that the readings are poles apart. Regarding the specimen I have decided to cut the specimen sheet in circular form using wire EDM.
dip coating can help you. Also, you can apply the coating on the surface by using film applicator and then cut the substrate in you desired size.
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