When I set a load between 100 and 500 grams, I cannot see indentation diagonals clear enough. The diagonals just don't extend from one corner of the pyramid to another or maybe they are not visible. However, when the load is 100 grams and lesser, the indentation diagonals become clearer and visible, but the HV value decreases to around 2 which I think is low for epoxy. So, what is the way ahead? What is the correct load?
Hi,
I work with epoxy coatings also and I can measure without problems using Micro Vickers hardness tester. What I have seen, is that with dark and rough coatings, it is more difficult to obtain a clear diagonal.
I usually measure with a load of 300 g (for 10 s). Perhaps you can also try to vary in addition to the load, the time and the magnification of the microscope (I use 10x). In my case, the value obtained for an epoxy coating is about 20 HV.
You can also try to use other types of methods like Persoz, Shore or Universal Hardnessmeter.
Hi,
I do not recommend using the Vickers method for determine the hardness of epoxy coatings. It is best to use the shore method. It is used to determine the hardness of plastics (Shore hardness test (ISO 868:2003) or ASTM D2240 Shore Hardness.
Gedvidas
Gedvidas Bikulcius Is Shore hardness recommended for polymer composites and polymer nanocomposite coatings as well ?
Gedvidas Bikulcius The reason why I asked this question is that there are Q1 Journals where in Micro Vickers hardness tester was used for hardness testing of polymers or their coatings. If at all I want to go for micro indentation hardness testing using Vickers, is there a need for surface polishing? Generally, this is done for metals. The polymer coating is smooth and flat.
Hi,
I work with epoxy coatings also and I can measure without problems using Micro Vickers hardness tester. What I have seen, is that with dark and rough coatings, it is more difficult to obtain a clear diagonal.
I usually measure with a load of 300 g (for 10 s). Perhaps you can also try to vary in addition to the load, the time and the magnification of the microscope (I use 10x). In my case, the value obtained for an epoxy coating is about 20 HV.
You can also try to use other types of methods like Persoz, Shore or Universal Hardnessmeter.
Apart from all the other considerations here done, please remember also that if you are testing a coating the indentation depth should be maximum one fourth or one fifth (1/5th) of the coating thickness otherwise you risk to have the underlying material influencing the results.
Dear Muralishwara Kakunje ,
Suitable load for epoxy coating can be used in the range of 0.22-40 N. Most suitable range is 0.22-10N. If Load is increased more than 40N, coating likely be delaminated from the substrates be seen evidently.
Hope it is helpful for you.
Ashish
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