Coating hardness 1

[Steved]

Hello:<br>
<br>
We have a coating on an Aluminum substrate that we need to know the hardness of. What are the recommended techniques and the required coating thicknesses to evaluate the hardness of only the coating. At this point, I don't know what the coating is but, it may be anodized.<br>
<br>
Thank you and have a great day.<br>
<br>
Steve DeLucia

 

[rembrandt]

Hi there, I suggest that you are perhaps looking for a 'BARCOL' hardness test, suggest you contact 'Elcometer Instruments' in Manchester, England, they should be able to clarify your query, after all they sell the Barcol Hardness Tester.

 

A Barcol tester won't work on such a thin coating, you'll get way too much effect of the substrate. You need at least 50-75 mils of coating to use the Barcol indenter. I haven't found a good hardness measurement for thin (<10 mils) coatings, would be curious to see what responses you get.

 

[chiaraP]

What about a standard microhardness or nanohardness tester (

http://www.csm-instruments.com/):

the indentation depth must be less than 1/10 of the coating thickness in order to have the coating hardness uninfluenced by the substrate.

 

[Steved]

chiaraP:
thanks for the information, I appreciate it.
steved

 

[TVP]

Wow, an ancient thread that was resurrected, and the originator is still around. This has to be a first for Eng-Tips.

Ok, putting my awe and wonderment aside, chiaraP's suggestion to investigate micro or nanohardness indentation is a good one. Anodic coatings can be quite thick (greater than 10 micrometers), and therefore appropriate for microhardness testing. We routinely use Vickers hardness with a 0.05 kg (50 g) indentation load to measure the hardness of chromium electroplating ( ~ 900 HV at 15-20 micrometer thickness). Vickers microhardness can be done with loads as low as 1 g.

 

[Steved]

TVP- thank you for the information. I am still around, same company but a different job.
Steved

 

[gvanbeek]

Depending on the coating a shore A or shore D can be used. If you are trying to determine cure, then DSC or DTMA (both destructive).

 

[Steved]

gvanbeek:

Thank you for the reply, I will pass teh nformation on.
Steved