Determination of Porosity

[demionkrishan]

Dear team & experts,
Is there anyway to check the coating porosity before Lab analysis?
I have few tungsten carbide samples and i have doubt regarding porosity, i want to
send the sample with confidence from my side. Can you please send your valuable
comments and suggestions?

[Vadim Verlotski]

Dear team & experts,
Is there anyway to check the coating porosity before Lab analysis?
I have few tungsten carbide samples and i have doubt regarding porosity, i want to
send the sample with confidence from my side. Can you please send your valuable
comments and suggestions?

Hi Krishan,

There is a simple non-destructive method of comparing the porosities of two layers. This is "felt pen method":
You take a felt pen and draw each one line on the polished surfaces of two coatings. After a few seconds ink is drawn into the layer by capillary forces: the faster the ink line disappears and the fainter it gets, the higher the open porosity of the layer.

On non-porous layers, the felt pen line will remain there without fading.
This method is significantly more sensitive than optical or electron microscopy because it responds not only to visible porosity but also to invisible crack networks and permeable grain boundaries as wide as a few nanometers.