Stained state and wear resistance of polymer coatings

Powders of polyamides PA 6 and PA 6.6 were deposited on the surface of steel heated to temperatures above melting points of these polymers. Strong wear-resistant coatings were formed on the surface after cooling. Measurements showed that, as the thickness of coatings decreases, their wear resistance increases. In order to reveal the nature of this phenomenon, stresses in polymer molecules were measured in coatings of mentioned polymers by infrared spectroscopy. It was found that the skeleton of polyamide molecules in coatings is compressed. This effect was explained by the formation of coordination compounds between nitrogen atoms of polyamide molecules and Fe$^{2+}$ ions. It was revealed that the compression of the skeleton of molecules leads to an increase in their strength and wear resistance of coatings.