Scratch resistance and tribological performance of thermosetting composite powder coatings system: A comparative evaluation

• Polyester and epoxy powder coatings filled with MoS2 were elaborated by ESD system.
• The effects of MoS2 on tribological response of thermosetting coatings are explored.
• The scratch resistance of polyester and epoxy coatings filled with MoS2 is analyzed.
• MoS2 have a higher anti-wear ability once incorporated into the polyester matrix.
• Epoxy powder matrix filled with 5 wt.% of MoS2 have the best scratch response.

The knowledge of the coating properties in terms of scratch and wear resistance is extremely important to prevent severe damage. This paper focused on the study of a comparative evaluation of the scratch and wear performance of two thermosetting powder coatings filled with different weight fractions of molybdenum disulfide (MoS2) solid lubricant. Indeed, the thermoset polyester and epoxy organic powder were deposited onto aluminum substrates by an electrostatic spray coating process. The effect of MoS2 solid lubricant on the friction and wear behavior of both polyester and epoxy composite powder coatings were assessed via reciprocating tribometer under dry friction conditions. The micro-mechanical performance of the scratch resistance of the composite coatings was conducted using progressive load scratch tests. The experimental findings of the tribological analysis have proven a significant reduction of the friction coefficient and a higher anti-wear ability of the polyester composite coatings compared with the epoxy matrix to which the addition of MoS2 particles has a little effect on the friction-reducing mechanism. Finally, the investigation of the scratch resistance of the polyester or epoxy composite powder coatings filled with MoS2 confirms that the incorporation of MoS2 particles to either polyester or epoxy matrices leads to a significant decrease of the critical loads characterizing the coating damage. From the residual depth trends and contact pressure analyses, the epoxy composite coatings reinforced by 5 wt.% of MoS2 are found to have a great scratch resistance response compared to the polyester composite reinforced by the same wt.% of MoS2.