Wear behavior of polyurethane/carbon black coatings on 6061 aluminum alloy substrates

In this paper, the effects of structural and process variables on wear resistance of polyurethane/carbon black coatings on the 6061 aluminum substrate are studied. These coatings are widely used in different industries because of their outstanding thermal, chemical stabilities and excellent mechanical properties. The parameters were polyol type (ester or ether), NCO/OH ratio and pigment concentration. The experiments were carried out based on the design of experiments using Taguchi method. Abrasion resistance tests were performed with a Taber Abrasion test device, and its morphology was examined by scanning electron microscopy (SEM). Fourier-transform infrared (FTIR) spectroscopy was used to characterize the synthesized polymer. The analysis of variance showed that among the studied parameters, polyol type and pigment concentration have the most significant effects on wear resistance. Coating with polyester polyol increases the wear resistance due to possible hydrogen bonding between hard and soft segments. Furthermore, the pigment particles provide equivalent physical crosslinks, so it increases the wear resistance. Finally, the coated sample including polyester polyol, 12phr carbon black and NCO/OH ratio equal to 1.4, provide the best wear resistance i.e. 0.2 mg. Also, the results showed that abrasion and cohesive wear are the dominant mechanisms for describing the wear behavior of studied coatings.