Abstract
This work studied comparison of the mechanical and barrier resistance properties between different structures of three multilayers polymeric coating on each side of the steel coupons. Epoxy filled with 1 wt%, 2 wt%, and 3 wt% micron or nano-sized alumina (Al
2
O
3
) particles represented the coating layers to steel on both sides. Barrier resistance was performed by immersing the coated steel specimens in salt solution and in a citric acid medium. Adding alumina (Al
2
O
3
) particles in micron and nano size to epoxy coatings improved the barrier resistance, tensile, and hardness under dry and wet conditions as compared to pure epoxy coating. Further increases in Al
2
O
3
micro/nanoparticles cause deterioration in tensile strength and barrier resistance. The steel lined with epoxy filled with 1 wt% Al
2
O
3
nanoparticles has a maximum tensile strength of 299.5 MPa and 280.9 MPa under dry and wet conditions, respectively. However, the steel lined with epoxy filled with 1 wt% Al
2
O
3
microparticles has a tensile strength of 296.5 MPa and 275.4 MPa under dry and wet conditions, respectively. Good properties were observed with stepwise graded micro/nanocomposite coatings. The steel lined with epoxy filled with 3 wt% Al
2
O
3
nanoparticles has maximum hardness of 46 HV and 40 HV under dry and wet conditions, respectively.