Corrosion Resistance of Electroless Ni-P-W/ZrO<sub>2</sub> Nanocomposite Coatings in Peracid Solutions

In current investigation, the Ni-P-W/ZrO2 electroless nanocomposite coatings are deposited upon mild steel substrate (AISI 1040 grade). The W/ZrO2 nanoparticles (50 to 130 nm range) were incorporated separately into acidic electroless Ni-P matrix as a second phase materials. The as-plated EL Ni-P-W/ZrO2 depositions were also heated at 400 οC in Argon atmosphere for one hour duration and analyzed by SEM/EDAX and XRD physical methods. The Ni-P-W/ZrO2 as-plated coupons revealed nebulous type structures while heated coupons showed crystalline structures in both cases. Furthermore Ni-P-ZrO2 coatings have very less cracks and gaps as compared to Ni-P-W coatings. The corrosion tests result in peracid (0.30 ± 0.02 % active oxygen) solutions point up that corrosivity of peracid ( 500 ppm Cl) is more than peracid (0 ppm Cl) and corrosion resistance of tested coupons varies as Ni-P-ZrO2 (as-plated) > Ni-P-ZrO2 (heated) > Ni-P-W (as-plated) > Ni-P-W (heated) > MS. The utilization of Ni-P-ZrO2 nanocomposite coatings in peracid solutions can be considered a cost effective option on the basis of its better cost/strength ratio in addition to its fair corrosion resistance.