Experimental Study of Nickel Electroplating and CuO Nanocoolant on Corrosion Rate and Hardness of ASTM A36 Steel

Abstract

ASTM A36 carbon steel is widely used as an alternative type of steel for the manufacturing and construction industry, but the poor corrosion resistance and relatively low surface hardness of the steel result in low performance in long-term operation. Therefore, manufacturing innovation is required to obtain high coating performance. In this article, ASTM A36 steel for material is obtained, in the method of enhancing surface properties with nickel electroplating and CuO nanocoolant diffusion at 0.25%, 0.5%, and 0.7% concentrations. Surface hardness was the established method of Vickers hardness testing, while the corrosion behavior of the ASTM A36 was measured with weight-loss immersion tests in HNO₃, H₂SO₄, and HCl solutions. The coating morphology and elemental distribution are explored by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX). Quantitatively, the uniformity of coatings was evaluated by looking at the mean, standard deviation, and CV of elemental composition. The results show that there are significant improvements in surface performance with the ratio of CuO concentration. Hardness increased by ca 9%; however, the highest hardness was recorded at 0.7% CuO. Corrosion test with acidic environment indicated a decrease in weight loss because the corrosion rate of 0.25–0.5% was reduced, and more effective protection can be obtained by 0.7% CuO. The EDX results showed that the coating containing 0.7% CuO had a greater elemental homogeneity, with CV <50%, and coatings containing low CuO had a significant inhomogeneity. SEM data confirmed that the 0.7% CuO coating created a deep, uniformly dense, and uninterrupted layer with a low level of porosity and agglomeration of the nanoparticles, which contributed to enhanced corrosion resistance. Ni–CuO coatings showed better corrosion resistance and microstructural uniformity due to homogeneous nanoparticle dispersion, outperforming conventional and reported coatings.