Desenvolvimento e avaliação do desempenho de filme compósito anticorrosivo reforçado de forma sustentável com resíduo de casca de arroz

Abstract

This study investigated the incorporation of rice husk ash (CCA) ranging from 5 to 40% into a poly(vinyl alcohol) (PVA) matrix for the development of composite films aimed at improving the corrosion resistance of SAE 1020 carbon steel. The results indicated that films with 40% CCA exhibited the best protective performance, with no visible corrosion on the substrate after 72 hours of exposure in a 3.5% NaCl solution. Scanning electron microscopy (SEM), confocal microscopy, and atomic force microscopy (AFM) analyses revealed that films with 40% CCA presented better surface uniformity with two distinct micro-regions. Fourier-transform infrared spectroscopy (FTIR) demonstrated interactions between the PVA matrix and CCA particles, with shifts in the hydroxyl group peak and changes in bands related to particle-polymer matrix interactions. Differential thermal analysis (DTA) and thermogravimetry (TG) showed that CCA is thermally stable, with mass loss associated with free water evaporation and organic compound decomposition. Electrochemical tests confirmed that films with 40% CCA exhibited superior corrosion resistance compared to both pure PVA and uncoated steel substrates. Wettability tests demonstrated a decrease in hydrophilicity as CCA concentration increased, and adhesion tests confirmed excellent adhesion at all tested concentrations. Additionally, the films were able to reduce mass loss by 20.7% compared to the uncoated substrate and by 8.5% compared to PVA without additives after 15 days of exposure, suggesting that PVA-CCA composite films are promising for corrosion protection of metallic substrates.