Efeito da adição de nanocristais de celulose extraídos do algodão na resistência à corrosão e nas propriedades dos eletrodepósitos de Cu-Sn.

Abstract

Cu-Sn coatings containing different concentrations of cotton nanocrystals (CNC) (0% v/v, 1% v/v, 2.5% v/v, 5% v/v, 7.5% v/v) were investigated. The addition of CNC in the deposition bath significantly influenced the morphology, composition, and structure of the coatings. The results showed that the presence of CNC particles considerably increased the Sn concentration in the coating, from 47,2 %wt. to 74,4 %wt. with the addition of 1% v/v CNC. The presence of CNC also reduced the roughness of the Cu-Sn coatings and promoted grain refinement, with a more pronounced effect in coatings containing 1% v/v and 2.5% v/v CNC. An improvement in current efficiency was observed with the addition of 1% v/v and 2.5% v/v CNC, reducing energy consumption by at least 25% for the electrodeposition of the coatings. Additionally, the addition of CNC significantly increased the contact angle of the coatings, with the coating obtained with 2.5% v/v CNC presenting a contact angle of 120.30°, showing potential for application as a solar reflector in humid and dusty conditions due to its highly hydrophobic character. The corrosion resistance of Cu-Sn coatings in 3.5% NaCl solution exhibited a marked improvement with the addition of CNC particles. The optimal content of 1% v/v cellulose nanocrystals was identified as the concentration that promotes coatings with maximum corrosion resistance, a result directly associated with the influence of nanocrystals on the morphology, crystalline structure, and, most importantly, the chemical composition of Cu-Sn coatings. These results highlight the potential of cellulose nanocrystals as effective additives to improve various performance aspects of Cu-Sn coatings.