Effect of chromated copper arsenate (CCA) on corrosion of metallic fasteners: Implications in boat building

Abstract

Wooden boat building involves the use of metal fasteners made of iron, copper etc. The scarcity of durable wood necessitates wood preservation. When preservative treated wood is nailed, the possibility of corrosion of the nail cannot be ignored. This demands further studies on the performance of the nail with respect to its resistance to corrosion. The main aim of this study is to find out the rate of corrosion of copper, iron, painted iron nails and galvanized iron screws drawn into rubber wood treated to three different retentions of chromated copper arsenate (CCA) viz. 16, 29, 42 kgm⁻³ and wood without any treatment. The experiments were conducted both in the laboratory and under estuarine conditions. The rate of corrosion is estimated by weight loss method. The results show that CCA does not affect corrosion in 16 and 29 kgm⁻³ retentions to a significant level, but in 42 kgm⁻³ retention, the corrosion rate is found to be accelerated significantly when analysed statistically. It can be concluded that in lower retentions, CCA does not influence corrosion of fasteners. The rate of corrosion is least in galvanized iron and painting of iron nail is found to effectively reduce corrosion.