Study of thermal stability of epoxy coatings electrodeposited on different substrates

摘要

The thermal stability of epoxy coatings electrodeposited on steel, phosphatized steel, steel electrochemically modified by Zn-Ni alloys and aluminium has been investigated. Epoxy coatings were formed by cathodic electrodeposition of epoxy adducts, using a constant voltage method. The rate of hydrogen evolution reaction in the polymer solution on different substrate surfaces was determined on Pt rotating disc using a slow sweep voltammetry. The characteristic thermal and thermooxidative degradation tem- peratures, as the measure of thermal stability, and activation energies of thermal degradation were determined by thermogravi- metric analysis. It has been observed that different catalytic activities of substrates for H2 evolution reaction give different rise to an increased amount of hydrogen bonds inside the polymer net and porosity of coating, strongly affecting the thermal and thermo- oxidative resistance of the polymeric material.