Corrosion Behavior of Silver by Outgassed Sulfur Species from Vulcanized Rubber (1)

— Examination of Corrosion Factors —

Abstract

Corrosion factors which influence the corrosion of silver by outgassed sulfur species from vulcanized rubber have been investigated by means of quartz crystal microbalance technique (QCM) and cathodic reduction technique. Silver sulfide was the only corrosion product identified during all the tests. Corrosion progressed linearly with time and the corrosion rate did not depend on humidity, but depended markedly on the temperature and the volume of rubber contained. In addition, it is clarified that the corrosion rate varies according to the types of rubber and even among various chroloprene products. Thus it is considered that the corrosion behavior of silver with vulcanized rubber is determined by the concentration of the sulfur gas species outgassed from the rubber. The free sulfur in the rubber is assumed to be the source. It may be suggested that the outgassing of sulfur gas is determined by diffusion of sulfur molecule S_x (x=2−8) in the rubber and this diffusion process determined the corrosion rate of silver.