Abstract :
The multilayer structure of commercially made mirrors can be subject to degradation under normal conditions, leading to
alterations of the mirror’s reflective properties. A protective coat of paint, containing an anticorrosive compound, is applied
to the copper surface to reduce the oxidation of the thin metallic films. The objective of this study is to analyse the behaviour
of the multilayer stack during salt spray tests neutral salt spray and CASS-test.. We followed the morphological and
chemical evolution of the interfacial area glass–silver–copper–paint.using scanning electron microscopy SEM., and
electron probe for micro analysis EPMA.. Studies of the surface of the coatings were performed with attenuated total
reflexion infrared spectroscopy IRTF-ATR.and SEM-EPMA. The observations revealed that a glass–silver decohesion
occurs starting at the edges of the material during the tests. The EPMA analyses of the exposed edges of the mirrors
indicated first that concentration of the anticorrosive pigment of the paint lead-based compound.decreased, especially at the
copper–paint interface, and second that the copper in the paint may diffuse to the surface of the coating. Finally, IRTF-ATR
spectroscopy and SEM-EPMA analyses of surfaces showed that the CASS-test leads to an acid attack of some pigments and
extenders of the paint particularly CaCO3.and leads to chemical modifications of the binder. These phenomena result in an
increase in the porosity and a weakening of the paint film. The results obtained with these surface analytical technics will
allow us to propose some degradation mechanisms of painted mirrors during salt spray tests. q1997 Elsevier Science B.V.
