Study of wettability of invar by an enamel.

The enamelling of invar surface has been studied in order to obtain a prote ction against oxidation. Substrate roughness, chemical composition of the e namel, temperature and time have been considered in the study of wettabilit y. The evolution of contact angle of the glass on several substrates has de monstrated the favourable influence of the preoxidation of invar on spreadi ng. The observation of cross sections of the samples has shown that oxidati on had created paths for penetration of the enamel into the alloy and that the oxide layer had been dissolved in the liquid at the end of the experime nts. The study of spreading of [glass + FeO] mixtures has clearly shown tha t wustite dissolving improved the adhesion. The enamelling process the tech nological parameters of which were deduced from experimental results, led t o a nearly 45 mum thick continuous and adhesive layer.