Composite materials associating an amorphous barium fluoride coating with a substrate and preparation processes of these materials

摘要

The invention gives a coating with a very high vitrification rate. The resulting surface has physicochemical characteristics which are similar to those of fluoride glass. In order to achieve this result, the material constituting the fluoride glass enamel quickly crosses the temperature range between the melting point and the glossy transition temperature. Moreover, the metallic substrate temperature must be high enough to enable an active physiochemical process at the glass-metal interface which results in a correct "hooking". A "hooking" temperature is higher than one where a physical adhesion occurs, which results from Van der Waals interactions without any formation of chemical bonds at the glass-metal interface. The particular chemical reactivity of molten fluorides, which otherwise results in critical problems of corrosion, is in this case a favorable factor which generally reduces the hooking temperature to a level which is far below the glass melting temperature.