| 摘要 |
The browning coating, which is external, comprises essentially a heating layer, made of lead-free enamel in which electrically conductive elements in the form of a metal powder are incorporated, this powder being intimately mixed with the enamel, generally in a proportion of 15 to 40 % by weight; a protective layer of lead-free enamel advantageously covers the heating layer. The layers are deposited on the outer surface of the container by silk-screen printing or by transfer or by an offset process and are subjected to baking at a temperature of between 620 and 800 DEG C. The metal powder is made up of at least one substance chosen from the following electrically conductive metals: transition metals, especially iridium, platinum, ruthenium, rhodium, palladium, silver, gold and the oxides of these metals.
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