Copper

from Wikipedia, the free encyclopedia

As copper plating refers to the coating of metallic objects with copper .

Procedure

For galvanic copper plating solution is used of cuprous oxide in potassium cyanide or cast iron, steel, iron bar, a solution of copper sulphate , Rochelle salt and caustic soda . Iron rusts easily under the copper cover and is advantageously leaded before copper-plating, transformed on the surface into steel through case hardening or painted with varnish or oil paint and then made conductive with graphite powder. Occasionally 1–2 mm thick copper coatings are produced. Iron and steel cover each other with a copper layer when they are immersed in a copper solution; but if this is to adhere well at some strength, special tricks have to be used.

One adds z. B. a concentrated copper vitriol solution with a little less than half its volume of English sulfuric acid, dips the steel objects into this liquid, pulls them out again immediately, rinses them a few times with hot water and dries them by rubbing them with chalk on a cloth . Copper-plating of iron and steel is often a preparatory work to create a base for gilding or tinning by boiling.

To copper-plate zinc , tartar , carbonate of copper oxide and water are heated to 75 ° C, then whipped chalk is added until the shower stops, filtered, the precipitate is washed out, all liquids are combined and the previously very brightly stained objects are placed in them take on a nice copper plating for a few minutes.

To copper-plate brass, heat it in the air until it has turned blackish brown, extinguish it in a zinc chloride solution, boil it in it, rinse it briefly, dry it, boil it in a zinc chloride solution containing copper (obtained by boiling zinc chloride solution with annealed copper sheet) and touch it while doing this on the back with a zinc stick, rinses, brushes and dries.

Iron can also be copper-plated if it is heated to white glow and immersed in molten copper in the absence of air. Wrought iron plates, which are copper-plated in this way, can be easily processed without the copper peeling off. However, since the implementation of this process is associated with considerable difficulties, it is usually copper-plated using the wet method. Iron sheets , which are temporarily galvanized, willingly take on a copper coating when immersed in molten copper that is covered with carbon to prevent air.

The copper-plating of iron and steel as preparation for gilding was known as early as 1603 , but copper-plating itself only gained practical importance after the invention of electroplating and was trained for practical use by Oudry in Auteuil in 1856 .

literature

  • TW Jelinek: Practical electroplating technology. A teaching and manual, seventh updated edition, Leuze Verlag, Bad Saulgau 2013, ISBN 978-3-87480-277-2 .
  • Emil Winckler: Vademecum of the gilders. Manual and auxiliary book for metal workers, especially for belters, sword sweepers etc .; Published by Otto Spamer, Leipzig 1860.
  • A. Martin: Repertory of Galvanoplastik u. Electroplating or metal reduction by wet method in thick and thin layers. Second volume, Die Galvanostegie, printed and published by Carl Gerold's Sohn, Vienna 1856.
  • Wilhelm Pfanhauser: The electrolytic metal precipitates. Textbook of electroplating with consideration of the treatment of metals before and after electroplating, seventh edition, Springer Verlag GmbH, Berlin / Heidelberg 1928.

Web links