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Red plague is caused by normally occurring electrode potential difference between the copper and silver, leading to galvanic corrosion occurring in pits or breaks in the silver plating. It develops in the presence of moisture and oxygen when the porosity of the silver layer allows them to come in contact with the copper-silver interface.
Excluding the continuous strip plating industry, copper is the second most commonly-plated metal after nickel. [6] Copper electroplating offers a number of advantages over other plating processes, including low metal cost, high-conductivity and high-ductility bright finish, and high plating efficiency.
The problem recurred when vessels were sheathed in copper to reduce marine weed accumulation and protect against shipworm. In an experiment, the Royal Navy in 1761 had tried fitting the hull of the frigate HMS Alarm with 12-ounce copper plating.
Electroplating of acid gold on underlying copper- or nickel-plated circuits reduces contact resistance as well as surface hardness. Copper-plated areas of mild steel act as a mask if case-hardening of such areas are not desired. Tin-plated steel is chromium-plated to prevent dulling of the surface due to oxidation of tin.
Schematic apparatus for electrotyping. An electric current flows from the battery, through the copper anode, the electrolyte, and the coated mold. A copper film (the electrotype) grows onto the electrically conducting coating of the mold. Electrotyping (also galvanoplasty) is a chemical method for forming metal parts that exactly reproduce a model.
Many techniques are used to mitigate the problem, including changes to the annealing process (heating and cooling), the addition of elements like copper and nickel, and the inclusion of conformal coatings. [2] Traditionally, lead has been added to slow down whisker growth in tin-based solders.
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Black for copper. Solution of sodium polysulfide 2.5%, items must be submerged in the solution after color developing, wash, dry and wax or varnish colored object. [27] Brown for copper. Items are boiled in at least 3-day-old water solution of 12% copper sulfate, after color being developed, the material is washed, dried and waxed or varnished ...