CHEMISTRY GLOSSARY

immersion plating    →   galvaniziranje uranjanjem

Immersion plating involves depositing a metallic coating on a metal immersed in a liquid solution, without the aid of an external electric current. Also called dip plating.

electroplating    →   galvaniziranje

Electroplating (also called electrodeposition) is the deposition of a metallic coating onto an object by putting a negative charge onto the object and immersing it into a solution which contains a salt of the metal to be deposited. The metallic ions of the salt carry a positive charge and are attracted to the part. When they reach it, the negatively charged part provides the electrons to reduce the positively charged ions to metallic form.

Typically, a brass or nickel object is coated with a layer of silver by making use of electrolysis of a silver solution, using the object to be coated as the cathode. The anode consist of pure silver, and the cathode is the object to be plated. The electrolyte is a mixure of silver nitrate with potassium cyanide. The reactions are:

The cyanide ensures a low concentration of silver ions, a condition for providing the best plating results.

blanching    →   blanširanje

1. Blanching is a heat treatment of foodstuffs to partially or completely inactivate the naturally occurring enzymes prior to freezing.

2. Blanching is a washing process for coins cleaning. The black surface layer of cupric oxide is removing by dipping the coins in hot dilute sulphuric acid (w(H₂SO₄) = 10 %).

tempering    →   kaljenje

Tempering is a rapid cooling of metals (often steels) from a suitable elevated temperature, thus changing its properties, e.g. steel becomes harder. This is generally accomplished by immersion in water, oil, polymer solution, or salt, although forced air is sometimes used.