by Oleg GAVRILIN, Cand. Sc. (Chem.), Russian Chemical-Technological University named after D. Mendeleev
Parts of machinery and mechanisms, other items made of steel and copper alloys, have as a rule to be protected from corrosion, electromagnetic and other damaging impacts. With this aim in mind, and also in order to increase wear resistance of rubbing surfaces and decorating elements, they have to be coated or plated with a fine layer of nickel.
The history of this technology covers quite a number of decades. Back in the first half of the last century-a period of rapid accumulation of chemical knowledge - there already existed techniques of galvanic plating, or coating, of metals. Specialists were also able to produce mirrors made of gold, silver and copper. This was done by placing into water solutions of metal salts glass articles upon which films of these metals precipitated. But using this technique for platings with nickel or cobalt failed to achieve the expected results.
It was only in the middle of the 19th century that specialists succeeded in obtaining nickel metal powder from its salt solutions in the presence of a reducing agent-hypophosphite of sodium. For chemical experts this was a sensation, but the effect was confirmed by numerous experiments. As for the practical applications of the discovery, they were not yet "on the agenda" and the find was shelved for the next half a century. But research in this general field went on, and in 1904 American chemical expert Prof. Roux was able to observe nickel coating forming on the surface of a steel plate placed into the aforesaid solution. But even then the novelty failed to attract due attention of industrial experts.
And it was only 40 years later that the effect was "rediscovered" and that was quite by chance. Later on experts developed appropriate technologies which were immediately claimed by industrial users. As for researchers, they focused on the structure of the new coating, and its performance i ... Read more