Study of the electrochemical corrosion during the contact of chemical platings of nickel alloys with various metals and in different media
The work purpose is an estimation of the processes of the electrochemical corrosion arising during the contact of chemical platings of nickel alloys with various metals and in different media.
The requirement of chemical methods of obtaining metal coatings from a liquid media has increased recently. Such platings in many cases are more dense, less porous and more corrosion-resistant.
The advantage of the given coatings is their thickness uniformity which remains on the details of a complicated profile. The alloys with metals which are not deposited in a pure state are possible to obtain in a chemical way of metallization. Thus, for example, at present it is impossible to deposit tungsten, molybdenum and vanadium separately but the conditions for ^deposition of these metals during chemical reduction with nickel and cobalt have been found. Chemically deposited nickel possesses highly protective properties due to smaller porosity and because the deposits which contain phosphorus are more stable to aggressive media. The alloys of nickel with phosphorus possess good plasticity, low porosity, low level of an internal stress, high corrosion-resistance and wear-resistance.
The study of the influence of chemical alloy coatings on electrochemical corrosion of iron is carried out. It is established, that the potentials of metals substrate (Fe) and plating (Ni-P) strongly depend on the media in which they are studied. Depending on the media a coating can act as the most active and as the least active in relation to iron, that is to protect a metal by electrochemical and mechanical mechanisms. The highest corrosion current is observed in nitric acid solution in iron - nickel electrode pair. It is more expedient to cover nickel- phosphoric plating on iron in the media close to 0.1 normal solutions of Hd (hydrochloric acid) and 10 % percent of NaC1 (sodium chloride). By the way sodium chloride in nature can exist as sea water.
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