Suffice widespread use of iron-nickel alloy, otherwise called Invar, require finding a fairly simple method of its production.
Many do not know that getting such alloy electroplating is performed.
iron-nickel alloy called Invar. It is widely used in precise instrument, namely, in the manufacture of geodesic wire, various standards of length, part of the watch, altimeters, lasers, etc. One of the easiest ways to obtain an iron-nickel alloy is galvanic.
Problem electroplating method for producing nickel-iron alloy and its removal path
Comparing the thermodynamic characteristics of bothmetals, scientists thought that is easy to obtain an alloy. In practice, it turned out just the opposite, since the reaction proceeds by-oxidation process - the iron is turned from bivalent to the trivalent state. This reduces the yield of the desired product current and degrades its physical characteristics, and sometimes completely eliminates them. To solve this problem can be the introduction of additives into the electrolyte complex consisting of amines and organic acids and forming a soluble compounds with ferric iron. As a result, it improves the elasticity of the sediment. To reduce the spread of the sediment thickness is used electrolyte mixing.
Electrolytes for applying iron-nickel alloy
Sulphate electrolyte produce an alloy of nickel-iron has the following composition:
;;;; Component g / l
Iron sulfate 2 ;;
Nickel sulfate 60 ;;
Boric acid 25 ;;;
Saccharin; ;;; 0.8
Sodium lauryl sulfate 0.4 ;;
electrolyte Mode pH 1.8-2
Temperature - 40-50 degrees Celsius
Cathodic current density - 3-7 A / dm 2
The anodes may be used assteel alloys or iron and nickel plate from nickel and iron. If we apply the plate, it is necessary to keep the ratio of the areas. Nickel plate area should be three times more iron.
The hydrochloric acid electrolyte produce an alloy of iron-nickel composition is:
;;;; Component g / l
Iron chloride ;; 150-160
Nickel chloride ;; 2-4
Hydrochloric acid 2-4 ;;;
Temperature - 50 degrees Celsius
Cathodic current density - 10 A / dm 2
The disadvantage of this electrolyte is the saturation of the hydrogen product, if done electrolysis current indicated. This increases the brittleness of metals.
Sulphamate and ftorboratny alloy electrolyteiron-nickel. This electrolyte provides a high deposition rate, the minimum internal tension and elasticity of the sediment. But because of the complexity of the composition and the high cost of the components it is not widely used in the industry. Therefore, this article is not given its composition.