CS201413B1 - Electrolyte for cathodic production of nickel-molybdenum alloys - Google Patents

Abstract

An aqueous electroplating solution comprises nickel sulphosalicylate in a 0.1 to 1.05 M concentration, and a molybdenum salt in a 0.001 to 0.02 M concentration. The electrolyte may also include a 0.01 to 0.02 M concentration of nickel halide e.g. nickel dibromide, and a 0.002 to 0.04 concentration of a surfactant. The electrolyte results in low stress platings.

Description

The invention relates to an electrolyte for cathodic deposition of nickel-molybdenum alloys. Electrolytically deposited nickel-molybdenum alloys are promising compared to pure nickel because some of their physical properties are significantly better.

However, the regulations reported so far in the literature state that the coatings have high internal stresses, so that the deposition of thick layers is not possible. In addition, the process has a very low cathodic current efficiency, particularly in solutions operating in the acidic region, where it reaches only about 30%.

The described electrolytes are based on nickel sulphate as the basic constituent, and further comprise complexing agents such as citric acid or tartaric acid and ammonia. Molybdenum is added in the form of sodium molybdate.

The electrolyte according to the invention for cathodic deposition of nickel-molybdenum alloys eliminates these disadvantages. The electrolyte comprises an aqueous solution of nickel sulfosalicylate at a concentration of from 0.1 to 1.05 M and a molybdenum salt, for example sodium molybdate, at a concentration of from 0.001 to 0.02 M. In another aspect of the invention, the electrolyte comprises a halide For example, nickel bromide at a concentration of from 0.01 to 0.2 M. According to a last aspect of the invention, the electrolyte preferably comprises ionic or non-ionic surfactants individually or in combination with each other, for example sodium lauryl sulphate,

201 413

201 413 at a concentration of 0.002 to 0.04 M. Nickel sulphosalicylate is the essential component of the electrolyte of the invention.

A suitable halide, for example nickel bromide, can be used to improve the dissolution of the anodes. Mooybdenum is also added in the form of molybdate. Due to the complexing properties of the basic electrolyte, it is not necessary to add further complexing agents such as organic hydrooicgeein, which impair the properties of the coatings. The electrolyte operates at a very low macro-tension level from 40 ° C. The stress level further decreases with increasing temperature. Although the sulfonic acid anion is stable in aqueous solutions even at higher temperatures, the temperature used is limited only by technology. problems, evaporation, corrosion and the like. Using cathodic current densities, they are in the range of 1 to 10 A.dm depending on the electrolysis conditions. Cathodic current efficiency is greater than 90% at pH values greater than 3.

Exemplary embodiments of the electrolyte of the present invention are shown in Examples 1-4.

Example 1

The electrolyte for the cathodic deposition of nickel alloys with a nickel molybdenum contained in eulfoealicylan konccnnraci 0.8M am ^ o-ybdenan sodium konceeuraci 0.01 M, ^{K and p} atodick Roudová densities cinLa A.dm 3 ^-2, tepkta Píizrá 50 ° C its ^pH was ⁴ .

The deposited layer had a molybdenum content of 7.5% by weight, its internal tension being

MPa and microhardness 800 HM,

Example 2

The electrolyte for the cathodic deposition of nickel-molybdenum alloys using a halide contained 0.75 M of sulfonyl chloride at a concentration of 0.05 M, and 0.05 M of bromide at a concentration of 0.05 M and sodium molybdate. in concentration 0,005 M ..

Cathodically deposited ^{and h s p} Roudová ustota be A.dm ^{7 -2,} tplot bath of 50 ° C and its ^pH b ^y lo 4th

The deposited layer had a molybdenum content of 2.5% by weight, its internal stress was 28 MPa and the microhardness was 500 HM.

Example 3

The electrolyte for the cathodic deposition of nickel-molybdenum alloys using a halide contained nickel-containing at a concentration of 0.75 M;

M and sodium molybdate at a concentration of 0.013 M.

^The atodick Prou ^{s d} s ^and the density be 5 A.dm ^-2, ripe tepbta 5 ° ^C and its ^{pH by} Lo '4th

The deposited layer had a molybdenum content of 6.11% by weight.

MPa and microhardness 597 HM.

201 413

Example 4

The electrolyte for the cathodic deposition of nickel alloys with molybdenum containing halide and wetting agent contained 0.75 M nickel sulfosalicylate, 0.05 M nickel bromide, 0.01 M sodium molybdate and 0.004 M sodium lauryl sulfate.

The cathodic current density was 5 A.dm- ² , the bath temperature was 60 ° C and its pH was 4.

The deposited layer had a molybdenum content of 6.2% by weight, an internal stress of 40 MPa and a microhardness of 620 HM.

Claims (2)

1. Electrolyte for cathodic deposition of nickel-molybdenum alloys; Characterized in that it consists of an aqueous solution of nickel sulphosalicylate at a concentration of 0.1 dc 1.05 M and mc lyt.den salts, e.g. 2) The electrolyte is, for example, nickel bromide in a concentration of 1 and 2, characterized in that it contains ionic or non-ionic agents individually or in combination, for example, copper lauryl sulphate, in a range of 0.002 to 0.04.