DD266814A1 - METHOD FOR THE ELECTROLYTIC SEPARATION OF GLAZING NICKEL LAYERS - Google Patents

Abstract

The invention relates to a method for the electrolytic deposition of decorative nickel layers with the aim that such coatings have a high leveling even at low layer thicknesses and are characterized by a good corrosion resistance. According to the invention, a mixture of pyridinium sulfonate and oxybenzaldehyde is added to the base electrolyte. In addition to the advantages listed above, the nickel coatings deposited from this electrolyte correspond to the requirements for bright nickel coatings in terms of gloss, ductility and scattering power. The invention is advantageous for the coating of mass parts, as well as for the decorative corrosion protection in vehicle construction, electrical engineering u. ae. used.

Description

Explanation of the nature of the invention

The object of the invention to ensure a hoho corrosion resistance even at steigondor concentration of the additives in the electrolyte is achieved in that dom electrolyte in contrast to known methods based on nickel sulfate, nickel chloride, boric acid, saccharin, nor a mixture of Na-2 Pyridinium ethanesulfonate and aromatic aldehydes containing hydroxy and alkoxy groups, the individual electrolyte components being present in the following concentrations:

Nickel sulphate (hydrate) 90 ... 230 g / l Nickel chloride (hydrate) 45 ... 200 g / l boric acid 3O ... 45g / l saccharin 0.5 ... 3.0 g / l Na-2-Pyridinlumethansulfonat 0.1. "1.0 g / l 4-oxy-3-ethoxybenzaldehyde-iodine) 4-oxy-3-methoxybenzaldehyde or) 0.03 ... 0.8 g / l 3-oxy-4-methoxybenzaldehyde)

In contrast to known processes, the synergistic effect of sulfobetainone and aromatic aldehydes which contain hydroxy and alkoxy groups is utilized in the solution according to the invention for achieving the said objective. The optimum concentration of Na-2-pyridiniumethanesulfonate in the electrolyte is 0.3 to 0.5 g / l, that of the o, aldehydes

The nickel is operated in agitated electrolyte under the following conditions:

- Cathodic current density: 0.5 ... 10A / dm ²

- Temperature: 50 ... 6O ⁰ C

- pH value: 3.5 ... 5.5

In comparison with US Pat. No. 3,862,019, the effectiveness of the proposed solution was demonstrated on the basis of 11 examples of electrolytes, and the working conditions and layer properties were summarized in Table 1.

Oio corrosion resistance of the nickel / chromium combinations (18Mm Ni, 0.25Mm Cr) was determined by the Corrodkote test, the leveling of the Nlckolschlchten by profilgrafischo measurement.

The sulfur content was determined spectrophotomotrically, the internal stresses were determined by contactometry and the ductility (relative elongation) was tested on a measuring device with different cylinders.

According to the values of Table 1 int for Corrodkoto-Tost, the corrosion resistance of the nickelol coatings of the solution according to the invention is 0.5 to 1.5 times higher than that of bekannton ancestor. This means that the proportion of the base metal corrosion could be substantially reduced. Dor effect stems from the fact that the proposed aldehydes do not favor the incorporation of sulfur in the Nickolschichten from the above sulfur-containing compounds. As can be seen from Table 2, by oxethylierteo butindlol depending on the concentration of the Schwofolgehalt in the nickel precipitate on the 2,5fachi> increase, while oxothyllorto aldehydes practically do not booin flow the Schwofoloinbau in the nickel layers, thus causing koine deterioration dor corrosion resistance. As a result of the synergistic effect of Na-2-Pyridlniumethansulfonat and oxethyliorten alcohols nickel layers with hohor leveling (75 ... 90%) already at layer thicknesses of 10μηι orhnlten. Dio layers are characterized by low internal stresses in the area of -SOOkg / cm ² ... + 2OOkg / cm ² . The ductility of the coatings, with an average of 4 to 9%, is significantly higher than that of nickel layers of known electrolytes . measured up to 4%. The proposed Eloktrolytzusammensetzung thus allows the deposition of more corrosion resistant and highly leveled Nickolschichten; without the other physical-mechanical properties worsened by these additives.

Ausfilhrungsbelsplel

Table 1 Examples of electrolyte composition g / l

Nickel sulphate (hydrate) 280 280 280 320 280 Nickel chloride (hydrate) 45 45 45 40 45 boric acid 30 30 30 30 35 saccharin 2 2 3 2 2 N-3-Sulfopropylpyrldinium 0.18 0.5 - - - 2-pyrldinlumothansulfonate sodium - - 0.15 0.5 0.4 Oxyethyliortos butynediol 0.1 0.2 - - - 4-oxy-3-Ethoxybonzaldohyd - - 0.05 0.4 0.6 4-oxy-3-Mothoxybenzaldehyd - - - - - 3-Oxy-4-Mothoxybonzaldehyd - - - - - corrosion resistance Ni Cr18MmlnGradASTM 6.5 6.0 7.5 6.5 7.0 Leveling Ni 10 μηι in% 78 85 75 89 84 Sulfur in% 0.07 0.08 0.026 0.06 0,049 Rolativo Elongation Ni 10 pm in% 3.85 2.2 6.9 3.85 4.3 Internal stress Ni 10 pm kg / cm ² -220 -150 -330 0 -30 Current density i _k A / dm ² 5 5 5 5 5 Elektrolyttemporatur ° C 50 50 50 50 60 pH of the electrolyte 4 4 4 4 4 Table 1 Examples Electrolyte composition g / l 6 7 8th 9 10 11

Nickel sulfate (hydrate) 90 250 280 280 260 280

Nickel chloride (hydrate) 200 45 45 45 45 45

Boric acid 45 30 30 30 30 30

Saccharin 2 2 0.5 2 2 2

N-3-sulfopropyl pyridine - - - - - -

2-pyridinium ethanesulfonate sodium 0.18 0.4 0.4 0.2 0.3 0.6

Oxyethylated butindolol - - - - -

4-oxy-3-ethoxybenzaldehyde - - - - - -

4-Oxy-3-Mothoxybenzaldehyde 0.05 0.2 0.6 - - -

3-oxy-4-methoxybenzaldehyde - - - 0.05 0.1 0.6 Corrosion resistance

Nl-Cr 18 pm In degrees ASTM 7.5 7.5 7 7 7 7.5

LevelingNM0Mmin% 78 86 85 83 82 88

Sulfur in% 0.027 0.048 0.037 0.036 0.038 0.032

Relative elongation Ni 10 μm in% 2.2 4.3 4.3 4.3 4.3 4.3

Innoro stressNMOMmkg / cm ² +200 -45 -35 +150 -90 +10

Current density i _k A / dm ² 5 5 5 0.5 5 10

Eloktrolyttomperatur'C 50 50 50 50 50 50

pH of the electrolyte 4 3.5} 4 5.5 4

Table 2 0.03 sulfur % Additives g / l 0.05 Saccharic) 2 0.1 Electrolyte 1 0.034 N-3-sulfopropyl 0.2 pyridinium 0.18 0,041 Electrolyte 1 + ethoxylated abutynediol 0.057 Electrolyte 1 + ethoxylated butynediol 0.079 Electrolyte 1 + ethoxylated butynediol 0.082 Electrolyte 1 + ethoxylated butynediol Saccharin 2 Electrolyte 2 0,025 2-pyridinium ethanesulfonate 0.18 0.023 to 0.027 Electrolyte 2 + aldehyde 0.03 0.026 to 0.028 Electrolyte 2 + aldehyde 0.05 0.026 to 0.028 Electrolyte 2 + aldehyde 0.1 0.031 to 0.035 Electrolyte 2 + aldehyde 0.2 0.02 to 0.033 Electrolyte 2 + aldehyde 0.4 0.032 to 0.035 Electrolyte 2 + aldehyde 0.6

Aldehyde: 4-oxy-3-ethoxybenzaldehyde or 4-oxy-3-methoxybenzaldehyde or (3-oxy-4-methoxybonaldehyde

Claims (2)

1. A process for the electrolytic deposition of shiny nickel layers based on nickel sulfate, nickel and / or sodium chloride and boric acid to achieve particularly corrosion-resistant and even at low layer thicknesses highly leveled nickel layers, characterized in that the base electrolyte in addition to known brighteners of the 1st class Na-2 Pyridinium ethanesulfonate and a mixture of aromatic aldehydes containing hydroxy and alkoxy groups. 2. The method according to item 1, characterized in that the electrolyte 0.1 to 1 g / l Na-2-pyridiniumethanesulfonate and 0.03 to 0.8 g / l of aromatic aldehydes, preferably 0.3 to 0.5 g / l Na 2-Pyridiniumthansulfonat and 0.1 ... 0.3g / l of aromatic aldehydes containing. Field of application (invention The invention relates to an electrolyte for bright nickel nickel sulfate, Nickol and / or sodium chloride and boric acid, which enables the deposition of heavily leveled nickel coatings even at low layer thicknesses. Under G'L'refuge the corrosion protection, this trend is important for vehicle construction. Further fields of application are the standard parts industry, electrical engineering / electronics, fittings manufacturer u.a. Characteristic of the known technical solutions There are known Glanznickol electrolytes with high leveling, which, as additional aliphatic compounds, contain sulto compounds derived from pyridine and acetylene. However, have goringoro corrosion resistance because of the presence of significant amounts of impurities in dioxin. According to US Pat. No. 3,882,019, shiny and corrosion resistant nickel layers are deposited from bright nickel elec- trates containing nickel sulfate, napthol chloride, boric acid, saccharine and as glass former and leveling additive N- (3-sulfopropyl) -pyridine- and oxo-thiorated acetyl alcohols. The most significant disadvantage of this electrolyte is that the corrosion resistance of the nickel layers decreases as the concentration of ethoxylated acetoethyl alcohols in the electrolyte increases. Object of the invention Ziol of the invention is a process for the electrolytic deposition of decorative nickel layers, which should have a high level of Einbniiny and a good corrosion resistance for material-economical reasons even at low film thicknesses.