DE1621151A1 - Corrosion-resistant, decorative chrome coatings - Google Patents

Description

PATENTANWÄLTE 8902 AUGSBURG-GÖGGINGEN, the

v. Eidiendorff-Strasse 10

DR. ING. E. LIEBAU Our sign _{R 6646}

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DiPLiNG. G. LIEBAU 1621151

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REIiIB NATIONALE DES USINES RENAULT Billancourt (Seine) France

Corrosion-resistant, decorative chrome coatings

Addition to patent ....... (file number -R, 41

The invention relates to various approaches Baths with which cracked nickel layers can be produced according to the process specified in the main patent.

According to the teaching of the main patent, the baths about contain door cracked expectant nickel layers essentially a nickel salt Ainet strong acid, "nickel chloride, and a nickel salt of a weak acid, such as the acetic, glucan _# tartaric, formic, halon, Citränen- or succinic acid,

009829/1250 "._"

. ■ ■ ORIGINAL BATHROOM

-Z-

In order to reduce the production costs of such baths and to reduce the cost of bath components carried over, one has tried a cheaper composition of these baths to reach.

According to the invention, good results could be achieved if part of the nickel ion was replaced by ammonium or alkali ion. According to the extension one can thus exchange:

- a part of the nickel salt of the strong acid against a sodium, potassium or ammonium salt of the strong acid;

- all or part of the nickel salt weak acid against a sodium, potassium or ammonium salt of the weak acid.

Generally speaking, the bathroom door is therefore cracked nickel plating according to the invention from the following components:

- a nickel acid containing strong acids such as nickel chloride, nickel sulphate, Jslickeisultamate, nickel luoborate;

- an alkali salt of strong acids, such as alkali chloride, alkali sulfate, Alkali luoborate;

- a salt of a weak acid belonging to the group of Above mentioned weak acids has been chosen, the weak acid in the form of the acid, the alkali salt or the Nickel salt can occur.

009829/1258,,

It is noteworthy that by changing the concentration of the components of the bath, in particular the proportion and the type of weak acid, depending on the desire a closer or wider association of the networks to which is to be achieved Putting the cracks together »The density of the cracks can also be determined by changing the pH of the bath andfer bath temperature vary. Furthermore, changing the dissolved nickel content allows variable values of the current density to be achieved, so that, depending on the executions and the shape of the parts to be treated, the most economical Bath for obtaining the micro-cracked chrome layers can be put together »

The following approaches for baths, adapted to the process according to the invention, are only intended to "not restrict the invention." Consider examples; the figures given are approximate to watch:

Example I.

Nickel chloride nickel acetate ammonium chlorine id pH

Current density temperature

009829/1268

BATH

15o g / l 5o g / l 12o g / l 4th 1 to Io A / dm ² 25 ° C.

duration

Density of the cracks 1 min.
about 300 cracks per cm

Example II

Nickel chloride gluconic acid ammonium chloride Ammonia current density temperature duration

Density of cracks zoo g / l

loo g / l

15o g / l

up to pH 3.5
up to 15 A / dm ²

Z5 ° C

1 min.
about 5oo cracks per cm

Example III

Nickel chloride Ammonium acetate ammonium chloride pH

Current density temperature duration

Density of cracks

15ο g / l Cracks per cm 5o j 12ο g / i 3.5 to 4 1 to Io A / dm ² 25 ° C 1 min. approximately 7oo

009 829/125 8

8AD ORIGINAL

Example IV

Nickel chloride ammonium acetate ammonium chloride.

Current density temperature density of cracks

15o g / l 5o g / l 12o g / i 3.5 to 4 1 to 15 A / dm ² 35 ° C

about 5oo cracks per cm

Example V

Nickel chloride sodium acetate Sodium chloride

Current density, temperature, density of the cracks 15o g / l 5o g / l

15o g / l

4th
up to Io A / dm ²

25 ° C
about 300 cracks per cm

All baths mentioned are compatible with suitable brighteners, as already stated in the main patent,

Patent claims:

009829/125 ORIGINAL BATHROOM

Claims (7)

Patent claims: 1. Process for coating surfaces of objects with a micro-cracked chrome plating on electrolytic Ways, according to which the objects are to be chromed be subjected to electrolytic treatment, which leads to the deposition of an intermediate nickel layer, in which cracks form, which cause cracks to form in the chrome layer during the chrome plating process, where- in the cracked nickel plating is done by means of an electrolyte that has a component that belongs to the group of nickel salts of strong acids and e.g. nickel chloride or nickel sulfamate or nickel fluoroborate is, according to patent ....... (file number - 4-r characterized in that the electrolyte is a second Has component represented by at least one alkali salt of a strong acid. 2. The method according to claim 1, characterized in that as the second component chlorides, fluoborates, sulfamates and Sulphates of sodium, potassium and ammonium or mixtures 009829/1268 " BATH ORIGINAL are selected from at least two of these salts. 3. The method according to claim 1 and / or 2, characterized in that that the electrolyte has as a third component an alkali salt of a weak acid, namely Sodium, potassium and ammonium salts of vinegar, ulucon, Tartar, maion, ant, milk; Lemon, amber " stinic acid or mixtures of at least two of these salts. 4. The method according to any one of the preceding claims, characterized characterized that the electrolyte has a component that comes from the primordial group of compounds is selected: acetic acid, mckelacetate, tartaric acid, nickel tartrate, formic acid, nickel formate, malonic acid, Nickel malonate, lactic acid, nickel lactate, citric acid, nickel citrate, succinic acid, nickel salt of succinic acid, or from a mixture of at least two of these compounds is formed. 5. The method according to one of the preceding.Ansprüche, thereby characterized in that the electrolytic bath in which the Nickel intermediate layer is formed, a brightener 009829/1258 BATH contains, which allows to increase the treatment time and whose composition and amount are chosen so that he has only a minimal influence on the potential and the tendency for cracks to form on the intermediate nickel layer, 6. The method according to claim 6, characterized in that «that one of the compounds mentioned below as a brightener or a mixture of at least two of these compounds is used: sulfonates, sulfonamides, aromatic sulfonimides, butyne-2-diol-1,4, heterocyclic amine derivatives Compounds such as 2-amino-thiazole, cobalt salts. 7. The method according to any one of claims 5 and 6, characterized in that when the lower nickel layer is a Bright or semi-gloss nickel layer is this nickel plating before the deposition of the cracked nickel layer Is subjected to depassivation. 0 09829/1268