Method for coating an object by means of a multilayer system with a nickel-phosphorus alloy

Abstract

A method for coating an article, wherein a surface of the article is at least partially coated with a coating that has a multiplicity of layers, wherein at least one layer of the coating is made of a nickel phosphorus alloy and wherein a mass fraction of the phosphorus in the nickel phosphorus alloy is at least 8%.

Claims

1. A method for coating an article, the method comprising: applying a plurality of layers to at least part of a surface of the article, the plurality of layers together forming a coating on the at least part of the surface of the article; wherein a first layer of the plurality of layers applied to the article is made of copper, a second layer of the plurality of layers is made of bright nickel, semi-bright nickel or matte nickel, a third layer of the plurality of layers is made of a nickel phosphorus alloy, and a fourth layer of the plurality of layers, which is applied directly to the third layer, is made of chromium, and wherein a mass fraction of the phosphorus in the nickel phosphorus alloy is at least 8%, and wherein the third layer made of the nickel phosphorus alloy is a fully continuous layer.

2. The method according to claim 1, wherein the article is made of copper, zinc, aluminum, iron, or plastic, or an alloy that includes copper, zinc, or steel.

3. The method according to claim 1, wherein the chromium of the fourth layer is deposited from a hexavalent or trivalent chromium electrolyte.

4. The method according to claim 1, wherein at least the third layer made of the nickel phosphorus alloy is applied electrolytically.

5. The method according to claim 1, wherein a fifth layer of the plurality of layers is applied on the fourth layer, the fifth layer being produced from an amorphous carbon layer (DLC).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 shows an article coated with the method according to the invention in a longitudinal section;

(3) FIG. 2 shows an article coated with the autocatalytic method according to the conventional art in a longitudinal section; and

(4) FIG. 3 shows an article coated with the electrolytic method according to the invention in a longitudinal section.

DETAILED DESCRIPTION

(5) FIG. 1 shows a coated article 1 in a longitudinal section, which has a body 2 with a surface 3. The surface 3 is coated with a coating 4, which has a first layer 5, a second layer 6, a third layer 7, a fourth layer 8, and a fifth layer 9. In the case of the variant embodiment of the invention proposed here, for example, the body 2 is steel, the first layer 5 is copper, the second layer 6 is matte nickel, the third layer 7 is a nickel phosphorus alloy, and the fourth layer 8 is a chromium layer. The fifth layer 9 includes a zirconium compound.

(6) In FIG. 2, a coated article 1 with a coating according to the conventional art is shown. The coating 4 here is applied by means of an autocatalytic coating method. The autocatalytic coating method is very slow, and thus time-consuming. Moreover, constant layer thicknesses are produced over all the contours in the autocatalytic coating method. This layer thickness is represented in FIG. 2 by means of the heavy line.

(7) In FIG. 3, the coated article 1 from FIG. 2 is represented once again, with the coating 4 having been applied here by means of an electrolytic coating method. It is readily apparent here that the outer contour 10 in this implementation no longer follows the contour of the coated article. Instead, deposits of different thickness of the coatings are produced on the surface of the coated article, which essentially follow the field lines of the electric fields in the electrolyte bath. It is clearly visible here that a significant reduction in the distance between corner regions 11 can be achieved through the electrolytic coating, in particular in the corner regions 11. Consequently, significantly smoother surfaces can be created as compared to coating with an autocatalytic method, in that gaps or pores that are present are filled or made significantly smaller. This results on the whole in a significantly higher-quality surface of the finished, coated article 1.

(8) The electrolytic coating method is additionally advantageous due to the fact that the entire component or the entire article 1 to be coated is not coated. Instead, it is possible to selectively coat regions of the article 1 to be coated, by which means unwanted coating of water-carrying sections can be avoided completely, but at least largely avoided. In the case of autocatalytic coating, this is not possible in this form without carrying out otherwise required and extremely resource-intensive covering or closure measures on the article 1 to be coated.

(9) The present invention is distinguished, in particular, by high corrosion protection in decorative multilayer systems.

(10) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.