DE2839671A1 - Electric contact with layered structure - is produced by depositing additional layer of soft rare metal onto layer of hard rare metal - Google Patents

Abstract

The contact consists of a core of conductive metal, such as bronze, German silver, copper or suitable alloys. It is coated by a nickel support layer for a rare metal alloy and is coated with additional layer (4) of a soft rare metal. he metal of the two layers are preferably of identical group and are 0.3-1.5 microns thick Typically gold, palladium or their alloys are used in the process. The contact structure safeguard high arcing resistance and long service life. The core coatings exclude porosity which is detrimental to the contact usefulness.

Description

DESCRIPTION

The invention relates to a method for producing contacts for electrical engineering, in which a contact core made of conductive metal such as bronze, Alpaca, copper or related alloys with a base layer of nickel for a precious metal is surrounded, which is then followed by a layer of a hard one Precious metal alloy is applied.

Such contacts are then used in the field of low-voltage technology used when it comes to minimum energy losses and maximum durability of the contacts goes. The precious metals are mainly gold, silver, palladium or their alloys used.

Efforts have been made for a long time to improve the wear resistance of precious metal coverings and thus to increase the service life of the contacts. For this reason have been worldwide Precious metal alloys (e.g. gold alloys) developed which increase the hardness of the pure Precious metals (of gold) considerably exceed.

However, these hard precious metal coverings have the expectations placed on them only partially fulfilled. Reliable contacts must be provided with pore-free coatings so that the thickness of the coverings must be in the range from 2 to several ß. As a result, the consumption of valuable precious metal is very high. Also the wear resistance could not be increased to the desired extent with these coverings.

The object of the invention is therefore to provide a method for production of contacts, which allows contacts with a low energy loss factor and with a significantly longer service life with the same precious metal consumption or with significantly reduced precious metal consumption with a slightly increased service life in relation to to establish the familiar contacts with hard gold.

This task is reflected in the characterizing part of the main claim Features solved.

Advantageous designs are described in the subclaims.

In the following the invention will be described with reference to a drawing showing shows a schematic representation of a contact produced according to the invention, explained in more detail.

A contact core 1 made of bronze, alpaca, copper or their alloys is with a carrier layer 2 for a noble metal, including preferably nickel is coated. A hard noble metal layer 3, e.g. made of hard gold, hard palladium, hard silver or corresponding hard precious metal alloys upset. Up to this stage the contacts correspond to those known up to now Production method in which the hard precious metal layer is at least 2 thick.

According to the invention, the hard noble metal layer 3 with an additional Noble metal layer 4 coated from soft noble metal, preferably a metal is chosen from the same family as layer 3, i.e.

when the layer 3 consists of hard gold or hard palladium the layer 4 correspondingly of pure, i.e.

soft gold or palladium.

Tests have shown that with a 1 strong hard noble metal layer 3 and a 1 strong soft noble metal layer 4 extend the service life of the contacts compared to contacts with a 2 thick, only one hard precious metal layer existing layer doubled.

In the case of contacts with a 0.5 thick hard noble metal layer 3 and compared to a 0.5 thick soft noble metal layer 4, the service life is extended Contacts with a known 2 thick layer made solely of hard noble metal 20%, whereby considerable amounts of precious metal were also saved.

If the contacts on the carrier layer 2 only had a 2 thick layer made of soft precious metal, they had a 40% shorter lifespan than that known contacts with a 2 strong hard precious metal layer.

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Claims (6)

Process for making contacts for electrical engineering. PATENT CLAIMS Process for the production of contacts for electrical engineering, in which a contact core made of conductive metal such as bronze, alpaca, copper or related alloys with a support layer made of nickel for a noble metal is surrounded, on which subsequently a layer of a hard noble metal alloy is applied, d u r c h it is not noted that on the layer (3) made of hard noble metal alloy an additional layer (4) made of a soft noble metal is applied. 2. The method according to claim 1, d a d u r c h g e k e n n -z e i c n e t that the metals of the layers (3, 4) are taken from the same family will. 3. The method according to claim 1 or 2, d a d u r c h g e -k e n n z e i c h n e t that the layer (3) made of hard noble metal alloy and the layer (4) made of soft precious metal each have a thickness of about 0.3 to 1.5. 4. The method according to claim 1 or 2, d a d u r c h g e -k e n n z ei c h ne t that the layer (3) made of hard noble metal alloy and the layer (4) made of soft precious metal each have a thickness of about 0.5. 5. The method according to any one of claims 1 to 4, d a d u r c h g e k It is noted that gold, palladium or their alloys are used as precious metals be taken. 6. Contacts produced according to the method according to any one of the claims 1 to 5, d u r c h e k e n n n z e i c h -n e t that they consist of a contact core (1), a carrier layer (2) and a coating system made of a hard noble metal alloy layer (3) and a soft noble metal layer (4) covering them, wherein the metals of the covering system are taken from a related family.