DE1080784B - Use of a palladium-iridium alloy as a material for electrical contacts and potentiometers - Google Patents

Description

GERMAN

In low-voltage technology, you always have high-quality precious metals for contacts and potentiometers and their alloys in use when it comes down to absolute switching reliability and to have uniform electrical conditions. Both with electrical contacts and with potentiometers it is important that the contact resistance at the contact point always remains constant and through external chemical influences are not changed. In the case of potentiometers in particular, there is a further requirement that the specific resistance is largely the same over the entire turn. When it comes to contacts also of particular importance that the contact migration when opening the contact points as possible is small.

Materials based on precious metals, which have proven themselves for electrical contacts and potentiometers, are mainly platinum alloys, for example alloys of platinum with iridium, nickel or Tungsten, gold alloys, for example alloys of gold with nickel, silver or copper, next to it also palladium-silver and palladium-copper alloys.

It has now been shown, surprisingly, that the use of an alloy of 10 to 35%, preferably 20 to 30%, iridium, the remainder palladium as material for electrical contacts and potentiometers significant technical advances in this area brings with it.

The alloys mentioned can be produced with a high degree of uniformity. You own because of her high chemical resistance a constant contact resistance and show straight in the field of low-voltage technology, a particularly small contact migration. This is also in the arc area, so with heavier loads, still remarkably small.

Since the palladium-iridium alloys are characterized by high hardness and wear resistance, are they are also particularly suitable when mechanical stress, such as due to abrasion.

It is noteworthy that the valuable properties of the material according to the invention also then remain if you add more metals in an amount of up to 15% and insofar replaced the palladium. The other platinum metals, gold and silver, but also base metals, such as nickel, copper and cobalt. In no case should the additional Alloy components exceed the iridium content of the alloys. Generally one gets from it refrain from choosing the addition of foreign metals above 5%.

use

a palladium-iridium alloy

as a material for electrical contacts

and potentiometer

Applicant:

W. C. Heraeus Society

with limited liability,

Hanau / M. _r Heraeusstr. 12/14

Dr. Konrad Ruthardt and Dr. Hermann Speidel,

Hanau / M.,
have been named as inventors

The use of the alloys mentioned as a material for electrical contacts and potentiometers compared to the use of platinum-iridium alloys, which has been known for many decades, which represent the oldest contact alloys based on platinum metal, considerable technical Advances that are shown below:

While at the beginning of operation the contact resistance in platinum-iridium alloys and palladium-iridium alloys practically coincides, the contact resistance increases after numerous switching operations in the case of platinum-iridium alloys. As the number of circuits increases contact disturbances thus occur in the platinum-based alloys, which are noticeable in them make that the contact resistances fluctuate extraordinarily and sometimes between double and twenty-five times the normal value. In contrast, the transition resistance remains in the palladium-iridium alloys is constantly low and increases with the number of Circuits barely above its original value.

In addition to the excellent chemical resistance, the palladium-iridium alloys are particularly important in terms of the contact resistance after numerous switching operations important for the platinum-iridium alloys are superior, the switching reliability of the palladium-iridium alloys is even after a long time Operating times far longer than with the platinum-iridium alloys. On top of that, with use the palladium-iridium alloys as a material for electrical contacts and potentiometers

00 J 507/362

a significant cost saving is associated, since palladium-based alloys are far more economical can be produced.

An example of an application is shown in the figure a rivet-shaped contact element is shown, the support 1 of which is made of the palladium-iridium alloy treated here with, for example, 20 to 30% iridium, while the shaft 2 and the lower one Part 3 of the rivet head can consist of a base metal commonly used for contacts.

Claims (2)

Patent claims: !. Use an alloy of 10 to 35%, preferably 20 to 30% iridium, the remainder palladium electrical Contacts and as a material for
Potentiometer. 2. Use of an alloy of the composition specified in claim 1, but which with a corresponding reduction in the palladium content up to 15%, preferably up to 5%, in total one or more other platinum metals, gold, silver, nickel, cobalt or Contains copper for the purpose stated in claim 1. Legacy Patents Considered:
German Patent No. 1 010 742. 1 sheet of drawings © 009 507/362 4.60