DE201666C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

CLASS 48 ». GROUP

Addendum to patent 201664 of August 20, 1907.

Patented in the German Empire on October 18, 1907. Longest duration: August 19, 1922.

Efforts to platinize base metals in such a way that they become the platinum for certain can replace technical purposes, have so far not led to a satisfactory result, especially not when it comes to the fact that the substitute against higher temperature should be resistant. "The present process enables

to produce a substitute for platinum that is insensitive to high temperatures, z. B. allows melting in glass and; is characterized by cheapness.

^ Nan uses the Metals of the iron group, whose representatives iron, cobalt, and nickel have, on the one hand, a high melting point, but also on the other Able to form alloys which have a coefficient of expansion that comes close to that of platinum own.

To the metals of the iron group or their alloys at all with a reasonably To provide a firmly adhering coating of platinum metal, it was usually first coated electrolytically with copper and then only electrolytically platinized, or you. has electrolytically mixed from a Solution of platinum and base metal deposited on the base metal (British patent specification 7853/1894) ..

These methods may be suitable for all those cases in which the platinum coating is only subjected to low stress; to satisfy this, however, higher demands, for example, can withstand temperatures of 900 to ⁰ C. iooo, they no longer meet the 'requirements because of the precipitation starts or peeling; experience shows that platinum alloys very easily with copper (according to Muspratt already at 350 ^° C.), but it then flakes off.

According to the present invention, one can have a tough coating that does not flakes off and does not tarnish on metals of the iron group or their alloys produce, if one in the following, for example described on the nickel manner moves.

A nickel article well prepared in the usual way for electroplating (Wire or sheet metal) is first treated in an electrolyte, which is 25 percent Contains platinum and 75 percent nickel. By using suitable current density and voltage (e.g. 0.6 to 0.8 amperes for 1 qdcm at 4 to 6 \ ^ olt) a precipitate is obtained little platinum and much nickel.

This precipitate is scraped as usual and dried and subjected to it, the object of annealing in hydrogen at 900 to 1000 ⁰ C..

As a result, the precipitate is welded onto the base, apparently the hydrogen plays a mediating role by having the

Penetrates or loosens metals and thereby creates an intimate connection, d. H. an intertwining this causes.

The object treated in this way is now brought into a second bath, which Contains 50 percent platinum and 50 percent nickel, and after electrolysis exactly as before also glowed in hydrogen, whereupon it is brought into a third bath, which Contains 75 percent platinum and 25 percent nickel; then the hydrogen is closed again glow.

The object, such as a wire, now consists of pure nickel inside, according to

! 5 towards the surface, however, always from one point of view richer in platinum alloy of platinum and nickel.

After the treatment in the third mixed electrolyte by coating with a thin layer of pure platinum, again followed in hydrogen at 1000 to JiOO ⁰ C. is annealed. This coating with pure platinum and annealing after each coating is repeated several times depending on the desired thickness of the platinum coating.

The thought of galvanic precipitation by annealing in a reducing atmosphere Welding onto the base metal is known per se (cf. the German Patent documents 132614 and 175937 as well as the British patent 15037/1903). The use of this idea in platinum plating in connection with the other measures specified above, however, results in a new and valuable technical product, the Platinum substitute represents for those cases in which since then only pure platinum or alloys of platinum metals could be used.

Claims (1)

Patent ^ claim: Process for the production of platinum coatings on difficult-to-melt base metals, such as iron, nickel, cobalt or their alloys, according to patent 201664, characterized in that instead of the one-time deposit of an alloy of platinum with one of the Base metals are alloys with a gradually increasing content of platinum metal and decreasing base metal content and only then multiple precipitations of pure platinum metal applied electrolytically while annealing every time in a reducing atmosphere such as hydrogen.