Method for manufacturing alloys of precious metals and alloys of precious metals thus obtained

Patent metadata

Field	Value
Publication number	US-11987869-B2
Application number	US-202017273918-A
Country	US
Kind code	B2
Filing date	Jul 17, 2020
Priority date	Jul 18, 2019
Publication date	May 21, 2024
Grant date	May 21, 2024

Abstract

A method for manufacturing an alloy formed from a boride of a precious metal, may involve reacting a source of the precious metal with a source of boron in a salt or a mixture of salts in the molten state. An alloy formed from a boride of a precious metal may include crystalline nanoparticles of MxBy with M being a precious metal, distributed in an amorphous matrix of B or in an amorphous matrix of B and of MzBa.

First claim

The invention claimed is:

1. A method for manufacturing a powder of alloy of a boride of a precious metal from the precious metal and from boron, the method comprising:
mixing a source of the boron, a source of the precious metal, and salt(s) in the solid state to obtain a mixture;
heating the mixture to a temperature between 100 and 1000° C. to react the source of the boron and the source of the precious metal in order to obtain the metal boride of the precious metal to obtain a heated mixture;
cooling the heated mixture;
separating solidified salt(s) from the boride of the precious metal, the boride of the precious metal being in form of the powder including aggregates formed by crystalline nanoparticles of the boride of the precious metal, M x B y , distributed in a matrix of amorphous boron B, a y/x ratio of the crystalline nanoparticles being greater than or equal to 1,
wherein the precious metal is selected from the group consisting of gold, silver, platinum, palladium, ruthenium, and iridium,
wherein the source of the precious metal is selected from the group selected from a sulfate, carbonate, acetate, nitrate, acetylacetonate, or mixture of two or more of any of these, of the precious metal, and
wherein the method comprises reacting the source of the precious metal with the source of the boron in the salt(s) in molten state.

2. The method of claim 1 , wherein the source of boron is selected from the group consisting of a borane, borohydride, or mixture of two or more of any of these.

3. The method of claim 2 , wherein the source of boron is sodium borohydride, NaBH 4 .

4. The method of claim 1 , further comprising:
mixing a powder of the precious metal and/or of further precious metal with the powder of the alloy to obtain a second mixture of the powder of the boride of precious metal with the precious metal and/or with the further precious metal;
sintering the second mixture, and
reducing the boride of the precious metal resulting from the sintering to a powder state,
wherein the method comprises enriching the powder of the alloy with further precious metal.

5. The method of claim 4 , wherein the powder of the precious metal and/or the further precious metal has a d50 of less than 70 μm, and
wherein the powder of the boride has a d50 of less than 70 μm.

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Miko Csilla
• Grosjean Rémi
• Bazin Jean-Luc

Classifications

• C22C32/0005

  with at least one oxide and at least one of carbides, nitrides, borides or silicides as the main non-metallic constituents · CPC title

• C22C1/10

  Alloys containing non-metals (C22C1/05, C22C1/08 take precedence) · CPC title

• C22C1/053

  with in situ formation of hard compounds · CPC title

• G04B19/042

  Construction and manufacture of the hands; arrangements for increasing reading accuracy (hands with illumination G04B19/305; specially shaped hands, e.g. figures or pictures G04B45/0061; clockwork in the hands G04B45/043; invisible drive of the hands G04B45/046) · CPC title

• G04B19/12

  Selection of materials for dials or graduations {markings} · CPC title