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1. WO2016110739 - PROCÉDÉS DE PRODUCTION DE CHROME MÉTALLIQUE ET D'ALLIAGES CONTENANT DU CHROME À FAIBLE TENEUR EN AZOTE ET PRODUITS AINSI OBTENUS

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIMS

1. Processes for producing metallic chromium or chromium-containing alloys with a nitrogen content of below 10 ppm comprising:

i) vacuum-degassing a thermite mixture comprising chromium compounds and metallic reducing agents, contained within a vacuum vessel capable of withstanding a thermite reaction, to an initial pressure less than 1 mbar;

ii) igniting the thermite mixture to effect reduction of the chromium compounds within said vessel under reduced pressure;

iii) solidifying the reaction products under reduced pressure; and

iv) cooling the reaction products to about ambient temperature under reduced pressure,

wherein steps ii) through iv) are conducted under a pressure below 1 bar.

2. Processes according to claim 1, wherein the vacuum vessel is a ceramic or metallic container lined with refractory material.

3. Processes according to claim 2, wherein the vacuum vessel is placed inside a vacuum-tight, water-cooled chamber for the entire reduction reaction.

4. Processes according to claim 1, wherein the reducing agent is aluminum.

5. Processes according to claim 4, wherein the aluminum reducing agent is in powder form.

6. Processes according to claim 1, wherein the thermite mixture additionally comprises at least one energy booster.

7. Processes according to claim 1 wherein the thermite mixture additionally contains an element selected from the group consisting of nickel, iron, cobalt, boron, carbon, silicon, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, rhenium, copper, and mixtures thereof in their metallic form or as compounds thereof capable of metallothermic reduction.

8. Processes according to claim 1, wherein after vacuum-degassing and before ignition, the pressure within the vacuum vessel is increased up to about 200 mbar by introduction of a non-nitrogenous gas.

9. A metallic chromium or chromium-containing alloy having a nitrogen content below 10 ppm.

10. A chromium-containing alloy additionally containing an element selected from the group consisting of nickel, iron, cobalt, boron, carbon, silicon, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, rhenium, copper, and mixtures thereof having a nitrogen content less than 10 ppm prepared by the process of claim 7.