METHOD FOR PRODUCING Cr-Ti-V HYDROGEN STORAGE ALLOYS

• US 20040134308A1
• Filed: 10/24/2003
• Published: 07/15/2004
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: Santoku Corporation (Proterial Ltd.)
• Original Assignee: Santoku Corporation (Proterial Ltd.)
• Inventors: Nakagawa, Junichi, Oka, Yutaka, Takata, Hiroaki, Neoda, Akira
• Granted Patent: US 7,175,721 B2
• Time in Patent Office: Days
• US Class Current: 75/10.27
• CPC Class Codes: B22F 9/008 Rapid solidification processing
• CPC Class Codes: B22F 9/04 starting from solid material, e.g. by crushing, grinding or milling C22C1/1084 takes precedence; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C
• CPC Class Codes: C01B 3/0031 Intermetallic compounds; Metal alloys; Treatment thereof
• CPC Class Codes: C22C 1/02 by melting C22C1/1036 takes precedence
• CPC Class Codes: C22C 27/06 Alloys based on chromium
• CPC Class Codes: H01M 4/383 Hydrogen absorbing alloys
• CPC Class Codes: H01M 8/04216 characterised by the choice for a specific material, e.g. carbon, hydride, absorbent
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/32 Hydrogen storage
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The invention relates to a method for producing high-performance Cr—Ti—V hydrogen storage alloys utilizing thermit process, whereby residence of adversely affecting impurities is inhibited, addition of not less than 10 at % of Ti as an alloy component is realized, and thermal burden on the crucible used in the method is reduced. The method includes the steps of: (A) providing an alloy material (1) comprising a Cr oxide, a V oxide, and a reducing agent Al, and an alloy material (2) comprising Ti; (B) placing said alloy materials in a crucible for thermit reduction so that the alloy material (1) is placed above the alloy material (2); (C) igniting the alloy material (1) placed in step (B) and melting all metal elements contained in the alloy materials with heat of thermit reaction of the alloy material (1); and (D) making an alloy melt obtained in step (C) into an alloy.

Claims

1. A method for producing a Cr—

Ti—

V hydrogen storage alloy utilizing thermit process comprising;

material preparation step (A) of providing an alloy material (1) comprising a Cr oxide, a V oxide, and a reducing agent Al, and an alloy material (2) comprising Ti;

material introduction step (B) of placing said alloy materials in a crucible for thermit reduction so that the alloy material (1) is placed above the alloy material (2);

metal melting step (C) of igniting the alloy material (1) placed in the crucible in step (B) for thermit reaction and melting all metal elements contained in the alloy materials with heat of the thermit reaction of the alloy material (1) to obtain an alloy melt; and

step (D) of making said alloy melt obtained in step (C) into an alloy.

2. The method of claim 1, wherein said alloy material (1) further comprises an oxidizing agent for providing additional heat by thermit reaction, and wherein a content of said Al is a sum of 70 to 90% of a theoretical Al amount required for reducing the Cr oxide and the V oxide, and an amount required for reducing said oxidizing agent.

3. The method of claim 2, wherein said oxidizing agent is selected from the group consisting of barium peroxide, potassium chlorate, sodium chlorate, and mixtures thereof.

4. The method of claim 1, wherein in said step (B), a separation layer having a melting point higher than that of Al is provided between the alloy materials (1) and (2).

5. The method of claim 4, wherein said separation layer is selected from the group consisting of an iron plate, a steel plate, and an alloy steel plate, each of 0.05 to 3.0 mm thick.

6. The method of claim 5, wherein said separation layer contains an auxiliary component selected from the group consisting of Fe, Mn, Mo, Ni, Co, and mixtures thereof.

7. The method of claim 1, wherein said crucible for thermit reduction comprises a separator plate having a sliding nozzle, said separator plate being capable of separating an interior of said crucible into at least upper and lower compartments, and wherein in placing the alloy materials (1) and (2) in the crucible in said step (B), the alloy materials (1) and (2) are arranged separated by said separator plate.

9. The method of claim 1, wherein said alloy materials (1) and (2) are provided so that a resulting Cr—

Ti—

V hydrogen storage alloy contains 25 to 70 at % Cr, 15 to 45 at % Ti, 5 to 45 at % V, and 0.01 to 2 at % Al, and has a melting point not higher than 1600°

C.

10. The method of claim 1, further comprising step (E) of melting said alloy obtained in step (D) with a rare earth metal selected from the group consisting of La, Ce, and misch metal in an amount of not less than 0.2 at % of said alloy to obtain an alloy melt, deoxidizing said alloy melt to lower its oxygen content to not higher than 0.1 wt %, and cooling and solidifying said deoxidized alloy melt.

8. The method of claim, wherein at least one of the alloy materials (1) and (2) further comprises an auxiliary component selected from the group consisting of Fe, Mn, Mo, Ni, Co, and mixtures thereof.