Metal wire rod composed of iridium or iridium alloy

Patent metadata

Field	Value
Publication number	US-10137496-B2
Application number	US-201515125491-A
Country	US
Kind code	B2
Filing date	Mar 23, 2015
Priority date	Mar 28, 2014
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

The present invention provides a metal wire rod composed of iridium or an iridium alloy, wherein the number of crystal grains on any cross-section in a longitudinal direction is 2 to 20 per 0.25 mm 2 , and the Vickers hardness at any part is 200 Hv or more and less than 400 Hv. The iridium wire rod is a material which is produced by a μ-PD method, and has low residual stress and which has a small change in the number of crystal grains and hardness even when heated to a temperature equal to or higher than a recrystallization temperature (1200° C. to 1500° C.). The metal wire rod of the present invention is excellent in oxidative consumption resistance under a high-temperature atmosphere, and mechanical properties.

First claim

The invention claimed is:

1. A metal wire rod composed of iridium or an iridium alloy, wherein the number of crystal grains on all cross-sections parallel to the longitudinal direction is 2 to 20 per 0.25 mm 2 , wherein the wire rod has a Vickers hardness of 200 Hv or more and less than 400 Hv.

2. The metal wire rod according to claim 1 , wherein the number of crystal grains in which the aspect ratio (x/y) based on a longitudinal direction (x) and a direction (y) vertical to the longitudinal direction is 1.5 or more is 20 or less per 0.25 mm 2 on all cross-sections parallel to the longitudinal direction.

3. The metal wire rod according to claim 1 , wherein the iridium alloy is at least any of an iridium alloy containing platinum, ruthenium, rhodium, and nickel in a total amount of 1 to 50% by mass.

4. A method for producing the metal wire rod, the wire rod being defined in claim 1 , comprising the steps of:
(a) providing a raw material made of a molten metal of iridium or an iridium-containing alloy in a molten state in a crucible having a nozzle serving as a die at a bottom of the crucible;
(b) bringing a growing crystal into contact with the molten metal contained in the crucible from the bottom;
(c) pulling the growing crystal downwardly away from the crucible at a constant speed through the nozzle at the bottom of the crucible to cool and to solidify the molten metal and thereby forming the wire rod;
(d) adjusting a pull-down speed of the growing crystal so that a solid-liquid interface between the molten metal and the solidified metal is around the center in a vertical direction of the nozzle; and
(e) adjusting a cooling rate of the wire rod to 120° C./sec to 1° C./sec until the temperature of the wire rod discharged from the nozzle becomes 1200° C. or lower.

5. The metal wire rod according to claim 2 , wherein the iridium alloy is at least any of an iridium alloy containing platinum, ruthenium, rhodium, and nickel in a total amount of 1 to 50% by mass.

6. A method for producing the metal wire rod, the wire rod being defined in claim 2 , comprising the steps of:
(a) providing a raw material made of a molten metal of iridium or an iridium-containing alloy in a molten state in a crucible having a nozzle serving as a die at a bottom of the crucible;
(b) bringing a growing crystal into contact with the molten metal contained in the crucible from the bottom ;
(c) pulling the growing crystal downwardly away from the crucible at a constant speed through the nozzle at the bottom of the crucible to cool and to solidify the molten metal and thereby forming the wire rod;
(d) adjusting a pull-down speed of the growing crystal so that a solid-liquid interface between the molten metal and the solidified metal is around the center in a vertical direction of the nozzle; and
(e) adjusting a cooling rate of the wire rod to 120° C./sec to 1° C./sec until the temperature of the wire rod discharged from the nozzle becomes 1200° C. or lower.

7. A method for producing the metal wire rod, the wire rod being defined in claim 3 , comprising the steps of:
(a) providing a raw material made of a molten metal of an iridium-containing alloy in a molten state in a crucible having a nozzle serving as a die at a bottom of the crucible;
(b) bringing a growing crystal into contact with the molten metal contained in the crucible from the bottom;
(c) pulling the growing crystal downwardly away from the crucible at a constant speed through the nozzle at the bottom of the crucible to cool and to solidify the molten metal and thereby forming the wire rod;
(d) adjusting a pull-down speed of the growing crystal so that a solid-liquid interface between the molten metal and the solidified metal is around the center in a vertical direction of the nozzle; and
(e) adjusting a cooling rate of the wire rod to 120° C./sec to 1° C./sec until the temperature of the wire rod discharged from the nozzle becomes 1200° C. or lower.

Assignees

• Tanaka Precious Metal Ind

Inventors

• Yoshikawa Akira
• Yokota Yuui
• Nakamura Muneki
• Tanaka Kunihiro
• Nakazawa Tatsuya
• Sakairi Koichi

Classifications

• C22C1/02

  by melting {(C22C1/1036 takes precedence)} · CPC title

• B22D11/005 Primary

  of wire (casting on wire B22D19/14) · CPC title

• C22C5/04

  Alloys based on a platinum group metal · CPC title

• B22D21/005

  with high melting point, e.g. Be 1280 degrees C, Ti 1725 degrees C · CPC title

• B22D11/00

  Continuous casting of metals, i.e. casting in indefinite lengths (metal drawing, metal extruding B21C) · CPC title