Ni-based superalloy part recycling method

Patent metadata

Field	Value
Publication number	US-2019010594-A1
Application number	US-201615932302-A
Country	US
Kind code	A1
Filing date	May 30, 2016
Priority date	Aug 18, 2015
Publication date	Jan 10, 2019
Grant date	—

Abstract

A method for recycling a Ni-based single crystal superalloy part or unidirectionally solidified superalloy part provided with a thermal barrier coating containing at least a ceramic on a surface of a Ni-based single crystal superalloy substrate or Ni-based unidirectionally solidified superalloy substrate, in which the method including the steps of: melting and desulfurizing a Ni-based single crystal superalloy part or Ni-based unidirectionally solidified superalloy part at a temperature of the melting point or more of the Ni-based single crystal superalloy or Ni-based unidirectionally solidified superalloy and less than the melting point of the ceramic; heating a casting mold for a recycled Ni-based single crystal superalloy part or casting mold for a recycled Ni-based unidirectionally solidified superalloy part to a temperature of the melting point or more of the Ni-based single crystal superalloy or Ni-based unidirectionally solidified superalloy; pouring the desulfurized melted Ni-based single crystal superalloy or Ni-based unidirectionally solidified superalloy into the casting mold, and producing a melting stock or growing a Ni-based single crystal superalloy or Ni-based unidirectionally solidified superalloy; and removing the melting stock or the recycled Ni-based single crystal superalloy part or recycled Ni-based unidirectionally solidified superalloy part from the casting mold. In this way, a method for recycling a Ni-based superalloy part, by which the recycle cost of a Ni-based superalloy part and the lifetime cost of a highly efficient gas turbine engine using a Ni-based superalloy part can be significantly reduced, and further a Ni-based superalloy part having the same high-temperature strength and oxidation resistance as those of a newly produced Ni-based superalloy part can be obtained, is provided.

First claim

1 . A method for recycling a Ni-based single crystal superalloy part provided with a thermal barrier coating containing at least a ceramic on a surface of a Ni-based single crystal superalloy substrate, the method comprising the steps of:
melting and desulfurizing the Ni-based single crystal superalloy part at a temperature of the melting point or more of the Ni-based single crystal superalloy and less than the melting point of the ceramic to prepare a desulfurized Ni-based single crystal superalloy; and forming a recycled Ni-based single crystal superalloy part or a melting stock using the Ni-based single crystal superalloy, wherein in a case of directly forming the recycled Ni-based single crystal superalloy part, the method comprises the steps of: heating a casting mold for a recycled Ni-based single crystal superalloy part to have a temperature of the melting temperature or more of the Ni-based single crystal superalloy; pouring the melted Ni-based single crystal superalloy into the casting mold for a recycled Ni-based single crystal superalloy part to grow the Ni-based single crystal superalloy; and removing the recycled Ni-based single crystal superalloy part from the casting mold for a recycled Ni-based single crystal superalloy part, and in a case of forming a recycled Ni-based single crystal superalloy part from a melting stock, the method comprises the steps of: pouring the melted Ni-based single crystal superalloy into a casting mold for a melting stock to form a melting stock; removing the melting stock from the casting mold for a melting stock; and producing a Ni-based single crystal superalloy part from the melting stock.

2 . The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein the method comprises the step of:
peeling off a thermal barrier coating excluding a bond coating or a thermal barrier coating including a bond coating, of the Ni-based single crystal superalloy part.

3 . A method for recycling a Ni-based single crystal superalloy part provided with an oxidation-resistant coating or a Ni-based single crystal superalloy part not provided with an oxidation-resistant coating, on a surface of a Ni-based single crystal superalloy substrate, the method comprising the steps of:
melting and desulfurizing the Ni-based single crystal superalloy part at a temperature of the melting point or more of the Ni-based single crystal superalloy to prepare a desulfurized Ni-based single crystal superalloy; and forming a recycled Ni-based single crystal superalloy part or a melting stock using the Ni-based single crystal superalloy, wherein in a case of directly forming the recycled Ni-based single crystal superalloy part, the method comprises the steps of: heating a casting mold for a recycled Ni-based single crystal superalloy part to have a temperature of the melting temperature or more of the Ni-based single crystal superalloy; pouring the melted Ni-based single crystal superalloy into the casting mold for a recycled Ni-based single crystal superalloy part to grow the Ni-based single crystal superalloy; and removing the recycled Ni-based single crystal superalloy part from the casting mold for a recycled Ni-based single crystal superalloy part, and in a case of forming a recycled Ni-based single crystal superalloy part from a melting stock, the method comprises the steps of: pouring the melted Ni-based single crystal superalloy into a casting mold for a melting stock to form a melting stock; removing the melting stock from the casting mold for a melting stock; and producing a Ni-based single crystal superalloy part from the melting stock.

4 . The method for recycling a Ni-based single crystal superalloy part according to claim 3 , wherein the method comprises the step of:
peeling off an oxidation-resistant coating of the Ni-based single crystal superalloy part coated with the oxidation-resistant coating.

5 . The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein
in the step of desulfurizing the Ni-based single crystal superalloy part, the Ni-based single crystal superalloy part is desulfurized so that a sulfur content of the Ni-based single crystal superalloy part is 3 PPM or less.

6 . The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein the method comprises the step of:
adding an element being deficient to perform composition adjustment so that an alloy composition of the recycled Ni-based single crystal superalloy falls within an acceptable composition range for a genuine material of the Ni-based single crystal superalloy part.

7 . The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein
the step of growing the recycled Ni-based single crystal superalloy comprises the steps of: forming a single crystal by unidirectional solidification; and subjecting the recycled Ni-based single crystal superalloy part to a solution treatment and an aging precipitation treatment.

8 . The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein the method comprises the steps of:
coating the recycled Ni-based single crystal superalloy part with a bond coating and a thermal barrier coating containing a ceramic, or with an oxidation-resistant coating.

9 . The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein
the recycled Ni-based single crystal superalloy part is at least one of a turbine rotor blade, a turbine vane, a combustor liner, a splash plate, a duct segment, and a turbine disk, of a Ni-based single crystal superalloy.

10 . A method for recycling a Ni-based unidirectionally solidified superalloy part provided with a thermal barrier coating containing at least a ceramic on a surface of a Ni-based unidirectionally solidified superalloy substrate, the method comprising the steps of:
melting and desulfurizing the Ni-based unidirectionally solidified superalloy part at a temperature of the melting point or more of the Ni-based unidirectionally solidified superalloy and less than the melting point of the ceramic to prepare a desulfurized Ni-based superalloy; and forming a recycled Ni-based unidirectionally solidified superalloy part or a melting stock using the Ni-based unidirectionally solidified superalloy, wherein in a case of directly forming the recycled Ni-based unidirectionally solidified superalloy part, the method comprises the steps of: heating a casting mold for a recycled Ni-based unidirectionally solidified superalloy part to have a temperature of the melting temperature or more of the Ni-based unidirectionally solidified superalloy; pouring the melted Ni-based superalloy into the casting mold for a recycled Ni-based unidirectionally solidified superalloy part to grow the Ni-based unidirectionally solidified superalloy; and removing the recycled Ni-based unidirectionally solidified superalloy part from the casting mold for a recycled Ni-based unidirectionally solidified superalloy part, and in a case of forming a recycled Ni-based unidirectionally solidified superalloy part from a melting stock, the method comprises the steps of: pouring the melted Ni-based unidirectionally solidified superalloy into a casting mold for a melting stock to form a melting stock; removing the melting stock from the casting mold for a melting stock; and producing a Ni-based unidirectionally solidified superalloy from the melting stock.

11 . The method for recycling a Ni-based unidirectionally solidified superalloy part according to claim 10 , wherein the method comprises the step of:
peeling off a therma

Assignees

• Nat Inst Materials Science

Inventors

• Harada Hiroshi
• Kawagishi Kyoko
• Kobayashi Toshiharu
• Yokokawa Tadaharu
• Osawa Makoto
• YUYAMA Michinari
• Suzuki Shinsuke
• JOH Yuichiro
• UTADA Satoshi

Classifications

• C22B7/00

  Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; {Methods of a general interest or applied to the winning of more than two metals (briquetting of scrap C22B1/248; preliminary treatment of scrap C22B1/005)} · CPC title

• C21D2201/04

  Single or very large crystals · CPC title

• C22F1/10 Primary

  of nickel or cobalt or alloys based thereon · CPC title

• C22B7/003

  only remelting, e.g. of chips, borings, turnings; apparatus used therefor · CPC title

• C22B23/02

  by dry processes · CPC title