Ni-based superalloy part recycling method

Patent metadata

Field	Value
Publication number	US-10689741-B2
Application number	US-201615932302-A
Country	US
Kind code	B2
Filing date	May 30, 2016
Priority date	Aug 18, 2015
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

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

The invention claimed is:

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 in a range from 1400° C. to 2000° C. 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 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, and
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 in a range from 1400° C. to 1600° C.;
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. 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.

4. 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.

5. 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.

6. The method for recycling a Ni-based single crystal superalloy part according to claim 1 , wherein
the step of melting and desulfurizing the Ni-based single crystal superalloy part is performed at a temperature in a range from 1500° C. to 1700° C., and
in the case of directly forming the recycled Ni-based single crystal superalloy part, the casting mold for the recycled Ni-based single crystal superalloy part is heated to have a temperature in a range from 1450° C. to 1600° C.

7. 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 in a range from 1400° C. to 2000° C. 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 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, and
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 in a range from 1400° C. to 1600° C.;
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.

8. The method for recycling a Ni-based single crystal superalloy part according to claim 7 , 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.

9. The method for recycling a Ni-based single crystal superalloy part according to claim 7 , 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.

10. The method for recycling a Ni-based single crystal superalloy part according to claim 7 , 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.

11. The method for recycling a Ni-based single crystal superalloy part according to claim 7 , 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.

12. The method for recycling a Ni-based single crystal superalloy part according to claim 7 , wherein
the step of melting and desulfurizing the Ni-based single crystal superalloy part is performed at a temperature in a range from 1500° C. to 1700° C., and
in the case of directly forming the recycled Ni-based single crystal superalloy part, the casting mold for the recycled Ni-based single crystal superalloy part is heated to have a temperature in a range from 1450° C. to 1600° C.

13. 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 in a range from 1400° C. to 2000° C. to prepare a desulfurized Ni-base

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

• B09B3/40

  involving thermal treatment, e.g. evaporation (processes using mineral binders involving a melting or softening step B09B3/29; involving radiation B09B3/50) · CPC title

• Y02T50/60

  Efficient propulsion technologies, e.g. for aircraft · CPC title

• Y02P10/20

  Recycling · CPC title

• C22B23/02

  by dry processes · CPC title

• C21D2201/04

  Single or very large crystals · CPC title