# US 11,440,139 B2 · Liquid enhanced laser stripping

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- Number: US 11,440,139 B2
- Document ID: US11440139B2
- Status: Granted
- Kind: B2
- Application number: 15/970,518
- Filed: 2018-05-03
- Published: 2019-11-07
- Granted: 2022-09-13
- Earliest claimed: 2018-05-03
- Assignees: Raytheon Technologies Corporation
- Applicants: United Technologies Corporation
- Inventors: Henry H. Thayer; Dmitri Novikov; Robert J. Meehan; Bartolomeo Palmieri
- Web page: https://patentgrep.com/patent/US11440139B2

## CPC

- B23K 26/362: Laser etching
- B23K 26/0622: by shaping pulses
- B23K 26/083: {Devices involving movement of the workpiece in at least one axial direction}
- B23K 26/0869: {Devices involving movement of the laser head in at least one axial direction}
- B23K 26/146: the fluid stream containing a liquid
- B23K 26/402: involving non-metallic material, e.g. isolators
- B23K 31/10: relating to cutting or desurfacing
- F01D 5/286: {Particular treatment of blades, e.g. to increase durability or resistance against corrosion or erosion (F01D5/288 takes precedence)}
- B23K 2101/001: {Turbines}
- B23K 2101/34: Coated articles {; Surface treated articles}
- B23K 2101/35: {Surface treated articles}
- B23K 2103/26: {Alloys of Nickel and Cobalt and Chromium}
- B23K 2103/52: {Ceramics}
- F05D 2230/13: using lasers
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

A method for stripping ceramic from a component includes applying a liquid to a ceramic coating of an outer surface of the component. The method also includes directing a plurality of laser pulses at the ceramic coating with the applied liquid in order to spall the ceramic coating from the component.

## Claims

### Claim 1

A method for stripping a ceramic coating from a component, comprising:
wetting a ceramic coating on an outer surface of the component with a liquid by spraying the liquid onto the ceramic coating; and
using a laser generator to direct a plurality of laser pulses at the ceramic coating with the applied liquid in order to spall the ceramic coating from the component, the laser generator including a fiber laser generator,
wherein the liquid includes an ink to absorb energy from the plurality of laser pulses such that the liquid changes from a liquid state to a gaseous state in response to receiving at least some of the plurality of laser pulses.

### Claim 2 (depends on 1)

The method of claim 1, wherein the fiber laser generator generates the plurality of laser pulses using an optical fiber as an active gain medium.

### Claim 3 (depends on 1)

The method of claim 1, wherein each of the plurality of laser pulses has a pulse duration that is between 2 nanoseconds and 500 nanoseconds.

### Claim 4 (depends on 1)

The method of claim 1, wherein each of the plurality of laser pulses has a power of between 500 watts and 10 kilowatts.

### Claim 5 (depends on 1)

The method of claim 1, further comprising at least one of moving the component relative to the plurality of laser pulses or moving the plurality of laser pulses relative to the component while directing the plurality of laser pulses at the ceramic coating in order to apply at least one pulse of the plurality of laser pulses to each area of the component that includes the ceramic coating in order to remove all of the ceramic coating.

### Claim 6 (depends on 1)

The method of claim 1, wherein the ceramic coating has a columnar structure grown on a metallic bond coating of the component such that the liquid fills in gaps between columns of the columnar structure.

### Claim 7 (depends on 1)

The method of claim 1, wherein the ceramic coating includes at least one of an yttrium stabilized zirconia or a gadolinium zirconate, and the component includes at least one of a nickel, a cobalt, a chromium, an aluminum, or an yttrium.

### Claim 8

A method for stripping a ceramic coating from a component, comprising:
applying a liquid including water to a ceramic coating of an outer surface of the component;
using a laser generator to direct a plurality of laser pulses at the ceramic coating with the applied liquid to spall the ceramic coating from the component, the laser generator including a fiber laser generator; and
at least one of moving the component relative to the plurality of laser pulses or moving the plurality of laser pulses relative to the component while directing the plurality of laser pulses at the ceramic coating,
wherein the liquid includes an ink to absorb energy from the plurality of laser pulses such that the liquid changes from a liquid state to a gaseous state in response to receiving at least some of the plurality of laser pulses.

### Claim 9 (depends on 8)

The method of claim 8, wherein each of the plurality of laser pulses have a pulse duration that is between 2 nanoseconds and 500 nanoseconds and a power of between 500 watts and 10 kilowatts.

### Claim 10 (depends on 9)

The method of claim 9, wherein the fiber laser generator generates the plurality of laser pulses using an optical fiber as an active gain medium.

### Claim 11 (depends on 9)

The method of claim 9, wherein the fiber laser generator generates the plurality of laser pulses using at least one of stimulated Raman scattering or four-wave mixing as a gain media.