# US 6,719,892 B2 · Selective removal of brazing compound from joined assemblies

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- Number: US 6,719,892 B2
- Document ID: US6719892B2
- Status: Granted
- Kind: B2
- Application number: 09/849,068
- Filed: 2001-05-04
- Published: 2003-01-30
- Granted: 2004-04-13
- Earliest claimed: 2001-05-04
- Assignees: United Technologies Corporation
- Inventors: Mark Jaworowski; Michael A Kryzman
- Web page: https://patentgrep.com/patent/US6719892B2

## CPC

- C25F 5/00: Electrolytic stripping of metallic layers or coatings
- B23K 1/018: Unsoldering; Removal of melted solder or other residues
- B23K 35/304: {with Cr as the next major constituent}
- B23K 2101/001: {Turbines}
- C25F: PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- 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

## Abstract

A process for selective removal of a nickel alloy brazing composition from a nickel-base alloy component includes the steps of providing a brazed assembly including nickel-base alloy components joined by nickel alloy brazing composition; immersing the assembly in an electrolyte; and applying a potential across the electrolyte at a magnitude wherein the nickel-base alloy components are electrochemically passive and the nickel alloy brazing composition dissolves whereby the brazing composition is removed from the components.

## Claims

### Claim 1

A process for selective removal of a nickel alloy brazing composition from a nickel-base alloy component, comprising the steps of:
providing a brazed assembly comprising nickel-base alloy components joined by nickel alloy brazing composition, wherein said nickel-base alloy components are provided from a material having a nominal composition as follows:
C Mn Si S Cr Co Nb + Ta Min — — — — 14.0 — 0.70 Max 0.80 1.00 0.50 0.01 17.0 1.0 1.20 Ni Cu Ti Al Fe — Min 0.70 — 2.25 0.40 5.0 % Max — 0.50 2.75 1.00 9.0 %
immersing said assembly in an electrolyte; and
applying a potential across said electrolyte at a magnitude wherein said nickel-base alloy components are electrochemically passive and said nickel alloy brazing composition dissolves whereby said brazing composition is removed from said components.

### Claim 2 (depends on 1)

The process of claim 1, wherein said electrolyte comprises a mineral acid solution.

### Claim 3 (depends on 2)

The process of claim 2, wherein said mineral acid solution is selected from the group consisting of solutions containing HCl, HNO3 and mixtures thereof.

### Claim 4 (depends on 1)

The process of claim 1, wherein said potential is greater than 0.0 and up to about 1.0 volts versus a Ag/AgCI reference electrode.

### Claim 5 (depends on 1)

The process of claim 1, wherein said brazing composition has a lower melting point than said components.

### Claim 6 (depends on 1)

The process of claim 1, wherein said brazing composition comprises nickel-chromium alloy brazing composition and wherein said components comprise nickel-chromium alloy components.

### Claim 7 (depends on 1)

The process of claim 1, wherein said brazing composition has a composition as follows:
Cr: 7.0% wt. B: 3.10% wt. Si: 4.50% wt. Fe: 3.0% wt. C: 0.06% wt. max Ni: remainder.

### Claim 8 (depends on 1)

The process of claim 1, wherein said brazing composition is a nickel-chromium alloy containing boron, silicon and iron, and said nickel-base alloy components are provided of a nickel-chromium alloy containing iron, titanium, at least one of niobium and tantalum, and aluminum.

### Claim 9 (depends on 1)

The process of claim 1, wherein the electrolyte consists essentially of a solution of one mineral acid selected from the group consisting of HCl and HNO3.

### Claim 10

A process for selective removal of a nickel alloy brazing composition from a nickel-base alloy component, comprising the steps of:
providing a brazed assembly comprising nickel-base alloy components joined by nickel alloy brazing composition;
immersing said assembly in an electrolyte; and
applying a potential across said electrolyte at a magnitude wherein said nickel-base alloy components are electrochemically passive and said nickel alloy brazing composition dissolves whereby said brazing composition is removed from said components, wherein said potential is greater than 0.0 and up to about 1.0 volts versus a Ag/AgCl reference electrode.

### Claim 11

A process for selective removal of a nickel alloy brazing composition from a nickel-base alloy component, comprising the steps of:
providing a brazed assembly comprising nickel-base alloy components joined by nickel alloy brazing composition;
immersing said assembly in an electrolyte, wherein the electrolyte consists essentially of a solution of one mineral acid selected from the group consisting of HCI and HNO3; and
applying a potential across said electrolyte at a magnitude wherein said nickel-base alloy components are electrochemically passive and said nickel alloy brazing composition dissolves whereby said brazing composition is removed from said components.