US4411730A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective chemical milling of recast surfaces
Assignee: RTX Corp
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Filing: 1982-01-11
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Granted: 1983-10-25
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Expires: 2002-01-11
Abstract
Abstract Disclosed is a process for machining nickel-base superalloys wherein a thermal-effect process, such as laser or electric discharge machining, is first used to remove material but leaves a recast layer. Next a chemical milling process is used wherein the etchant only attacks and removes the recast layer. The etchant is comprised by volume percent of 40-60 HNO 3 , 5-20 HCl, and balance H 2 O, with which is included 0.008-0.025 moles/liter FeCl 3 and at least 0.016 moles/liter CuSO 4 . The FeCl 3 improves removal rate but tends to cause unwanted pitting and intergranular attack. These tendencies are inhibited by the addition of CuSO 4 ; preferably the molar ratio of CuSO 4 to FeCl 3 is 2:1. The beneficial combination of FeCl 3 and CuSO 4 is usable in other etchants.
Inventors
- 👤 Robert E. Fishter
- 👤 Henry Lada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:45
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/20; C23F1/28
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
88 words
Machining the surface of a nickel-base superalloy workpiece by the process which comprises: removing workpiece material using a thermal-effect process which causes melting and vaporization of metal, thereby leaving on the workpiece surface a recast layer; and contacting the surface from which material is removed with an etchant comprised by volume percent of 40-60 HNO 3 , 5-20 HCl, balance H 2 O, at least 0.016 moles/liter CuSO 4 and 0.008-0.025 moles/liter FeCl 3 , thereby chemically dissolving the recast layer without substantially removing other workpiece surface material.
Claim 2
Dependent Claim
88 words
Machining the surface of a nickel-base superalloy workpiece by the process which comprises: removing workpiece material using a thermal-effect process which causes melting and vaporization of metal, thereby leaving on the workpiece surface a recast layer; and contacting the surface from which material is removed with an etchant comprised by volume percent of 40-60 HNO 3 , 5-20 HCl, balance H 2 O, at least 0.016 moles/liter CuSO 4 and 0.008-0.025 moles/liter FeCl 3 , thereby chemically dissolving the recast layer without substantially removing other workpiece surface material.
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein the thermal-effect process is one utilizing beam energy, such as from a laser or electron beam.
Claim 4
Dependent Claim
15 words
The process of claim 1 wherein the thermal-effect process is one utilizing an electric discharge.
Claim 5
Dependent Claim
15 words
The process of claim 2 wherein the removal of material produces holes in the workpiece.
Claim 6
Dependent Claim
38 words
The process of claim 1 wherein the etchant is maintained at 40°-80° C. and which further comprises sensing the completion of removal of the recast layer from a substantial diminution in the evolution of gas at the workpiece.
Claim 7
Dependent Claim
19 words
The process of claim 1 wherein the molar ratio of FeCl 3 and CuSO 4 is maintained at 1:2.
Claim 8
Dependent Claim
35 words
The process of claim 1 wherein the etchant consists by volume percent of about 50 HNO 3 , 10 HCl, 40 H 2 O, with 1.3 g/l FeCl 3 and 2.6 g/l CuSO 4 .
Claim 9
Dependent Claim
32 words
The process of claims 1 or 7 where in the superalloy is based on the alloy consisting by weight percent of 10Co, 9Cr, 2Ti, 5Al, 12W, 1Cb, 0.15C, 0.015B, 0.05Zr, balance Ni.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-24 | 1987-04-25 | 1987-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-24 | 1991-04-25 | 1991-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-24 | 1995-04-25 | 1995-10-25 | $7700.00 | Window Closed / Lapsed |