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US4116755A
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Chem-milling of titanium and refractory metals
Assignee: McDonnell Douglas Corp
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Filing: 1977-09-06
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Granted: 1978-09-26
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Expires: 1997-09-06
Abstract
Abstract An improved composition and process for chemically milling titanium, refractory metals, and their alloys, resulting in decreased absorption of hydrogen, thus allowing chemical milling of beta titanium and alpha beta titanium, which normally cannot be chemically milled in conventional chemical milling solutions because of hydrogen embrittlement. The chemical milling solution itself consists of a mixture of nitric acid; hydrofluoric acid or fluoride salts; derivatives of carbonic acid, such as carbamide; derivatives of monocarboxylic acids containing alkali metal ions, such as sodium benzoate; and a source of sodium ions compatible with the remainder of the composition, preferably sodium nitrate. The addition of sodium benzoate results in a more uniform metal removal rate, thus permitting the producing of high precision parts.
Inventors
- 👤 Dolphus L. Coggins
- 👤 John Gumbelevicius
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:42
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/26
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
117 words
A method of chemically milling and surface treating a material selected from the group consisting of titanium, columbium, molybdenum, tungsten, tantalum, and their alloys without excessive hydrogen absorption comprising the steps of: (a) exposing said material to a solution containing per liter of solution about 126 to about 700 g pure nitric acid equivalent, an amount of fluoride producing material sufficient to provide the equivalent of about 8.8 to about 176.1 of pure hydrofluoric acid, at least 10 grams of a derivative of carbonic acid, at least about 1.5 gm monocarboxylic acid derivative containing alkali metal ions, (b) at a temperature of about 0°-110° C, (c) for a period of time sufficient to remove the undesired material.
Claim 2
Independent Claim
117 words
A method of chemically milling and surface treating a material selected from the group consisting of titanium, columbium, molybdenum, tungsten, tantalum, and their alloys without excessive hydrogen absorption comprising the steps of: (a) exposing said material to a solution containing per liter of solution about 126 to about 700 g pure nitric acid equivalent, an amount of fluoride producing material sufficient to provide the equivalent of about 8.8 to about 176.1 of pure hydrofluoric acid, at least 10 grams of a derivative of carbonic acid, at least about 1.5 gm monocarboxylic acid derivative containing alkali metal ions, (b) at a temperature of about 0°-110° C, (c) for a period of time sufficient to remove the undesired material.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein said solution includes at least about 0.541 g of sodium ions per liter.
Claim 4
Dependent Claim
17 words
The method of claim 1 wherein the metal removal rate is between 0.025 mm/surface/min to 0.15 mm/surface/min.
Claim 5
Dependent Claim
13 words
The method of claim 1 wherein the monocarboxylic acid derivative is sodium benzoate.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein the carbonic acid derivative is selected from the group consisting of carbamide, urea nitrate, urea oxalate, and semicarbazide.
Claim 7
Dependent Claim
12 words
The method of claim 5 wherein the carbonic acid derivative is carbamide.
Claim 8
Dependent Claim
18 words
The method of claim 2 wherein material from which the portion of sodium ions come is sodium nitrate.
Claim 9
Dependent Claim
91 words
A composition for chemically milling and surface treating a material selected from the group consisting of titanium, columbium, molybdenum, tungsten, tantalum, and their alloys without excessive hydrogen absorption comprising per liter of solution (a) about 126 to about 700 g pure nitric acid equivalent, (b) an amount of fluoride producing material sufficient to provide the equivalent of about 8.8 to about 176.1 of pure hydrofluoric acid, (c) at least 10 grams of a derivative of carbonic acid and (d) at least about 1.5 gm monocarboxylic acid derivative containing alkali metal ions.
Claim 10
Dependent Claim
91 words
A composition for chemically milling and surface treating a material selected from the group consisting of titanium, columbium, molybdenum, tungsten, tantalum, and their alloys without excessive hydrogen absorption comprising per liter of solution (a) about 126 to about 700 g pure nitric acid equivalent, (b) an amount of fluoride producing material sufficient to provide the equivalent of about 8.8 to about 176.1 of pure hydrofluoric acid, (c) at least 10 grams of a derivative of carbonic acid and (d) at least about 1.5 gm monocarboxylic acid derivative containing alkali metal ions.
Claim 11
Dependent Claim
19 words
The composition of claim 8 wherein said solution includes at least about 0.541 g of sodium ions per liter.
Claim 12
Dependent Claim
13 words
The composition of claim 8 wherein the monocarboxylic acid derivative is sodium benzoate.
Claim 13
Dependent Claim
24 words
The composition of claim 8 wherein the carbonic acid derivative is selected from the group consisting of carbamide, urea nitrate, urea oxalate, and semicarbazide.
Claim 14
Dependent Claim
12 words
The composition of claim 8 wherein the carbonic acid derivative is carbamide.
Claim 15
Dependent Claim
19 words
The composition of claim 9 wherein the material from which the portion of sodium ions come is sodium nitrate.
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) | 1981-09-25 | 1982-03-27 | 1982-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-25 | 1986-03-27 | 1986-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-25 | 1990-03-27 | 1990-09-26 | $7700.00 | Window Closed / Lapsed |