US2481306A - Electrochemical polishing of tantalum - Google Patents
Electrochemical polishing of tantalum Download PDFInfo
- Publication number
- US2481306A US2481306A US49853A US4985348A US2481306A US 2481306 A US2481306 A US 2481306A US 49853 A US49853 A US 49853A US 4985348 A US4985348 A US 4985348A US 2481306 A US2481306 A US 2481306A
- Authority
- US
- United States
- Prior art keywords
- tantalum
- metal
- anodic
- acid
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 title description 12
- 229910052715 tantalum Inorganic materials 0.000 title description 8
- 238000005498 polishing Methods 0.000 title description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 14
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 6
- 235000011167 hydrochloric acid Nutrition 0.000 description 6
- 239000002253 acid Substances 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/22—Polishing of heavy metals
- C25F3/26—Polishing of heavy metals of refractory metals
Definitions
- This invention relates to electropolishing of metals and electrolytes employed in that operation. More particularly the invention comprises a method of electropolishing tantalum and an electrolyte comprising hydrofluoric acid and a strong acid such as hydrochloric or sulfuric acid.
- tantalum metal exhibits valve action. That is, when a current is passed through the metal, as an electrode submerged in an electrolyte, and in such a direction as to make the metal anodic, a resistance is created causing the flow of current to cease. When this occurs, even the slight degree of anodic solution necessary for electropolishing cannot take place, and it is this phenomenon which has heretofore prevented the electropolishing of tantalum.
- An object of this invention is to provide a method of polishing tantalum metal wherein the valve action of the metal is overcome.
- Another object of the invention is to provide an electrolyte enabling the contemplated method to be carried out
- the tantalum metal to be polished is made anodic in an aqueous solution, containing hydrofluoric acid together with hydrochloric acid and/or sulfuric acid of a certain, predetermined, critical composition and concentration, thereby obtaining, upon passage of current at a certain critical anodic current density, a dissolution of the surface irregularities of the metal giving it a fine high polish.
- composition and concentration of the electrolytic bath employed will preferably be:
- Hydrochloric acid 32-38 the total combined acid concentration being be tween 34% and 45%, the balance being substantially water, in the case hydrochloric acid is employed;
- a current density of from 40 to 60 milliamperes per square centimeter has been found to avoid valve action, employing an electrolytic bath having a composition and concentration as above stated.
- the metal may dissolve too rapidly with excessive loss of material and production of an etched surface or it may valve, that is, the passage of current may cease and the surface of the metal remain unchanged or the metal may behave erratically and a periodic pulsation of current, accompanied by the formation of fiaky material dropping from the surface, may result.
- Tantalum is made anodic at a current density of 67 milliamperes per square centimeter in an aqueous solution of hydrofluoric and hydrochloric acids, which is 4%, by weight, hydrogen fluoride and 34%, by weight, hydrogen chloride.
- the operation is conducted at room temperature. In about 10 minutes the surface has developed a high mirror-like finish.
- Tantalum is made anodic with a current density of 40 milliamperes per square centimeter in an aqueous solution of hydrofluoric and sulfuric acids, which is 4%, by weight, hydrogen fluoride and 89%, by weight, sulfuric acid.
- the operation is conducted at room temperature. In this case polishing will result after about 20 minutes of electrolysis.
- tantalum metal can be electropolished employing the electrolytes, set forth, at the indicated ranges of concentrations, and the current densities, also as indicated.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Description
Patented Sept. 6, 1949 ELECTROCHEMICAL POLISHING OF TANTALUM John F. Gall, Narberth, and Henry C. Miller, Wyndmoor, Pa., assignors to The Pennsylvania Salt Manufacturing Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing.
Original application March 15,
1944, Serial No. 526,656. Divided and this application September 17, 1948, Serial No. 49,853
2 Claims. (01. 204-140) This invention relates to electropolishing of metals and electrolytes employed in that operation. More particularly the invention comprises a method of electropolishing tantalum and an electrolyte comprising hydrofluoric acid and a strong acid such as hydrochloric or sulfuric acid.
It is known that tantalum metal exhibits valve action. That is, when a current is passed through the metal, as an electrode submerged in an electrolyte, and in such a direction as to make the metal anodic, a resistance is created causing the flow of current to cease. When this occurs, even the slight degree of anodic solution necessary for electropolishing cannot take place, and it is this phenomenon which has heretofore prevented the electropolishing of tantalum.
An object of this invention is to provide a method of polishing tantalum metal wherein the valve action of the metal is overcome.
Another object of the invention is to provide an electrolyte enabling the contemplated method to be carried out,
Certain other objects and advantages are apparent from a consideration of this specification and claims.
According to the invention, the tantalum metal to be polished is made anodic in an aqueous solution, containing hydrofluoric acid together with hydrochloric acid and/or sulfuric acid of a certain, predetermined, critical composition and concentration, thereby obtaining, upon passage of current at a certain critical anodic current density, a dissolution of the surface irregularities of the metal giving it a fine high polish.
The composition and concentration of the electrolytic bath employed will preferably be:
Percent Hydrofluoric acid 2-7 Hydrochloric acid 32-38 the total combined acid concentration being be tween 34% and 45%, the balance being substantially water, in the case hydrochloric acid is employed; and
Percent Hydrofluoric acid 2-7 Sulfuric acid 75-98 the total combined acid concentration being between 77 and 100%, the balance being substantially Water, When sulfuric acid is employed. The percentage figures are by weight.
A current density of from 40 to 60 milliamperes per square centimeter has been found to avoid valve action, employing an electrolytic bath having a composition and concentration as above stated.
A substantial departure from the conditions of the invention will result in unsatisfactory polishing. The metal may dissolve too rapidly with excessive loss of material and production of an etched surface or it may valve, that is, the passage of current may cease and the surface of the metal remain unchanged or the metal may behave erratically and a periodic pulsation of current, accompanied by the formation of fiaky material dropping from the surface, may result.
As specific examples of the invention yielding good results, the following are cited:
Example 1 Tantalum is made anodic at a current density of 67 milliamperes per square centimeter in an aqueous solution of hydrofluoric and hydrochloric acids, which is 4%, by weight, hydrogen fluoride and 34%, by weight, hydrogen chloride. The operation is conducted at room temperature. In about 10 minutes the surface has developed a high mirror-like finish.
Example 2 Tantalum is made anodic with a current density of 40 milliamperes per square centimeter in an aqueous solution of hydrofluoric and sulfuric acids, which is 4%, by weight, hydrogen fluoride and 89%, by weight, sulfuric acid. The operation is conducted at room temperature. In this case polishing will result after about 20 minutes of electrolysis.
The cited examples are in no Way restrictive of the invention, its essence being the discovery that tantalum metal can be electropolished employing the electrolytes, set forth, at the indicated ranges of concentrations, and the current densities, also as indicated.
This application is a division of our co-pending application Serial No, 526,656 of the same title as this application filed March 5, 1944 (now Patent Number 2,466,095).
We claim:
1. The electropolishing of metallic tantalum by making it anodic in an electrolyte, containing 2%-'7% by weight of hydrogen fluoride and 32 38% by weight of hydrochloric acid, the combined acid concentration being between 84% and 45%, the balance being substantially water, and passing current at an anodic current density of from 40 to milliamperes per square centimeter until the metal surface has developed a high, mirror-like polish.
2. The electropolishing of metallic tantalum by making it anodic at a current density of 67 milliamperes per square centimeter in an aqueous solution of hydrofluoric and hydrochloric acids containing 4% by weight of hydrogen fluoride and 34% by weight of hydrogen chloride, the balance being substantially water, until the metal surface has developed a high, mirror-like polish.
JOHN F. GALL. V HENRY C. MILLER.
REFERENCES CITED The following references are of record in the file of this patent:
4 UNITED STATES PATENTS Number Name Date 2,1l5,005 Blaut et a1 Apr. 26, 1938 FOREIGN PATENTS Number Country Date 530,041 Great Britain Dec. 4, 1940 OTHER REFERENCES Comprehensive Treatise On Inorganic and Theoretical Chemistry, by Mellor, vol. 9 929), page 891.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49853A US2481306A (en) | 1944-03-15 | 1948-09-17 | Electrochemical polishing of tantalum |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US526656A US2466095A (en) | 1944-03-15 | 1944-03-15 | Electrochemical process for polishing tantalum |
| US49853A US2481306A (en) | 1944-03-15 | 1948-09-17 | Electrochemical polishing of tantalum |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2481306A true US2481306A (en) | 1949-09-06 |
Family
ID=26727614
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US49853A Expired - Lifetime US2481306A (en) | 1944-03-15 | 1948-09-17 | Electrochemical polishing of tantalum |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2481306A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2775553A (en) * | 1952-12-31 | 1956-12-25 | Sprague Electric Co | Electrolytic etching process for electrolytic capacitors |
| US3024095A (en) * | 1958-04-25 | 1962-03-06 | Nat Res Corp | Acid treatment of tantalum to remove surface irregularities |
| US3314867A (en) * | 1963-11-01 | 1967-04-18 | James K Gore | Method of etching tantalum and niobium for electroplating |
| US4174269A (en) * | 1978-06-21 | 1979-11-13 | Ppg Industries, Inc. | Method of treating electrodes |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2115005A (en) * | 1936-10-15 | 1938-04-26 | Samuel J Blaut | Electrochemical treatment of metal |
| GB530041A (en) * | 1938-03-30 | 1940-12-04 | Enar Boerje Bergsman | Improvements in or relating to electrolytic polishing of metals |
-
1948
- 1948-09-17 US US49853A patent/US2481306A/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2115005A (en) * | 1936-10-15 | 1938-04-26 | Samuel J Blaut | Electrochemical treatment of metal |
| GB530041A (en) * | 1938-03-30 | 1940-12-04 | Enar Boerje Bergsman | Improvements in or relating to electrolytic polishing of metals |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2775553A (en) * | 1952-12-31 | 1956-12-25 | Sprague Electric Co | Electrolytic etching process for electrolytic capacitors |
| US3024095A (en) * | 1958-04-25 | 1962-03-06 | Nat Res Corp | Acid treatment of tantalum to remove surface irregularities |
| US3314867A (en) * | 1963-11-01 | 1967-04-18 | James K Gore | Method of etching tantalum and niobium for electroplating |
| US4174269A (en) * | 1978-06-21 | 1979-11-13 | Ppg Industries, Inc. | Method of treating electrodes |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH03501753A (en) | Electrochemical processing method for articles made of conductive materials | |
| Neergat et al. | Electrodissolution of 304 stainless steel in neutral electrolytes for surface decontamination applications | |
| US2481306A (en) | Electrochemical polishing of tantalum | |
| US2466095A (en) | Electrochemical process for polishing tantalum | |
| US3284326A (en) | Electrolytic etching of anodisable metal foil | |
| US2294227A (en) | Method of electrolytically polishing steel | |
| US3378669A (en) | Method of making non-porous weld beads | |
| US2753301A (en) | Electropolishing of copper and its alloys | |
| US2773821A (en) | Composition for use in electropolishing | |
| US2330170A (en) | Electrolytic polishing of metal | |
| US2594124A (en) | Electrolytic polishing of metals | |
| US2578898A (en) | Electrolytic removal of metallic coatings from various base metals | |
| US2997429A (en) | Electropolishing of titanium and titanium alloys | |
| US3242062A (en) | Fluorine-cuntaining electrolyte for electrolytic cutting of metals | |
| US2366712A (en) | Method of anodically polishing stainless steel | |
| US2429676A (en) | Electrolyte for and method of anodically polishing nickel | |
| USRE28849E (en) | Surface preparation process for recoating of used coated metallic electrodes | |
| US2832730A (en) | Electrolytic production of elemental boron | |
| US2941875A (en) | Method of etching a germanium surface | |
| US3841978A (en) | Method of treating a titanium anode | |
| CN113544316B (en) | Electrolytes for electrochemical machining of γ-γ′ nickel-based superalloys | |
| US2424674A (en) | Electrolytic bright polishing | |
| US3829367A (en) | Electrolytic polishing of metals | |
| US2131427A (en) | Process of electrolytically depositing iron and nickel alloy | |
| US1888118A (en) | Production of fluorine |