US3732152A - Anodized magnesium and magnesium alloys - Google Patents
Anodized magnesium and magnesium alloys Download PDFInfo
- Publication number
- US3732152A US3732152A US00162316A US3732152DA US3732152A US 3732152 A US3732152 A US 3732152A US 00162316 A US00162316 A US 00162316A US 3732152D A US3732152D A US 3732152DA US 3732152 A US3732152 A US 3732152A
- Authority
- US
- United States
- Prior art keywords
- magnesium
- bath
- anodized
- anodizing
- alloys
- 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
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title abstract description 13
- 229910000861 Mg alloy Inorganic materials 0.000 title abstract description 7
- 229910052749 magnesium Inorganic materials 0.000 title description 4
- 239000011777 magnesium Substances 0.000 title description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 abstract description 30
- 239000011734 sodium Substances 0.000 abstract description 9
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 abstract description 8
- 229910052708 sodium Inorganic materials 0.000 abstract description 8
- 238000007743 anodising Methods 0.000 description 12
- 238000000034 method Methods 0.000 description 8
- 238000000576 coating method Methods 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- CMZUMMUJMWNLFH-UHFFFAOYSA-N sodium metavanadate Chemical compound [Na+].[O-][V](=O)=O CMZUMMUJMWNLFH-UHFFFAOYSA-N 0.000 description 3
- 229910000166 zirconium phosphate Inorganic materials 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- VSYMNDBTCKIDLT-UHFFFAOYSA-N [2-(carbamoyloxymethyl)-2-ethylbutyl] carbamate Chemical compound NC(=O)OCC(CC)(CC)COC(N)=O VSYMNDBTCKIDLT-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/30—Anodisation of magnesium or alloys based thereon
Definitions
- a method for anodizing the surface of magnesium metal or magnesium alloys which comprises immersing said metal or alloys in an aqueous bath co 'ntaining sodium hydroxide and sodium hexafluorotitanate and passing an alternating current through said bath-to form the anodized coating on said metal or alloy, the temperature of said bath being held from room temperature to 80 F. during the anodizing treatment.
- the amount of sodium hydroxide employed in the bath is from 10-50 g.p.l. and the amount of sodium hexafluorotitanate is from 5-15 g.p.l.
- At least two metallic specimens are employed in the bath. Both of these specimens act as electrodes. More than two metallic specimens may be used provided they are in electrical contact with either of these metallic electrodes.
- the bath is held at a temperature below 80 F. by use of external cooling.
- the alternating current is regulated by means of an autotransformer.
- the occurrence and completeness of the film formation is reflected by an almost immediate rise in the voltage to maintain the current flow, which results in a nearly complete shut-off of the current within a few minutes with a terminal voltage of 110-120 volts.
- the protective value of the anodized coating was determined by using a standard Salt Fog TestASTM- B117-64.
- Average corrosion rates were calculated from the weight loss. Maximum pit depths were estimated by means of a needle point depth gauge.
- Magnesium alloys may be anodized in the same manner as that used to anodize magnesium metal and therefore are included in the term magnesium metal.
- EXAMPLE 1 Two magnesium metal panels were suspended as electrodes in an aqueous bath which contained 25 g.p.l. NaOH and 6.25 g.p.l. Na TiF The bath was provided with external means to cool the liquid. An initial alternating current of 20 amps per sq. ft. and 5 volts was passed through the bath. The magnesium metal panels were coated with an anodized continuous coating which had a light gray color. The current dropped to nearly zero within 1 or 2 minutes with a rapid rise in voltage to 110-120 volts. This indicated a completeness of the anodizing coating. To insure completeness these conditions were held for 12 minutes. During the anodizing the bath temperature was held at -80 F.
- EXAMPLE 2 In this run the procedure described in Example 1 was repeated except that sodium vanadate was also used in the bath in addition to sodium hexafiuorotitanate and sodium hydroxide.
- the bath contained the following composition:
- a method for anodizing the surface of magnesium metal which consists essentially of passing an alternating current through an aqueous bath containing at least two magnesium metal specimens; said metal being the electrodes in said bath, said bath comprising sodium hydroxide and sodium hexafiuorotitanate, the amount of sodium hydroxide in said bath being from 10 to 50 g.p.l. and the amount of sodium hexafiuorotitanate being from 5 to 15 g.p.l.
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 Metals (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
MAGNESIUM METAL OR MAGNESIUM ALLOYS ARE ANODIZED BY IMMERSING IN AN AQUEOUS BATH CONTAINING SODIUM HYDROXIDE AND SODIUM HEXAFLUOROTITANATE AND PASSING AN ALTERNATING CURRENT THROUGH THE BATH.
Description
United States Patent Oflice 3,732,152 Patented May 8, 1 973 3,732,152 ANODIZED MAGNESIUM AND MAGNESIUM ALLOYS David L. Hawke, Metuchen, N.J., assignor to N L Industries, Inc., New York, N.Y. No Drawing. Filed July 13, 1971, Ser. No. 162,316 Int. Cl. C23b 9/06 U.S. Cl. 204-56 M 2 Claims ABSTRACT OF THE DISCLOSURE Magnesium metal or magnesium alloys are anodized by immersing in an aqueous bath containing sodium hydroxide and sodium hexafiuorotitanate and passing an alternating current through the bath.
BACKGROUND OF THE INVENTION Various methods have been used in the past to form protective films on magnesium or magnesium alloys through anodizing. Films formed by the methods in common use are inherently porous, and unless sealed by supplementary coatings, they fail to retard, and may in fact stimulate, pitting corrosion in saline environments.
SUMMARY OF THE INSTANT INVENTION A method for anodizing the surface of magnesium metal or magnesium alloys which comprises immersing said metal or alloys in an aqueous bath co 'ntaining sodium hydroxide and sodium hexafluorotitanate and passing an alternating current through said bath-to form the anodized coating on said metal or alloy, the temperature of said bath being held from room temperature to 80 F. during the anodizing treatment.
The amount of sodium hydroxide employed in the bath is from 10-50 g.p.l. and the amount of sodium hexafluorotitanate is from 5-15 g.p.l.
In addition it has also been found that sodium vanadate (NavO -nH O) in amount of 5-15 g.p.l. tends to enhance the anodizing effect.
At least two metallic specimens are employed in the bath. Both of these specimens act as electrodes. More than two metallic specimens may be used provided they are in electrical contact with either of these metallic electrodes.
DESCRIPTION OF THE PREFERRED EMBODIMENTS In carrying out the instant invention it is desirable to use dilute solutions in the bath. It has been found that good anodizing coatings are obtained when the aqueous bath contains only -50 g.p.l. NaOH and from 5-15 g.p.l. sodium hexafluorotitanate. When such concentrations are used in the bath, an anodizing coating appears to form within one minute after the alternating current is passed through the bath. The voltage rises rapidly to about 120 while the current falls to a low value. The anodized film is light gray in color and appears to be about 1 micron in thickness.
The bath is held at a temperature below 80 F. by use of external cooling. The alternating current is regulated by means of an autotransformer. In carrying out the anodizing procedure, the occurrence and completeness of the film formation is reflected by an almost immediate rise in the voltage to maintain the current flow, which results in a nearly complete shut-off of the current within a few minutes with a terminal voltage of 110-120 volts.
The protective value of the anodized coating was determined by using a standard Salt Fog TestASTM- B117-64.
Average corrosion rates were calculated from the weight loss. Maximum pit depths were estimated by means of a needle point depth gauge.
Magnesium alloys may be anodized in the same manner as that used to anodize magnesium metal and therefore are included in the term magnesium metal.
In order to describe more fully the instant invention, the following examples are presented:
EXAMPLE 1 Two magnesium metal panels were suspended as electrodes in an aqueous bath which contained 25 g.p.l. NaOH and 6.25 g.p.l. Na TiF The bath was provided with external means to cool the liquid. An initial alternating current of 20 amps per sq. ft. and 5 volts was passed through the bath. The magnesium metal panels were coated with an anodized continuous coating which had a light gray color. The current dropped to nearly zero within 1 or 2 minutes with a rapid rise in voltage to 110-120 volts. This indicated a completeness of the anodizing coating. To insure completeness these conditions were held for 12 minutes. During the anodizing the bath temperature was held at -80 F.
The anodized panels were then tested in a standard Salt Fog Test and the test results obtained were measured as the rate of corrosion and the depth rate of pitting. The results are recorded as follows:
Salt fog test py Corrosion rate 0.009 Depth of pitting 0.4-0.8
EXAMPLE 2 In this run the procedure described in Example 1 was repeated except that sodium vanadate was also used in the bath in addition to sodium hexafiuorotitanate and sodium hydroxide.
The bath contained the following composition:
G.p.l. NaOH 25 NfigTIFs NaVO -nH O 6.25
The anodized magnesium panels were tested in the same standard Salt Fog Test and the results are recorded as follows:
Corrosion rate 0.00 28 Depth of pitting 0.2
These corrosion figures are well below the corrosion results obtained by using the prior art anodizing techniques which employ the well known standard alkaline anodizing baths.
While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto, and other variations and modifications may be employed within the scope of the following claims.
1. A method for anodizing the surface of magnesium metal which consists essentially of passing an alternating current through an aqueous bath containing at least two magnesium metal specimens; said metal being the electrodes in said bath, said bath comprising sodium hydroxide and sodium hexafiuorotitanate, the amount of sodium hydroxide in said bath being from 10 to 50 g.p.l. and the amount of sodium hexafiuorotitanate being from 5 to 15 g.p.l.
(2. Method according to claim 1 in which said hath also contains sodium vanadate in an amount from 5 to 15 g.p.l.
References Cited UNITED STATES PATENTS Loose et a1. 20456 M X Evangelides 204-56 M X Richaud 20432 Wright et al 204-56 R Fruchtnicht 204-46 M 10 FREDERICK C. EDMUNDSON, Primary Examiner
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16231671A | 1971-07-13 | 1971-07-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3732152A true US3732152A (en) | 1973-05-08 |
Family
ID=22585117
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00162316A Expired - Lifetime US3732152A (en) | 1971-07-13 | 1971-07-13 | Anodized magnesium and magnesium alloys |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3732152A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3956095A (en) * | 1974-04-30 | 1976-05-11 | Canadian Gas Association | Sacrificial anode |
| US5240589A (en) * | 1991-02-26 | 1993-08-31 | Technology Applications Group, Inc. | Two-step chemical/electrochemical process for coating magnesium alloys |
| US5470664A (en) * | 1991-02-26 | 1995-11-28 | Technology Applications Group | Hard anodic coating for magnesium alloys |
| US20060102484A1 (en) * | 2004-11-12 | 2006-05-18 | Woolsey Earl R | Anodization process for coating of magnesium surfaces |
| CN107460522A (en) * | 2016-06-06 | 2017-12-12 | 宁波瑞隆表面技术有限公司 | A kind of method that magnesium alloy differential arc oxidation prepares blue ceramic film layer |
-
1971
- 1971-07-13 US US00162316A patent/US3732152A/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3956095A (en) * | 1974-04-30 | 1976-05-11 | Canadian Gas Association | Sacrificial anode |
| US5240589A (en) * | 1991-02-26 | 1993-08-31 | Technology Applications Group, Inc. | Two-step chemical/electrochemical process for coating magnesium alloys |
| US5470664A (en) * | 1991-02-26 | 1995-11-28 | Technology Applications Group | Hard anodic coating for magnesium alloys |
| US20060102484A1 (en) * | 2004-11-12 | 2006-05-18 | Woolsey Earl R | Anodization process for coating of magnesium surfaces |
| CN107460522A (en) * | 2016-06-06 | 2017-12-12 | 宁波瑞隆表面技术有限公司 | A kind of method that magnesium alloy differential arc oxidation prepares blue ceramic film layer |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AS | Assignment |
Owner name: FARLEY METALS, INC., 233 SOUTH WACKER DRIVE, CHICA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:NL INDUSTRIES, INC. A NJ CORP.;REEL/FRAME:004217/0800 Effective date: 19831212 |
|
| AS | Assignment |
Owner name: NATWEST USA CREDIT CORP. Free format text: SECURITY INTEREST;ASSIGNOR:FARLEY METALS, INC.,;REEL/FRAME:004739/0041 Effective date: 19870729 |
|
| AS | Assignment |
Owner name: FARLEY, INC. Free format text: CHANGE OF NAME;ASSIGNOR:FARLEY METALS, INC.;REEL/FRAME:004917/0556 Effective date: 19880809 |
|
| AS | Assignment |
Owner name: BANK OF NEW YORK, THE Free format text: SECURITY INTEREST;ASSIGNOR:FARLEY INC.;REEL/FRAME:005221/0038 Effective date: 19890404 |
|
| AS | Assignment |
Owner name: FARLEY, INC. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:NATWEST USA CREDIT CORP.;REEL/FRAME:005221/0044 Effective date: 19890331 |
|
| AS | Assignment |
Owner name: FARLEY INC. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANK OF NEW YORK, THE;REEL/FRAME:005489/0398 Effective date: 19900717 |
|
| AS | Assignment |
Owner name: FARLEY INC. Free format text: CHANGE OF NAME;ASSIGNOR:FARLEY METALS, INC., A CORP. OF DE;REEL/FRAME:005847/0581 Effective date: 19871222 |