CA1047755A - Corrosion inhibition - Google Patents
Corrosion inhibitionInfo
- Publication number
- CA1047755A CA1047755A CA200,837A CA200837A CA1047755A CA 1047755 A CA1047755 A CA 1047755A CA 200837 A CA200837 A CA 200837A CA 1047755 A CA1047755 A CA 1047755A
- Authority
- CA
- Canada
- Prior art keywords
- water
- corrosion
- methylphosphonic acid
- soluble salts
- amino tris
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
Abstract
ABSTRACT OF THE DISCLOSURE
Use of compositions of low molecular weight polymers and amino tris (methylphosphonic acid) or its water-soluble salts to inhibit the corrosion of metals by oxygen-bearing waters.
Use of compositions of low molecular weight polymers and amino tris (methylphosphonic acid) or its water-soluble salts to inhibit the corrosion of metals by oxygen-bearing waters.
Description
liC,l;O~ NI) OF Tl-lE 11~ l JON
This ill\ elltion r elates to the inl~ itic)n or co] ro ;ion in ~-atel-systenls w llich lltilize oxygen-l)earing watel s.
More particularly, this in~elltion r clatcs to the use of compo-sitions comprising~ low Inolecular weioht l~oly~llers and amiMo tris 10 (methylphosphonic acid) or its water-soluble salts to inhibit the corrosion oI nletals in water systems which contain oxygen-bearing wate r s .
. .
Oxygen corrosion is, of cOul se, a serious problem in any metal-containing water system. The corrosion of iron and steel is 15 of principal concern because of their extensive use in many types oI
water systen~s. Copper and its alloys, aluminum and its alloys, and galvanized steel are also used in water systems and are subject to corroslon. We have discovered corrosion inhibitors which will inhibit oxygen corrosion in water systems containing such metals.
- 20 SUMMARY OF Tl~E INVENTION
We have found that compositions comprising low molecular weight polymers and amino tris (methylphosphonic acid) or its water-soluble salts are effective corrosion inhibitors. Suitable polymers include water-soluble salts of acrylates and methacrylates, un-25 hydrolyzed or partially hydrolyzed acrylamides, and acrylamido_ methyl propane sulfonates. The polymers may be homo-, co-, or ~'' - . .
:: : , ~. - , -~: ,, ' -- . :
.: ., ' ' ',,: ' - . ' '' . . . - .
`: ' ~ - \
~0477S5 ter- polymers of any of the aforementioned polymers and may have a molecular weight of from about 500 to about 10, 000. The pre-ferred molecular weight, however, is about 1, 000.
Our corrosion-inhibiting compositions can contain a ratio of 5 polymer to amino tris (methylphosphonic acid) or its water-soluble salts of from about 10:1 to about 1:5 by weight. The preferred ratio, however, is from about 5:1 to 1:2 by weight. These compositions will effectively inhibit corrosion of metals when maintained in a water system at a concentration of at least about 5 ppm at the above 10 ratios and, preferably, about 30 ppm. Maximum concentrations are determined by the economic considerations of the particular appli-cation.
lt may, of course, be desirable to add zinc to the compositions of this invention for certain applications. The zinc ion may be supplied 15 in many ways. For example, it may be added by utilizing a water-soluble zinc salt, such as, zinc chloride, zinc acetate, zinc nitrate, or zinc sulfate or it may be supplied by adding powdered zinc to a solution of the composition.
Compounds such as benzotriazole or mercaptobenzothiazole 20 may also be added to the final formulation in varying amounts to improve its usefulness in a wider variety of industrial applications where both steel and copper are present in the same system.
The following tables show the results of experiments which demonstrate the effectiveness of the compositions of this invention in `25 inhibiting metallic corrosion. These tests were run in synthetic ':
~ ~ C 1 -Pittsburgh water. Steel electrodes were used in polarization test cells with the initial pH at 7. 0. Inhibitor concentrations were calcu-lated on the basis of 100 percent active material. The amount of corrosion that had taken place was determined from the current den-5 sity at the intersection of an extrapolation of the so-called "Tafel"
portion of the anodic polarization curve with the equilibrium or "mixed"
potential value, usually referred to as the corrosion potential, "Ecorr"~
Application of Faraday~s Law allows a computation of a direct mathe-matical relationship between the current density at ECorr~ expressed 10 in amperes per square centimeter and a more useful corrosion rate expression such as milligrams of steel consumed per square decimeter ~ -of surface per day (m. d. d. ) and mils per year (m. p. y. ). This re-lationship is such that a current dens~ty value of 4. 0 x 10-7 amperes/
. ~
cm2 = 1. 0 mg/dm2/day. Further, the m. p. y. value is calculated from 15 the formula: m. p.y. = m. d. d. x 1. 44 , using a density value of 7. 87 g/ -~
3 density cm for steel.
` The following table illustrates the synergistic effect of a composition comprising sodium polyacrylate and amino tris (methyl-phosphonic acid) or its water-soluble salts as a corrosion inhibitor in 20 tests run at 35C.
`': ' .'`' .
-- 3 .
! ' .: . . . , , . , ' , . : ' ~ ' .
~047755 Table 1 DosageCorrosion Rate Inhibitor Svstem (mg/l) (mdd) Control 0 100 Amino tris (methylphosphonic acid) 15 50 Sodium Polyacrylate (molecular weight~ 1, 000) 30 78 Amino tris (methylphosphonic acid) +
Sodium Polyacrylate15 + 30 12 The following tables illustrate the effectiveness of various compositions of this invention as corrosion inhibitors in 5-day tests -run at 140 F., and pH of 6. 0.
Table 2 DosageCorrosion Rate Inhibitor System (mg/l) (mg/dm2/day) Contro 1 - - - 2 5 0 Partially Hydrolyzed Polyacrylamide (molecular weight ~~7,000) 25 143 Aminomethylene Pho sphonate (AMP) 1 2 11 5 - -Partially Hydroly~ed Polyacrylamide Am.inomethylene Phosphonate 25 + 12 42 _ 4 --' ' Cl :1047755 Table 3 Do sageCorro sion Rate Inhibitor System(mg/l)(mg/dm2/day) Control - _- 2 50 Partially Hydrolyzed Polyacrylamide 15 200 Amino tris (methylphosphonic acid) 7. 5 90 Zinc 10 90 10 Partially Hydrolyzed Polyacrylamide Amino tris (methylphosphonic acid) ;-Zinc 15 + 7. 5 + 10 6 :
This ill\ elltion r elates to the inl~ itic)n or co] ro ;ion in ~-atel-systenls w llich lltilize oxygen-l)earing watel s.
More particularly, this in~elltion r clatcs to the use of compo-sitions comprising~ low Inolecular weioht l~oly~llers and amiMo tris 10 (methylphosphonic acid) or its water-soluble salts to inhibit the corrosion oI nletals in water systems which contain oxygen-bearing wate r s .
. .
Oxygen corrosion is, of cOul se, a serious problem in any metal-containing water system. The corrosion of iron and steel is 15 of principal concern because of their extensive use in many types oI
water systen~s. Copper and its alloys, aluminum and its alloys, and galvanized steel are also used in water systems and are subject to corroslon. We have discovered corrosion inhibitors which will inhibit oxygen corrosion in water systems containing such metals.
- 20 SUMMARY OF Tl~E INVENTION
We have found that compositions comprising low molecular weight polymers and amino tris (methylphosphonic acid) or its water-soluble salts are effective corrosion inhibitors. Suitable polymers include water-soluble salts of acrylates and methacrylates, un-25 hydrolyzed or partially hydrolyzed acrylamides, and acrylamido_ methyl propane sulfonates. The polymers may be homo-, co-, or ~'' - . .
:: : , ~. - , -~: ,, ' -- . :
.: ., ' ' ',,: ' - . ' '' . . . - .
`: ' ~ - \
~0477S5 ter- polymers of any of the aforementioned polymers and may have a molecular weight of from about 500 to about 10, 000. The pre-ferred molecular weight, however, is about 1, 000.
Our corrosion-inhibiting compositions can contain a ratio of 5 polymer to amino tris (methylphosphonic acid) or its water-soluble salts of from about 10:1 to about 1:5 by weight. The preferred ratio, however, is from about 5:1 to 1:2 by weight. These compositions will effectively inhibit corrosion of metals when maintained in a water system at a concentration of at least about 5 ppm at the above 10 ratios and, preferably, about 30 ppm. Maximum concentrations are determined by the economic considerations of the particular appli-cation.
lt may, of course, be desirable to add zinc to the compositions of this invention for certain applications. The zinc ion may be supplied 15 in many ways. For example, it may be added by utilizing a water-soluble zinc salt, such as, zinc chloride, zinc acetate, zinc nitrate, or zinc sulfate or it may be supplied by adding powdered zinc to a solution of the composition.
Compounds such as benzotriazole or mercaptobenzothiazole 20 may also be added to the final formulation in varying amounts to improve its usefulness in a wider variety of industrial applications where both steel and copper are present in the same system.
The following tables show the results of experiments which demonstrate the effectiveness of the compositions of this invention in `25 inhibiting metallic corrosion. These tests were run in synthetic ':
~ ~ C 1 -Pittsburgh water. Steel electrodes were used in polarization test cells with the initial pH at 7. 0. Inhibitor concentrations were calcu-lated on the basis of 100 percent active material. The amount of corrosion that had taken place was determined from the current den-5 sity at the intersection of an extrapolation of the so-called "Tafel"
portion of the anodic polarization curve with the equilibrium or "mixed"
potential value, usually referred to as the corrosion potential, "Ecorr"~
Application of Faraday~s Law allows a computation of a direct mathe-matical relationship between the current density at ECorr~ expressed 10 in amperes per square centimeter and a more useful corrosion rate expression such as milligrams of steel consumed per square decimeter ~ -of surface per day (m. d. d. ) and mils per year (m. p. y. ). This re-lationship is such that a current dens~ty value of 4. 0 x 10-7 amperes/
. ~
cm2 = 1. 0 mg/dm2/day. Further, the m. p. y. value is calculated from 15 the formula: m. p.y. = m. d. d. x 1. 44 , using a density value of 7. 87 g/ -~
3 density cm for steel.
` The following table illustrates the synergistic effect of a composition comprising sodium polyacrylate and amino tris (methyl-phosphonic acid) or its water-soluble salts as a corrosion inhibitor in 20 tests run at 35C.
`': ' .'`' .
-- 3 .
! ' .: . . . , , . , ' , . : ' ~ ' .
~047755 Table 1 DosageCorrosion Rate Inhibitor Svstem (mg/l) (mdd) Control 0 100 Amino tris (methylphosphonic acid) 15 50 Sodium Polyacrylate (molecular weight~ 1, 000) 30 78 Amino tris (methylphosphonic acid) +
Sodium Polyacrylate15 + 30 12 The following tables illustrate the effectiveness of various compositions of this invention as corrosion inhibitors in 5-day tests -run at 140 F., and pH of 6. 0.
Table 2 DosageCorrosion Rate Inhibitor System (mg/l) (mg/dm2/day) Contro 1 - - - 2 5 0 Partially Hydrolyzed Polyacrylamide (molecular weight ~~7,000) 25 143 Aminomethylene Pho sphonate (AMP) 1 2 11 5 - -Partially Hydroly~ed Polyacrylamide Am.inomethylene Phosphonate 25 + 12 42 _ 4 --' ' Cl :1047755 Table 3 Do sageCorro sion Rate Inhibitor System(mg/l)(mg/dm2/day) Control - _- 2 50 Partially Hydrolyzed Polyacrylamide 15 200 Amino tris (methylphosphonic acid) 7. 5 90 Zinc 10 90 10 Partially Hydrolyzed Polyacrylamide Amino tris (methylphosphonic acid) ;-Zinc 15 + 7. 5 + 10 6 :
Claims (4)
1. A method for inhibiting the corrosion of metals in a water system which comprises maintaining in the water of said system from about 5 to 30 ppm of a composition comprising polyacrylamide having a molecular weight of from about 500 to about 10,000 and amino tris (methylphosphonic acid) or its water-soluble salts.
2. The method of Claim 1, wherein the ratio of polyacrylamide to amino tris (methylphosphonic acid) or its water-soluble salts is from about 10:1 to about 5:1 by weight.
3. The method of Claim 1, wherein the ratio of polyacrylamide to amino tris (methylphosphonic acid) or its water-soluble salts is from about 5:1 to about 1:2 by weight.
4. The method of Claim 1, 2 or 3, which further contains zinc.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US36708073A | 1973-06-04 | 1973-06-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1047755A true CA1047755A (en) | 1979-02-06 |
Family
ID=23445853
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA200,837A Expired CA1047755A (en) | 1973-06-04 | 1974-05-23 | Corrosion inhibition |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5021951A (en) |
| AU (1) | AU6918574A (en) |
| BE (1) | BE815853A (en) |
| CA (1) | CA1047755A (en) |
| DE (1) | DE2426516A1 (en) |
| FR (1) | FR2231780A1 (en) |
| LU (1) | LU70233A1 (en) |
| NL (1) | NL7406595A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5828348B2 (en) * | 1976-12-27 | 1983-06-15 | 栗田工業株式会社 | Metal corrosion prevention method |
| JPS62284090A (en) * | 1986-05-30 | 1987-12-09 | Katayama Chem Works Co Ltd | Method for preventing tarnish of aluminum-base metal |
| JPS63202349A (en) * | 1987-02-19 | 1988-08-22 | Baiotetsuku:Kk | Feed for domestic animal |
| JPS63202348A (en) * | 1987-02-19 | 1988-08-22 | Baiotetsuku:Kk | Production of feed for domestic animal |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3518203A (en) * | 1966-06-28 | 1970-06-30 | Drew Chem Corp | Corrosion and scale inhibitor compositions and processes therefor |
| GB1208827A (en) * | 1968-02-23 | 1970-10-14 | Grace W R & Co | Composition and process for inhibiting scaling and/or corrosion in cooling water systems and for stabilizing phosphate solutions |
| US3663448A (en) * | 1970-09-25 | 1972-05-16 | Calgon Corp | Inhibiting scale deposition |
-
1974
- 1974-05-16 NL NL7406595A patent/NL7406595A/xx unknown
- 1974-05-21 AU AU69185/74A patent/AU6918574A/en not_active Expired
- 1974-05-23 CA CA200,837A patent/CA1047755A/en not_active Expired
- 1974-05-29 FR FR7418578A patent/FR2231780A1/en active Granted
- 1974-05-31 DE DE19742426516 patent/DE2426516A1/en not_active Withdrawn
- 1974-05-31 BE BE145024A patent/BE815853A/en unknown
- 1974-06-04 JP JP6259974A patent/JPS5021951A/ja active Pending
- 1974-06-04 LU LU70233A patent/LU70233A1/xx unknown
Also Published As
| Publication number | Publication date |
|---|---|
| LU70233A1 (en) | 1975-03-06 |
| DE2426516A1 (en) | 1974-12-19 |
| AU6918574A (en) | 1975-11-27 |
| JPS5021951A (en) | 1975-03-08 |
| BE815853A (en) | 1974-12-02 |
| FR2231780B1 (en) | 1978-05-26 |
| FR2231780A1 (en) | 1974-12-27 |
| NL7406595A (en) | 1974-12-06 |
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