Passivating inhibitors cause a large anodic shift of the corrosion poten- tial, forcing the metallic surface into the ... such as phosphate, tungstate, and molybdate, that require the presence of oxygen to passivate steel. .... in metal-cleaning proc
potentials and statistical mechanical methods to answer many application .... Fresh sour brine was prepared every day for the testing period. Inhibitor Solutions. A 10000 ..... TABLE 6: MC Simulation Results for Adsorption: Number of Occupied ...
Corrosion is controlled by anodic (passivating) inhibitors including nitrate and chromate as well as by cathodic (e.g., zinc salt) inhibitors. Organic inhibitors (e.g., benzotriazole) are sometimes used as secondary inhibitors, especially when excess
Natalya V. Likhanova. Additional information is available at the end of the chapter http://dx.doi.org/10.5772/57252. 1. Introduction. In most industries whose facilities are constituted by metallic structures, the phenomenon of corrosion is invariabl
ability to form a thin, passivating film directly on the anodic portion of metal. Besides chromates and phosphates (or their combina- tions) silicates, nitrites and .... diethylamine, acridine, acriflavin, etc. These materials are used for combating
resistance, corrosion inhibition, organic amines, marine environment, diffusion, migration ... This design allows variability in the type of concrete membrane, i.e., ...
processed graphene into the design process and practical fiber architectural engineering. ... Keywords: (Graphene, fibers, conducting, 3D scaffolds, biomimetic).
facility can be catastrophic if proper methods of prevention are not utilized. ..... High-temperature corrosion on carburized steels that forms a porous scale of.
Imidazoline and its precursor, amide, are very effective inhibitor ... Amide is also a hydrolyzed product of imidazoline under normal operating conditions. 67 The ...
and 85% corrosion inhibition efficiency (CIE) respectively while the other salts gave less than 40% ..... 93-97, 2005.  V. P. Persiantsava, (1987) âChemistry ...
Apr 23, 2014 - age readings a USB 16 channel relay module (Denkovi DAE-. CB/Ro16/Di4-USB) with remote control via USB was used. All the equipment ...
Dec 1, 2017 - Figure 3a,b show much less corrosion product, but still show some local attack on the sample in the inhibitor .... Schematic summary of synthesis of thermosensitive ionic microgels via quaternized. Figure 6. ..... are those which are fr
Aug 11, 2018 - Three organic environmentally friendly corrosion inhibitors were ..... metal, acting as a mixed type inhibitor by absorbing onto the metal surface ...
Jun 15, 1988 - phthalocyanines as corrosion inhibiting coatings - poyeriz by .... inhibitors of the phthalocyanine type show promise in a number of forms.
corrosion inhibition of mild steel in 1M H2SO4 solution are given in Table 3 ..... H[sub 2]SO[sub 4] Containing Benzotriazole, Journal of The Elec- trochemical ...
compounds were tested on carbon steel SAE1018 immersed in a solution like. NACE TM 0177 without and with H2S. Evaluation of the compounds was carried.
described in ASTM G-5-93 standard. A computer-controlled potentiostat (Model Solartron ECI-1286) and a frequency response analyzer (Solartron .... surface. By using Faraday's law, the Cu thickness reduction rate was calculated as: Î´ = (âm â 3600
the performance of carbon dioxide corrosion inhibitors for oilfield pipelines in the West .... corrosion. The corrosion rate increased nearly 7-fold for both types of ...
Dec 8, 2017 - School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK. Received: 20 November ... discovery of new, benign organic compounds to fill that role. ..... QSAR/QSPR as an application of artificial neural networks.
Nov 20, 2007 - dependent on the structure and chemical properties of the species formed under the specific ... The synthesized triazo phosphonates are used as inhibitors ..... serves as the basis for all modern corrosion inhibitor formulations.
... 4% of the GDP. Corrosion not only has economic implications, but also social and these engage the safety and ...... synthesized under microwave irradiation and evaluated as CIs for acid environment. Weight loss and .... alcohols isolated from sug
Introduction. Acid treatments have been applied to wells in oil and gas bearing rock formations for many years. Acidizing is probably the most widely used work-over and stimulation practice in the oil industry. By dissolving acid soluble components w
organic and inorganic corrosion inhibitors to the environment has provoked the search .... Polarization studies indicated that inhibitors are acted as mixed type.
States Patent [191
4,714,564 Dec. 22, 1987
Patent Number: Date of Patent:
Lynch et al
HIGH PERFORMANCE MULTIFUNCTIONAL CORROSION INHIBITORS ESPECIALLY FOR COMBINING AT 20 TO 50 WEIGHT PERCENT' WITH SOAP OR PAINT
Chares T. Lynch, Fairborn; Fred W. Vabidlek, Dayton; Mohammad Khobalib, Fairborn, all of Ohio
The United States of America as represented by the Secretary of the Air Force, Washington, D.C.
252/2 Langguth et al ....................... Shen .................................... 260/583 Marsh et al ...................... 252/389.2 Murray et al .................... 252/389.2 252/175 Foroulis .............. Buckman et al.................... 252/180 Hogue et al .......................... 422/12 Suzuki ....................... 252/389.52 X Manabe et a].................... 252/389.2 252/389.62 W illiams ......................... 106/14.42 Bird et al......................... Christensen et al ......... 252/389.2 X PUBLICATIONS
Primary Examiner-Matthew A. Thexton Attorney, Agent or Firm-Charles E. Bricker; Donald J. Singer
ASTRACr [571 'A multifunctional corrosion inhibitor consisting essentially of an alkali metal borate, an alkali metal nitrate, an alkali metal nitrite, an alkali metal metasilicate, an alkali metal phosphate, mercaptobenzothiazole and at least one selected surfactant.
4 Claims, 7 Drawing Figures
Al 7075-T -
-OST EEL 0-0 Cu
UfNHBTO 9C-6 BRS
Sheet 1 of 7
Dec. 22, 1987
\ \\ 0u
Dec. 22, 1987
Sheet 2 of 7
E 2 NL
0o0 (30S- Aw)
Dec. 22, 1987
Sheet 3 of 7
0u -z 0 Cy
(3I S-AU) 0 0
Dec. 22, 1987
Sheet 4 of 7
00 VI) za
Sheet 5 of 7
Dec. 22, 1987
L) - I-
• mmm lm m m m
Dec. 22, 1987
Sheet 6 of 7
t 2 -w
Dec. 22, 1987
Sheet 7 of 7
4,714,564 HIGH PERFORMANCE MULTIFUNCTIONAL CORROSION INHIBITORS ESPECIALLY FOR COMBINING AT 20 TO 50 WEIGHT PERCENT WITH SOAP OR PAINT
RIGHTS OF THE GOVERNMENT The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of 10 any royalty.
disposal on humans, animals and plants. Consequently, it is necessary to develop substitutes for such popular inhibitors as chromate based formulations and high phosphate based formulations. A previous study on corrosion prevention of carrierbased aircraft revealed that a considerable savings could be realized in terms of corrosion maintenance by merely rinsing the aircraft with water to remove detrimental particles, such as salt and ash. How, ever, in rinsing aircraft, a very good possibility exists that the water will be trapped in crevices or so-called dry-bay areas. The trapped water, often chemically hard, can cause serious corrosion problems, hence completely jeopardizing the advantage of water rinsing as a corrosion-control method. Therefore, the incorporation of a low concentration of a nontoxic, water-soluble inhibitor into the rinse water becomes a desirable means for improving corrosion resistance. The value of borax-nitrite as a corrosion inhibitor has long been recognized. Earlier work has shown this combination to be very effective in controlling general corrosion as well as crevice corrosion of high strength steels. However, the borax-nitrite combination was not found to be effective against the corrosion of other ferrous and nonferrous metals and alloys. For example, nitrite inhibitors are more effective at higher pH ranges (e.g., 8-9) than at more acidic levels. Very high pH levels, however, can be deleterious to some aluminum alloys since aluminum is amphoteric, subject to attack aluins. by sn by strong basic solutions.
BACKGROUND OF THE INVENTION Tis invention relates to corrosion inhibiting compositions and to a process for inhibiting the corrosion of 15 metals. In particular, this invention relates to a multifunctional inhibitor that provides both anodic and cathodic corrosion inhibition for a broad spectrum of metallic materials and structures in aggressive media such as brine, bilge solution and high-chloride contami- 20 nated water. The financial loss due to the degradative effects resulting from corrosion reactions amounts to billions of dollars annually. In an attempt to combat the problem of corrosion and minimize its economic disadvantages, a 25 U.S. Air Force research effort was initiated to develop improved inhibiting compositions. Aus a part of this research effort a survey and screening of conventional inhibitor compositions such as the polyphosphates,it cates, orthophosphates, chromates, nitrites, and combi- 30 nations thereof was undertaken to determine their effectiveness in inhibiting corrosion of aircraft structures. May, 1981, now abandoned we disclose corrosion inhibFilm-forming inhibitors, such as emulsified or soluble iting compositions which are biodegradable, contain no oils, long chain amines, alcohols and carboxylic acids 3 chromates, and offer important and unique advantages o studied. wen over chromate-based inhibitor combinations. The conUnfortunately, anodic inhibitors, such as the chromates, may cause accelerated corrosion when in contact positions are multifunctional, providing both anodic with a metal in too low a concentration, such as where and cathodic protection. The compositions are nonthe concentratmion decreases during use. The result may toxic, low in cost, soluble in aqueous solution and probe a metal surface protected in most areas, but giving 40 vide protection for a broad spectrum of metallic strucrise to accelerated corrosion in small, highly anodic tures. Concentration of the inhibitor composition in areas of the metal surface. On the other hand, a signifiaqueous rinsing solution is nominally 0.3 to 0.5 percent, cant advantage of chromate inhibiting formulations is by weight, of the rinse solution. The inhibiting compositheir broad protective ability against general corrosion tions include sodium borate, sodium nitrite, sodium of many metals and alloys. 45 hexametaphosphate, sodium metasilicate, sodium iiFor nonchromate systems, a rather complex mixture trate and mercaptobenzothiazole in a predetermined is required to achieve such broad-based protection. The range of concentrations. simple borax-nitrite system is, for example, effective for We have found that the effectiveness of the composimany steels, but must be complemented by other inhibitions disclosed by us in the aforesaid application Ser. tors to provide adequate protection for high strength 50 No. 265,734 can be improved by the addition thereto of aluminum alloys, particularly in the presence of corroselected surfactant compounds. These improved corrosive contaminants such as sodium chloride. sion inhibiting formulations are particularly useful in Other inhibitor systems are applicable only to a himvery aggressive environments containing chloride ion ited number of alloys or lack the degree of protection in excess of 100 ppm (0.1 weight percent). Such high for satisfactory and adequate protection for aerospace 55 levels may be found in coastal areas and in urine, which and other high performance (high strength, high contiq approximately one weight percent sodium strength:weight ratio, high fatigue resistance) structural chloride, ct about 6000 ppm of chloride ion. alloys. Still other inhibitor systems have not been found Accordingly, it is an object of the present invention satisfactory for use with high performance alloys in the to provide an improved multifunctional corrosion in. presence of sodium chloride. Commercial formulatiom 60 hibiting composition. which have been tested on aerospace alloys, such as Other objects and advantages of the present invention 7075-T6AI, 2024-T3AI. and 4340 steel, in the presence will be readily apparent to those skilled in the art from of sodium chloride in aqueous solutions have ranged a consideration of the following disclosure. from totally ineffective to partially effective in S RmerO65 SUMMARY OF THE INVENTION sion tests. Toxicity has become an incresingly important conIn accordance with the present invention there is sideration in recent years, both with respect to handling provided an improved corrosion inhibiting composition of the compounds prior to use, and to the effects of consisting essentially of a mixture of an alkali metal
4,714,5644 borate, an alkali metal nitrite, an alkali metal nitrate,an e, an alkali metalonephosphate, mercaptobenzotlfiazole (M BT), at least selected
TABLE 1-continued so tone
surfactant. In some formulations, zinc sulfate and benCoad zotriazole (BT)b arefp also ~required. The alkali metal can 5 Component 5du r.Nitrate be either sodium or potassium. Sica BRIEF DESCRIPTION OF THE DRAWINGS Phosphate MRT In the drawings; FIG. I illustrates the anodic-polarization behavior of 10 type 7075-T6 aluminum in local top water, distilled water, 0.11M NaC1 and the basic inhibitor solution; FIG. 2 illustrates the effect of increasing chloride concentration upon the breakdown of passivity of type 15 7075-T6 aluminum; FIG. 3 illustrates the effect of increasing chloride concentration upon the breakdown of passivity of type 4340 steel; FIG. 4 illustrates the effect of adding a surfactant to an inhibitor solution in preserving passivity of type 20 7075-T6 aluminum;
BT ZUSo0 Surfactant
igho t pe ce t Pefert
.000-015 .003-06 006-03
.003-012 .005-05 0030-.025
Con en raion of Dr i esrcent) Ingredients (percent) 13.5-17.5 0.5-1.75 0.84.9 0.25-0.5
0.25-0.5 1.0-2.0 1.0-2.0
The surfactant is a selected anionic or nonionic surface active material. The selected surfactants employed in the corrosion inhibitor of the present invention are, in general, proprietary materials. Table II, below, lists the surfactants employed according to the present invention by (1) an arbitrary designation, (2) a brief description of the composition of the surfactant, (3) the cornmercial name of the surfactant, and (4) the source for such surfactant. TABLE II Proprietary Surface Active Agents
The Richardson Company
Sodium Dodecylben.ene Suifonate
Sodium salt of Phosphonic acid
Corrosion inhibitor (commercial
Boeshield T-9 Oxy Metal Industries
formulaton) with complex sulfoate compound
Des Plaines, Illinois Monsanto Company St. Lous. Missouri
CorpMadison Heights. MI
Dialkyl alkyl phophonae
Mobil Chemical Company
Phoephoroua Division Richmond, Virginia
High molecular weight phosphate
Octylpbenoxy polyethoxy ethanol
High molecular weight calcium
St. LouIS. Missouri Rohm and Han Co. Indutuial Chemicals. NA Philadelphia. Pennsylvania
The Southland Corp. Arthur C. Trask Chemical
High molecular weight Barium sulfoate
Sodium alt of a complex Phosphate ester
Division Summit. Illinois The Southland Corp Arthur C. Trak Chemical Division Summtt Illinois OAF Corporation New York. New York
FIG. 5 illustrates the effect of adding a surfactant to Referring now to the drawings, FIG. 1 shows the an inhibitor solution in preserving passivity of type 4340 50 anodic polarization behavior of type 7075-T6 aluminum Gl. in distilled water, local tap water, a 0.1 molar solution of FIG. 6 illustrates the anodic polarization of type sodium chloride and local tap water containing the 7075-T6 aluminum in natural and in synthetic urine, and corrosion inhibitor disclosed in the aforementioned FIG. 7 illustrates the effects of adding the inhibitor application Ser. No. 265,734. This figure illustrates a composition of this invention for preserving the passiv- 5 very high corrosion current and breakdown in passivity ity of various metals in synthetic urine solution. in tap water and in 0. IM NaCI, as well as illustrating the DESCRIPTION OF THE PREFERRED EMBODIMENTS heamounts of each component of the incentration Theinhibiting 60 composition of this invention are given in Table I, below. TABLE I Cnation i .aqu
solution(weh aCnt Cormponsrl Dom Nitrite
Wood .20-L0o .04-23
Preferred' 0.25-1.40 .05-20
r o ry Insrdlmts (praent) 8.0-70.0 8.5-14.0
protecton afforded by the aforesaid corrosion inhibitor. FIG. 2 illustrates the effect of increasing chloride conupon the breakdown of passivity of type 7075-T6 aluminum. FIG. 3 illustrates a similar type of behavior with type 4340 steel. FIGS. 4 and 5 illustrate the effect of adding 125 ppm of sodium dodecylbenzene sulfonate (SAR) to solutions of incresing chloride concentration, each containing 65 the basic inhibitor mentioned above. A comparison of FIG. 4 with FIG. 2, although not strictly comparable, clearly indicates the increased protection afforded by the addition of sodium dodecylbenzene sulfonate to the
4,714,5646 basic inhibitor formulation. A more direct correlation is
seen by reference to FIGS. 5 and 3. FIGS. 6 and 7 illustrate the anodic polarization behavior of various metals in a synthetic urine solution. The composition of the synthetic urine is given in TabLe 5
Component Phosphate MBT Err SAL SAE
III below. TABLE III Ingedients of Synthetic Urine (Wt in gimAiter)
Formulation I. is preferred for use where the concentration of chloride is very high, e.g., brine. Formulations 2 and 3 are recommended for use in aggressive
solutions such as are found in the bilge areas of aircraft. Formulation 4 will provide protection in high chloride FIG. 6 illustrates that the corrosive behavior of synthetic urine closely approximates that of natural urine. 30 contaminated water, i.e., up to about I weight percent NaC l. FIG. 7 illustrates the anodic polarization behavior of Formulation 6 is a preferred formulation for general type 7075-T6 aluminum, type 4340 steel, copper and purpose use. f is effective where little or no dilution is brass in synthetic urine and in synthetic urine inhibited expected during use and low concentrations of chloride by the multifunctional inhibitor formulation containing 35 and other aggressive reactants are present, i.e., up to 125 ppm of sodium dodecylbenzene sulfoate. about 100 ppm chloride ion. Formulation 5 is effective More specific inhibitor formulations are given in in situations where no dilution is expected and the conTables IV and V below. All amounts are given in centration of chloride ion or other aggressive reactant is weight percent (in aqueous solution). very low. Formulation 7 is for contact inhibitors to TABLE IV 40 form a protective surface layer during immersion. Formulation The concentrations of the various components can be Component Borate Nimte Nitrate Silicate
1 0.35 .20 .20 .01
2 0.35 .20 .20 .01
3 0.35 .20 .20 .0!
4 0.35 .20 .20 .01
varied by about 20% for conditions where dilution in use is expected. In Table VI, below, the representative results of tests with several experimental formulations are summarized. 45 These immersion tests were carried out on type 7075-T6
aluminum and type 4340 steel in IM NaCI solutions. TABLE VI Imersmon Test Results
"tme of Exposure Surface Appearance (weeks) (Visual Observation)
Several pits Better Clean & shiny; few pits Inhibitor required Clean Few pits Cleam. Few fine pits Many pits at edge Clean &shiny Clean & shiny Clea pits Cleai. several pits Dull. patches of Corrosion Several pit
Better Inhibitor required
Clean Clean. few corrosion streaks
Improve meat required Better Inhibitor required
4,714,5648 TABLE VI-continued Immersion Test Results Time of Inhibitor No wt % in IM NaCI
itors and as immersion-type inhibitors. The corrosion In Table VI above and in Table VII, below, the term inhibitor may be compounded dry, and stored in bulk borate refers to sodium borate tetrahydrate, nitrate to for later solution in water. In the dry form, the corrosodium nitrate, nitrite to sodium nitrite, silicate to sodium metasilicate pentahydrate, and phosphate to so- 30 sion inhibitor may be incorporated from 20 to 50 weight percent. preferably about 30 weight percent, into a dium hexametaphosphae. In Table VII below, the representative results of tests commercial soap formulation, e.g., a handsoap, for use in the lavatory of an aircraft or ship. with several experimental formulations are summarized. The corrosion inhibitor may be incorporated into a These tests were carried out on type 7075-T6 aluminum, type 4340 steel, and brass in synthetic urine solution, 35 coating composition, such as a paint primer by encapsulating the inhibitor formulation with a cellulosic or and in a mixture of synthetic urine and coffee. TABLE VII Time of Inhibitor wt % in No synthetic urine
Clean,. one pit appearing on one surface Clean &shiny Clean &shiny
*EaesK Rn 1Swinch was "0% systhed stinge and 50%eufi
The corrosion inhibiting formulations of this invention may be used in aqueous solution as rinse-type mnhib-
nylon or other suitable encapsulating material using
conventional encapsulating techniques, and incorporat-
ing 20 to 50 weight percent. preferably about 30 weight percent, of the encapsulated inhibitor into a conven-
Component Benzotrazole (BT)
Concentration 0.25 to 0.5
tional coating composition. The corrosion inhibiting 5 components may be released if the coated surface is 2. The soap of claim I wherein the concentration of said corrosion inhibiting composition is about 30 weight scratched or otherwise physically damaged. Various modifications can be made to the above depercent. 3. A paint formulation comprising from 20 to 50 scribed invention. 10 weight percent of an encapsulated, dry multifunctional We claim: corrosion inhibiting composition, said composition consisting essentially of the following components in the 1. A soap formulation comprising from 20 to 50 approximate concentrations indicated, in weight perweight percent of a multifunctional corrosion inhibiting cent: composition, said composition consisting essentially of 15 the following components in the approximate concentrations indicated, in weight percent: Component
Alli metal borate
Alkali mea nitrite
Alkali metal mniite All-Ii metl metailicate
Alkali metal phosplute Mercatobenzothiazoe (MT) At least one selected surfactant and, optional, the following components:
0.8 to 0.25 to 1.05 to
0.9 0.5 2.0
Component Alkali meta borte
Concentration 68.0 to 70.0
Alkali metal nitrate ltrite Alkai metal Alkali metal metl meticate Alkali phosphate
8.5 13.5 0.5 0.8
to to to to
14.0 17.5 1.7 0.9
Mercaptobenzothiazole (MBT) At leat one selected surfactant he olowinz com22nents: = dT op0ol Zinc sulfate Benzotuiazole (BT)
0.25 to 1.05 to
1.0 to 0.25 to
4. The paint of claim 3 wherein the concentration of said corrosion inhibiting composition is about 30 weight 30 percent. a