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  • THE INHIBITION OF VAPOR-PHASECORROSION: A REVIEW

    INTERIM REPORT D IBFLRF No. 209 E TEUJAN 8 NO6

    By

    G.E. FodorBelvoir Fuels and Lubricants Research Facility (SwRI)

    Southwest Research Institute0D San Antonio, Texas

    (V) Under Contract to

    U.S. Army Belvoir Researchand Development Center

    I Materials, Fuels and Lubricants LaboratoryO ~Fort Belvoir, Virginia

    Contract No. DAAK7O-85-C-0007

    Approved for public release; distribution unlimitedrLUJ

    October 1985

    86 1 28 018

  • 4. 1

    Disclaimers FThe findings in this report are not to be construed as an official Department of theArmy position unless so designated by other authorized documents,.

    -Trade names cited in this report do not constitute an official endorsement or appro-* val of the use of such commercial hardware or software.

    DTIC Availability Notice

    Qualified requestors may obtain copies of this report from the Defense Technical. ,Information Center, Cameron Station, Alexandria, Virginia 22314. S

    Disposition Instructions-

    Destroy this report when no longer needed. Do not return it to the originator.

    %-

  • PAGESARE

    MISSINGIN

    ORIGINALDOCUMENT

  • Unclass~ified A /. SECURITY CLASSIFICATION OF THIS PAGE

    REPORT DOCUMENTATION PAGEI. REPORT SECURITY CLASSIFICATION Ib. RESTRICTIVE MARKINGS

    Unclassified None?A SECURITY CLASSIFICATION AUTHORITY 3. OISTRIBUTION/AVAILABILITY OF REPORT

    N/A Approved for public release;2b. DECLASSIFICATION/DOWNGRADING SCHEDULE distribution unlimited

    4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBER(S)

    Interim Report BFLRF No. 209

    69. NAME OF PERFORMING ORGANIZATION Ob. OFFICE SYMBOL 7s. NAME OF MONITORING ORGANIZATIONBelvoir Fuels & Lubricants (tNappce )Research Facility (SwRI) ________________________ 1-B. ADDRESS (City. State, and ZIP Code) 7b. ADDRESS (C/y, Stae, aid ZIP Coda

    6220 Culebra RoadSan Antonio, Texas 78284 .. _.,_.-" ,_"_"_._Se. NAME OF FUNDINGISPONSORING Sb. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER

    ORGANIZATION Of *P&4, "US,Army Belvoir R&D Center .. ''.

    STRBE-VF DAAK7O-85-C-0007; WD 178c, ADDRESS WCO, State, wd ZIP Code) 10. SOURCE OF FUNDING NUMBERS

    Materials, Fuels, & Lubricants Laboratory PROGRAM PROJECT TASK WORK UNITFort Belvoir, VA 22060-5606 ELEMENTNO. NO. NO. ACCESSION NO.

    11. TITLE (Inckjd. Scurkiy C~lcationA".

    The Inhibition of Vapor Phase Corrosion: A Review (U)

    12. PERSONAL AUTHOR(S)

    Fodor, George E..13A. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT IY... Month, Day) 15. PAGE COUNTInterim FROM ,JL.SL5 TO Septiz 1985 October 6216, SUPPLEMENTARY NOTATION

    17. COSATI CODES 18. SUBJECT TERMS lContinue on rewern ff n.vesary and identffy by bkoc* number

    FIELD GROUP SUB.GROUP Inhibition Vapor

    Phase Corrosion

    19. ABSTRACT (Continue on revw-e it necesaety and Identify by block number) .

    : AThis report documents a limited literature review on vapor phase corrosion and itsinhibition. The report discusses theoretical and practical considerations, andincludes definitions, classification, mechanisms of corrosion protection, andevaluation of inhibitors. Protection of ferrous and nonferrous alloys is discussed, .and specific examples are given. Also included are chemical structural identificationof cited organic compounds as well as a summary of commercial preservation procedures.A Lotal of 132 references with dates up to 1984 are given. ~L..(.

    2D. DISTRIBUTION/ AVAILABILITY OF ABSTRACT '21. A'BSTRACT SECURITY CLASSIFICATION '

    2 UNCLASSIFIED/ UNLIMITED [3 SAkiE AS RPT. [3 DTIC USERS Unclassified

    22a. NAME OF RESPONSIBLE INDIVIDUAL 22b, TELEPHONE (Unchde ArU Codae) c. OFFICE SYMBOL

    Mr. F.W. Schaekel (703) 664-3576DD FORM 1473. 84 MAR 83 APR aditkm may be ued until exhausted. SECURITY CLASSIFICATION OF THIS PAGE

    AkNtllereditloneiweobeo l re o ,,Unclassified

    ".4

  • FOREWORD '*-

    This report was prepared at the Beivoir Fuels and Lubricants Research Facility(SwRI) located at Southwest Research Institute, San Antonio, TX, under Contract

    No. DAAK70-85-C-0007, for the period 1 July 1985 through 30 September 1985. .Work was funded by the U.S. Army Beivoir Research and Development Center, Ft.Belvoir, VA, with Mr. F.W. Schaekel (STRBE--VF) serving as contracting officer'srepresentative. Project technical monitor was Mr. M.E. LePera, STRBE-VF.

    I AL

    Accesior, For70NNTIS CRA&I0DV~JC TAB

    J.;titica tioji

    R I-I,

    3Y

    ID.....(.........1

    .. . ....1

  • ACKNOWLEDGEMENTS

    The author gratefully acknowledges contributions by Messrs. F.W. Schaekel and H

    Roger Thiesfeld (Belvoir R&D Center); Dr. Fred F. Lyle, Jr. (Southwest Research

    Institute); and Mr. E.A. Frame (Belvoir F&t. Research Facility).

    4r

    2-

  • TABLE OF CONTENTS I.--

    Section Page "

    1. INTRODUCTION........................................... 5

    IL DEFINITION AND) CLASSIFICATION OF INHIBITORS ................ 6

    III. MECHANISM OF ACTION BY VCI................................ 9

    IV. VAPOR PH-ASE CORROSION INHIBITORS......................... 10

    Protection of Ferrous Metals............................... 14Protection of Copper and Copper Alloys ................. 15Protection of Silver ............................... 16Protection of Aluminum ................................ 16Protection of Ferrous and Nonferrous Metals .................. 17

    V. EVALUJATION OFYVC~s........................................ 21

    VI. APPLICATIONS ............................................. 23

    VIL R.EFERENCES......................................... 25

    APPENDICES

    APPENDIX A--I DE NTIFI[CATION OF COMPOUNDS ................. 35APPENDIX B--SUMMARY OF COMMERCIAL PRESERVATION

    PROCEDURES ............................................ 51

    3

  • LIST OF ILLUSTRATIONS

    FigurePae.*-ro.

    r.I Mechanism of Corrosion Inhibition ...... ................... 9 6~ F.-

    p LIST OF TABLES

    Table Page

    I Inhibiting Efficiencies of Different Organic Substances,Deduced From Accelerated Atmospheric Corrosion Tests 12... 1

    2 Protection of Various Alloys by Corrosion Inhibitors ............... 24

    %* S

  • . .'. .

    "1. INTRODUCTION

    The direct cost of atmosph nc corrosion of metals and alloys in the United States

    alone has been estimatedt to be between $5 billion to over $20 billion annually.

    This atmospheric corrosion, known by some researchers** as vapor phase corrosion

    (VPC), is due to the individual and combined action of oxygen, moisture, andatmospheric pollutants.1 'Additional contributors to VPC are rain, snow, dust, soot,

    ash, wind, and radiation (light, heat, etc.). The rate of VPC may be accelerated by"both acids and bases, depending upon the metal.

    r ~..,.-...

    Rosenfeld3 showed that the mechanism of this attack is electrochemical, in which"the electrolyte is composed of a thin film of humidity on the surface of the metal.

    It has been shown for iron that when relative humidity is below 60 percentr .-o

    corrosion Is expected, while above 75 to 80 percent, the degree of corrosion will be

    high.

    ,.Detrimental effects caused by photochemical reactions of sulfur dioxide andnitrogen oxides have been demonstratedby-Ser- .

    . Classical methods of protecting equipment from atmospheric attack include (a)

    using coating materials or paints and (b) alloying the metal to increase its -

    resistance to corrosion. An effective and relatively inexpensive method of

    controlling VPC in closed environments is through the use of vapor phase corrosion

    inhibitors (VCI). These materials, while having an appropriate vapor pressure,

    possess "high passivating properties, strong tendencies toward surface adsorption,and the ability to form a comparatively strong and stable bond with the metal

    surface.'*.. ".

    Superscript numbers refer to the references at the end of this report. Some researcher. limit "vapor phase corrosion" to mean an attack in a closedspace while "atmospheric corrosion" refers to corrosion in the open air.

    .5......... . -. . -. ...... .. .. . ... .... .. ., ............... ............ ...... .. . . ..

    S~~~~~~~~~~~~~~~~~~~. . . .............. " ;;;:', =,'', , v.".:.-..:.."..'..:.'...." :",.

  • IL DEFINITION AND CLASSIFICATION OF INHIBITORS

    General electrochemical reactions may be written to describe corrosion that may _

    take place at the anode and at the cathode. For a divalent metal, the following -

    equations may be written:

    Anodic oxidation: "

    Ma 2 + 2 e- . ,,.

    Metal Divalent Electrons_L

    Cathodic Reduction:

    2 H* + 2e -. H2 (gas)

    !i.1/202 + 2 H* + 2 e- H20

    02 + 4 H+ + 4e- 2 H20

    1/202 + H20 + 2 .- - 2 (OH)--

    All corrosion takes place at the anode, where the metal, MO, loses electron(s) and r

    becomes a positive ion. This oxidation will proceed only if the produced electrons

    and ions are removed at the cathode. These reactions occur as anode-cathode ,'-

    reaction pairs, and each is called a "half-cell reaction."

    Each half-cell reaction has a half-cell potential associated with it. These

    electrode potentials vary with concentration of the reacting species of the ..".-,.,

    electrolyte and the temperature.

    6t . .... .

  • For the reaction

    IL + mM ,, 0" oO + pP

    where I is the number of moles of substance L, m is the number of moles of

    substance M, etc. The electrode potential, E, of the reaction is given by the .

    Nernst equation:

    RT (

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