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Selecting A Corrosion Inhibitor Milacron Marketing Co. Technical Report No. 2/03Page 1 of 32/03

Selecting A CorrosionInhibitor

INTRODUCTION

Corrosion, an ongoing concern for industry, maycause reduced service life or complete failure ofmanufactured parts and finished goods. These issuesdirectly impact the cost efficiency of the manufacturingprocess and cost of the finished goods. Corrosioninhibitors can be used to prevent the problemsassociated with corrosion

WHAT IS CORROSION?

Corrosion is the destructive attack to metal by achemical or electrochemical reaction with itsenvironment.

The terms corrosion and rusting are often usedinterchangeably. The term rust typically is applicableto ferrous materials, iron and steel. The most term touse is "corrosion" because it is inclusive of non-ferrousmetals as well.

Metallic staining is light corrosion resulting indiscoloration or tarnish of the metallic surface. Stainingdoes not need a wet environment to occur. Stainingmay be white and powdery, green, black or brown incolor. This type of corrosion is generally found withaluminum, brass & copper materials.

Examples of Corrosion

Galvanized part with white corrosion

Cold Rolled Steel Corrosion

Cast iron with and without corrosion

What is a Corrosion Inhibitor?

A corrosion inhibitor is a material that attaches or coatsthe metal surface, providing a protective barrier film,which in turn stops the corrosive reaction fromdeveloping. Temporary coatings are often used toprevent corrosion during storage and shipment, andbetween machining or processing operations. The mosteffective corrosion inhibitor coatings, at one time, wereoil or solvent-based materials. In recent years waterbased products have been developed and are beingused with success.

Aluminum Staining

CIMCOOL Technical ReportMilacron Marketing Co. | Consumable Products Division | Cincinnati, Ohio 45209

Selecting A Corrosion Inhibitor Milacron Marketing Co. Technical Report No. 2/03Page 2 of 32/03

Choosing a Corrosion Inhibitor

When choosing the corrosion inhibitor for yourapplication several things need to be considered. Materials to be protected Protection effectiveness timeframe (1week, 1

month, 1 year, etc.) Method of application (dip, spray, brush, etc.) Type of protection required (in process, storage or

shipping) Part handling and fingerprint suppression Type and thickness of coating residue desired Storage, packaging and/or shipping conditions

(temperature, humidity & seasonal conditions) Removal methods (if required) Interaction with subsequent processes, if not

removed Environmental, health and safety requirements Type of product (Oil/Solvent or Water-based)

desired

Oil/Solvent-Based Inhibitors

Corrosion inhibitors of this type rely principally on theformation of barrier coatings to prevent water fromcontacting metal surfaces. These materials aretypically used direct from their container without anyneed for thinning or preparation for use.

The protective coating they form varies (semi-hard,soft, oily, transparent, colored) with the specificproduct. Removal methods for these coatings aredependent on the specific product and may vary fromthe use of an alkaline cleaner or degreaser to the useof a solvent. The coatings can be applied by brush,dip, and spray methods.

For parts that need longer term protection (months toyears) or those stored in severe environmentalconditions (i.e. outside storage) oil-based inhibitors arepreferred due to their heavy film and the waterrejecting properties they possess.

For additional information on CIMCOOL CIMGUARD

Oil/Solvent Based Corrosion Inhibitors refer to Table1at the end of this document.

Water-Based Inhibitors

Water-based corrosion inhibitors rely on modifying thecharacteristics of the metal surfaces themselves todecrease their susceptibility to oxidation and corrosionformation. Water-based inhibitors are typically sold asa concentrate and diluted with water for use, makingtheir cost less than most oil/solvent-based products.

Water-based corrosion inhibitors generally have verydesirable characteristics. The chemical films formedare thin and typically transparent when dry. Applicationmethods for these coatings include spray, brush orimmersion. They are cleaner to use and eliminateconcerns of solvent fumes. The films rarely have to beremoved prior to subsequent operations but if removalis necessary it is done easily with mild water-basedcleaners.

Water-based inhibitors can be effective in preventingcorrosion for extended periods of time (weeks tomonths) under reasonable plant storage and protectedshipping conditions. Since water-based products workby decreasing the susceptibility of the metal tooxidation rather than by completely excluding water andair, these inhibitors often are not as effective asoil/solvent-based coatings in shipping and outsidestorage of parts.

For additional information on CIMCOOL CIMGUARD

Water-based Corrosion Inhibitors refer to Table 2 atthe end of this document.

Supplemental Protection

Adverse atmospheric conditions encountered duringshipping and long-term storage may require moreprotection for the metal than that provided by oil/solventor waterbased corrosion inhibitors alone. In thesecases Vapor-phase Corrosion Inhibitor (VCI) papers,pellets or films may be used as supplementalprotection.

Consult with your regional CIMCOOL TechnicalService Engineer for specific recommendations, or callCIMCOOL Technical Service at 1-513-458-8199.

CIMCOOL Technical ReportMilacron Marketing Co. | Consumable Products Division | Cincinnati, Ohio 45209

Selecting A Corrosion Inhibitor Milacron Marketing Co. Technical Report No. 2/03Page 3 of 32/03

Table 1. Table 2.