1、Designation: D2651 01 (Reapproved 2016)Standard Guide forPreparation of Metal Surfaces for Adhesive Bonding1This standard is issued under the fixed designation D2651; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.INTRODUCTIONIt is impossible and impractical to
3、present a single surface-preparation method for a metal group,such as aluminum alloys, stainless steels, magnesium alloys, etc. The wide variety of individual alloysand heat treatments under each group, the fact that certain adhesives exhibit specific compatibilitieswith surface preparation and the
4、complexity and nature of parts being bonded preclude the use of anall-inclusive procedure for a metal group. Procedures for aluminum alloys are well standardized,possibly because more bonding has been done with these alloys. Preliminary tests should be conductedwith the specific adhesive and the exa
5、ct lot of metals to determine performance. This is especially truefor stainless steel. The adhesive manufacturers recommendation should also be considered.1. Scope1.1 This guide covers procedures that have proved satisfac-tory for preparing various wrought metal surfaces for adhesivebonding. It does
6、 not address the preparation of cast metals.1.2 Surface preparation methods are included for:Metal SectionAluminum Alloys 7Stainless Steel 8Carbon Steel 9Titanium Alloys 10Magnesium AlloysCopper and Copper Alloys11121.3 Procedures included herein are based on the commercialpractice of numerous agenc
7、ies and organizations. The methodsmay be revised or supplemented, as necessary, to includemethods based on proven performance.1.4 The surface preparation of metal systems used forqualification and quality control testing of the adhesive shouldbe agreed upon by both manufacturer and user.1.5 The valu
8、es stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate sa
9、fety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D907 Terminology of AdhesivesD1125 Test Methods for Electrical Conductivity and Resis-tivity of WaterD2674 Methods of Analysis of Sulfochromate Etch SolutionUs
10、ed in Surface Preparation of AluminumD3933 Guide for Preparation of Aluminum Surfaces forStructural Adhesives Bonding (Phosphoric Acid Anodiz-ing)2.2 ASM International Document:3Metals Handbook Volume V2.3 Military Specifications:4MIL-A-8625 Type II, Anodic Coatings for Aluminum andAluminum AlloysMI
11、L-M-3171 Magnesium Alloy, Processes for Pretreatmentand Prevention of Corrosion1This guide is under the jurisdiction ofASTM Committee D14 on Adhesives andis the direct responsibility of Subcommittee D14.80 on Metal Bonding Adhesives.Current edition approved May 1, 2016. Published May 2016. Originall
12、yapproved in 1967. Last previous edition approved in 2008 as D2651 01 (2008).DOI: 10.1520/D2651-01R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards
13、Document Summary page onthe ASTM website.3Available from American Society of Metals (ASM International), 9639 Kins-man Rd., Materials Park, OH 44073-0002, http:/www.asminternational.org.4Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,Philadelphia, PA 19111-5094, http:/quicksear
14、ch.dla.mil.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1MIL-M-45202 Magnesium Alloy, Anodic Treatment of2.4 SAE Standards:5Aerospace Material Specification 2470 E Anodic Treatmentof Aluminum Base Alloy, Chromic Acid Treatment3. Ter
15、minology3.1 DefinitionsMany of the terms in this guide are definedin Terminology D907.4. Apparatus4.1 Trays or Pans, suitable for preparation of laboratoryspecimens and small parts. Generally in production, a series oftanks containing the necessary solutions is arranged withoverhead cranes to transp
16、ort parts to be prepared. Tanks shouldbe lined with suitable materials to resist the solutions, andmethods for circulating the solutions and heating with tempera-ture controls should be included if required.4.2 Hooks, Baskets, Clamps, or other holding devices, maybe used to convey parts being prepar
17、ed. The use of a 300 Seriesstainless steel for such equipment is suggested. Other metalsmay be used if they are resistant to the solution used.5. Conditions5.1 HandlingAll parts during and after processing andbefore bonding should be handled as little as possible and onlywith clean, lint-free cotton
18、 or nylon fabric gloves.5.2 Water used for preparing solutions should be distilled,steam condensate, demineralized, deionized or otherwisetreated, if necessary, to obtain a condition of not more than 50ppm of solids and have a pH between 5.5 and 10, or not morethan 50 ppm of dissolved solids and not
19、 over 30 micromhsconductance (see Test Methods D1125). Rinsing may be doneby spray or by dipping in a tank in which the water is circulatedand constantly being renewed by an overflow method. Afterremoving from any rinse the water-break test is commonlyused. If the water film is discontinuous, it ind
20、icates that theprocess is unsatisfactory and must be repeated (see 5.5.4).Other methods, such as indicator paper and contact angle, havebeen used to determine the effectiveness of the process.Rinsing should be sufficiently long and vigorous to assureremoval of soluble residue chemicals, or particles
21、. Criticalspecific temperatures are specified for the rinse water in someprocesses. Where not specified, temperature is not critical. Thenumber of times a process may be repeated depends upon theamount of metal removed in relation to the tolerance require-ments for the part and whether clad or bare
22、metal is used.Generally, not more than two repeat treatments are permitted.NOTE 1No entirely foolproof method exists to determine bondabilityof a metal surface after preparation. Trial bonding followed by testing andevaluation against mechanical strength standards should be conducted todetermine ini
23、tial and continuous effectiveness of a method.5.3 SolutionsThe life of solutions should be standardized.The useful life of solutions depends upon the number and sizeof the parts being prepared. Solutions should be sampledperiodically and analyzed for materials pertinent to the particu-lar treatment
24、method, such as, titration for hexavalent chro-mium (CrO3), iron, chlorides, aluminum, etc. A pH reading oracid content of trichloroethane vapor degreasing solution, orboth, should be obtained. Standards should be established andrecords kept for such tests on each lot or vat of solution.Records shou
25、ld indicate the continuous conditions of solutions,such as amount of constituents added to bring solutions withinlimits, amount of contaminants present and date prepared (seeMethods D2674).5.4 Room Conditions for surface preparation as well asother adhesive bonding operations should be controlled fo
26、rtemperatures of 18 to 24C (65 to 75F), relative humidity of40 to 65 %, air-filtered to remove dust and pressure maintainedat slightly higher than ambient.5.4.1 The time and conditions between surface preparationand applying adhesive primer, if used, and bonding are critical.Usually, the time should
27、 not exceed 8 h and parts should becovered or wrapped in Kraft paper. Prepared surfaces canchange their characteristics on standing and adhesives varywidely in their tolerance of adherend surface conditions. Inproduction bonding of complicated or large parts, the timeinterval may exceed 8 h. Investi
28、gation should be made todetermine the time limitation of the adhesive and the rate ofchange on the surface of the adherend. On the basis of theresults of such an investigation, it may be possible to extendthe length of time and establish standards for the intervalbetween surface preparation and adhe
29、sive application to fitproduction schedules. Contaminating operations in the areashould be avoided. Especially detrimental are paint or otherspraying operations, processes using powdered materials, oilvapors from pumps and other machinery and spraying of moldrelease agents.5.5 Common Steps:5.5.1 Rem
30、ove ink markings or stamped identifications fromthe metals. This can be accomplished by wiping with a clothwetted with a variety of commercial solvents, such as acetone,methyl ethyl ketone, lacquer thinner and naphtha.5.5.2 The preferred degreasing method is vapor degreasingwith 1,1,1-trichloroethan
31、e. Commercial vapor degreasingequipment is usually used. This equipment has a deep tankwith provision for heating a chlorinated solvent to 82 to 87C(180 to 190F). Parts are suspended in the vapor zone abovethe hot liquid and allowed to remain until there is condensationand run off (approximately 5 m
32、in). This step is repeated ifnecessary until all visible contamination is removed. The partsare raised above the tank and allowed to dry thoroughly.Previously bonded parts, such as honeycomb core materials,are usually not degreased due to difficulty in removing residue.5.5.3 Following vapor degreasi
33、ng, mechanical or chemicalcleaning methods are usually employed.5.5.4 A water-break test is a common method used toanalyze surface cleanliness. This test depends on the observa-tion that a clean surface (one that is chemically active or polar)will hold a continuous film of water, rather than a serie
34、s ofisolated droplets. This is known as a water-break-free condi-tion. A break in the water film indicates a soiled or contami-nated area. Distilled water should be used in the test, and a5Available from Society of Automotive Engineers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-0001, http:/www
35、.sae.org.D2651 01 (2016)2drainage time of about 30 s should be allowed. Any trace ofresidual cleaning solution should be removed or a falseconclusion may be made. If a water-break-free condition is notobserved on the treated surface, it should not be used forbonding. The surface should be recleaned
36、until the test ispassed. If continuous failures occur, the treating process itselfshould be analyzed to determine the cause of the problem.6. Report6.1 The report for all methods consists of flow charts, recordsheets or other methods that indicate all steps in the surfacepreparation used, with space
37、s for entries made upon comple-tion of each step.ALUMINUM ALLOYS7. Procedure7.1 Aluminum alloys may be pretreated with many differentmethods, using both acidic and basic cleaners.7.2 A typical pretreatment would normally involve thefollowing steps:7.2.1 Vapor degrease or non-etching alkaline cleaner
38、,7.2.2 Rinse,7.2.3 Acid or alkaline, and7.2.4 Rinse.7.3 After 7.2.4, the parts may be dried or they may be givenan anodizing treatment.7.4 Typical pretreatments are listed in 7.4.1. Refer to theappropriate literature for details on cleaning techniques andprocedures.7.4.1 Alkaline degreasing solution
39、s may be used instead of,or in addition to, vapor degreasing. Commercially availableproprietary solutions may be used. A common degreasingmethod is to immerse for 10 min at 70 to 82C (160 to 180F)in the following solution by weight: 3.0 parts sodiummetasilicate, 1.5 parts sodium hydroxide, 0.5 parts
40、 sodiumdodecylbenzene sulfonate, such as Nacconol 90G6, to 133.0parts water.7.4.2 Acid etching solutions typically used are the follow-ing:7.4.2.1 Sulfuric Acid/Sodium Dichromate (optimized FPLetch).Material ConcentrationSulfuric Acid (66Be or Baume) 38 to 41.5 oz/gal (287.9 to 310.0 g/L)Sodium Dich
41、romate 4.1 to 9.0 oz/gal (2867.3 g/L)Aluminum Alloy2024 bare 0.2 oz/gal (1.5 g/L), minTemperature 66 to 71C (150 to 160F)Immersion Time 12 to 15 min7.4.2.2 P-2 Etch (Sulfuric Acid/Ferric Sulfate).Material ConcentrationSulfuric acid (6.5 to 9.5 N) 27 to 36 % by weightFerric sulfate 135 to 165 g/L (18
42、 to 22 oz/gal)Temperature 60 to 65C (140 to 150F)Immersion Time 10 to 12 min7.4.3 Phosphoric Acid Anodizing can be performed in ac-cordance with Guide D3933.7.4.4 Sulfuric Acid AnodizingA method found suitable forbare aluminum (nonclad), machined, or chemically milledparts which must be corrosion pr
43、otected is to anodize withsulfuric acid. Do not seal the anodized parts with boiling waterbefore bonding. Do not allow the time interval betweentreatment and bonding to exceed 72 h, and cover or wrap allparts during the interval with a non-contaminating vaporbarrier material.NOTE 2Details of the pro
44、cess are contained in Specification AMS2470 E or Military Specification MIL-A-8625.7.4.5 Proprietary CleanersSome proprietary, commer-cially available metal surface preparations have been foundsuitable for preparing the surfaces for adhesive bonding.Full-scale property tests should be run with the m
45、etal surfacesso prepared with the adhesive in question before accepting theprocess.7.4.6 Secondary BondingWhen secondary bonding(bonding of parts that contain previously bonded areas) orrepair of a disbonded assembly in service is necessary, it isusually impossible and undesirable to immerse these p
46、arts insurface-preparation solutions without destroying or harmingthe original adhesive bond. Satisfactory surface preparationshave been accomplished by using paste-type etchants. Thesepaste systems can be made by adding fumed silica to thesulfuric-dichromic acid solutions. The application of thesep
47、aste systems allows for their use in fairly controlled areas. Theetching time is generally 10 to 20 min. Exercise extreme careto ensure removal of all traces of the etchant. A thoroughrinsing with distilled water may be necessary to ensurecomplete removal. Several commercial products are available.S
48、ome commercial compounds under the classification of “washprimers” have been found to perform satisfactorily in place ofthe paste type systems. Bond strengths obtained using either ofthese surface preparations are somewhat lower than those fromthe immersion processes.7.4.7 Brush Plate Bond Etch (Sty
49、lus Method):7.4.7.1 GeneralThis method of electrochemical surfacepreparation, although not widely known, has been effectivelydemonstrated for small batch runs where tanks and othercapital-intensive methods might have been used. Almost all ofthe solutions, “brushes” (or styli), and electrical power suppliesare proprietary. When this method is used, the entire “family”of proprietary items should be used; mixed usage of itemsbetween vendors should not occur.7.4.7.2 General PrecleaningRemoval of grease, oil, andother organic soils can be accomplished with virt
