1、Designation: D 2651 01Standard Guide forPreparation of Metal Surfaces for Adhesive Bonding1This standard is issued under the fixed designation D 2651; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.INTRODUCTIONIt is impossible and impractical to present a single sur
3、face-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 complexity and natur
4、e 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 exact lot of metals to
5、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 not address the pre
6、paration of cast metals.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 Surface preparation methods are included for:Metal SectionAluminum Alloys 7Stainless Steel 8Carbon Steel 9Titanium Alloys 10Magnesium AlloysCopper
7、and Copper Alloys11121.4 Procedures included herein are based on the commercialpractice of numerous agencies and organizations. The methodsmay be revised or supplemented, as necessary, to includemethods based on proven performance.1.5 The surface preparation of metal systems used forqualification an
8、d quality control testing of the adhesive shouldbe agreed upon by both manufacturer and user.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 safety and health prac
9、tices and determine the applica-bility of regulatory limitations prior to use.22. Referenced Documents2.1 ASTM Standards:D 907 Terminology Relating to Adhesives3D 1125 Test Methods for Electrical Conductivity and Re-sistivity of Water4D 2674 Methods of Analysis of Sulfochromate Etch Solu-tion Used i
10、n Surface Preparation of Aluminum3D 3933 Guide for Preparation of Aluminum Surfaces forStructural Adhesives Bonding (Phosphoric Acid Anodiz-ing)32.2 ASM International Document:5Metals Handbook Volume V2.3 Military Specifications:6MIL-A-8625 Type II, Anodic Coatings for Aluminum andAluminum AlloysMIL
11、-M-3171 Magnesium Alloy, Processes for Pretreatmentand Prevention of CorrosionMIL-M-45202 Magnesium Alloy, Anodic Treatment of2.4 SAE Standards:7Aerospace Material Specification 2470Anodic Treatmentof Aluminum Base Alloy, Chromic Acid Treatment1This guide is under the jurisdiction of ASTM Committee
12、D14 on Adhesives andis the direct responsibility of Subcommittee D14.80 on Metal Bonding Adhesives.Current edition approved Oct. 10, 2001. Published December 2001. Originallypublished as D 2651 67. Last previous edition D 2651 90 (1995).2A surfactant that has been found suitable for this purpose con
13、sists of a 50 %mixture of a cationic and a fluochemical surfactant such as Zonyl FSC manufacturedby E.I. DuPont, Wilmington, DE 19898.3Annual Book of ASTM Standards, Vol 15.06.4Annual Book of ASTM Standards, Vol 11.01.5Available from ASM International, Metals Park, OH 44073.6Available from Standardi
14、zation Documents, Order Desk, Bldg. 4, Section D,700 Robbins Ave., Philadelphia, PA 19111, Attn: NPODS.7Available from the Society of Automotive Engineers (SAE), 400 Common-wealth Dr., Warrendale, PA 15096.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428
15、-2959, United States.3. Terminology3.1 DefinitionsMany of the terms in this guide are definedin Terminology D 907.4. 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 w
16、ithoverhead cranes to transport 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
17、to convey parts being prepared. 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 only
18、with clean, lint-free cotton 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
19、 of dissolved solids and not over 30 micromhsconductance (see Test Methods D 1125). 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
20、film is discontinuous, it indicates 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 re
21、sidue chemicals, or particles. 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 p
22、art and whether clad or bare 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
23、 be conducted todetermine initial 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
24、to the particu-lar treatment 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
25、 vat of solution.Records should indicate the continuous conditions of solutions,such as amount of constituents added to bring solutions withinlimits, amount of contaminants present and date prepared (seeMethods D 2674).5.4 Room Conditions for surface preparation as well asother adhesive bonding oper
26、ations should be controlled fortemperatures 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 cri
27、tical.Usually, the time should 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 timein
28、terval may exceed 8 h. Investigation 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 intervalbetwee
29、n surface preparation and adhesive 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 age
30、nts.5.5 Common Steps:5.5.1 Remove 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 degre
31、asingwith 1,1,1-trichloroethane. 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 condensation
32、and run off (approximately 5 min). 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.
33、5.5.3 Following vapor degreasing, 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
34、 of water, rather than a series 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 adrainage time of about 30 s should be allowed. Any trace ofresidual cleaning solut
35、ion 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 until the test ispassed. If continuous failures occur, the treating process itselfshould be analyzed to det
36、ermine 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 surfaceD 26512preparation used, with spaces for entries made upon comple-tion of each step.ALUMINUM ALLOYS7. Procedure7.1 Aluminum alloys may
37、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,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
38、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 solutions may be used instead of,or in addition to, vapor degreasing. Commercially availableproprietary solu
39、tions 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 sodium metasili-cate, 1.5 parts sodium hydroxide, 0.5 parts sodium dodecyl-benzene sulfonate, such as Nacconol 90G8, to 133.0 partswater.7.4.2 Acid etching s
40、olutions 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 Dichromate 4.1 to 9.0 oz/gal (2867.3 g/L)Aluminum Alloy2024 bare 0.2 oz/gal (1.5 g/L), minTemperatur
41、e 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 to 22 oz/gal)Temperature 60 to 65C (140 to 150F)Immersion Time 10 to 12 min7.4.3 Phosphoric Aci
42、d Anodizing can be performed in ac-cordance with Guide D 3933.7.4.4 Sulfuric Acid AnodizingA method found suitable forbare aluminum (nonclad), machined, or chemically milledparts which must be corrosion protected is to anodize withsulfuric acid. Do not seal the anodized parts with boiling waterbefor
43、e 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 process are contained in SpecificationAMS 2470E, or, Military Specification MIL-A8625.7.4.5 Propri
44、etary 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 metal surfacesso prepared with the adhesive in question before accepting theprocess.7.4.6 Second
45、ary 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 parts insurface-preparation solutions without destroying or harmingthe original adhesive bond. S
46、atisfactory 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 thesepaste systems allows for their use in fairly controlled areas. Theetching time is generally 10 t
47、o 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.Some commercial compounds under the classification of “washprimers” have been found to perform s
48、atisfactorily 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 (Stylus Method):7.4.7.1 GeneralThis method of electrochemical surfacepreparation, although not wide
49、ly 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 virtually anysolvent, including trichlorotrifluoroethane and similar non-flammable types.7.4.7.3 Mechani
