1、Designation: F21 14Standard Test Method forHydrophobic Surface Films by the Atomizer Test1This standard is issued under the fixed designation F21; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in
2、 parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the detection of the presence ofhydrophobic (nonwetting) films on surfaces and the presenceof hydrophobic organic material
3、s in processing environments.When properly conducted, the test will enable detection offractional molecular layers of hydrophobic organic contami-nants. On very rough or porous surfaces the sensitivity of thetest may be significantly decreased.1.2 The values stated in SI units are to be regarded as
4、thestandard. The inch-pound values given in parentheses are forinformation only.1.3 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 practices and det
5、ermine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C813 Test Method for Hydrophobic Contamination on Glassby Contact Angle MeasurementD351 Classification for Natural Muscovite Block Mica andThins Based on Visual QualityD1193 Specification for
6、Reagent WaterD2578 Test Method forWettingTension of Polyethylene andPolypropylene FilmsD5946 Test Method for Corona-Treated Polymer Films Us-ing Water Contact Angle MeasurementsD7334 Practice for Surface Wettability of Coatings, Sub-strates and Pigments by Advancing Contact Angle Mea-surementD7490 T
7、est Method for Measurement of the Surface Tensionof Solid Coatings, Substrates and Pigments using ContactAngle MeasurementsF22 Test Method for Hydrophobic Surface Films by theWater-Break Test3. Terminology3.1 Definitions:3.1.1 hydrophilic, adjhaving a strong affinity for water;wettable.3.1.1.1 Discu
8、ssionHydrophilic surfaces exhibit zero con-tact angle with water. A sessile drop of water applied to thesurface will immediately spread out to form a film.3.1.2 hydrophobic, adjhaving little affinity for water;nonwettable.3.1.2.1 DiscussionHydrophobic surfaces exhibit contactangles between a sessile
9、 drop of water and the surfaceappeciably greater than zero.3.1.3 sessile drop, na drop of liquid sitting on the upperside of a horizontal surface.3.1.4 water-break, na break in the continuity of a film ofwater on a surface on removal from an aqueous bath or onremoval of a flowing water source from t
10、he surface.3.1.5 contact angle, nthe interior angle that a drop makesbetween the substrate and a tangent drawn at the intersectionbetween the drop and the substrate as shown in Fig. 1; this isthe angle formed by a liquid at the three phase boundary wherea liquid, gas (air), and solid intersect.4. Su
11、mmary of Test Method4.1 The atomizer test3is performed by subjecting the drysurface to be tested to a fine water spray. The interpretation ofthe test is based upon the pattern of wetting. In the absence ofhydrophobic films, the impinging water droplets will wet thesurface and spread immediately to f
12、orm a continuous waterfilm. Contaminated areas having a surface tension lower thanwater will cause the water to bead up at that location. Mostcommon film contaminants such as oils, silicones, or fluoro-carbon greases have surface tensions significantly lower thanwater. In areas where these hydrophob
13、ic materials are present1This test method is under the jurisdiction of ASTM Committee E21 on SpaceSimulation andApplications of Space Technology and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Nov. 1, 2014. Published November 2014. Originallyapproved
14、in 1962. Last previous edition approved in 2007 as F21 65(2007). DOI:10.1520/F0021-14.2For 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 Document Summary
15、 page onthe ASTM website.3Linford, H. B., and Saubestre, E. B., “A New Degreasing Evaluation Test: TheAtomizer Test,” ASTM Bulletin, May 1953, p. 47.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1on the surface, the sprayed droplets
16、will not wet the surface andspread but will tend to remain as fine droplets.5. Significance and Use5.1 The atomizer test as described in this test method israpid, nondestructive, and may be used for control and evalu-ation of processes for the removal of hydrophobic contami-nants. The test may also
17、be used for the detection and controlof hydrophobic contaminants in processing environments. Forthis application, a surface free of hydrophobic films is exposedto the environment and subsequently tested.45.2 This test method is related to Test Method F22. This testmethod may be suitable as an altern
18、ative to the water-break testwhen the surface of interest should not or cannot be immersedor doused with water, or when such immersion or dousing isimpractical.NOTE 1This test method is not appropriate where line of sightevaluation is not feasible; or for assembled hardware where there is a riskfor
19、entrapment of water in faying surfaces or complex structures where itmay not be effectively removed.5.3 This test method is not quantitative and is typicallyrestricted to applications where a go/no go evaluation ofcleanliness will suffice.5.4 For quantitative measurement of surface wetting, testmeth
20、ods that measure contact angle of a sessile drop of wateror other test liquid may be used in some applications. Mea-surement methods based on contact angle are shown in TestMethods C813, D5946, and D7490; and Practice D7334.5.4.1 Devices for in situ measurement of contact angle areavailable. These d
21、evices are limited to a small measurementsurface area and may not reflect the cleanliness condition of alarger surface. For larger surface areas, localized contact anglemeasurement, or other quantitative inspection, combined withwater break testing may be useful.5.5 This test method is only for use
22、on test surfacescomposed of materials, such as metal surfaces, that arehydrophilic (“wettable”) when clean. Some materials such asgold and many plastics are poorly wetted by water, makingcontamination difficult to detect by this method.6. Interferences6.1 Loss of sensitivity may result from any of t
23、he followingfactors:6.1.1 The presence of hydrophilic substances, such as tracesurfactants, on the surface to be tested, test equipment, or testmaterials,6.1.2 An unusually rough or porous surface condition, or6.1.3 A test surface composed of a material that is signifi-cantly hydrophobic (not “wetta
24、ble”) when clean.6.2 On hot parts or in elevated temperature conditions,water may evaporate before surface wetting can be accuratelyobserved.7. Apparatus7.1 Spray Gun Atomizer.57.2 Low Power Microscope (5 to 50), and light source forobservation of small piece parts (optional).8. Reagents and Materia
25、ls8.1 Acetone, reagent grade.68.2 Mica Blanks, preferably 25 by 50 by 0.38 mm (1 by 2 by0.015 in.) or larger.78.3 Oleic or Stearic AcidA 0.005 to 0.05% solution inacetone.8.4 Compressed AirFiltered, oil-free, low-pressure 100kPa (15 psi) min compressed air or other suitable gas that isfree of hydrop
26、hobic and hydrophilic substances.NOTE 2Freedom of the water and the gas from hydrophobic andhydrophilic contamination may be determined in accordance with Appen-dix X1.8.5 WaterDeionized or distilled water per SpecificationD1193 Types II, III, or IV is preferred. Water of higher ioniccontent may ren
27、der the test destructive.The water used must befree of hydrophobic and hydrophilic substances (see Note 2).9. Procedure9.1 Testing of Surfaces9.1.1 Hold the test surface 250 to 500 mm (10 to 20 in.)from the atomizer and spray with a fine mist of water for aperiod of 1 to 10 s.9.1.2 Immediately after
28、 spraying, observe the behavior ofthe water on the test surface to detect general or localizedbeading.9.1.3 Dry the surface of any remaining water on completionof the test. Corrosion sensitive surfaces should be driedimmediately by a flow of clean, oil-free air or nitrogen. Dryingmay be enhanced by
29、a rinse with isopropyl alcohol prior todrying with oil-free air or nitrogen.NOTE 3The presence of oil or contaminants in the drying gas or the4Feder, D. O., and Koontz, D. E., “Detection, Removal and Control of OrganicContaminants in the Production of Electron Devices,” ASTM STP 246, Am. Soc.Testing
30、 Mats., p. 40 (1959).5PaascheAir Brush Model VL-1 or its equivalent has been found satisfactory forthis purpose.6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC.7Mica meeting quality levelV-6 or better per Classification D351 has been foundto be
31、acceptable.FIG. 1 Contact AngleF21142processing environment may recontaminate the surface and invalidate thewater-break test results.9.2 Testing of Processing Environments9.2.1 Expose a smooth test surface, verified clean andwater-break-free, to the environment and subsequently performthe test as de
32、scribed in 9.1. A freshly cleaved mica blank maybe used as the test surface.NOTE 4For testing of the water itself for background contamination,exposure may be by immersion of the test surface in the water or bydeposition of a sample of the water on the test surface. The proceduredescribed in Appendi
33、x X1 may be used to increase the sensitivity of thistest.10. Interpretation of Results10.1 Surfaces tested as described in 9.1 shall be consideredfree of hydrophobic contaminants by this test if the impingingwater droplets spread immediately to form a thin, continuousuniform water film as shown in F
34、ig. 2. If hydrophobiccontaminants are present, as evidenced by discontinuous ornonuniform water films, the degree of contamination may beestimated by comparison of the pattern of wetting with Figs.3-6.11. Precision and Bias11.1 Precision and bias are intended to be adequate for useas an in-process m
35、onitoring method.11.1.1 RepeatabilityRepeatability of this test method re-quires inspectors that have been trained in the observation ofsurfaces for water breaks.11.2 Bias:11.2.1 No absolute standard traceable to the National Insti-tute of Standards and Technology is available, therefore thebias of
36、this test method cannot be determined at this time.12. Keywords12.1 hydrophilic films; organic contamination; surface con-tamination; water-breakFIG. 2 Atomizer Test of Nickel Specimen with No Detectable Hydrophobic Contaminant (2 Reduced One-Half in Reproduction)F21143FIG. 3 Atomizer Test of Nickel
37、 Specimen Showing Trace of Hydrophobic Contaminant (2, Reduced One-Half in Reproduction). NoteSlight Discontinuities in Otherwise Uniform Water FilmFIG. 4 Atomizer Test of Nickel Specimen Showing Traces of Hydrophobic Contaminant (2, Reduced One-Half in Reproduction)F21144FIG. 5 Atomizer Test of Par
38、tially Contaminated Nickel specimen (2, Reduced One-Half in Reproduction)FIG. 6 Atomizer Test of Nickel Specimen with Hydrophobic Film Covering Surface (2, Reduced One-Half in Reproduction)F21145APPENDIX(Nonmandatory Information)X1. CALIBRATION AND STANDARDIZATIONX1.1 Calibration and Standardization
39、X1.1.1 The degree of freedom of the test equipment andmaterials from hydrophobic contamination is proportional tothe number of alternate spraying and drying cycles required toproduce detectable hydrophobic contamination on a freshlycleaved mica surface. This test may be performed with greatersensiti
40、vity by masking a portion of the freshly cleaved surfaceunder test with a mica sheet (having both surfaces freshlycleaved) during the sequential test cycle. After the desirednumber of sprays, the mask shall be removed and the entiresurface retested for a detectable difference in wetting behaviorbetw
41、een the two areas.X1.1.2 To assure that test results are not obscured byflooding or by hydrophilic contaminants, a freshly cleavedmica surface from which the solvent from one drop (0.05 to0.10 mL) of a 0.005 to 0.05% solution of oleic or stearic acidin acetone has been allowed to evaporate should cl
42、early showthe demarcation between the clean and contaminated areas.The absence of a clear demarcation between the clean andcontaminated areas is an indication that hydrophilic contami-nants may be present in the test water.ASTM International takes no position respecting the validity of any patent ri
43、ghts asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at an
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