1、Designation: C 813 90 (Reapproved 2004)Standard Test Method forHydrophobic Contamination on Glass by Contact AngleMeasurement1This standard is issued under the fixed designation C 813; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the detection of hydrophobiccontamination on glass surfaces by means of contact
3、 anglemeasurements. When properly conducted, the test will enabledetection of fractions of monomolecular layers of hydrophobicorganic contaminants. Very rough or porous surfaces maysignificantly decrease the sensitivity of the test.1.2 This standard does not purport to address all of thesafety conce
4、rns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent Water3.
5、 Terminology3.1 Definitions:3.1.1 advancing anglethe largest angle observable when aliquid droplet is increased in size.3.1.2 hydrophilichaving a strong affinity for water; wet-table.3.1.2.1 DiscussionHydrophilic surfaces exhibit zero con-tact angles.3.1.3 hydrophobichaving little affinity for water
6、; nonwet-table.3.1.3.1 DiscussionHydrophobic surfaces exhibit contactangles appreciably greater than zero: generally greater than 45for the advancing angle.3.1.4 receding anglethe smallest angle observable when aliquid droplet is decreased in size.3.1.5 sessile dropa drop of liquid sitting on the up
7、per sideof a horizontal surface.3.1.5.1 DiscussionSee Fig. 1.4. Summary of Test Method4.1 The contact angle test is performed by depositingdroplets of permanganate-distilled water or reagent water inaccordance with Specification D 1193 on the surface to betested using a mounted hypodermic syringe, s
8、aid dropletsbeing deposited in such a way, as described herein, as tomeasure the advancing contact angle. The measurements shallbe made by either of these two well-known methods: (1)viewing the sessile drop through a comparator microscopefitted with a goniometer scale with direct measurement of thea
9、ngle; or (2) photographing the sessile drop and measuring theangle with a protractor. The interpretation of the measurementsis based on the fact that organic contamination on surfacesresults in contact angles appreciably higher than the near-zeroangles measured on clean surfaces or those contaminate
10、d byhydrophilic materials.5. Significance and Use5.1 The contact angle test is nondestructive and may be usedfor control and evaluation of processes for the removal ofhydrophobic contaminants. The test may also be used for thedetection and control of hydrophobic contaminants in process-ing ambients.
11、 For this application, a surface free of hydropho-bic films is exposed to the ambient conditions and is subse-quently tested.6. Interferences6.1 Loss of sensitivity may result from either of the follow-ing factors:6.1.1 The presence of hydrophilic substances on the surfaceto be tested, or in the wat
12、er used for the test, or6.1.2 An unusually rough or porous surface.7. Apparatus7.1 Low-Power Comparator Microscope (53 to503), with goniometer scale and light source for illuminationof small drops.7.2 Camera, that can take photographs of the drop if thisalternative method is used.7.3 Protractor, to
13、measure the angle if the alternativemethod is used.1This test method is under the jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subcommittee C14.02 onChemical Properties and Analysis.Current edition approved Oct. 1, 2004. Published October 2004. Or
14、iginallyapproved in 1975. Last previous edition approved in 1999 as C 813 90 (1999).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 p
15、age onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.4 Hypodermic Syringe or Micrometer Buret, in a fixedmount. The needle of the syringe or the buret tip should be BDgage 20 to 26 or equivalent and should have a
16、square-cut tip.7.5 Movable Platen, on which to mount the specimen whenviewing the drop in profile.8. Reagents and Materials8.1 Purity of WaterEither Type II reagent water in accor-dance with Specification D 1193, or water distilled from a3-g/L potassium permanganate solution is usually satisfactory.
17、The water used must be free of hydrophobic and hydrophilicsubstances. To test the purity of the water for freedom fromhydrophobic contamination, a freshly cleaved sheet of micashall be used as the test surface for the measurement of theadvancing contact angle of the water as described in Section10.
18、If the average of two such advancing contact angledeterminations is not less than 4, further purification of thewater is required.8.2 Mica.8.3 Polytetrafluoroethylene Sheet.9. Calibration and Standardization9.1 Contact angles of water on clean polytetrafluoroethyleneshall be measured to familiarize
19、the operator with the test andserve as a check on the equipment and techniques. Advancingangles on polytetrafluoroethylene vary from 108 to 125,depending on the particular type of this high polymer used.10. Procedure10.1 Randomly select at least two sites where measurementswill be made on the test s
20、urface. Bring the syringe needle intoclose proximity to the test surface and, with the test surface ina horizontal position, manipulate the hypodermic syringe so asto force a drop having a volume of 0.02 to 0.05 mL onto thesurface to give an advancing angle (Note 1). The needle shouldremain immersed
21、 in the drop and should be centered in thedrop. Care must be taken that when the syringe plunger isreleased no motion is imparted to the plunger so as to cause anyretraction of the drop. Any retraction will cause the contactangle to be less than the true advancing angle (Note 2). Foreach site, measu
22、re two advancing angles by measuring thecontact angle on the left side and on the right side of the dropafter each of two successive incremental increases in the dropsize (a total of four measurements for each drop for theadvancing angle). By making left- and right-side determina-tions, the effect o
23、f a slightly nonlevel surface is alleviated.Where any consistent differences between the left-side andright-side determinations are noted, it is preferable to level theplaten before proceeding (Note 3).NOTE 1Drops that are not deposited on a surface so as to exhibitadvancing or receding angles may h
24、ave any value of the contact anglebetween this range of values.NOTE 2It is important that when making an advancing angle mea-surement, water be added to the drop until the drop advances.NOTE 3Because of possible contamination by material present in theatmosphere, it is desirable to make the measurem
25、ents promptly and toallow samples to sit unprotected no longer than necessary. Storage ofsamples in plastic containers or in containers with plastic or coated linersshould also be avoided. It is also very important to clean syringes andneedles carefully before making determinations on different spec
26、imens.Silicone grease is a common contaminant that must be avoided.11. Interpretation of Results11.1 Consider surfaces tested as described in Section 10 freeof hydrophobic contaminants by this test if the advancing angleis no greater than 5. Under these conditions, organic contami-nation will be no
27、greater than several percent of a monomo-lecular layer in coverage. It must be kept in mind that veryclean surfaces without oxide layers such as silicon and gold arenonwettable by water and exhibit high contact angles.12. Precision and Bias12.1 Interlaboratory tests show that between-laboratoryvaria
28、tions are about 610. Within-laboratory variations can beconsiderably less if the test is conducted with care.13. Keywords13.1 contact angle; contamination; glass; organicFIG. 1 Schematic Diagram Indicating Measurement of ContactAngleC 813 90 (2004)2ASTM International takes no position respecting the
29、 validity of any patent rights 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
30、 subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Hea
31、dquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This st
32、andard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 813 90 (2004)3
