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1、Reference number ISO 15721:2001(E) ISO 2001 INTERNATIONAL STANDARD ISO 15721 First edition 2001-04-15 Metallic coatings Porosity tests Porosity in gold or palladium coatings by sulfurous acid/sulfur dioxide vapour Revtements mtalliques Essais de porosit Porosit des revtements dor ou de palladium par
2、 essai lacide sulfureux/vapeur de dioxyde de soufre Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproduction or networking permitted without license from IHS -
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6、ess given below. ISO 2001 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs
7、 member body in the country of the requester. ISO copyright office Case postale 56 ? CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2001 All rights reserved Copyright International Organization for Standardization Pr
8、ovided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15721:2001(E) ISO 2001 All rights reservediii ContentsPage Foreword.iv Introduction.v 1Scope 1 2Normat
9、ive references1 3Terms and definitions .2 4Apparatus.2 5Reagents.2 6Safety hazards2 7Procedure.3 8Examination4 9Precision.5 10Test report5 Annex A (informative) Significance and use 6 Bibliography7 Copyright International Organization for Standardization Provided by IHS under license with ISO Licens
10、ee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15721:2001(E) iv ISO 2001 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of nati
11、onal standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Internat
12、ional organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the ru
13、les given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the po
14、ssibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 15721 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coati
15、ngs, Subcommittee SC 7, Corrosion tests. Annex A of this International Standard is for information only. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproducti
16、on or networking permitted without license from IHS -,-,- ISO 15721:2001(E) ISO 2001 All rights reservedv Introduction The test method makes use of concentrated sulfurous acid (H2SO3), which emits sulfur dioxide (SO2) gas according to the equilibrium reaction: H2SO3= SO2+ H2O WARNING The sulfur diox
17、ide gas that is released by the sulfurous acid is toxic, corrosive and irritating. The sulfurous acid shall only be handled and used in a fume cupboard. Prior to starting the test, suitable preparation shall be made to dispose of approximately 200 ml to 500 ml of sulfurous acid used in the test. The
18、 procedure is similar to one first proposed by Lee and Ternowski 4. Exposure periods may vary, depending upon the degree of porosity to be revealed. Reaction of the gas with a corrodible base metal at pore sites produces reaction products that appear as discrete spots on the gold or palladium surfac
19、e. Individual spots are counted with the aid of a lens or low-power stereomicroscope. This test method is suitable for coatings containing 95 % or more of gold or palladium on substrates of copper, nickel and their alloys which are commonly used in electrical contacts. This test is considered destru
20、ctive because it reveals the presence of porosity by contaminating the surface with corrosion products and it undercuts the coating at pore sites or at the boundaries of the unplated areas. Any parts exposed to this test shall not be placed in service. The present test method is capable of detecting
21、 virtually all porosity or other defects that could participate in corrosion reactions with the substrate or underplate. The test is rapid, simple and inexpensive. In addition, it can be used on contacts with a complex geometry such as pin-sockets (it may be useful to open contact structures with de
22、ep recesses to permit reaction of the sulfur dioxide with the interior significant surfaces). Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproduction or netwo
23、rking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproduction or networking permitted without license from IHS -,-,-
24、INTERNATIONAL STANDARDISO 15721:2001(E) ISO 2001 All rights reserved1 Metallic coatings Porosity tests Porosity in gold or palladium coatings by sulfurous acid/sulfur dioxide vapour WARNING This International Standard does not purport to address all of the safety concerns, if any, associated with it
25、s use. It is the responsibility of the user of this International Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see clause 6. 1Scope This test method covers equipment and methods f
26、or determining the porosity of gold or palladium coatings, particularly electrodeposits and clad metals used on electrical contacts. It is designed to show whether the porosity level is less than or greater than a given value which by experience is considered by the user to be acceptable for the int
27、ended application. This porosity test involves corrosion reactions in which the products delineate defect sites in coatings. Since the chemistry and properties of these products may not resemble those found in natural or service environments this test cannot be recommended for the prediction of the
28、electrical performance of contacts unless correlation is first established with service experience. This test is intended to be used for quantitative descriptions of porosity (such as number of pores per unit area or per contact) on coatings that have a sufficiently low pore density so that the corr
29、osion sites are well separated and can be readily resolved. As a general guideline this can be achieved for pore densities up to about 100/cm2. Above this value the tests are useful for the qualitative detection and comparisons of porosity. A variety of other porosity testing methods are described i
30、n the literature 5,6. Other ISO porosity test methods are described ISO 10308, ISO 12687, ISO 14647 and ISO 15720. 2Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated referen
31、ces, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated refer
32、ences, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 2064, Metallic and other inorganic coatings Definitions and conventions concerning the measurement of thickness. ISO 2079, Surface treatm
33、ent and metallic coatings General classification of terms. ISO 2080, Electroplating and related processes Vocabulary. ISO 10308, Metallic coatings Review of porosity tests. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standar
34、ds 1/9972545001 Not for Resale, 04/22/2007 08:51:19 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15721:2001(E) 2 ISO 2001 All rights reserved 3Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 2064, ISO 2079
35、, ISO 2080 and ISO 10308 as well as the following apply. 3.1 corrosion products those reaction products emanating from the pores that protrude from, or are otherwise attached to, the coating surface after a vapour test exposure 3.2 metallic coatings includes platings, claddings or other metallic lay
36、ers applied to the substrate NOTEThe coatings can comprise a single metallic layer or a combination of metallic layers. 3.3 porosity presence of any discontinuity, crack or hole in the coating that exposes a different underlying metal 4Apparatus 4.1Test chamber, of any convenient size, made of glass
37、 or acrylic resin with a gas-tight lid, such as a glass desiccator of 9 l to 10 l, capacity. The ratio of chamber volume in cubic centimeters to the generating solution (sulfurous acid) surface area in square centimeters shall not exceed 25?1. 4.2Specimen holders, or supports, of glass, polytetraflu
38、oroethylene, or other inert materials. It is essential that the specimens be so arranged that they do not impede gas circulation. Specimens shall not be closer than 25 mm from the wall and 75 mm from the solution surface. The measurement areas of the specimens shall be at least 12 mm apart. NOTEDo n
39、ot use a porcelain plate or any other structure that would cover more than 30 % of the liquid surface cross- sectional area. This is to ensure that movement of air and vapour within the vessel will not be restricted during the test. 4.3Stereomicroscope, having a?10 magnification shall be used for po
40、re counting. In addition a movable source of illumination capable of giving oblique lighting on the specimen surface is required. An eyepiece is recommended for the convenience in locating the contact area or other significant measurement areas. 5Reagents Sulfurous acid (H2SO3), “analytical grade re
41、agent“, or better, in individual well-sealed bottles. 6Safety hazards 6.1Carry out these test procedures in a clean, working fume cupboard. The SO2gas that is emitted is toxic, corrosive, and irritating. 6.2Use caution however, when actually performing the tests that the drafts often found in fume c
42、upboards do not cause significant cooling of the chamber walls which may lead to condensation of water and acceleration of the test. It is often convenient to enclose the reaction vessel in a box with a loose-fitting cover and to keep the box in a fume cupboard during the test. 6.3Observe normal pre
43、cautions in handling corrosive acids. In particular, wear eye protection completely enclosing the eyes, and make eye wash facilities readily available. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not f
44、or Resale, 04/22/2007 08:51:19 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15721:2001(E) ISO 2001 All rights reserved3 7Procedure 7.1Cleaning Handle specimens as little as possible and only with tweezers, microscope-lens tissue, or clean, soft cotton gloves. Prior t
45、o the test, inspect the samples under?10 magnification using the stereomicroscope (4.3) for evidence of particulate matter. If present, such particles shall be removed by blowing them off with clean, oil-free air. If this is not successful, discard the sample and draw a replacement sample from the b
46、atch. Then clean the samples with solvents or solutions that do not contain chlorinated hydrocarbons, CFCs or other known ozone-destroying compounds. The procedure outlined in note 1 has given satisfactory results for platings with mild to moderate surface contamination. NOTE 1Suggested cleaning pro
47、cedure. a)Keep individual contacts separated if there is a possibility of damaging the measurement areas during the various cleaning steps. b)Clean samples for 5 min in an ultrasonic cleaner which contains a hot (65 ?C to 85 ?C) 2 % aqueous solution of a mildly alkaline (pH 7,5 to pH 10) detergent.
48、c)After ultrasonic cleaning, rinse samples under warm running tap water for at least 5 s. d)Rinse samples ultrasonically for 2 min in fresh deionized water to remove the last detergent residues. e)Immerse in fresh methanol or isopropanol, and ultrasonically “agitate“ for at least 30 s in order to remove the water from the samples. f)Remove and dry samples until the alcohol has completely evaporated. If an air blast is used as an aid for drying, the air shall be oil-free, cl