ISO INTERNATIONAL STANDARD 18332 First edition 2007-02-01 Metallic and other inorganic coatings Definitions and conventions concerning porosity Revetements métalliques et autres revetements inorganiques - Definitionsetprincipesconcernantlaporosite Reference number ISO 18332:2007(E) X ISO @ ISO 2007 ISO 18332:2007(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through ISO established has the right to be represented on that committee. International organizations, governmental and Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO 18332 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings SubcommitteeSC7,Corrosiontests ii ISO 18332:2007(E) INTERNATIONAL STANDARD Metallic and other inorganic coatings Definitions and conventions concerning porosity 1 Scope This International Standard defines porosity and its associated terms, and outlines the principles involved in thereby assisting the user to select the most suitable test for the product and its service application. The porosity test cannot be used to establish corrosion-performance standards. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IsO 10308:2006,Metallic coatings-Review of porosity tests 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 porosity holes, cracks or other discontinuities (3.3) in the coating that expose the underlying metal or substrate to the environment 3.2 pore in a coating basis metal [ISO 2080:1981] NOTETypes of pores are shown in ISO 10308. 3.3 discontinuity opening in an otherwise continuous coating that exposes a different underlying meta NOTE Typically, the openings are cracks, micro-holes, pores or pits in the coating. They can also be voids or breaks in the coatingcausedbymechanical damage,suchas scratchesornon-conductive inclusions inthebasismetal (seeIsO10308) 3.4 corrosion product substance formed as a result of corrosion [ISO 8044:1999] 1 ISO 18332:2007(E) 4 Purpose of porosity testing The main purpose of porosity testing is to determine the quality of the coating and its freedom from porosity, particularly on those areas of the significant surface that demand a functional requirement, for example, as electricalcontacts For the purpose of porosity testing of metallic and related inorganic coatings, there are two modes of corrosion that need to be considered, i.e. electrochemical and chemical. Either type of test can be used to identify the the basis material and any undercoat. In general, electrochemical tests are of an “accelerated nature", with relatively short exposure times carried out under controlled chemical, electrical and physical conditions; these are ideal for process control purposes. Exposure tests (liquid immersion tests, solution-fog tests, gas atmosphere tests) are usually of long duration and can be either static or cyclic, depending on product requirements, and are particularly suitable for qualification purposes. NOTEFor a classification of porosity tests, see ISO 10308. 5Principles 5.1Electrochemical tests In electrochemical testing, the basis metal/coating combination is generally used as the anode of an el