Table of Contents

Abstract

RECONFIRMATION NOTICE
Technical Committee MT-009 has reviewed the content of this publication and in accordance with Standards Australia procedures for reconfirmation, it has been determined that the publication is still valid and does not require change.
Certain documents referenced in the publication may have been amended since the original date of publication. Users are advised to ensure that they are using the latest versions of such documents as appropriate, unless advised otherwise in this Reconfirmation Notice.
Approved for reconfirmation in accordance with Standards Australia procedures for reconfirmation on 20 March 2017.
The following are represented on Technical Committee MT-009:
Australasian Institute of Surface Finishing
Australian Chamber of Commerce and Industry
Australian Industry Group
Australian Steel Institute
Bureau of Steel Manufacturers of Australia
Galvanizers Association of Australia
Galvanizing Association of New Zealand
New Zealand Metal Roofing Manufacturers

Scope

This Standard sets out methods for assessing the degree of porosity in electroplated metallic coatings, such as gold, palladium and rhodium, that cover undercoats and basis metals that form visible compounds due to coating porosity, when exposed to sulfur dioxide-hydrogen sulfide atmospheres.
Electroplated coatings of non-tarnishing precious metals, such as gold and rhodium for engineering purposes, are required to retain their design characteristics over long periods of storage and use. These characteristics include the following: (a) Low contact resistance.
(b) Solderability.
(c) A stable surface suitable for carrying high frequency currents. Impairment of performance may result from—
(i) the formation of corrosion products at discontinuities in the coating; or
(ii) corrosion of the coating itself due to its composition not being adequate to withstand the environmental conditions.
Environments containing sulfur compounds can cause these types of corrosion on precious metal coatings.
The test methods described in this Standard employ the use of hydrogen sulfide (H2S)
which will affect silver and copper but not nickel or tin, and, for thicker coatings, the
additional use of sulfur dioxide (SO2) which will produce visible effects on any basis metal
or undercoat.
The test chosen should be capable of revealing pores that expose the basis metal or an undercoat. For normal service conditions, the thickness of any undercoat specified should safeguard against the penetration of corrosion into the basis metal. However, when the coating is subjected to exceptionally severe environmental conditions, the development of special tests may be required.
NOTE: Special tests are a matter for agreement between the purchaser and the supplier.
Another type of porosity test for precious metal coatings is given in AS 2331.3.6.
NOTE: The test procedures described in this Standard do not necessarily include all of the precautions required to satisfy health and safety aspects. Care should be taken to ensure that the procedures are carried out only by people who have received suitable training. Guidance in the handling and use of hazardous chemicals is given in AS/NZS 2243.1 and AS/NZS 2243.2.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	Standards Australia
ProductNote	Reconfirmed 07/04/2017. This standard has been reconfirmed in Australia in 2017 and remains current in New Zealand. Reconfirmation Notice 07/04/2017
Pages
ISBN
Committee	MT-009
Supersedes	DR 99372 AS 2331.3.5-1980 DR 99384