1、BRITISH STANDARD BS 4292-2: 1989 Method for specifying Electroplated coatings of gold and gold alloys Part2: Gold and gold alloys for decorative and protective purposes UDC669.21:621.357.7.002.2:001.4BS 4292-2:1989 This British Standard, having been prepared under the directionof the Surface Coating
2、s(other than Paints) Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 31August1989 BSI03-1999 First published March1968 First revision August1989 The following BSI references relate to the work on this standard: Committee referenceSRC/5 Draft for comm
3、ent86/55015DC ISBN0580171728 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Surface Coatings (other than Paints) Standards Committee (SRC/-) to Technical CommitteeSRC/5, upon which the following bodies were represented: British Coal Cor
4、poration British Jewellers Association British Metal Finishing Suppliers Association British Telecommunications plc Cutlery and Silverware Association Electronic Engineering Association Institute of Metal Finishing Institution of Corrosion Science and Technology Joint Committee of Assay Offices of G
5、reat Britain Metal Finishing Association Ministry of Defence National Association of Goldsmiths of Great Britain and Ireland Telecommunication Engineering and Manufacturing Association (TEMA) Amendments issued since publication Amd. No. Date of issue CommentsBS 4292-2:1989 BSI 03-1999 i Contents Pag
6、e Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Information to be supplied by the purchaser to the electroplater 1 4 Basis material 2 5 Coating classification code 3 6 Undercoats 3 7 Coatings 3 Table 1 Summary of information required 2 Table 2 Appropriate undercoa
7、ts for use with gold and gold alloy decorative and protective coatings 4 Publications referred to Inside back coverBS 4292-2:1989 ii BSI 03-1999 Foreword This Part of BS4292has been prepared under the direction of the Surface Coatings (other than Paints) Standards Policy Committee. BS4292was first p
8、ublished in1968.This revision differs from the previous edition in that it has been drafted as a method for specifying requirements for electroplated gold and gold alloy coatings, i.e.it is based on requirements to be agreed between the interested parties. It is not intended to replace the requireme
9、nts specified in British Standards for particular articles. It also differs in that coatings for engineering and for decorative purposes are dealt with in separate Parts, and by the introduction of a minimum mass of1mg of gold per square centimetre of surface area. It no longer describes methods of
10、test, previously included in appendices, which are now published separately together with additional tests as BS6670-1toBS6670-6. This Part of BS4292together with Part1, which covers coatings of gold and gold alloys for engineering purposes and is published simultaneously, supersede BS4292:1968, whi
11、ch is withdrawn. As this standard is based on requirements to be agreed between the interested parties, it is not appropriate for any claim to be made that a coating complies with BS4292-2. This Part of BS4292describes a method for specifying electroplated coatings of gold, including gold alloys, fo
12、r use for general decorative purposes and for specialized applications where relatively thick coatings, to withstand continuous wear over considerable periods, are required. Decorative purposes are those for which the appearance of the finished article is of prime importance, while engineering purpo
13、ses are those for which the coating has to fulfil primarily functional tasks, although protection against corrosion may be a requirement in both cases. This Part of BS4292defines gold coatings as pure gold or gold alloy coatings having a pure gold content of at least1mg of gold per square centimetre
14、 of surface area. Where gold alloys are to be specified they contain a minimum of58.5% pure gold and, in the case of multilayer coatings, a minimum of58.5% pure gold in each layer. Attention is drawn to the provisions in Section1and Schedule1of the Hallmarking Act1973in so far as they relate to the
15、description applied to an article that has a coating specified in accordance with this Part of BS4292. According to these provisions it is an offence in the course of a trade or business to apply to an unhallmarked article a description indicating that it is made partly of gold, unless the descripti
16、on is “rolled gold” or “gold plated”. The description “rolled gold” is not appropriate in the case of an electroplated coating. Attention is also drawn to the expression in certain contexts of gold contents in terms of parts per thousand (by mass), also known as “thousandths” (millimes) or “fineness
17、”. In this standard, percentages by mass to one decimal place are used. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer im
18、munity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the a
19、mendment table on theinside front cover.BS4292-2:1989 BSI 03-1999 1 1 Scope This Part of BS4292describes a method for specifying requirements for electrodeposited coatings (single-layer, double-layer or multilayer) of gold and its alloys on metallic and non-metallic materials for general decorative
20、and/or protective purposes. This standard is not applicable to: a) coatings on screw threads; b) coatings applied on sheet or strip in the unfabricated form; c) gold alloy coatings containing less than58.5% by mass of pure gold; or d) coatings containing less than1mg of gold per square centimetre of
21、 surface area. In the case of double-layer and multilayer coatings, the thickness requirements apply to the total gold coating, but the requirements for gold content apply to each layer (see7.1). NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 D
22、efinitions For the purposes of this Part of BS4292,the definitions given in BS5411-1apply together with the following. 2.1 significant surface the part of the article covered or to be covered by the coating and for which the coating is essential for serviceability and/or appearance 2.2 gold or gold
23、alloy coating an electrodeposited coating of gold or gold alloy containing at least1mg of gold per square centimetre of surface area and, in addition, a pure gold content not less than58.5% by mass NOTEThe minimum thickness of a pure gold coating satisfying this requirement is0.54m. To meet this min
24、imum mass per unit area, single-layer gold alloy coatings will be necessarily thicker than0.54m. This minimum thickness applies only to gold electrodeposits of greater than98% gold content by mass. 2.3 double-layer gold or gold alloy coating a gold or gold alloy coating consisting of two discrete la
25、yers of differing gold content, both of which have a gold content not less than58.5% by mass with a combined minimum mass of1mg of gold per square centimetre of surface area (see7.1) 2.4 multilayer gold or gold alloy coating a gold or gold alloy coating consisting of more than two discrete layers of
26、 differing gold content, each of which has a gold content not less than58.5% by mass and which together give a total minimum mass of1mg of gold per square centimetre of surface area (see7.1) 3 Information to be supplied by the purchaser to the electroplater NOTEA summary of clause references pertain
27、ing to this information is given in Table 1. 3.1 Essential information The information listed ina) tof) shall be supplied by the purchaser to the electroplater. a) The number of this British Standard, i.e.BS4292-2. b) A detailed indication of the significant surface, e.g.by drawings or by the provis
28、ion of suitably marked samples and, in addition, the relevant details if the requirements for the finish differ for various parts of the significant surface (see7.2). c) The classification code of the coating required (see clause5) and the method to be used to determine the gold coating thickness as
29、 agreed between the purchaser and the electroplater (see7.3). NOTEThe required gold coating thickness is contained within the coating classification code. d) The type (bright, matt, etc.) and colour of the surface finish required indicated, for example, by the provision of a preliminary sample havin
30、g the required colour finish supplied by the electroplater for approval by the purchaser (see7.2). NOTEThe final surface finish will be dependent on the initial surface roughness of the basis material (see clause4). e) The method(s) of test for adhesion to be employed (see7.6). f) The sampling proce
31、dure, selected from BS6001or BS6041,and the sampling and acceptable quality levels (AQLs) required. NOTEThis Part of BS4292does not specify sampling orAQLs. 3.2 Additional information The additional information listed ina) tol), as applicable, shall be supplied by the purchaser to the electroplater,
32、 if necessary in consultation with the electroplater. a) The minimum gold content of the coating and the method to be used to determine the gold content as agreed between the purchaser and the electroplater (see7.5).BS4292-2:1989 2 BSI 03-1999 Table 1 Summary of information required b) The density v
33、alue to be used for the determination of gold electrodeposit thickness if the test method employed requires a density correction (see7.3). c) Details of any intentional alloying elements (see7.5). d) The nature of the basis material, its surface condition and roughness, and where the basis material
34、is supplied by the purchaser, the lead content, if any, of the material (see clause4). e) Appropriate undercoats and whether thickness measurements are to be carried out (see clause6 and Table 2). f) Whether or not double-layer or multilayer coatings are required (see5.2 and7.1). g) Requirements for
35、 corrosion resistance and/or freedom from porosity and the methods of test to be used including tests for coatings of thickness less than54m intended for use in corrosive service conditions (see7.4). h) The microhardness of the coating and the method of test, selected from BS5411-6,to be used (see7.
36、7). i) Requirements for solderability and the method of test to be used (see7.8). j) Requirements for resistance to wear and the method of measurement to be used (see7.9). k) The positions where unavoidable contact marks and other defects are acceptable (see7.2). 4 Basis material The nature of the b
37、asis material, its surface condition and roughness shall, if appropriate, be specified by the purchaser see3.2 d). If the purchaser supplies the basis material, the electroplater shall be notified of any lead content see3.2 d). NOTEThis Part of BS4292does not specify requirements for the condition,
38、finish or surface roughness of the basis material prior to electroplating. However, it should be recognized that the surface roughness of the gold or gold alloy coating will be dependent on the initial surface roughness of the basis material and this should not therefore be cause for rejection of th
39、e gold coating. Information required Relevant clauses Other related clauses Essential information Additional information, ifrequired Reference (i.e.the number of this Part of BS4292) 3.1 a) Significant surface 3.1 b) 7.2 Coating classification code 3.1 c) 3.2 a) clause5 and6, 7.3, 7.5 Final appearan
40、ce 3.1 d) 7.2 Adhesion 3.1 e) 7.6 Sampling 3.1 f) Method of determination of gold content 3.2 a) 7.5 Gold density 3.2 b) 7.3 Composition 3.2 a) 3.2 c) 7.5, clause 5 Basis material 3.2 d) clause4 Undercoats 3.2 e) clause6 Double-layer or multilayer coatings 3.2 f) 7.1 Corrosion resistance/freedom fro
41、m porosity 3.2 g) 7.4 Microhardness 3.2 h) 7.7 Solderability 3.2 i) 7.8 Wear resistance 3.2 j) 7.9 Positions where defects or contact marks are acceptable 3.2 k) 7.2BS4292-2:1989 BSI 03-1999 3 5 Coating classification code 5.1 The purchaser shall supply the following information to the electroplater
42、 by quoting the appropriate classification code described in5.2 seealso3.1 c) and3.2 a): a) the chemical identity of the basis material; b) if appropriate, the nature of the undercoat metal and its thickness (see3.2 e) and clause6); c) the minimum gold content by mass of the coating if containing le
43、ss than98% pure gold (see7.5); d) the minimum thickness, in micrometres, of the gold or gold alloy coating on the significant surface (see7.3). 5.2 The coating classification code consists of four parts, the first two of which are separated by an oblique stroke, as follows: a/bcd where If multilayer
44、 coatings are specified, the principle of working from the substrate to the surface is applied. 5.3 Examples of classification codes 5.3.1 Examples of complete classification codes are as follows: Fe/Ni10Au5.0(i.e.a coating having a thickness of54m minimum on steel, using a nickel undercoat of104m m
45、inimum thickness); Zn/Cu8Ni10Au(60.0)2.0(i.e.a coating having a specified gold content of at least60.0% by mass and a thickness of24m minimum on die-cast zinc alloy, using an undercoat of104m nickel on one of84m copper); Cu/Au(75.0)1.0(i.e.a coating having a specified gold content of at least75.0% b
46、y mass and a thickness of1.04m minimum on copper alloy). 5.3.2 An example of a complete classification code for a multilayer coating is Cu/Au(80.0)2.0Au0.5 (i.e.a coating having a specified minimum thickness of0.54m of pure gold on an undercoating specified as containing at least80% gold by mass and
47、 a minimum thickness of24m on a copper alloy base). 6 Undercoats NOTE 1Undercoats may be necessary on any basis material for the following reasons: a) to improve corrosion resistance of the coating; b) to improve the adhesion of the coating; c) to reduce the risk of diffusion through the coating; d)
48、 to reduce the risk of contamination of the electrolyte by the basis material; e) to improve the solderability of the coating and the retention of solder; f) to reduce the surface roughness of the coating; g) to reduce the porosity of the coating. Typical undercoats used are copper, nickel, palladiu
49、m, tin-nickel alloy and combinations of these metals. To promote good adhesion, it may be necessary to deposit a gold strike coating immediately prior to the main gold deposition. NOTE 2For arduous conditions of service, thicknesses greater than the minimum values specified inTable 2 may be required. Table 2 gives appropriate undercoats for use with gold and gold alloy decorative coatings see3.2 e). Any other undercoats required for special purposes shall also be specified by the purchaser. If thickness measurements on any undercoats are specified by the purchaser
