1、BRITISH STANDARD BS2868:1968 Specification for Cadmium anodes and cadmium oxide for electroplatingBS2868:1968 This British Standard, having been approved by the Surface Coatings (other thanPaints) Industry StandardsCommittee and endorsed by the Chairman oftheEngineering Divisional Council, was publi
2、shed undertheauthority of theGeneralCouncil on 6August1968 BSI 11-1999 First published July1957 First revision August1968 The following BSI references relate to the work on this standard: Committee referenceSRE/8 Draft for comment67/2973 ISBN 580 00260 8 Co-operating organizations The Surface Coatin
3、gs (other than Paints) Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Assay Offices Committee of Great Britain Association of Metal Sprayers B
4、ritish Bolt, Nut, Screw and Rivet Federation British Cycle and Motor Cycle Industries Association Limited* British Electrical and Allied Manufacturers Association British Jewellers Association British Non-Ferrous Metals Research Association* British Steel Industry Chemical Industries Association* El
5、ectricity Council, the Central Electricity Generating Board and the Area Boards in England and Wales Electronic Engineering Association Engineering Equipment Users Association Greater London Council Institute of Metal Finishing* Institute of Sheet Metal Engineers Institute of Vitreous Enamellers Met
6、al Finishing Association* Ministry of Defence, Army Department Ministry of Defence, Navy Department Ministry of Technology Society of Motor Manufacturers and Traders Limited* Tin Research Institute* Vitreous Enamel Development Council Zinc Development Association* The scientific and industrial organ
7、izations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: British Sulphate of Copper Association Institution of Chemical Engineers Royal Institute of Chemistry Scientific Instru
8、ment Manufacturers Association Society of Chemical Industry United Kingdom Cutlery and Silverware Manufacturers Association Individual firms Amendments issued since publication Amd. No. Date CommentsBS2868:1968 BSI 11-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 S
9、cope 1 2 Cadmium anodes 1 3 Cadmium oxide 1 Appendix A Apparatus and reagents for use in analytical methods 2 Appendix B Limit test for mercury 2 Appendix C Determination of cadmium oxide 2 Appendix D Determination of loss on ignition 3 Appendix E Determination of insoluble matter 3BS2868:1968 ii BS
10、I 11-1999 Foreword This standard makes reference to the following British Standards: BS1752, Laboratory sintered or fritted filters. BS3630, Methods for the sampling and analysis of zinc and zinc alloys Part4:Sampling of ingot zinc, zinc alloy ingots and zinc alloy die castings for spectrographic an
11、alysis. BS3978, Water for laboratory use. This British Standard is one of a series of standards that has been prepared to meet the requirements of electroplaters, others in the series being: BS558, BS564, Nickel anodes and nickel salts for electroplating. BS622, Potassium and sodium cyanides for ele
12、ctroplating. BS1468, Tin anodes and tin salts for electroplating. BS1561, Silver anodes and silver salts for electroplating. BS2656, Zinc anodes, zinc cyanide and zinc oxide for electroplating. BS2657, Fluoroboric acid and metallic fluoroborates for electroplating. BS2867, Copper sulphate for electr
13、oplating. BS2884, Copper cyanide for electroplating. 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 immunity from legal o
14、bligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to3 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.
15、BS2868:1968 BSI 11-1999 1 1 Scope This British Standard specifies requirements for cadmium anodes and cadmium oxide for electroplating. 2 Cadmium anodes 2.1 Physical form. Cadmium anodes for electroplating shall be supplied in cast, rolled or extruded form as specified by the purchaser. 2.2 Chemical
16、 composition. The cadmium content shall be not less than99.95%. The mercury content shall not exceed0.004% when determined by the method described in Appendix B. The cadmium content cannot be determined by chemical methods but shall be obtained by difference using spectrographic means for determinin
17、g the impurities, which shall not exceed the, following: 2.3 Sampling and preparation of sample. When an analysis is required, the sample shall be selected and prepared in the manner described in BS3630-4 1) . 3 Cadmium oxide 3.1 Physical form and appearance. Cadmium oxide for electroplating shall b
18、e in the form of a brown powder and shall correspond to the formula CdO. 3.2 Chemical composition. The material shall contain not less than99% of cadmium oxide when determined by the method described in Appendix C. The mercury content shall not exceed0.004% when determined by the method described in
19、 Appendix B. 3.3 Impurities. Any impurities present shall not exceed the following limits when determined spectrographically: 3.4 Loss on ignition. The loss on ignition shall not exceed0.5% when determined by the method described in Appendix D. 3.5 Insoluble matter. The total insoluble matter shall
20、not exceed0.1% when determined by the method described in Appendix E. 3.6 Sampling and size of sample. A representative sample, weighing not less than250g shall be taken for the purpose of examination under this standard. The sample shall be taken from freshly opened packages and shall be packed in
21、a clean, dry airtight bottle and sealed. NOTEThe British Standards Institution is the owner of a registered certification trade mark. This is shown below, enclosed in the words “Approved to British Standard”. This mark can be used only by manufacturers licensed under the certification mark scheme op
22、erated by the BSI. The presence of this mark on or in relation to a product is an assurance that the goods have been produced to comply with the requirements of the British Standard under a system of supervision, control and testing operated during manufacture and including periodical inspection at
23、the manufacturers works in accordance with the certification mark scheme of the BSI. Further particulars of the terms of licence may be obtained from the Director, British Standards Institution;2 ParkStreet, London, W.1. Total impurities 0.05% Antimony+arsenic+thallium 0.01% 1) BS3630, “Methods for
24、the sampling and analysis of zinc and zinc alloys”, Part4, “Sampling of ingot zinc, zinc alloy ingots and zinc alloy die castings for spectrographic analysis”. Total metals 0.05% Antimony+arsenic+thallium 0.01%BS2868:1968 2 BSI 11-1999 Appendix A Apparatus and reagents for use in analytical methods
25、Wherever appropriate, British Standard laboratory glassware should be used in the methods of test. All reagents shall be of a recognized analytical reagent quality and distilled water 2)shall be used whenever water is specified. Appendix B Limit test for mercury B.1 Reagents The following reagents s
26、hall be used: Sodium cyanide. Sodium hydroxide. Acid mixture (30ml HNO 3 ,30ml H 2 O,10ml HCl). Alkaline stannous chloride solution: Dissolve1.2g of stannous chloride crystals in20ml of water disregarding any precipitate formed by hydrolysis and pour whilst stirring into20ml of20% sodium hydroxide s
27、olution. Prepare as required, filtering before use. Litmus paper. B.2 Procedure Dissolve5.0g (anodes) or7.0g (oxide) of the sample in30ml of the acid mixture. Evaporate to about10ml, cool, make just alkaline, to litmus paper with20% sodium hydroxide solution and add15g sodium cyanide and5g of sodium
28、 hydroxide dissolved in50ml of water (solid sodium cyanide and sodium hydroxide may be added if the volume after making alkaline with sodium hydroxide solution is greater than50ml). Cool, dilute to100ml and filter50ml through a filter paper 3)into a Nessler cylinder. Add1ml alkaline stannous chlorid
29、e solution and mix thoroughly. A turbidity is visible if the sample contains more than0.004% of mercury. Appendix C Determination of cadmium oxide C.1 Reagents The following reagents shall be used: Sulphuric acid, sp. gr.1.84. Sulphuric acid,50%v/v. Sulphuric acid,5N (14%v/v). Sulphuric acid,1%v/v H
30、ydrochloric acid,50%v/v. Hydrogen sulphide. C.2 Procedure Dissolve0.5g of the sample in 200 ml of5N sulphuric acid, filter through a sintered glass crucible (porosity Grade 4 4) ), and saturate the cold solution with hydrogen sulphide. Filter off the precipitate of cadmium sulphide and wash with1% s
31、ulphuric acid saturated with hydrogen sulphide. Dissolve the precipitate in20 ml of50% hydrochloric acid and evaporate to fumes with28ml of sulphuric acid (sp.gr.1.84). Dilute the solution to200ml and again precipitate the cadmium as sulphide with hydrogen sulphide. Dissolve the precipitate through
32、the filter with hot50% hydrochloric acid and transfer to a weighed platinum dish, add2ml of50% sulphuric acid to the solution and then evaporate to dryness. Ignite the residue of cadmium sulphate to constant weight at500 C. 2) BS3978, “Water for laboratory use”. 3) Whatman No.40 is suitable. 4) BS17
33、52, “Laboratory sintered or fritted filters”. Percentage of cadmium oxide in sample Weight of CdSO 4 g ()0.616100 Weight of sample g () - =BS2868:1968 BSI 11-1999 3 Appendix D Determination of loss on ignition Heat10g of the sample for two hours in an open muffle at500 C. Determine the loss in weigh
34、t. Appendix E Determination of insoluble matter E.1 Reagent The following reagent shall be used: Potassium cyanide. E.2 Procedure Mix20g of sample and30g of potassium cyanide by coning or repeated stirring (there must be no grinding). Introduce the mixture into a1litre flask which is half filled wit
35、h water. Heat the mixture to4550 C, swirl for five minutes, and then maintain the flask at that temperature for four hours. Dilute to1litre, shake, set aside overnight, and then filter through a tared sintered glass crucible (porosity Grade4 5) ). Wash the residue with cold Water, dry the crucible a
36、t105 C and re-weigh. Carry out a blank determination on30g of potassium cyanide taken through the entire procedure. 5) BS 1752, “Laboratory sintered of fritted filters”. Percentage loss on ignition loss in weight g ()100 Weight of sample g () - = Percentage of insoluble matter in sample Weight of re
37、sidueg ()Weight of blankg () Weight of sample g () -100 =BS2868:1968 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level.
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