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1、BRITISH STANDARD BS ISO 7625:2006 Sintered metal materials, excluding hardmetals Preparation of samples for chemical analysis for determination of carbon content ICS 77.160 ? Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled C
2、opy, (c) BSI BS ISO 7625:2006 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2007 BSI 2007 ISBN 978 0 580 50226 2 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 7625:2006. It supe
3、rsedes BS 5600-3.3:1987 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee ISE/65, Sintered metal components. A list of organizations represented on ISE/65 can be obtained on request to its secretary. This publication does not purport to include all the
4、necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University
5、, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 7625:2006(E) INTERNATIONAL STANDARD ISO 7625 Second edition 2006-09-15 Sintered metal materials, excluding hardmetals Preparation of samples for chemical analysis for determination of carbon content Matriaux mtalli
6、ques fritts, lexclusion des mtaux-durs Prparation des chantillons pour analyse en vue du dosage du carbone BS ISO 7625:2006 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank Un
7、iversity, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii 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 no
8、rmally 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. International organizations, governmental and non-governmental, in liaison with ISO, also take part in
9、 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 rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepa
10、re International Standards. 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 possibility that so
11、me 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 7625 was prepared by Technical Committee ISO/TC 119, Powder metallurgy, Subcommittee SC 3, Sampling and testing methods for sintered metal mat
12、erials (excluding hardmetals). This second edition cancels and replaces the first edition (ISO 7625:1983), which has been technically revised. Clause 6 has been added. BS ISO 7625:2006 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Unco
13、ntrolled Copy, (c) BSI iv Introduction The chemical analysis of sintered metal materials, excluding hardmetals, is carried out as it would be for solid metals, by using existing standard methods. However, as these sintered materials very often contain carbonaceous constituents, the correct determina
14、tion of carbon content (free or total) requires that certain precautions be taken when preparing the sample for analysis from components. Samples prepared in accordance with this International Standard may also be suitable for chemical analysis for other elements. BS ISO 7625:2006 Licensed Copy: Lon
15、don South Bank University, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Sintered metal materials, excluding hardmetals Preparation of samples for chemical analysis for determination of carbon content 1 Scope This International Standard specifies meth
16、ods for preparing a sample from one or more sintered parts of materials to be analysed for free or total carbon content. Combined carbon is determined as the difference between total and free carbon. This standard covers the preparation of samples for the determination of carbon by a chemical method
17、, i.e. combustion in oxygen and measurement of the carbon dioxide produced, in accordance with ISO 437. It does not cover the preparation of samples for carbon determination by physical methods, such as metallography or spectroscopy. 2 Normative references The following referenced documents are indi
18、spensable 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 437, Steel and cast iron Determination of total carbon content Combustion gravimetric me
19、thod ISO 2738, Sintered metal materials, excluding hardmetals Permeable sintered metal materials Determination of density, oil content, and open porosity 3 Principle Elimination of impregnated or surface carbon. Preparation of samples for analysis by fragmentation or machining, taking care not to lo
20、se any free carbon. 4 Materials This International Standard applies to parts of materials in which carbon is uniformly distributed and present in the forms shown in Table 1. It does not apply to parts in which the carbon is not uniformly distributed throughout the part. In instances where the carbon
21、 is not uniformly distributed, for example a case-hardened part, the method of selecting the sample should be agreed upon between the supplier and the purchaser. The presence of carbonaceous materials in the pores or on the surface of the part to be analysed interferes with the determination of carb
22、on, see Table 2. BS ISO 7625:2006 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 Table 1 Forms of carbon that can be determined by chemical analysis Form of carbon Typical materials Comments Combined carbon
23、(as carbides or in solid solution) Carbon-containing steels and super-alloys Determined as the difference between total and free carbon Free carbon Bronze and steel containing graphite; material impregnated with a graphite-containing liquid Determined by combustion of the residue of selective dissol
24、ution of the metal in the sample. Total carbon Determined by direct combustion of the sample Table 2 Origins of carbonaceous material and feasibility of carbon determination by chemical methods Carbonaceous material Origin Feasibility 1 Liquid or semi-liquid organic substances on the surface or in t
25、he pores Sizing lubricant, quenching oil, impregnating lubricant, cutting fluid, grease. 2 Waxes and wax-like substances Sizing lubricant, corrosion protective 3 Deposits of carbon on the parts Sintering, heat treatment Carbon determination is possible only when these organic substances are totally
26、eliminated by the method described in Clause 5 4 Solid organic substances, for example, plastics materials on the surface or in the pores Sealant material In general, it is not possible to eliminate these substances, and determination of carbon is not possible 5 Procedure 5.1 Removal of interfering
27、carbonaceous material Carbonaceous materials (see Table 2) that affect the carbon determination shall be removed from the part or parts to be analysed as specified in 5.1.1 and 5.1.2. 5.1.1 Impregnated organic substances in the pores or on the surface (see Cases 1 and 2 in Table 2) shall be removed
28、by Soxhlet degreasing with an appropriate solvent, in accordance with ISO 2738. The solvent used shall be stated. NOTE When the impregnated liquid contains fine carbon particles, for example colloidal graphite, only a fraction of these particles may be removed by Soxhlet degreasing. In such a case,
29、the determination of free carbon and total carbon would be invalid, but calculation of combined carbon would still be valid if the free carbon and total carbon are determined on the same part or parts after degreasing. 5.1.2 Surface deposits of carbon (see Case 3 in Table 2) shall be removed by mech
30、anical treatment. BS ISO 7625:2006 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 3 5.2 Final preparation The sample for analysis shall consist of small fragments of a size appropriate to the analysis method t
31、o be used, prepared by one of the following methods: crushing in a mortar made of a material which does not alter the sample composition; drilling, milling or turning. Such machining shall be performed dry by using hardmetal or ceramic tools. Care shall be taken to avoid overheating, oxidation and c
32、ontamination of the fragments. Where drilling is used, the part shall be drilled through completely and the distribution of drilling holes shall be uniform over the whole surface of the part. If the part is too thick, the holes shall be drilled to the middle from both faces of the part. Where crushe
33、d or machined fragments contain fine particles (for example free graphite), care shall be taken not to lose these particles during handling. Where segregation is expected to be a problem, the entire sample should be analysed after being divided into a suitable number of test portions. The carbon con
34、tent is then calculated as the average of the results from each portion. In general, a sufficient quantity of fragments, representative of the part or parts, shall be prepared. The samples for analysis shall be kept in a container that is tightly sealed, in order to avoid contamination. 6 Precision
35、When the degreasing is carried out according to ISO 2738 as stated in 5.1.1, the carbon content after oil removal can be considered suspect if reproducibility and repeatability are greater than 5 %, at the 95 % confidence level. BS ISO 7625:2006 Licensed Copy: London South Bank University, London So
36、uth Bank University, Thu Mar 01 10:07:48 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 7625:2006 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Eu
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