1、BRITISH STANDARD BS 6783-5: 1986 ISO 7524:1985 Sampling and analysis of nickel, ferronickel and nickel alloys Part 5: Method for determination of carbon in nickel, ferronickel and nickel alloys by infra-red absorption after induction furnace combustion ISO title: Nickel, ferronickel and nickel alloy
2、s Determination of carbon content Infra-red absorption method after induction furnace combustion UDC 669.24 + 669.1524-198:546.26:543.422.4.062BS6783-5:1986 This British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Committee, waspublished under the authorityo
3、f the Board of BSI andcomes into effect on 31December 1986 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference NFM/10 Draft for comment 84/39887 DC ISBN 0 580 15524 2 Committees responsible for this British Standard The preparation of this British Standa
4、rd was entrusted by the Non-ferrous Metals Standards Committee (NFM/-) to Technical Committee NFM/10, upon which the following bodies were represented: British Non-ferrous Metals Federation British Steel Industry Engineering Equipment and Materials Users Association Ministry of Defence Process Plant
5、 Association Stainless Steel Fabricators Association of Great Britain Coopted members Amendments issued since publication Amd. No. Date of issue CommentsBS6783-5:1986 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Refer
6、ence 1 3 Principle 1 4 Reagents and materials 1 5 Apparatus 1 6 Sampling and samples 1 7 Procedure 1 8 Expression of results 2 9 Notes on procedure and equipment 2 10 Test report 4 Annex A Examples of compositions of nickel, ferronickel and nickel alloys 5 Annex B Features of commercial high frequen
7、cy induction furnaces and infra-red carbon analysers 6 Annex C Alternative non-aqueous titrimetric finish for determination of carbon 6 Table 1 Results of statistical analysis 3 Table 2 Examples of composition of nickel (%) 5 Table 3 Examples of composition of ferronickel (%) 5 Table 4 Examples of c
8、omposition of nickel alloys (%) 5 Table 5 Results from titrimetric finish 7 Publication referred to Inside back coverBS6783-5:1986 ii BSI 10-1999 National foreword This Part of BS 6783 has been prepared under the direction of the Non-ferrous Metals Standards Committee. It is identical with ISO 7524:
9、1985 “Nickel, ferronickel and nickel alloys Determination of carbon content Infra-red absorption method after induction furnace combustion” published by the International Organization for Standardization (ISO). At present this British Standard consists of nine Parts all concerned with analysis of ni
10、ckel, ferronickel and nickel alloys. Further International Standards are in preparation on sampling and analysis of nickel, ferronickel and nickel alloys and, when available, these will be published as further Parts of this British Standard. Terminology and conventions. The text of the International
11、 Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British St
12、andards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Part of BS 6783”. In British Standards it is current practice to use the symbol “L” for litre (and in its
13、submultiples) rather than “l”. 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 obligations. Cross-refe
14、rence International Standard Corresponding British Standard ISO 5725:1981 BS 5497 Precision of test methods Part 1:1979 Guide for the determination of repeatability and reproducibility for a standard test method (Technically equivalent) Summary of pages This document comprises a front cover, an insi
15、de front cover, pagesi andii, pages1 to8, 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 amendment table on the inside front cover.BS6783-5:1986 BSI 10-1999 1 1 Scope and field of appl
16、ication This International Standard specifies an infra-red absorption method after combustion for the determination of the carbon content of nickel and ferronickel in the range 0,001 to 2,0% (m/m), and of nickel alloys in the range 0,001 to 0,5% (m/m). Examples of compositions are given in Annex A.
17、2 Reference ISO 5725, Precision of test methods Determination of repeatability and reproducibility by inter-laboratory tests. 3 Principle Combustion of a test portion in a flow of oxygen at a high temperature in a high frequency induction furnace in the presence of fluxes and accelerators. Measureme
18、nt of the carbon dioxide formed using an infra-red analyser and an integration procedure. 4 Reagents and materials 4.1 Oxygen (O 2 ), 99,5% (m/m) minimum. 4.2 Ascarite or soda lime, 0,7 to1,2mm(14to22mesh). 4.3 Magnesium perchlorate Mg(ClO 4 ) 2 0,7 to1,2mm(14to22mesh). 4.4 Glass-wool 4.5 Crucibles
19、and lids 4.5.1 Ceramic crucibles shall be of precise dimensions so that the sample is positioned correctly in the induction coil of the furnace (see9.1). 4.5.2 For carbon levels of less than 0,01% (m/m) pre-ignite the crucibles in air or oxygen in a furnace for not less than 1 h at 1 100 C and store
20、 in a desiccator or closed container. A resistance furnace with a combustion tube through which a flow of oxygen passes may be used. Crucible lids, used to help retain the solid oxidation products in the hot zone, are pre-ignited in a similar manner. 4.6 Fluxes: low carbon tin, copper plus tin or co
21、pper (see 9.2). 4.7 Accelerators: low carbon copper, iron, tungsten or nickel (see 9.2). 4.8 Standard reference steels, containing 0,01 to2,5% (m/m) carbon. 5 Apparatus The apparatus required for combustion in a high frequency induction furnace and the subsequent infra-red absorption measurement of
22、the evolved carbon dioxide may be obtained commercially from a number of manufacturers. Follow the manufacturers instructions for the operation of the equipment. A pressure regulator is required to control the oxygen pressure to the furnace according to the manufacturers specification (usually 28 kN
23、/m 2 ). Features of commercial equipment are given in Annex B. 6 Sampling and samples 6.1 Sampling and preparation of the laboratory sample shall be carried out by normal agreed procedures or, in case of dispute, by the relevant International Standard. 6.2 The laboratory sample normally is in the fo
24、rm of a powder, granules, millings or drillings and no further preparation of the sample is necessary. 6.3 If it is suspected that the laboratory sample is contaminated with oil or grease from the milling or drilling process, it shall be cleaned by washing with high purity acetone and drying in air.
25、 6.4 If the laboratory sample contains particles or pieces of widely varying sizes, the test portion should be obtained by riffling. 7 Procedure WARNING The risks related to combustion analysis are mainly burns in pre-igniting the ceramic crucibles and in the fusions. Use crucible tongs at all times
26、 and suitable containers for the used crucibles. Normal precautions for handling oxygen cylinders shall be taken. Oxygen from the combustion process shall be removed effectively from the apparatus since a high concentration of oxygen in a confined space can present a fire hazard. 7.1 Stabilizing the
27、 equipment 7.1.1 Condition and stabilize the equipment by combusting several samples, similar to those to be analysed (7.4), using appropriate fluxes and accelerators. NOTEIt is not necessary to use pre-ignited crucibles. 7.1.2 Allow the instrument to cycle several times with oxygen flowing and adju
28、st the instrument zero. 7.2 Blank test and zero adjustment 7.2.1 Charge a pre-ignited crucible (4.5) with the quantity of flux and accelerator to be used in the determination (7.4).BS6783-5:1986 2 BSI 10-1999 7.2.2 Place the crucible and contents on the pedestal post of the furnace, raise to the com
29、bustion position and lock the system. Operate the furnace in accordance with the manufacturers instructions. See 9.3 and Annex B. NOTE 1The reading obtained corresponds to the blank due to the crucible, flux and accelerator. NOTE 2The blank should not exceed 0,001 % (m/m) carbon. NOTE 3If the blank
30、reading is abnormally high, investigate and eliminate the source of contamination. 7.2.3 Adjust the instrument reading using the zero adjust or, on some instruments, the blank offset control. 7.2.4 Repeat 7.2.1 to 7.2.3 to obtain a reproducible reading within the precision limits of the instrument.
31、NOTEAn alternative procedure is to record the reading of the blank test and make the correction using a calibration graph. 7.3 Calibration 7.3.1 Select a series of certified standard reference steels (4.8). 7.3.2 Weigh an appropriate amount (usually 1,00 g) of the standard reference steel (4.8) into
32、 a pre-ignited crucible to cover the high end of the calibration range. Add the pre-selected amounts of flux and accelerator and combust as in 7.2.2. Note the instrument reading. 7.3.3 Adjust the instrument reading to correspond to the correct level of carbon in the standard reference steel accordin
33、g to the manufacturers operating instructions. 7.3.4 Repeat 7.3.2 to check the repeatability of the reading. 7.3.5 Repeat 7.3.2 with a standard reference steel of lower carbon content to provide a calibration check over the required range. Adjust the linearity control, if available, according to the
34、 operating instructions. NOTE 1It is often convenient and more rigorous to use fractional masses of several standard reference steels of high carbon content than a variety of low carbon samples for this check. NOTE 2Most instruments give a read-out directly as a percentage by mass of carbon, however
35、, a calibration graph can be plotted. 7.4 Determination 7.4.1 Weigh, to the nearest 0,001 g, 0,9 to 1,1 g of the test sample, and transfer to a pre-ignited crucible(4.5) containing a suitable amount of the preferred flux (4.6). Add the appropriate quantity of accelerator (4.7), if required. The flux
36、 and accelerator used will depend on the individual characteristics of the equipment and the type of material being analysed. Typical additions to a 1,0 g test portion are 2 g of copper, 2 to 3 g of tungsten or1g of copper plus 1 g of iron. Place the crucible lid in position. 7.4.2 Place the crucibl
37、e and contents on the pedestal post of the furnace, raise to the combustion position and lock the system. Operate the furnace in accordance with the manufacturers instructions. See 9.3 and Annex B. 7.4.3 Record the analyser reading and repeat the determination. NOTE 1It is important that a high temp
38、erature be maintained after the sample is fused to ensure complete transfer of the carbon dioxide from the furnace to the infra-red analyser. NOTE 2A quiescent combustion is necessary to avoid splashing on to the crucible lid where the fused mass may be removed from the induction heating zone. 8 Exp
39、ression of results 8.1 Calculation 8.1.1 If the instrument has been calibrated to give a read-out directly as a percentage by mass of carbon with automatic compensation for the mass of the test portion, take the average of the two determinations and report the result. 8.1.2 If the instrument has bee
40、n calibrated based on a 1,00 g test portion and does not have automatic mass compensation, divide each reading by the respective mass, in grams, of the test portion. Average the two determinations and report the result. 8.1.3 With some instruments it will be necessary to prepare a calibration graph
41、of instrument reading versus the mass, in micrograms, of carbon. Read off the graph the mass, in micrograms, of carbon in the test portion, correct for the blank and mass of the test portion. Average the two determinations and report the result. 8.2 Precision The method specified in this Internation
42、al Standard was subjected to an interlaboratory test programme involving eight laboratories in five countries. Five samples were analysed in duplicate, according to the procedure, on two different days. Repeatability and reproducibility were calculated according to ISO 5725 with the results given in
43、 Table 1. 9 Notes on procedure and equipment 9.1 Crucibles and lids Ceramic crucibles are required for containing the sample, any additions which may be necessary and for the subsequent fusion. They shall be of precise dimensions for the system and fit the supporting pedestal post so that the test p
44、ortion in the crucible is positioned correctly within the induction coil for heating.BS6783-5:1986 BSI 10-1999 3 Typical dimensions of combustion crucibles are Crucibles are pre-ignited at 1 100 C in oxygen to remove carbon. Lids, placed on the crucible, help to retain the solid oxidation products i
45、n the hot zone of the induction coil. The crucible lids are pre-ignited in a similar manner to the crucibles, see 4.5.2. 9.2 Fluxes and accelerators 9.2.1 A flux addition has the effect of bonding together small particles of sample for more effective furnace coupling and to produce a more fluid melt
46、. Tin, copper plus tin, copper and tungsten have been found satisfactory. 9.2.2 Copper, iron, tungsten and nickel are common accelerators. An accelerator addition is made for several reasons: a) to provide a good coupling medium for induction heating for an otherwise unsatisfactory sample, for examp
47、le a finely divided sample or material of complex composition; b) to act as a chemical fuel to increase the combustion temperature; c) to increase the mass of material in the crucible without increasing the mass of the test portion when it is necessary to use small samples. Any flux or accelerator s
48、hall have a low carbon content and be used in the calibration procedure. The total blank from all sources (oxygen, refractories, flux and accelerator) shall not exceed0,001% (m/m) carbon. NOTESome materials act as both a flux and an accelerator. 9.3 Features and operation of high frequency induction
49、 furnaces 9.3.1 Features of commercial equipment are given in Annex B. 9.3.2 Purify the oxygen supply using tubes packed with ascarite (4.2) and magnesium perchlorate (4.3) and maintain a flow rate of about 0,5 l/min while on stand-by. 9.3.3 Maintain a glass-wool filter between the furnace chamber and the analyser and change as necessary. The furnace chamber, pedestal post and filter trap should be cleaned frequently to remove oxide residues. 9.3.4 The manufacturer may recommend setting the programming unit to give a pre-burn period before
