BS EN ISO 439:2020 pdf download.Steel and cast iron – Determination of silicon content – Gravimetric method.
3? Terms? and? definitions
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4 Principle
Dissolution of a test portion with hydrochloric and nitric acids.
Conversion of acid-soluble silicon compounds to hydrated silicon dioxide by evaporation with perchloric acid until white fumes appear. Filtration of the hydrated silicon dioxide and acid-insoluble silicon compounds, ignition to form impure silicon dioxide and then weighing.
Treatment of the ignited residue with hydrofluoric and sulfuric acids, followed by ignition and weighing.
5 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and
grade 2 water as specified in ISO 3696.
5.1 Hydrochloric acid, ρ approximately 1,19 g/ml.
9.2 Precision A planned test of this method was carried out by 26 laboratories, at nine levels of silicon, each laboratory making three determinations of the silicon content at each level. The test samples used are listed in Table A.1, and the experimental precision data obtained are shown in Table A.2. The results obtained were treated statistically in accordance with ISO 5725-2:1994 and ISO 5725-3:1994. A graphical representation of the experimental precision data is given in Annex B. The smoothed precision data, expressed as a percentage (mass fraction), shown in Table 2 were calculated from the relationships between the silicon content mean values and repeatability and reproducibility experimental data (see Annex A and Annex B). NOTE 1 Two of the three determinations were carried out under repeatability conditions as defined in ISO 5725-1, i.e. one operator, same apparatus, identical operating conditions, and a minimum period of time. NOTE 2 The third determination was carried out at a different time (on a different day) by the same operator as in NOTE 1 using the same apparatus. NOTE 3 When revising the present document, the precision data were revaluated: this new statistical treatment has led to the removal of the whole data of one laboratory.
10 Test report
The test report shall include the following information:
a) all information necessary for the identification of the sample, the laboratory and the date of analysis or of the test report;
b) method used by reference to this document, i.e. ISO 439:2020;
c) results and unit in which they are expressed;
d) any unusual features noted during the determination;
e) any operation not specified in this document, or any optional operation which might have influenced the results.BS EN ISO 439 pdf download.