ISO-6437-1984.pdf
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1、International Standard INTERNATlONAL ORGANIZATION FOR STANDAROIZATION*MEXJlYHAPOnHAR OPl-AHHBAUMR i-IO CTAHAAPTH3AUIIM.ORGANlSATION INTERNATIONALE DE NORMALISATION Copper alloys - Determination of chromium content - Titrimetric method Alliages de cuivre - Dosage du chrome - M V2 is the volume, in mi
2、llilitres, of the iron ammonium sulfate solution (3.11.1) used in the titration. 3.11.2.2 Potentiometric standardization Transfer 30 ml of the potassium dichromate solution (3.10) to a 600 ml beaker containing 15 ml of the sulfuric acid (3.51, 25 ml of the orthophosphoric acid solution (3.71, and ab
3、out 330 ml of water. Titrate using the procedure specified in 5.4.2. The titre of the iron ammonium sulfate solution, expressed as milligrams of chromium per millilitre of solution, is given by the formula in 3.11.2.1. Daily standardization of the iron(lll ammonium sulphate solu- tion is required. 4
4、 Apparatus Ordinary laboratory apparatus, and 4.4 Beakers, capacity 600 ml, tall form. 4.2 Potentiometric titration apparatus. 5 Procedure 5.1 Test portion Weigh, to the nearest 0,001 g, about 2 g of the test sample.11 5.2 Dissolution of test portion Transfer the test portion (5.1) to a 600 ml tall-
5、form beaker (4.1). Add 20 ml of the hydrochloric acid (3.11, 10 ml of the nitric acid (3.21, and 1 ml of the hydrofluoric acid (3.3). When ef- fervescence ceases, add IO ml of the orthophosphoric acid solution (3.7) and 30 ml of the perchloric acid (3.4). Bring to the boil and evaporate until thick
6、white perchloric fumes appear. Maintain until the test portion is totally dissolved. Reduce the heat and boil gently for 5 min. Cool. Add 30 ml of water and boil for 5 min. Cool. 5.3 Oxidation of residual chromium(lll) Add 150 ml of water to the solution (5.21, bring to the boil and add 5 ml of the
7、potassium permanganate solution (3.8). Boil for 3 min., then add 10 ml of the hydrochloric acid solution (3.6) and boil for 15 min. Allow to cool. 5.4 Determination 5.4.1 Volumetric titration with indicator To the test solution (5.3), add 25 ml of the orthophosphoric acid solution (3.7) and 0,l ml o
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- ISO 6437 1984
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