BSISO11877:2008 ISO INTERNATIONAL 11877 STANDARD First edition 2008-06-01 Hardmetals Determination of siliconin cobalt metal powders Photometric method Metaux durs-Dosage du siliciumdans les poudres metalliques de cobaltMethodephotometrique Reference number ISO 11877:2008(E) ii BS IS0 11877:2008 Contents Page Foreword iv 1 Scope. 2 Principle 3 Reagents.. Apparatus and equipment.. 5 Preparation of acid mixture for sample treatment 6 Preparation of solutionsforreceiver 7 Procedure. 2 8 Photometricdetermination. 3 9 Preparation of blank and calibration solutions .3 10 Expressionof the result. 11 Test report Bibliography... ili BS IS0 11877:2008 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 normally carried out through IsO non-governmental, in liaison with isO, also take part in the work. iso collaborates closely with the InternationalElectrotechnicalCommission(lEC)onallmattersofelectrotechnicalstandardization International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2 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 rights. IsO shall not be held responsible for identifying any or all such patent rights. Samplingandtestingmethodsforhardmetals iv BSISO 11877:2008 HardmetalsDeterminationofsiliconincobaltmetal powders Photometric method 1 Scope ThisInternational Standardspecifies a photometric method tobe used forthedeterminationofthe mass fraction of silicon in the range of 20 μg/g to 300 μg/g in cobalt metal powders. 2Principle After treatment of the sample with a mixture of acids, the so-formed silicon tetrafluoride is distlled into a mixture of boric acid and sodium molybdate. The obtained molybdatesilicate complex is extracted with methyl- isobutylketone and the absorbance of the solution is measured. 3 Reagents Reagents of the highest purity and only double-distilled water or water of equivalent purity shall be used 3.1 Hydrofluoric acid, 40 %bymass. 3.2 Nitric acid, 65 % by mass. 3.3 Hydrochloric acid, 30 % by mass. 3.4 Sulfuric acid, 96 % by mass. 3.5 Perchloric acid, 70 % by mass. 3.6 Sodium hydroxide solution, 30 % by mass. 3.7 Boric acid. 3.8 Sodium molybdate. 3.9 Amidosulfuric acid. 3.10 Methyl-isobutylketone 3.11 Acetone. 3.12 Water. 3.13 Nitrogen. 3.14 4Siliconstandardsolution,100μg/ml. 1 BS ISO 11877:2008 4Apparatus and equipment All apparatus and equipment in contact with reagents shall be made of silicon-free material like PTFE (polytetrafluoroethylene), PP (polypropylene), PE (polyethylene) and TPX (methylpenten-polymer). 4.1 Apparatus for acid treatment and distillation, for separation of silicon tetrafluoride 4.2 Test-tube shaker. 4.3 Refrigerator. 4.4 Platinum thimbles, for weighing the sample. 4.5 Graduated flasks, stock bottles and pipettes 5Preparationof acid mixtureforsampletreatment Mix30ml ofhydrofluoric acid,20mlofnitric acid,20 mlofperchloric acidand30 mlof waterinaPTFEflask. 6 Preparationofsolutionsforreceiver 6.1 SolutionI Dissolve 37,2 g of boric acid and 14,4 g of sodium molybdate in water in a graduated PP flask and fill up to 1 000 ml with water. 6.2 Solutionll Dissolve 19,4 g of amidosulforic acid in a graduated PP flask and fill up to 100 ml with water. 7 Procedure 7.1 Pour 30 ml of solution I and 1 ml of solution Il into a graduated 100 ml flask. 7.2 Pour 3 ml of the acid mixture into the distilling flask, and add 100 mg of the sample weighed to a platinum thimble. 7.3 7.4Heat the apparatus to 170 ± 10C, within approximately 25 min, and keep it at this temperature for 50 min. Control the purge gas during distillation. 7.5 When the distillation time is over, remove the receiver flask and rinse the inlet tube with water. 7.6 800 μl to 1 000 μl) and leave it for 1 h.