A procedure is described for the determination or columbium in rustless and heat‐resisting high chromium nickel steel. Provision is made for the presence of tungsten, titanium, and molybdenum. By a slight adjustment of conditions, tungsten precipitation is quantitative and a simultaneous determination may be made. The efficiency of hydrolysis separations is discussed and a method of sulphurous acid hydrolysis from divalent iron solution recommended. An examination of the separation of columbium from tungsten by the magnesia method1 has indicated that errors are introduced due to the formation of colloidal columbic acid which prevents a quantitative separation of these two metals. Colloid formation is overcome by using a modified wash liquor. This paper is the first of two to be published on this subject.
A method is described for the determination of silicon in such tungsten and titanium based compounds and materials as tungstic oxide, ammonium tungstate, tungsten metal and carbide, titanium metal and carbide and mixtures of them with molybdenum carbide, tantalum and cobalt. It depends upon calcination to oxide, fusion with sodium carbonate, extraction of the fusion product under conditions that prevent adsorptive and hydrolysis losses of silicic acid and determination by an adaptation of the molybdisilicic acidmolybdenum blue reaction. Optimum conditions for the application of this reaction to the materials under review are given, and results are shown that establish the validity of the method for a series of synthetic mixtures.
The conventional barium sulphate method for sulphur in steel is critically reviewed with particular reference to its performance on chromium steels. It is shown that serious error can occur firom loss of sulphur by co-precipitation with basic chromium compounds formed during the baking treatment to remove residual nitrate, and because of this and the difficulty of ensuring effective control of the baking operation the reliable range of the method is limited to comparatively simple steels.
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