SU1522094A1 - Method of determining nitrogen in steels - Google Patents

Abstract

This invention relates to analytical chemistry, in particular to methods for analyzing steels and alloys. The aim of the invention is to improve the accuracy of the determination of nitrogen in steels and alloys and to reduce the analysis time. This goal is achieved by dissolving the sample, introducing potassium pyrophosphate in an amount of at least 25 g per 0.1 g of the amount of iron, chromium, manganese and vanadium, oxidizing manganese and vanadium with potassium permanganate and amperometric titration of calcium ions with calcium hypochlorite. 4 tab.

Description

This invention relates to analytical chemistry, in particular to methods for analyzing steels and alloys.

The aim of the invention is to improve the accuracy of determining nitrogen in steels and alloys and reducing the analysis time.

Example. A sample of the sample is placed in a conical flask with a capacity of 250 cm and dissolved in 20-50 cm of a diluted 1: 4 solution of sulfuric acid. After the sample is dissolved, the flask with the solution is cooled, hydrogen peroxide is added to the solution and heated. After cooling, 5 cm of phosphoric acid (square 1, 7) are added and the solution is evaporated twice to shadelenyl sulfuric acid vapor. The flask is cooled, the resulting salts are dissolved in 20-40 C of water when heated (boil for 5 min), cooled and transfer the solution into a 100 cm volumetric flask, water up to the mark and mix.

Select the appropriate. and the herb and placed under stirring in. glass with a capacity of 200 cm, containing a solution of potassium pyrophosphate with a concentration of 800 g / dm in a weight amount of 25-30 g per 0.1 g of the amount of iron, chromium, manganese and vanadium.

Options aliquots are given in table.1.

The resulting solution should be clear. If necessary, then water is added cationized to

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with

41b

a volume of 50 cm. Using NaOH (1; 4), the pH of the solution is set at 8-9, 1-2 cm of manganic acid, potassium (10 g / dm) is added to a stable cherry-red color, 30 cm of electrolyte (1.5) are added mol / Dm solution of potassium bromide + 0.1 mol / dm borax). The pH of the solution to be titrated should be 8-9.

The beaker with the solution is placed on the magnetic stirrer table, 2 platinum electrodes are immersed, stirring is turned on, a potential of 0.25 V is established and titrated with calcium hypochlorite solution. The titer of the calcium hypochlorite solution is set by the standard ammonium chloride solution, carried out through the course of the analysis.

At the same time, a control experiment was conducted on the nitrogen content in the reagents.

The correctness of the method was tested on standard samples of alloyed steel C44 and 2904, metallic chrome F8, manganese metallic F29, ferrovanadium F32.

The results of the analysis are presented in table 2.

As can be seen from the data presented in Table 2, the method is characterized by high accuracy and good reproducibility even at low nitrogen levels,

Table 3 presents the results of the analysis of standard solutions by the proposed method and the prototype method.

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"As can be seen from Table 3, the proposed method is characterized by higher accuracy and reproducibility.

B of Table 4 presents data illustrating the effect of the amount of potassium microphosphate introduced on the results of the determination of nitrogen in the presence of 0.1 g of chromium, iron, manganese and vanadium.

Claims (1)

As can be seen from Table 4, reliable results were obtained when the content of potassium pyrophosphate in the solution was at least 25 g per 0.1 g of the sum of chromium, iron, manganese and vanadium. With a lower content of potassium pyrophosphate, the results of the determination of nitrogen are scaled, since, along with NH4 ions, Cr ions are also titrated. The analysis time of the proposed method as compared with the prototype is halved due to the elimination of the lengthy operation of merging with perchloric acid. Claims. The method for determining nitrogen in steels x,. including sample dissolution followed by amperometric titration of ammonium ions formed by calcium hypochlorite, characterized in that, in order to improve the accuracy of determination and reduction of the analysis time, the solution obtained after dissolving the sample is injected at least 25 g of potassium pyrophosphate 0.1 g total of iron, chromium, manganese and vanadium, and the oxidation of manganese and vanadium with potassium permanganate. 20 TO 35 Table 1 C44 Steel High Editor N. Gorvat Compiled by N. Kutseva Tehred M. Khodaich Proofreader T. Paliy / Order 6952/40 Circulation 789 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., 4/5 table 2 Subscription