GOST 6689.11-92

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  ГОСТ 6689.11-92

GOST 6689.11−92 Nickel, alloys Nickel and copper-Nickel. Method for the determination of tungsten

GOST 6689.11−92

Group B59

STATE STANDARD OF THE USSR

NICKEL, ALLOYS NICKEL AND COPPER-NICKEL

Method for the determination of tungsten

Nickel, nickel and copper-nickel alloys. Method for the determination of tungsten

AXTU 1709

Date of introduction 1993−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR

DEVELOPERS

V. N. Fedorov, Y. M. Leybov, Boris Krasnov, A. N. Bulanova, I. A. Vorobyev

2. APPROVED AND promulgated by the Decree of Committee of standardization and Metrology of the USSR from 18.02.92 N 167

3. REPLACE GOST 6689.11−80

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

_______________

* Probably a mistake of the original. Should read GOST 6689.1−92. — Note the manufacturer’s database.

This standard specifies a gravimetric method for the determination of tungsten (at a mass fraction of from 2 to 4%) in Nickel alloys according to GOST 19241.

1. GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 25086 with the addition of sec. 1 GOST 6689.1.

2. GRAVIMETRIC METHOD FOR THE DETERMINATION OF TUNGSTEN

2.1. The essence of the method

The method is based on the isolation of tungsten in tungsten acid, separating the precipitate and calcining it to tungsten trioxide. The precipitate is weighed, treated with a solution of sodium hydroxide, filtered off and calcined. The tungsten content is calculated by difference of weight of solids before and after treatment with sodium hydroxide solution.

2.2. Reagents and solutions

Nitric acid according to GOST 4461, diluted 3:2.

Hydrochloric acid according to GOST 3118 and diluted 1:10.

Sodium hydroxide according to GOST 4328 and a solution of 100 g/DM.

Dimethylglyoxime according to GOST 5828, a solution of 10 g/DMsolution of sodium hydroxide 100 g/DM.

Volframovich sodium (NaWO·2HO).

A standard solution of tungsten: 0,895 g NaWO·2HO dissolved in water. The solution was transferred to volumetric flask with a capacity of 500 cm, made up to the mark with water.

1 cmof the solution contains 0.001 g of tungsten.

The exact content of tungsten set gravimetric meth

Odom.

2.3. Analysis

A sample of alloy weighing 1 g is placed in a beaker with a capacity of 250 cm, add 20 cmof nitric acid, cover with watch glass, glass or plastic plate and dissolved by heating. Glass or plate and the side of the Cup then rinsed with water and a solution of precipitated tungsten acid is evaporated to dryness. To the dry residue add 10 cmof concentrated hydrochloric acid and again evaporated to dryness. The dry residue is dissolved in 10 cmof concentrated hydrochloric acid under heating, and adding 100 cmof hot water.

The precipitate tungsten acid is filtered in two medium density filter, a glass and the filter cake is washed with hot hydrochloric acid (1:10) to a negative reaction of wash water to Nickel (the sample with an alkaline solution dimethylglyoxime). The remnants of tungsten acid, adhering to the walls of the glass, remove the pieces of paper filter and are attached to the residue on the filter. The filter with precipitate was placed in a platinum crucible, dried, burned, and calcined at 750−800 °C to constant weight. To the calcined residue is added 6 g of sodium hydroxide and carefully add 10−15 cmof hot water. After 4−5 min the contents of the crucible are poured into a beaker, rinse the crucible with a little water and the solution in a glass diluted with water to 100−150 cm. The solution was filtered through two medium density filter and washed with hot water until the disappearance of the alkaline reaction of wash water universal indicator paper. The filter is placed in the same crucible, dried, burned, and calcined at 750−800 °C to constant weight. By difference the mass of the crucible with tungsten trioxide before treatment with sodium hydroxide solution and after treatment find the content of tungsten trioxide

.

2.4. Processing of the results

2.4.1. Mass fraction of tungsten () in percent is calculated by the formula

,

where is the mass of the platinum crucible with tungsten trioxide before treatment with sodium hydroxide solution, g;

 — the mass of the platinum crucible after treatment with sodium hydroxide solution, g;

0,7931 — the conversion factor from the mass of tungsten trioxide on the weight of the tungsten;

 — the weight of the portion of alloy,

2.4.2. Discrepancies in the results of three parallel measurements (rate of convergence) and the results of the two tests (index of reproducibility) shall not exceed 0.1% and 0.14%, respectively.

2.4.3. Control of accuracy of analysis results is carried out by additives in accordance with GOST 25086.