GOST 22720.4-77
GOST 22720.4−77 Rare metals and alloys on their basis. Method for determination of nitrogen (with Change No. 1)
GOST 22720.4−77
Group B59
STATE STANDARD OF THE USSR
RARE METALS AND ALLOYS ON THEIR BASIS
Method for determination of nitrogen
Rare metals and their alloys. Method for the determination of nitrogen
AXTU 1709*
______________
* Introduced advanced Edit. N 1.
Date of introduction 1979−01−01
The decision of the State standards Committee of the Council of Ministers of the USSR from September 29, 1977 N 2341 introduction installed from 01.01.79
Proven in 1983 by the Decree of Gosstandart from 27.07.83 3511 N validity extended to 01.01.89*
________________
* Expiration removed by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS No. 5/6, 1993). — Note the manufacturer’s database.
REPRINTING. November 1983
The Change N 1, approved and put into effect by the Decree of the USSR State Committee for standards from
Change No. 1 made by the manufacturer of the database in the text IUS N 5, 1988
This standard applies to niobium, tantalum, vanadium, zirconium, hafnium, molybdenum, tungsten, rare earth metals, alloys of niobium-tungsten, molybdenum-rhenium, molybdenum-zirconium, zirconium-niobium-titanium, cobalt-rare-earth metals, nitrides of zirconium and gallium, and sets the volumetric method for the determination of nitrogen (for the mass concentration of nitrogen from 5·10% and above).
Upon dissolution of the sample in the appropriate acid nitrogen in the bound form (in the form of nitrides and solid solution), goes into solution with the formation of ammonium salts. After the distillation of ammonia from alkaline solution (by the method of Kjeldahl) determination acidometry done in the presence of the mixed indicator.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 22720.0−77.
2. APPARATUS, REAGENTS AND SOLUTIONS
Installation for determination of nitrogen (see drawing).
1 — flask-trap, filled with sulphuric acid; 2 — flask-trap filled with water; 3 — hot plate; 4 — distillation flask of heat-resistant glass with a capacity of 500 cmwith ground stopper, equipped with a drip funnel with a tap; 5 — refrigerator 6 — vessel for trapping ammonia; 7 — microburette 2nd class
Sulfuric acid according to GOST 14262−78, OS.h. and diluted 1:1, 1:4.
Sulfuric acid of concentration 0.05 mol/l(0,1 n) and 0.005 mol/l
(0,01 n).
1 cmof 0.01 N. the solution corresponds to 0.14 mg of nitrogen.
Hydrochloric acid according to GOST 14261−77, OS.CH., diluted 1:1 and 1:4.
Hydrofluoric acid (hydrofluoric acid) according to GOST 10484−78.
Potassium sulfate according to GOST 4145−74.
Hydrogen peroxide (perhydrol) according to GOST 10929−76.
Zinc granulated GOST 3640−79*, h.d. a.
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* On the territory of the Russian Federation GOST 3640−94. — Note the manufacturer’s database.
Copper sulfate according to GOST 4165−78.
The technical rectified ethyl alcohol according to GOST 18300−72*.
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* On the territory of the Russian Federation GOST 18300−87. — Note the manufacturer’s database.
Sodium hydroxide (caustic soda) according to GOST 4328−77 h. d. a., the solution is prepared as follows: 400 g of sodium hydroxide dissolved in small portions in 1000 cmof water. To the obtained solution add 2−3 pieces of zinc and a few crystals of copper sulphate, mix and boil for 40−60 minutes, adding water to maintain the original volume. The prepared solution is stored in tightly closed plastic container.
Mixed indicator prepared as follows: 0,062 g methyl red and 0,041 g of methylene blue dissolved in 100 cmof ethanol and stored in a tightly closed flask.
Water, bidistilled freshly distilled.
(Changed edition, Rev. N 1).
3. PREPARATION FOR ASSAY
3.1. Assemble the installation drawing and check tightness of the whole system (with aspirator) prosushivaniem air evenly at a speed of 3−4 bubbles per 1 second.
Before starting work, make the cleaning of the alkali solution and the entire system of the device from traces of ammonia. For this purpose in a distillation flask and pour 50 cmof sodium hydroxide and 50 cm
of water. The vessel for trapping of ammonia poured 25−30 cm
of water and 2−3 drops of mixed indicator. Microburette fill in 0.01 n sulfuric acid solution. Distilling flask with sodium hydroxide solution heated to boiling and boil for 5−10 minutes. the Completeness of ammonia removal is controlled by a colour change of the mixed indicator, adding from the burette drop by drop 0.01 N. the solution of sulfuric acid to restore the violet color of the solution. The cleanup is complete, if the purple color persists for 3−5 min. Analyses must be undertaken in premises which are working with ammonia and its salts.
(Changed edition, Rev. N 1).
4. ANALYSIS
For determination of nitrogen in the analyzed materials use three samples in the form of powder, chips or foil with a mass of 0.5 g; in the analysis of nitrides — three samples weighing 0.05 g. the conditions of dissolution of the analyzed materials are given in table.1.
Table 1
| The analyzed metal |
The conditions of dissolution |
| Niobium |
The sample is placed in a conical flask with a capacity of 100 cm |
| Tantalum |
The sample is placed in a platinum Cup, moisten with 2 cm |
| Zirconium, hafnium |
The sample is placed in a beaker with a capacity of 100 cm |
| Vanadium |
The sample is placed in a conical flask with a capacity of 100 cm |
| Tungsten |
The sample is placed in a conical flask with a capacity of 100 cm |
| Molybdenum |
The sample is placed in a conical flask with a capacity of 100 cm |
| Rare earth metals and alloys | The sample is placed in a beaker with a capacity of 100 cm |
| Alloy molybdenum-rhenium |
The sample is placed in a conical flask with a capacity of 100 cm |
| Alloy niobium-tungsten- molybdenum-zirconium |
The sample is placed in a conical flask with a capacity of 100 cm |
| The alloy zirconium-niobium-titanium |
The sample is placed in a platinum Cup, moistened with 5 cm |
| Nitride of zirconium |
The sample is placed in a conical flask with a capacity of 100 cm |
| Gallium nitride |
The sample is placed in a conical flask with a capacity of 100 cm |
(Changed edition, Rev. N 1).
4.1. Distillation
In a distillation flask, which was previously produced by alkali cleaning and the entire system of the device of traces of ammonia (see sect.3), transfer the solution obtained in accordance with the requirements specified in table.1. The tap of the funnel is closed and the contents of the flask are thoroughly mixed. Heated the solution and within 45 minutes produce a distillation of ammonia, supporting the continuous boiling of the solution. As Stripping of ammonia the color of the mixed indicator changes from violet-red to green. Immediately after the appearance green color is added from burette dropwise a 0.01 n solution of sulfuric acid to restore the purple-red color of the solution. Stripping done when the color of mixed indicator in the vessel for trapping ammonia continues to maintain a weak purple-red color within 5 minutes, the obtained results introduce the amendment in the reference experiment for contamination of reagents.
5. PROCESSING OF THE RESULTS
5.1. Mass fraction of nitrogen (a) percentage calculated by the formula
where is the volume of sulfuric acid (density 1.84 g/cm
), consumed for titration of ammonia, cm
;
— the volume of sulfuric acid solution consumed for titration of the solution at a Supervisory experience, cm
;
— the mass of sample, g.
(Changed edition, Rev. N 1).
5.2. Allowable absolute differences between the results of two parallel measurements with a confidence probability of 0.95 should not exceed the values given in table.2. For intermediate values of the mass fraction of nitrogen permissible divergence is determined by linear interpolation.
Table 2
| The mass fraction of nitrogen, % | Allowable absolute differences, % |
5·10 |
3·10 |
1·10 |
5·10 |
5·10 |
1,5·10 |
1·10 |
2·10 |
2·10 |
3·10 |
| 2,0 |
3·10 |
