GOST 14338.4-82

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  ГОСТ 14338.4-82

GOST 14338.4−82 Molybdenum. Methods for determination of nitrogen, oxygen and hydrogen

GOST 14338.4−82

Group B59

STATE STANDARD OF THE USSR

MOLYBDENUM

Methods for determination of nitrogen, oxygen and hydrogen

Molybdenum. Methods for determination of nitrogen, oxygen and hydrogen

Date of introduction 1984−01−01

The decision of the State Committee of USSR on standards from 30 Sep 1982 N 3870 introduction installed from 01.01.84

By the decree of Gosstandart of the USSR from 21.04.88 N 1106 validity period extended till 01.01.92*
________________
* Expiration removed by the resolution of Gosstandart of the USSR from 27.09.91 N 1524 (IUS No. 12, 1991). — Note the manufacturer’s database.

REPLACE GOST 14338.4−74

REPRINTING. August 1988


This standard sets the photometric method for the determination of nitrogen (at a mass fraction of nitrogen from 0.0001 to 0.1%) and the method of reaction gas chromatography (reductive melting in an atmosphere of inert carrier gas argon or helium) to determine the nitrogen (in the mass fraction of nitrogen 0,001−0,1%), oxygen (when the mass fraction of oxygen of 0.001−0.1%) and hydrogen (with mass fraction of hydrogen of 0.0001−0.1%) for the metallic molybdenum (powder, rod billet, rod, wire, strip, foil).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 14338.0−82.

2. PHOTOMETRIC METHOD

The photometric method for the determination of nitrogen is based on the Stripping of the formed ammonia from the alkaline solution in a quartz apparatus (Kjeldahl) followed by absorption of ammonia with sulfuric acid and determining the nitrogen.

2.1. Apparatus, reagents and solutions

Quartz distillation apparatus for producing the double-distilled water.

Quartz distillation apparatus for distillation of ammonia.

Microburette with a capacity of 5 cmand a burette with a capacity of 50 cmaccording to GOST 1770−74.

Microbes type CF-1 or any other type that provides weighing with an accuracy of 0.00001 g.

Types photoelectrocolorimeter FEK-56M, PEC-60.

The device for determination of nitrogen content (Fig.1) consists of the distillation flask 1with ground stopper, to which is soldered a funnel 2 for infusion of the study solution; eliminator 3; of the refrigerator 4, the ground to the drip tray and the receiver; the receiver 5 with ground stopper 6.

Damn.1

The Help Of Nessler’s Reagent.

Rectified ethyl alcohol according to GOST 18300−72*.
________________
* On the territory of the Russian Federation GOST 18300−87. Here and further. — Note the manufacturer’s database.

Sulfuric acid GOST 4204−77, diluted 1:1 with bidistilled water pre-boiled in a quartz vessel, and 0.02 n solution, prepared from fixanal.

Hydrochloric acid by the GOST 3118−77, diluted 1:10.

Ammonium sulfate according to GOST 3769−78, OS.CH., standard solution: 0,01179 g of salt dissolved in bidistilled water in a volumetric flask with a capacity of 1000 cm. Top up the solution with bidistilled water to the mark and mix.

1 cmof the solution contains 0,0000025 g of nitrogen.

Potassium hydroxide solution: 500 g of potassium hydroxide dissolved in a flask with a capacity of 2000 cm, poured bidistillated water to a volume of more than 1000 cm, the solution was evaporated to a volume of 1000 cmand cooled to room temperature, cover the flask with a stopper that is connected through the hole with a flask for washing of gases containing concentrated sulfuric acid.

Reference solution: in a volumetric flask with a capacity of 50 cmimpose 5 cmof 0.02 n solution sulfuric acid, 0.5 cmof the help of nessler’s reagent, made up to the mark with bidistilled water and stirred

T.

2.2. Preparation for assay

Samples of molybdenum metal are crushed, cleaned of contaminants and oxides by washing them first with hydrochloric acid (1:10), then with bidistilled water and ethanol. After rinsing the sample was dried in air.

2.3. Analysis

Depending on the mass fraction nitrogen in the sample take the sample in accordance with table.1.

Table 1

The sample is placed in a flask with a hydraulic stopper, add 10 cmsulphuric acid (1:1) and heated on an open stove until dissolved. After cooling, the solution is diluted with bidistilled water up to 50−60 cmand poured into a distillation flask.

Distillation flask with the solution attached to the installation. The receiver is introduced 5 cmof 0.02 n sulfuric acid solution and at a weak suction flow a small current of steam. Then slowly, in small portions, pour into the distillation flask through the funnel 80 cmof a solution of potassium hydroxide to neutralize the acid and obtaining an alkaline environment. After all lye is introduced into a flask, amplify the current of steam-air mixture and suctioning.

After the first drops of condensate distillation are still 15 min Released ammonia, entrained vapor, is absorbed in the receiver of 0.02 n sulfuric acid solution. Usually collected condensate and the acid of 30−40 cm.

After a specified time turn off the vacuum, quickly open the tap of the funnel, release the air in a distillation flask and then turn off the steam.

Disconnect the refrigerator and transfer the resulting condensate in a volumetric flask with a capacity of 50 cm. The fridge and the receiver is washed with bidistilled water, using minimum water. Wash liquid is collected in the volumetric flask with the condensate, is added to the flask 0.5 cmof the help of nessler’s reagent, add the solution to the mark with bidistilled water and stirred. The solution is kept for 30 min for the formation of complex compounds of ammonia with the help of nessler’s reagent. Then measure the optical density of the analyzed solutions and solutions comparison photocolorimeter with blue filter N 4 (wavelength 440 nm) in a cuvette with a thickness of the light absorbing layer was 50 mm.

Simultaneously with the sample hold control experience for contamination of the reagents is carried out through all stages of the analysis using the same reagents and in the same quantities that the analysis of the test sample

.

2.4. Construction of calibration curve

In a volumetric flask with a capacity of 50 cmimpose 5 cmof 0.02 n sulfuric acid solution, and then from 0.4 to 5.0 cm(with an interval of 0.2 cmand from 5.0 to 40 cmwith an interval of 5 cm) of a standard solution of ammonium sulfate and 0.5 cmof the help of nessler’s reagent.

The solutions were topped up to the mark with bidistilled water and stirred. The solutions were incubated for 30 minutes, then measure the optical density of colored solutions and solution comparison photocolorimeter with blue filter N 4 (wavelength 440 nm) in a cuvette with a thickness of the light absorbing layer was 50 mm.

A solution of comparison when measuring optical density using a solution containing all the applied reagents.

On the found values of optical densities and their corresponding nitrate concentrations to build calibration graphs

.

2.5. Processing of the results

2.5.1. Mass fraction of nitrogen (a) percentage calculated by the formula

,

where the amount of nitrogen in the sample was found in the calibration schedule g;

the amount of nitrogen in solution in the reference experiment, was found in the calibration schedule g;

 — the weight of the portion of the sample,

2.5.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 does not exceed the values given in table.2.

Table 2

3. THE METHOD OF REACTION GAS CHROMATOGRAPHY

The method of reaction gas chromatography is based on the release of hydrogen, nitrogen and oxygen (regardless of their location) and the gas phase in the form of molecular hydrogen and nitrogen, and carbon monoxide, respectively, under conditions of intermittent (pulse) heating to ~3500 °C in a graphite capsule, with subsequent transportation of argon and helium gas mixture in the column of the gas chromatograph.

3.1. Apparatus, reagents and solutions

Installation (DWG.2) consists of a balloon with argon or helium 1; gas chromatograph type lxm-8МД (model 1), lxm-72, or any other, not conceding on the parameters specified above, 2; recording type potentiometer KSP-4 (completed with a gas chromatograph) 3; pneumatic impulse resistance furnace (for analysis) 4; cylinder with argon or helium 5, 6; pneumatic impulse resistance furnace (pre-drainage capsules) 7; power supply pulse furnace 8 (Fig.3).

Damn.2

Damn.3

The power supply circuit of the pulse furnaces consists of the automatic contactor type AP 50−3M 1; autotransformer type OMN 40−250−75 V4 2; voltmeter type e-378, 0250 3; magnetic actuator type PME-222 4; transformer type OSU-20/05, or any other similar type up to 5 kW 5; ammeter type e-378, 1000/5 6; current transformer of type TM-40, 1000/5 7; impulse furnace 8; time relay 9 type VL 27У4 (providing exposure from 0 to 10), intermediate relays of the type PE-21 (for relay); button launcher of the type KMZ-2 10.

Note. Circuit for power pulse furnace allowed the use of other electrical equipment, providing the load current (the load is the graphite capsule) 500−600 And at a safe voltage of 10−12 V, pulsed 4−5 s, with an interval of 2−2,5 min.


The synthetic zeolite 5 A (SAA), grain size of 0.25−0.5 mm.

The ethyl ether according to GOST 8981−78, H. h

Rectified ethyl alcohol according to GOST 18300−72.

Acetone according to GOST 2603−79, H. h. or h.d. a.

The aviation gasoline according to GOST 1012−72.

Carbon tetrachloride according to GOST 20288−74, H. h. or h.d. a.

Cotton calico.

Chromatographic column: stainless steel (4x0,5; 6x1,0; 8x1,0 length of 1.5m and 3.0 m).

Gauge type MT-60, 0,16−0,25 MPa (1,6−2,5 ATM).

The throttle needle for fine adjustment of the type OH-6.

Microbes MV-1 or any other type that allows you to weigh with an accuracy of 0.00001 g.

Pressure regulator RDF-31 or any other equivalent type capable of ensuring stable pressure in the pneumatic furnace lift in the range of 0.15−0.25 MPa (1.5 to 2.5 bar).

The stopwatch according to GOST 5072−79.

Clip with a reading device of the type SRO-25 according to GOST 11098−75.

Capsule graphite brand S-2 or S-3 (DWG.4).

Notes:

1. The cap should fit snugly to the body without forming cracks.

2. The end surface of the collected capsule should be strictly parallel.

3. Length of capsule with cover (20,65±0,05) mm

Damn.4

Tape Plexiglas to capsules.

Stainless steel hook for cleaning the interior of the furnace chamber.

Flowmeter General RM according to GOST 13045−81.

Argon gas high purity cylinder according to GOST 10157−79.

Helium gas of high purity.

Standard materials: steel SG-1 (N 81−71 in the state Register) steel SG-3 (N 577−74 on the state registry) steel SG-2 (N 416−73 on the state Register). Use standard samples category OSO, SOP, which certified the content of a component is not different from that analyzed more than two times.

3.2. Preparation for assay

Samples of molybdenum metal pre-cleaned from oxide film, rinsed in gasoline or carbon tetrachloride and dried with acetone. Powder of molybdenum metal used in the analyses without preparation.

For batches, take the pieces with the diameter from 2.0 to 2.8 mm, i.e. the pieces need to be sifting into the hole of 2.8 mm sieve and did not pass into the hole of 2.0 mm. sieve the Powder material is charged into the capsule using a small spatula.

Select the capsule in length with a tolerance of 0.05 mm (at the lever bracket) and degassed them at a temperature of ~3500 °C. For the analysis of samples taken capsules without cracks, the capsules with a small crack can be used for control experiments.

3.3. Analysis

Include chromatograph and set the optimum mode of chromatographically.

Set graphite capsule with the analyzed sample.

Depending on the mass fraction of nitrogen, hydrogen, oxygen in the sample, take a portion of the sample in accordance with table.3.

Table 3

Slide the handle of the valve until it stops and at the same time include a stopwatch and starting the power button on the furnace.

30 with the handle the valve is returned to its original position and after the release of the hydrogen peak on the recorder switch knob «out of the accident» to the desired range for the designated item.

After 2 minutes replace the old capsule for a new one.

Upon completion of the work, in order to avoid the ingress of air into the chromatograph, it should be «conserve» — to close the regulator on the cylinder with argon gas for chromatograph. When the pressure of argon in both columns close to zero, establish a very weak flow of carrier gas in the device for the foam flowmeter and switch off the power button chromatograph.

3.4. Processing of the results

3.4.1. Mass fraction of nitrogen, hydrogen, oxygen () in percent is calculated by the formula

,

where is the calibration coefficient, which is calculated for each of the element in the calibration of the instrument with standard samples;

the peak height of the element minus the peak obtained in a control experiment, mm.

 — the weight of the portion,

The calibration factor should be checked and adjusted, especially after repair, different adjustments: change cylinders feeding the chromatograph and the oven for analysis after prolonged inactivity of the installation.

3.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 does not exceed the values given in table.4.

Table 4

3.4.3. The method used in the disagreement in assessing the quality of molybdenum.