GOST 13084-88

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  ГОСТ 13084-88

GOST 13084−88 Powders of high-alloyed steels and alloys. Technical specifications (with Amendment)

GOST 13084−88

Group 56

STATE STANDARD OF THE USSR

POWDERS OF HIGH-ALLOYED STEELS AND ALLOYS

Specifications

Powders of high-alloyed steels
and alloys. Specifications

GST 14 7900

Valid from 01.01.90
to 01.01.95*
_______________________________
* Expiration removed by Protocol No. 4−93
The interstate Council for standardization,
Metrology and certification (I & C N 4, 1994). -
Note the manufacturer’s database.

INFORMATION DATA

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

PERFORMERS

V. I. Matorin, PhD. tech. of Sciences; Yu. Managin, d-R tekhn. Sciences; V. T. Ababkov, PhD. geologist. Sciences; V. V. Karataev (supervisor); T. A. Korobov (supervisor); V. F. Lykov

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on standards 29.06.88 N 2552

3. The frequency of inspection — 5 years

4. REPLACE GOST 13084−67

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

AMENDED, published in the IUS N 9, 1989

An amendment made by the manufacturer of the database


This standard covers powders of high-alloyed steels and alloys manufactured by the joint recovery of compounds of oxides, metal powders with calcium hydride. Powders intended for the manufacture of corrosion-resistant products, machine parts, instruments, porous and dense sheets, strips, wire, metallurgical semi-finished products (forgings, rods, tapes, tubes) and for other purposes.

1. TECHNICAL REQUIREMENTS

1.1. The powder must be manufactured in accordance with the requirements of this standard for technological regulations approved in the prescribed manner.

1.2. The main parameters

1.2.1. Powders of high-alloyed steels and alloys are divided as follows:

chemical composition — the brand PH17N2, PH18N15, PH23N18, PH18N9T, PH30, PH20N80, PH13M2, PHN28MDT, PH40N60;

for particle size distribution, maximum grain size: largest — 280 ám, average 160 ám, small — 56 mm;

for bulk density — 21, 23, 24, 25, 26.

The symbol of the powder is placed under the following abbreviations:

powder — P;

brand powder is the letter of the item and a number indicating the average content of element in percent;

granulometric composition — 280, 160, 56;

bulk density — 21, 23, 24, 25, 26.

Examples of symbols:

Powder brand Х17Н2, grain-size composition of 160, with a bulk density of 24:

PH17N2−160−24 GOST 13084−88

Powder grade CR20NI80, particle size distribution 56, with a bulk density of 26:

PH20N80−56−26 GOST 13084−88

1.3. Features

1.3.1. Chemical composition of powders of high-alloyed steels and alloys shall conform to the standards specified in table.1.

Table 1

Notes:

1. Standards the mass fraction of oxygen rejection symptom are not. Definition of necessary.

2. Standards the mass fraction of oxygen in the powders and PHN28MDT PH40N60 determined by agreement between manufacturer and consumer.

1.3.2. At the customer’s request powder brand PH18N9T made without titanium. Mass fraction of titanium impurities should be not more than 0.08%.

1.3.3. Granulometric composition of powders should conform to the standards specified in table.2.

Table 2

1.3.4. The powder should have impurities and lumps.

1.3.5. Moisture content of powder should be not more than 0.2%.

1.3.6. Bulk density depending on class size and brand of powder should conform to the standards specified in table.3.

Table 3

Note. Standards bulk density brands PHN28MDT and PH40N60 determined by agreement between manufacturer and consumer.

1.3.7. Standards the fluidity of the powder is determined by agreement between manufacturer and consumer.

1.4. Packaging

1.4.1. The powders are Packed in polyethylene bags according to GOST 17811−78, which is placed in a metal jar with GOST 5037−78 or metal cans for NTD.

The capacity of the jars 40 DM(0.04 m), cans — 7−15 DM.

At the request of the consumer, the powder is Packed in jars of smaller capacity.

1.4.2. Banks set in slatted wooden boxes according to GOST 2991−85 (type V or VI), or in stackable crates according to GOST 12082−82 (type II-1, II-2 and II-3), or other NTD, or formed into transport packets according to GOST 21929−76, 24597−81 GOST, GOST 21650−76, 26381−84 GOST and GOST 26663−85.

1.5. Marking

1.5.1. Each package or the Bank is supplied with a label showing:

trademark or the manufacturer and trademark;

name or designation of the brand of powder, particle size distribution and bulk density;

batch number;

net mass;

the date of issue.

Same label is placed inside each package or jar.

1.5.2. Transport marking under GOST 14192−77* with application of manipulation sign «Afraid of dampness».
______________
* On the territory of the Russian Federation GOST 14192−96. — Note the manufacturer’s database.

2. ACCEPTANCE

2.1. Powder take batches weighing up to 1 ton Batch consist of a powder of the same brand and the same confusion and needs to be issued a document on quality in accordance with GOST 7566−81*.
________________
* On the territory of the Russian Federation GOST 7566−94. Here and further. — Note the manufacturer’s database.

2.2. For quality control of Packed powder from the party selected sample of 10% of the packing units, but not less than two.

If unsatisfactory results at least in one of the figures on it, repeat tests are carried out at twice the sample from the same batch. The results of repeated tests apply to the entire party.

2.3. Allowed the manufacturer to determine product quality to acquire a sample from equalization prior to packaging.

If unsatisfactory results at least one indicator thereon, a second test on the newly selected sample. The results of repeated tests spread to the entire party.

2.4. The mass percent oxygen and bulk density for grades PHN28MDT and PH40N60 as well as the fluidity of powder of all grades is determined by the requirement of the user.

3. TEST METHODS

3.1. Tests carried out on one representative sample of weight 400−500 g.

Sample preparation GOST 23148−78*.
______________
* On the territory of the Russian Federation GOST 23148−98. — Note the manufacturer’s database.

The pit samplings carried out any probe. Point selection is chosen randomly.

The selection of new samples from equalization to re-testing carried out after additional mixing of the powder for 5 min.

3.2. Determination of the chemical composition of the powders is carried out according to GOST 12344−78*, GOST 12345−80**, GOST 12346−78, 12347−77 GOST, GOST 12348−78, 12350−78 GOST, GOST 12352−81, 12354−81 GOST, GOST and GOST 12355−78 12356−81.
______________
* On the territory of the Russian Federation GOST 12344−2003;
** On the territory of the Russian Federation GOST 12345−2001. — Note the manufacturer’s database.

Determine the mass fraction of oxygen, iron, calcium, and chromium (>35%) given in the Appendix.

Allowed the determination of the chemical composition of other methods providing the required accuracy of the analysis.

3.3. Granulometric composition is determined by GOST 18318−73* grids number: 028, 016 and 0056.
______________
* On the territory of the Russian Federation GOST 18318−94. — Note the manufacturer’s database.

3.4. The lack of lumps and impurities in the powder checked visually.

3.5. To determine the mass fraction of moisture a portion of the powder mass 10 g by drying at a temperature of 100−105 °C is brought to constant weight. Heating is carried out in a neutral atmosphere. Weighed with an accuracy of ±0.002 g.

3.6. Bulk density is determined according to GOST 19440−74*.
______________
* On the territory of the Russian Federation GOST 19440−94. — Note the manufacturer’s database.

3.7. The fluidity of the powder is determined according to GOST 20899−75* or other methods providing the required accuracy. If there is disagreement — according to GOST 20899−75*.
______________
* On the territory of the Russian Federation GOST 20899−98. — Note the manufacturer’s database.

4. TRANSPORTATION AND STORAGE

4.1. Powder transporterowych all types of transport in covered vehicles in accordance with cargo carriage regulations applicable to transport of this type and technical conditions of loading and fastening of cargoes, approved by the Ministry of Railways of the USSR.

4.2. General requirements transportation by GOST 7566−81.

4.3. Powders are transported by rail carload or small shipments in the packaged form.

Permitted to transport the cans with the powder train in universal containers with a capacity of 3 or 5 tonnes and road user without any additional packaging.

4.4. Powders must be stored in a dry heated room at temperatures below 0 °C in the absence of acidic and other aggressive environments.

5. MANUFACTURER’S WARRANTY

The manufacturer guarantees the conformity of powders of high-alloyed steels and alloys with the requirements of this standard when complying with the storage conditions.

A storage warranty period — 1 year from the date of manufacture.

APPLICATION (recommended). The METHOD of determining the mass fraction of oxygen at the gas-analyzer «LEKO» RO-116

APP
Recommended

This method sets the definition of oxygen from 0.05 to 0.80%. Method is intended for control of finished products and technological processes.

1. GENERAL REQUIREMENTS

1.1. The sample mass for the analysis of 0.3−0.5 g weighing Accuracy of ±0.001 g.

1.2. The sample of powder, supplied for analysis should be clean, uniform, dry.

1.3. Determination of the mass fraction of oxygen is carried out in two batches. Before the analysis is carried out a control experiment (the measurement of the mass fraction of oxygen in the empty crucible). Then carry out the analysis of two batches of a standard sample with a chemical composition corresponding to the requirements of this methodology. The analysis result should be the arithmetic mean of two parallel definitions when the following terms and conditions:

discrepancies between the results of the parallel definitions should not exceed admissible (at p = 0.95) are given in table.4;

Table 4

played in the standard sample, the value of the mass fraction should not vary from certified more than .

If any of the conditions, a second determining if and when re-definitions at least one of these conditions is not met, the results of the definitions recognize incorrect definition cease to identify and eliminate the causes of violation of the normal course of analysis.

2. THE ESSENCE OF THE METHOD

The method is based on melting of the sample in graphite crucibles and determining the quantity of released carbon dioxide by infrared absorption.

3. EQUIPMENT, REAGENTS

The detector «LEKO» RO-116.

Brush for cleaning the bottom electrode of the furnace.

Brush for cleaning the upper electrode of the furnace.

Tweezers for crucible.

Tweezers for samples.

Graphite crucibles «LEKO» (height 22 mm, inner diameter 0.8 mm) or produced by the Novocherkassk plant of the brand To 0,03.

Helium gas purified grade B with a purity of at least 99.99% or a gaseous nitrogen according to GOST 9293−74.

Air to power the pneumatic system of the instrument coming under the pressure of 273 kPa (2.8 kgf/cm).

Perchlorate magnesium.

Askari.

Wool.

The technical rectified ethyl alcohol according to GOST 18300−72*.
______________
* On the territory of the Russian Federation GOST 18300−87. — Note the manufacturer’s database.

Woven fabrics of cotton coarse calico group according to GOST 11680−76.

Silicone grease.

4. PREPARATION FOR ASSAY

4.1. Conduct the gas supply to the appliance.

4.1.1. Open the valve on the cylinder with the carrier gas (helium, nitrogen), set the output pressure from the system 273 kPa (2.8 kgf/cm).

4.1.2. Open the valve on the compressed air system, set the pressure at the outlet of the system 273 kPa (2.8 kgf/cm).

4.1.3. Press the «GAS» on the control panel: flow meters on the front panel show the flow of the purge and the flow analysis.

4.2. If the device was off, then it is heated and blown by a carrier gas for 2 hours.

4.3. Press «MONITOR», the print device outputs data on the conditions of operation of the system. If necessary, adjust the data according to the instruction manual.

4.4. Conduct the calibration weights.

4.5. By switching the toggle switch in the «ON» position, the voltage applied on the stove EF-100. The control lamp on the front panel lights up.

4.6. Serves water cooling on the stove.

4.7. If necessary, calibrate the instrument using standard samples or gases according to the operating instructions.

5. ANALYSIS

The analysis is carried out in a manual mode of operation of the device.

5.1. In the computer memory is introduced the result of the reference experiment.

5.2. The sample is weighed on electronic scales installed on the device. By pressing «ENTER» on the remote control enter its mass in memory of the device.

5.3. Lowered the lower electrode furnace by pressing the «LOADER CONTROL».

5.4. Carry out cleaning of the electrodes of the furnace.

5.5. Tweezers set the crucible in the recess of the lower electrode.

5.6. Click the «LOADER CONTROL» — the furnace is closed.

5.7. Press «ANALYZE» on the control panel, there is a degassing of the crucible at a temperature of about 3000 °C (1100 A).

Degassing time 20 (when using crucibles produced by the Novocherkassk plant — 30). After 20 s, the furnace is cooled to 10 C.

5.8. Click the «LOADER CONTROL» — oven opening. With a Cup of weights poured into degassed crucible of the analyzed sample.

5.9. Click the «LOADER CONTROL» — the furnace is closed.

5.10. Press «ANALYZE» — begins the analysis process.

5.10.1. For 10 with is a purge stream of carrier gas furnace space from atmospheric gases.

5.10.2. Then using the crucible passes current of 900 A. the Contents of the crucible is melted, and the evolved carbon monoxide the carrier gas stream is directed into an infrared cell, where the released oxygen is measured in the form of carbon monoxide.

5.10.3. The result is displayed on the digital display and fixed printing station.

The mass fraction of oxygen percentage corresponds with the value on the digital display.

ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF MASS FRACTION OF IRON

This method sets the determination of iron (at mass fraction of iron from 0.1 to 1.0%). The analysis carried out in two parallel batches. General requirements for method of analysis according to GOST 20560−81.

1. The essence of the method

The method is based on the determination of the atomic iron absorption at a wavelength of 248.3 nm. For the atomization of fluids used flame air-acetylene.

The iron concentration in the analyzed solution is 0,000002−0,00001 g/cm.

2. Equipment, reagents, solutions

Laboratory scales for General purpose according to GOST 24104−80* 2nd accuracy class with the largest weighing limit of 200 g or any other scale, providing the same metrological characteristics.
________________
* On the territory of the Russian Federation GOST 24104−2001. Here and further. — Note the manufacturer’s database.

Atomic absorption spectrophotometer.

Lamp with hollow cathode for the determination of iron.

Soluble and gaseous acetylene for technical GOST 5457−75.

A can of compressed air or air line.

Hydrochloric acid by the GOST 3118−77.

Nitric acid GOST 4461−77.

Distilled water GOST 6709−72.

Iron carbonyl refined.

Standard solution of iron is prepared as follows: 0.1 g of carbonyl iron are dissolved in 20 cmof salt and 5 cmof nitric acid. Evaporated almost to dryness, add 5 cmof hydrochloric acid of 20 cmof water, boil to dissolve the salts. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmstandard solution contains 0.0001 g of iron.

The device is ready to work in accordance with the instructions.

3. Analysis

A portion of the alloy powder weighing 0.2 g was placed in a beaker with a capacity of 150 cmand was dissolved with heating in 30 cmof hydrochloric acid. After dissolution add 5−7 cmof nitric acid and evaporated almost to dryness. Then add 5 cmof hydrochloric acid of 20 cmof water, heated to dissolve the salts and filtered through the filter «white ribbon» in a volumetric flask with a capacity of 100 cm. A glass filter and washed 3−4 times with hot water. The contents of the flask topped up to the mark with water and mix.

The optical density of the atomic vapour of iron is measured on atomic absorption spectrophotometer in the flame of air-acetylene.

To measure the optical density of the atomic vapor iron when the mass fraction of iron 0.5 to 1.0% aliquot part of the solution is 5 cmis placed in a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

After each measurement, spray water and check the zero of the instrument. The iron concentration set at the calibration schedule.

To build a calibration curve in a volumetric flask with a capacity of 100 cmare placed sequentially 2,0; 4,0; 6,0; 8,0; 10,0 cmstandard solution of iron, which corresponds to the 0,000002, 0,000004, 0,000006, 0,000008, 0,00001 g/cmof iron. Then all flasks are poured by 5 cmof hydrochloric acid, made up to the mark with water and mix. Fotometrirovanie are in the order of increasing concentrations of iron.

On the found values of optical density and relative concentration of iron to build a calibration curve in the coordinates: the number of the measured element in g/cm; optical density of the analyzed solution.

When working with the transmitter extinction plotting is not required.

4. Processing of the results

Mass fraction of iron () in percent is calculated by the formula

,

where is the concentration of the measured equivalent in the sample solution taking into account the values of the reference experiment, g/cm;

 — initial solution volume, cm;

 — the volume of dilution aliquotes part of the solution, cm;

 — volume aliquote part of the solution, cm;

 — the weight of the portion,

Allowable absolute differences between the results of two parallel measurements at a confidence level =0.95 is given in table.5.

Table 5

ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF THE MASS FRACTION OF CALCIUM

This method sets the determination of calcium (when calcium mass fraction from 0.05 to 0.25%). The analysis carried out in two parallel batches. General requirements for method of analysis according to GOST 20560−81.

1. The essence of the method

The method is based on measuring absorption of radiation by atoms of the calcium resonance line 422,7 nm. The concentration of calcium in the atomization is 0,000002−0,00001 g/cm.

To suppress ionization and eliminate the effect of accompanying elements in the analyzed solution was added to solutions of chloride salts of potassium and strontium.

2. Apparatus, reagents and solutions

Laboratory scales for General purpose according to GOST 24104−80 of the 2nd accuracy class with the largest weighing limit of 200 g or any other scale, providing the same metrological characteristics.

Spectrophotometer atomic absorption.

Lamp with hollow cathode for the determination of calcium.

Acetylene, dissolved and gaseous technical GOST 5457−75.

A can of compressed air or air line.

Electric resistance furnace laboratory according to GOST 13474−79.

Thermocouple chamber of Commerce.

Desiccator, according to GOST 25336−82.

The platinum crucible according to GOST 6563−75.

Distilled water GOST 6709−72.

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

Nitric acid GOST 4461−77.

Potassium chloride according to GOST 4234−77.

Strontium chloride 6-water according to GOST 4140−74.

Calcium carbonate according to GOST 4530−76.

Oxalic acid according to GOST 22180−76 with a mass concentration of 0.1 g/cm.

Methyl orange (indicator), a solution with a mass concentration of 0.001 g/cm.

Ammonia water according to GOST 3760−79.

Ammonium oxalate according to GOST 5712−78, a solution with a mass concentration of 0.1 g/cm.

Silver nitrate according to GOST 1277−75, a solution with a mass concentration of 0.001 g/cm.

The primary Nickel GOST 849−70*.
______________
* On the territory of the Russian Federation GOST 849−97. — Note the manufacturer’s database.

Electrolytic refined chromium.

3. Preparation for assay

3.1. Potassium chloride is prepared as follows: of 95.35 g of potassium chloride dissolved in 400 cmof water at low heat. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.05 g of potassium.

3.2. Strontium chloride is prepared as follows: 152,15 g chloride of strontium are dissolved under low heat in 400 cmof water, cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.05 g of strontium.

3.3. Standard solution of calcium is prepared as follows: 0.25 g of calcium carbonate, previously dried at 110 °C to constant weight, moistened with water and dissolved in 40 cmof hydrochloric acid diluted 1:1. The solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.0001 g of calcium.

Mass concentration of calcium in a standard solution was checked by gravimetric method.

For this aliquot part of the standard calcium solution 100 cmis placed in a conical flask with a capacity of 500 cm, is poured 10 cmof hydrochloric acid and dilute with water to 150 cm.

The solution is heated to boiling, pour 15−20 cmof a solution of oxalic acid, add 2 drops of methyl orange indicator and neutralize with ammonia. After changing the color of the solution add 5−6 drops of ammonia and boil for 15 min.

After 2 h the precipitate was filtered off on the filter «blue ribbon» containing a small amount filtrowanie mass. The residue in the flask washed on a filter and washed 8−10 times with a warm solution of ammonium oxalate and then with water until termination of the reaction the chlorine ion in the washing water (test the filtrate with a solution of silver nitrate).

The filter with precipitate was placed in a preheated to constant weight platinum crucible, carefully incinerated, calcined at 1000−1100 °C to constant weight, cooled in a desiccator and weighed.

Mass concentration of calcium (), g/cm, is calculated by the formula

,

where is the mass of the precipitate of calcium oxide, g;

0,7147 — the coefficient of conversion of calcium oxide to calcium;

 — aliquota part of the standard calcium solution taken for analysis, cm.

3.4. Devices ready to work in accordance with the operating instructions.

4. Analysis

A portion of the alloy powder weighing 0.2 g was placed in a beaker with a capacity of 150 cm, flow 20 cmof hydrochloric acid and dissolved with moderate heating. Then add drop by drop nitric acid until the termination of foaming solution and boil to remove oxides of nitrogen.

The solution was transferred to a volumetric flask with a capacity of 50 cm, pour 2 cmof a solution of potassium chloride, 5 cmof a solution of chloride of strontium, mixed, made up to the mark with water and mix again.

After each measurement, spray water and check the zero of the instrument.

The value of optical density of the analyzed solution given the values of optical density of control solution set the mass fraction of calcium in the calibration schedule.

To build a calibration curve of six tumblers with a capacity of 150 cmwas placed 0.12 g of Nickel powder, 0.08 g of electrolytic chromium and consistently poured 0,0; 1; 2; 3, 4, 5 cmstandard solution of calcium, which corresponds to 0,0, 0,000002, 0,000004, 0,000006, 0,000008, 0,000010 cmof calcium. The first glass that does not contain a standard solution of calcium, serves as the control (zero) experience. Then all the glasses are poured 20 cmof hydrochloric acid and further analysis is carried out as specified in clause 4.

Fotometrirovanie are in the order of increasing concentrations of calcium.

The found average values of optical density and relative concentration of calcium with accounting control experience to build a calibration curve in the coordinates: the number of the measured element in g/cmis the optical density of the analyzed solution.

When working with extinctions Converter construction of calibration curve is not required. In this case, the deposition after spraying of the sample in g/cmaccording to the instruction manual of the device TES-1.

5. Processing of the results

Mass fraction of calcium () in percent is calculated by the formula

,

where is the mass concentration of calcium in the sample solution given in the reference experiment, g/cm;

 — the volume of the analyzed solution, cm;

 — the weight of the portion,

The absolute allowable differences between results of two parallel measurements at a confidence level =0.95 is given in table.6.

Table 6

TITRIMETRIC METHOD FOR THE DETERMINATION OF THE MASS FRACTION OF CHROMIUM

This method sets the determination of chromium (in mass fraction of chromium from 35.0 to 50.0%). The analysis carried out in two parallel batches. General requirements for method of analysis according to GOST 20560−81.

1. The essence of the method

The method is based on the oxidation of chromium (III) neccersarily ammonium to chromium (VI) in sulfate medium in the presence of silver nitrate. Chromic acid is titrated with a solution of iron (II) in the presence of an indicator phenylanthranilic acid.

2. Apparatus, reagents and solutions

Laboratory scales for General purpose according to GOST 24104−80 of the 2nd accuracy class with the largest weighing limit of 200 g or any other scale, providing the same metrological characteristics.

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

Nitric acid GOST 4461−77.

Sulfuric acid GOST 4204−77, diluted 1:1, 1:4, 1:20.

Manganese sulfate 5-water according to GOST 435−77, a solution with a mass concentration of 5 g/DM.

Orthophosphoric acid according to GOST 6552−80.

Silver nitrate according to GOST 1277−75, a solution with a mass concentration of 1.5 g/DM.

Ammonium neccersarily according to GOST 20478−75, a solution with a mass concentration of 200 g/DM.

Sodium chloride according to GOST 4233−77, a solution with a mass concentration of 50 g/DM.

Phenylantranilic acid solution with a mass concentration of 2 g/DM.

Sodium carbonate according to GOST 83−79.

Salt of protoxide of iron and ammonium double sulfate (salt Mora) according to GOST 4208−72, solution with molar concentration of the equivalent 0,1 mol/DM.

Potassium dichromate, solution with molar concentration of the equivalent 0,1 mol/DM.

Distilled water GOST 6709−72.

3. Preparation for assay

3.1. Phenylanthranilic acid, a solution of 0.2 g phenylanthranilic acid and 0.2 g of sodium carbonate dissolved in 100 cmof hot water. The solution was cooled.

3.2. Sol Mora, solution with molar concentration of the equivalent 0,1 mol/DM. 40 g of Mohr salt dissolved in 200 cmof sulphuric acid, diluted 1:20, solution transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with sulfuric acid diluted 1:20, and stirred.

Mass concentration of salt Mora set according to the standard model, similar in chemical composition and mass fraction of chromium to the sample and carried through all stages of analysis, as specified in clause 4, or potassium dichromate.

Mass concentration of salt Mora () for the standard sample, expressed in g/cmchromium, calculated by the formula

,

where  — mass fraction of chromium in the standard sample, %;

 — weight of standard sample, g;

 — the volume of salt solution Mora, used for titration, sm.

To establish the mass concentration of salt solution Mora on a solution of potassium dichromate taken 25 cmof a solution with molar concentration of the equivalent 0,1 mol/DMpotassium dichromate, and placed in a conical flask with a capacity of 250 cm, dilute with water to 100 cm, 30 cm, pouredsulphuric acid, diluted 1:4.5 cmphosphoric acid, 5−6 drops of a solution phenylanthranilic acid and titrated with Mohr salt solution until the green color of the solution.

Mass concentration of salt Mora (), expressed in g/cmchromium, calculated by the formula

,

where mass concentration of a solution of potassium dichromate, expressed in g/cmchrome;

 — the volume of potassium dichromate solution taken for titration, cm;

 — the volume of salt solution Mora, used for titration of a solution of potassium dichromate, cm.

3.3. Potassium dichromate solution with molar concentration of the equivalent 0,1 mol/DM: contents of an ampoule of standard titer (0.1 mol/DMmolar concentration of potassium dichromate equivalent) quantitatively transferred to a volumetric flask with a capacity of 1 DM, is dissolved in water, made up to the mark with water and mix.

1 cmof the mortar is 0,001733 g of chromium.

4. Analysis

A portion of the alloy powder with a mass of 0.1 g was placed in a conical flask with a capacity of 500 cm, 40 cm pouredhydrochloric acid diluted 1:1 and moderately heated to dissolve. Then poured dropwise nitric acid until the termination of foaming solution and an excess of 2−3 cm. The solution was boiled to remove oxides of nitrogen, cooled, carefully poured 10 cmof sulphuric acid diluted 1:1, and evaporated to the appearance of its vapors. After cooling, pour 150 cmof water and heated to dissolve the salts.

The solution is poured 1 cmof a solution of sulphate of manganese, 1 to 2 cmof phosphoric acid, 10 cmof a solution of silver nitrate, 20−40 cmnaternicola solution of ammonia and heated until the appearance of crimson color. Then the solution was heated to the complete destruction of excess ammonium naternicola, poured 5cmof sodium chloride solution and gently boil until the disappearance of the crimson color.

The solution was cooled to room temperature, dilute with water to 250−300 cm, flow 20 cmof sulphuric acid, diluted 1:4, 5−6 drops of a solution phenylanthranilic acid and titrated with Mohr salt solution until the green color of the solution.

5. Processing of the results

Mass fraction of chromium () in percent is calculated by the formula

,

where is the mass concentration of salt solution Mora, expressed in g/cm;

 — the volume of salt solution Mora, used for titration, cm;

 — the weight of the portion,

Allowable absolute differences between the results of two parallel measurements at a confidence level =0.95 is given in table.7

Table 7