GOST 24018.5-80

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  ГОСТ 24018.5-80

GOST 24018.5−80 heat-resistant Alloys on a Nickel basis. Method for the determination of lead and bismuth (with Amendments No. 1, 2)

GOST 24018.5−80

Group B39

INTERSTATE STANDARD

ALLOYS HIGH-TEMPERATURE NICKEL-BASED

Method for the determination of lead and bismuth

Nickel-based fire-resistant alloys.
Method for the determination of lead and bismuth

ISS 77.120.40
AXTU 0809

Date of introduction 1981−07−01

INFORMATION DATA

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

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 28.02.80 N 958

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)

6. EDITION (August 2004) with Changes No. 1, 2 approved in December 1985, December 1990 (IUS 4−86, 3−91)


This standard establishes the inversion-voltammetric method for determination of lead and bismuth (in mass fractions of lead and bismuth from 0.0001% to 0.005%).

The method is based on the preconcetration of lead and bismuth on a stationary mercury drop electrode or a mercury-graphite electrode at a potential of minus 0.85 and In the solution of 1 mol/lcitric acid and 1 mol/DMammonium chloride with the subsequent registration of the current of anodic dissolution of lead and bismuth at a potential of 0.55 V, respectively minus and minus 0.18 V relative to silver chloride electrode in the presence of the main alloy components (option 1).

When the mass fraction of copper in excess of 0.03% determination of bismuth is carried out after preliminary separation from the major components of the ammonia coprecipitation on ferric hydroxide (option 2).

(Changed edition, Rev. N 1, 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 24018.0.

2. APPARATUS, REAGENTS AND SOLUTIONS

Polarograph AC or polarograph oscilloscope.

Cells with external anode (mercury in a saturated solution of potassium chloride), silver chloride reference electrode, a stationary mercury drop electrode of any design, providing the required normative-technical documentation the reproducibility of the analytical signal or a solid electrode (4 mm) from graphite-containing material of any method of manufacture, providing the required normative-technical documentation the reproducibility of the analytical signal.

Mercury brands r0 according to GOST 4658 containing no moisture.

Nitrogen gas according to GOST 9293 or argon according to GOST 10157.

Hydrochloric acid according to GOST 14261 and diluted 1:1.

Nitric acid according to GOST 11125 and diluted 1:15.

Hydrofluoric acid according to GOST 10484.

Citric acid according to GOST 3652.

Ammonium chloride according to GOST 3773.

Background for polarographically containing 1 mol/lcitric acid and 1 mol/DMammonium chloride. If necessary, a background electrolyte is subjected to further electrochemical purification from impurities of non-ferrous metals with a mercury cathode within 4−5 h at a potential of minus 1.2 V, which is kept constant by using a potentiostat (drawing).

1 — the working mercury electrode; 2 — platinum contact; 3 — stirrer; 4 — auxiliary electrode
from the spectra of coal; 5 — silver chloride reference electrode; 6 — polyethylene vessel; 7 — cover;
8 — glass tube for supplying nitrogen; 9 — siphon alloy electrolyte

Ascorbic acid food.

Potassium chloride according to GOST 4234, saturated solution.

Perchloric acid, a solution with a mass concentration of 57 g/cm, (g/DM).

Iron nitrate, a solution of 1 g of iron carbonyl was dissolved with heating in 20 cmof nitric acid 1:1, cooled, diluted with water to 100 cmand mixed.

Potentiostat any model operating in the mode specified capacity.

Mercury (II) nitrate oxide according to GOST 4520, a solution with a mass concentration of 1 g/DM: 0.1 g of mercury nitrate are dissolved in 80 cmof nitric acid (1:15). The solution was transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Ammonia water according to GOST 24147.

Bismuth brands Ви0; Vi00; Ви000; Ви0000 according to GOST 10928.

Standard solutions of bismuth.

Solution a: 0.1 g of bismuth was dissolved with heating in 30 cmof nitric acid, boil the solution to remove the oxides of nitrogen, cooled, transferred to a volumetric flask with a capacity of 1 DMtopped up to the mark with water and mix.

1 cmstandard solution contains 0.0001 g of bismuth.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, add 2 cmof hydrochloric acid, made up to the mark with water and mix.

1 cmstandard solution B has the 0.00001 g of bismuth.

Solution: 5 cmof solution B is placed in a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

1 cmstandard solution contains 0,000001 g of bismuth.

Solutions B and C were prepared immediately before use.

Lead of stamps C0; C00; C000; S0000 according to GOST 3778.

Standard solutions of lead.

Solution a: 0.1 g of lead is dissolved by heating in 30 cmof nitric acid. The solution was 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 lead.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, add 2 cmof hydrochloric acid, made up to the mark with water and mix.

1 cmstandard solution B has the 0.00001 g of lead.

Solution: 5 cmof solution B is placed in a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

1 cmstandard solution contains 0,000001 g of lead.

Solutions B and C were prepared immediately before use.

(Changed edition, Rev. N 1, 2).

3. ANALYSIS

3.1. Option 1

A sample of alloy weighing 0.5 g were placed in a glass (or flask) with a capacity of 250−300 cm, add 15 cmof hydrochloric acid and 5 cmof nitric acid and dissolve the sample when heated. The solution was evaporated to wet salts, poured 5cmof hydrochloric acid and again evaporated to moist salts. This operation is repeated twice.

Salt dissolved in 5 cmof hydrochloric acid, quantitatively transferred into a platinum Cup, the Cup of glassy carbon or Teflon beaker, add 3 cmhydrofluoric acid and heated until complete dissolution of the precipitate of tungsten and molybdenum acids, and hydrolysis products of titanium and niobium. The solution was cooled, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water, mixed and immediately placed in a plastic or Teflon container and lid.

For the determination of lead and bismuth in the polarographic cell is filled 20 cmof the background electrolyte, previously purged with nitrogen or argon for 5 min, add in accordance with the table.1 aliquot part of the investigated solution, depending on the mass fraction of lead and bismuth in the alloy, 0.01−0.02 g ascorbic acid and mix.

Table 1

Set on polarography potential of minus 0.85 and In and carried out the concentration of lead and bismuth on a stationary mercury drop electrode in a continuously stirred solution over 2−3 min. At the end of the accumulation time, stop stirring and allow solution to settle down 15, and then remove the anodic polarization curve with linearly varying electrode potential of minus 0.85 and In to minus 0.05; registering a peak of dissolution of lead and bismuth at a potential of 0.55 V, respectively minus and minus is 0.18 V. When the content of copper in the solution greater than 60-fold relative to the bismuth, the determination is carried out with the stop of the sweep voltage at a potential of minus 0.25 In, during which the solution was stirred for 15 s, after which give a solution to calm down with 15, include a scan voltage and record the peak dissolution of bismuth. The sensitivity of the instrument when registering polarogram is selected so that the height of the recorded peak was at least 10 mm. For each dimension, get a new drop of mercury.

When working with solid electrodes in the mode of mercury-graphite in the polarographic cell is filled 20−25 cmof the background electrolyte was previously purged with nitrogen for 5 min, add 3−4 drops of solution of nitrate of mercury (II) (10 ág/cm) and conduct electroconnection of lead in the mixture in a background electrolyte at a potential of minus 0.85 and b for 2 min in stirred solution. Stop mixing and allow solution to settle down 15s, then remove the anodic polarization curve, registering the maximum ionization current of lead in the minus potential of 0.54 V. the Registration of curves is carried out three times, including the first measurement in the calculations is not taken into account. After each recording electrode is electrochemically cleaned at a potential of plus 0.2 V in a stirred solution for 30 s.

For the determination of lead and bismuth in background electrolyte in a polarographic cell, add aliquot part of a researched solution in accordance with the table.1A, 0.01−0.02 g of ascorbic acid, stirred and spend electroconnection lead and bismuth as described above.

Table 1A

Then remove the anode polarization curve to record the maximum ionization current lead at a potential of 0.54 and bismuth in the minus potential of 0.18 V. When the content of copper in solutions of greater than 60-fold relative to the bismuth, the registration of the polarization curve is carried out with the stop of the sweep voltage at a potential of minus 0.25 In, during which the solution was stirred for 15 s. Next, the solution was allowed to calm down with 15, include a scan voltage and record the maximum current electroactivity bismuth.

The sensitivity of the device during the registration of the voltammograms are selected so that the height of the recorded peak was at least 10 mm.

3.2. Option 2

A sample of alloy weighing 0.5 g were placed in a glass or flask with a capacity of 250−300 cm, flow 15 cmof hydrochloric acid and 5 cmof nitric acid, 8 cmof perchloric acid and dissolve the sample when heated. The solution was evaporated to release vapors of perchloric acid for the oxidation of chromium. Salt is dissolved by heating in 50 cmof water, poured 1 cmof solution of nitrate of iron (III) and adding ammonia solution to come off the precipitate of ferric hydroxide and excess of 1−2 cmof ammonia. Solution and the precipitate was boiled for 1−2 min and filtered through a medium density filter (white ribbon). Precipitate was washed 5−6 times with hot water, dissolve on the filter in a 10 cmhot hydrochloric acid (1:1) and washed 2−3 times with hot water collecting the filtrate and washings in a beaker, in which was conducted the deposition. The operation of the deposition and dissolution of sediment is repeated.

The solution was transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

If the alloy contains titanium and niobium, the solution is transferred into a platinum Cup, the Cup of glassy carbon or Teflon beaker, add 3 cmhydrofluoric acid and heated until complete dissolution of the precipitate of titanium and niobium.

The solution was cooled, diluted with water to about 25 cm, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water, mixed and immediately transferred into a polyethylene or Teflon container and lid.

Aliquote parts of a solution according to table.1 or tab.1A is used for the determination of bismuth in

claim 3.1.

3.1, 3.2. (Changed edition, Rev. N 1, 2).

3.3. The content of lead and bismuth find by the method of standard additions. Aliquot part of the standard solution (see p.3.1) add in polarographically the solution was stirred for 1 min and further analysis are as under determination of lead and bismuth the test solution.

The value of the standard additives are selected so that the peak height of lead and bismuth after the introduction of the additive increased 1.5−2 times.

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of lead and bismuth () in percent is calculated by the formula

,

where is the peak height of lead or bismuth in polarography of test solution, mm;

the peak height of lead or bismuth in the solution polarographically idle experience, mm;

the peak height of lead or bismuth after introduction into a cell of standard addition, mm;

 — the volume of standard addition, cm;

 — concentration of standard solution, g/cm;

 — the weight of the portion of alloy, suitable aliquote part of the solution

G.

4.2. The absolute discrepancies in the results of parallel measurements (at p = 0.95) must not exceed the permissible values given in table.2.

Table 2

(Changed edition, Rev. N 2).