GOST 23859.9-79
GOST 23859.9−79 heat-resistant Bronze. Method for the determination of cobalt (with Amendments No. 1, 2)
GOST 23859.9−79
Group B59
INTERSTATE STANDARD
BRONZE HIGH-TEMPERATURE
Method for the determination of cobalt
Bronze fire-resistance. Method for the determination of cobalt
AXTU 1709
Date of introduction 1981−01−01
Resolution of the USSR State Committee for standards, dated 16 October 1979, N 3937 time of the introduction set with 01.01.81
Limitation of actions taken by Protocol No. 5−94 of the Interstate Council for standardization, Metrology and certification (ICS 11−12−94)
EDITION with Amendments No. 1, 2 approved in June 1985, March 1990 (IUS 9−85, 7−90).
This standard sets the photometric method for the determination of cobalt (at a mass fraction of cobalt from 0.1 to 2%) in high-temperature copper alloys.
The method is based on the interaction of cobalt (II) with nitroso-R-salt in which the cobalt (II) is oxidized to cobalt (III) with the formation of red color complex, characterized by high strength. Optical density of the solution of the complex measured at 500 nm.
(Changed edition, Rev. N 1, 2).
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 25086−87 with the addition of a GOST 23859.1−79, sec. 1.
(Changed edition, Rev. N 2).
2. APPARATUS, REAGENTS AND SOLUTIONS
Photoelectrocolorimeter or spectrophotometer.
Nitric acid GOST 4461−77 and diluted 1:1.
Hydrofluoric acid (hydrofluoric) according to GOST 10484−78.
Sulfuric acid GOST 4204−77, diluted 1:1.
Sodium acetate according to GOST 199−78, a solution of 500 g/DM.
Nitro-R-salt, a solution of 10 g/DM, is stored in a vessel made of dark glass.
Cobalt sulfate according to GOST 4462−78.
Cobalt grade K0 GOST 123−98.
Standard solutions of cobalt.
Solution A. 0.5 g of cobalt dissolved in 20 cmof nitric acid, diluted 1:1, add 20 cm
of sulphuric acid diluted 1:1, and evaporated to start the selection, the dense white smoke of sulfuric acid. Cooled, the residue is dissolved in a small amount of water, transfer the solution into a measuring flask with a capacity of 1 DM
and topped to the mark with water.
The solution can also be prepared from sulphate of cobalt. To do this, 2,385 g CoSO·7H
O dissolved in water and transferred the solution into a measuring flask with a capacity of 1 DM
and dilute to the mark with water. 1 cm
of the solution contains 0.0005 g of cobalt.
Solution B. 10 cmof the solution transferred to a volumetric flask with a capacity of 100 cm
and then filled to the mark with water. 1 cm
of a solution of 0.00005 g contains cobalt.
Electrolysis installation with a source of DC power.
Platinum electrodes according to GOST 6563−75.
Sec. 2. (Changed edition, Rev. N 1, 2).
3. ANALYSIS
3.1. The weight of bronze weighing 0.5 g is placed in a platinum Cup, add 15 cmof nitric acid, diluted 1:1, 2−3 cm
hydrofluoric acid and heated to dissolve sample. After the dissolution, the Cup is cooled, add 10 cm
sulphuric acid diluted 1:1, and is evaporated prior to the allocation of white smoke of sulfuric acid. The residue is cooled, add 30−40 cm
of water and heated until complete dissolution of salts. The solution was transferred to a beaker with a capacity of 250−300 cm
, add 10 cm
of nitric acid (1:1), water up to 150 cm
and produce copper by electrolysis according to GOST 23859.1−79. The solution after electrolysis is evaporated and transferred in a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
In a volumetric flask with a capacity of 100 cmis placed aliquot part of the solution — 10 cm
(when the mass fraction of cobalt from 0.1 to 1%) or 5 cm
(when the mass fraction of cobalt from 1% to 2%), add 10 cm
of a solution of sodium acetate and 10 cm
of the solution, nitroso-R-salt and heated to boiling. In the boiling solution, carefully pour 5 cm
of concentrated nitric acid and boil for 2 minutes, the Cooled solution is poured to the mark with water and measure the optical density in a cuvette with a thickness of absorbing layer 1 cm at 500 nm in spectrophotometer or photoelectrocolorimeter with a green filter (
=540 nm).
As a solution comparison solution is used in the reference experiment containing all of the reagents in the same quantities and prepared in the same way. In the result enter the absorption correction is the same aliquote part of the analyzed solution treated similarly but without introduction nitrosated derivatives
o-R-salt.
3.2. Construction of calibration curve
Eight volumetric flasks with a capacity of 100 cmplaced 0; 1,0; 2,0; 4,0; 6,0; 8,0; 10,0 and 12.0 cm
of a solution of cobalt, add 10 cm
of a solution of sodium acetate and further receives, as described in Chapter 3.1. As a solution comparison, using a solution not containing cobalt.
Sec. 3. (Changed edition, Rev. N 1, 2).
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of cobalt () in percent is calculated by the formula
where is the mass of cobalt was found in the calibration schedule g;
— the weight of the portion of alloy, suitable aliquote part of the solution,
4.2. Discrepancies in the results of three parallel definitions should not exceed the values permitted by the divergence (
the rate of convergence), calculated according to the formula
where — mass fraction of cobalt in the alloy, %.
(Changed edition, Rev. N 2).
4.3. Discrepancies in the results analysis, obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (a measure of reproducibility) shall not exceed the values calculated according to the formula
where — mass fraction of cobalt in the alloy, %.
4.4. Control of accuracy of analysis results is carried out according to State standard samples of heat-resistant (CR) bronze or supplements method, or comparison of the results obtained by atomic absorption method in accordance with GOST 25086−87.
4.3, 4.4. (Added, Rev. N 2).
