GOST 12556.1-82

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  ГОСТ 12556.1-82

GOST 12556.1−82 Alloys platinum-rhodium. Method for the determination of rhodium (Change No. 1)

GOST 12556.1−82

Group B59

STATE STANDARD OF THE USSR

ALLOYS OF PLATINUM-RHODIUM

Method for the determination of rhodium

Alloys platinum-rhodium. Method for the determination of rhodium

AXTU 1709*
______________
* Introduced advanced Edit. N 1.

Valid from 01.01.84
to 01.01.89*
_______________________________
* Expiration removed
Protocol N 3−93 Interstate Council
for standardization, Metrology and certification
(IUS No. 5/6, 1993). — Note the manufacturer’s database.

DEVELOPED by the Ministry of nonferrous metallurgy of the USSR

PERFORMERS

A. A. Kuranov, G. S. HAK, N. With. Stepanova, N. D. Sergienko, T. I. Belyaev, E. E. Safonova

INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

Zam. Minister Vladimir Boroday

APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards, dated 30 September 1982, N 3865

REPLACE GOST 12556−67 in part of sec. 2

The Change N 1, approved and put into effect by the Decree of the USSR State Committee for standards from 13.06.88 N 1730 with 01.01.89

Change No. 1 made by the manufacturer of the database in the text IUS N 9, 1988


This standard specifies the spectrophotometric method for the determination of rhodium in platinum-rhodium alloys (in mass fraction of rhodium from 4.5 to 40.5%).

The method is based on measuring the light absorption of the complex of rhodium chloride in hydrochloric acid solution in the presence of a reducing agent — hydroxylamine hydrochloride.

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 22864−83.

(Changed edition, Rev. N 1).

1.2. The numerical value of the result of the analysis must end with a digit of the same rank as that of the normalized indicator grade composition.

(Added, Rev. N 1).

2. APPARATUS, REAGENTS AND SOLUTIONS

Spectrophotometer UV — visible, type SF-16.

The induction melting furnace according to GOST 10487−75.

Crucibles porcelain No. 4 according to GOST 9147−80.

Argon gas GOST 10157−79.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1, 1:6.

Nitric acid GOST 4461−77.

Mixture of nitric and hydrochloric acids in a ratio of 1:3.

Hydroxylamine hydrochloride according to GOST 5456−79, a solution with a mass fraction of 10%;

Platinum according to GOST 13498−79 brand PL 99, 93.

Nickel GOST 9722−79*.
______________
* On the territory of the Russian Federation GOST 9722−97. — Note the manufacturer’s database.

Rhodium GOST 13098−67* brand Rd is 99.9.
______________
* On the territory of the Russian Federation GOST 13098−2006. — Note the manufacturer’s database.

A standard solution of rhodium: two plates of rhodium (a length of 100 mm, a width of 30−40 mm, thickness 1 mm), weighed, fixed in the mounting clips for the electrolytic solution and is immersed in hydrochloric acid (1:1).

The dissolution of lead with alternating current at a voltage of 12−15 V, current density of 0.65 A/cmfor 2 h To preserve the original volume (300 cm) in glass periodically add fresh portions of hydrochloric acid. After reconstitution, the current is turned off, Unscrew the plate, washed with water, dried and weighed. The solution was evaporated to 150 cm, cooled and filtered in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

The insoluble residue is calcined in a tared crucible, reduced in a current of hydrogen and weighed.

A lot of rhodium () in grams contained in 1 cmof a solution, calculated by the formula

,

where is the mass of the plates to dissolve, g;

 — weight plates after dilution, g;

is the mass of the insoluble residue,

(Changed edition, Rev. N 1).

3. PREPARATION FOR ASSAY

3.1. Method of chemical dissolution of the alloy (with a mass fraction of rhodium to 15.0%)

A portion of the alloy with a weight of 2.5 g was dissolved with heating in 100 cmof a mixture of acids. The solution was evaporated to ~5 cmand transferred to hydrochloric acid by evaporation twice with 10 cmof hydrochloric acid (1:1). The solution was transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:6) and stirred.

3.2. The method of transferring the alloy into solution by fusion with Nickel (with a mass fraction of rhodium in excess of 15.0%)

A portion of the alloy with a mass of 1.0 g finely chopped, placed in a magnesite crucible and melted in high frequency induction furnace under the protection of argon with Nickel (table.1) followed by quenching in water.

The resulting bead is carefully cleaned, washed with hot water, dissolved by heating in 100 cmof the mixture of acids and then analyzing according to claim 3.1.

3.3. Preparation of a standard solution of alloy

Sample of platinum and Nickel (see table.1) dissolved in 50−100 cmof the mixture of acids, is added a certain amount of a standard solution of rhodium, corresponding to a mass of rhodium (see table.1), evaporated to ~5 cmand then carry out the analysis according to claim 3.1.

Table 1

3.4. Preparation of solutions comparison

3.4.1. For alloys with a mass fraction of rhodium to 15.0%

A suspension of platinum (see table.1) dissolved in 50−100 cmof the mixture of acids, is evaporated to 5 cmand then performed analysis on PP.3.1 and 4.1.

3.4.2. For alloys with a mass fraction of rhodium in excess of 15%

Sample of platinum and Nickel (see table.1) dissolved in 50−100 cmof the mixture of acids, is added a certain amount of a standard solution of rhodium corresponding to a rhodium weight (table.2), is evaporated to 5 cmand then performed analysis on PP.3.1 and 4.1.

Table 2

4. ANALYSIS

4.1. In glasses with a capacity of 100 cmis placed aliquote part (tab.3) analyzed and the standard solution alloy is heated to 60−70 °C and pour 3 cmof a solution of hydroxylamine for the recovery of platinum. The solutions were kept for 1 h, transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:6) and stirred. After 2 h, measure the optical density of the solution at a wavelength of 490 nm in cuvettes with the thickness of the light absorbing layer 2 see

Table 3

Solution comparison for alloys with a mass fraction of rhodium to 15% is the platinum solution is carried out through all stages of analysis (see p.3.4.1).

Solution comparison for alloys with a mass fraction of rhodium in excess of 15% is the solution of platinum, Nickel and rhodium, carried out through all stages of analysis (see p.3.4.2).

5. PROCESSING OF THE RESULTS

5.1. Mass fraction of rhodium () in percent is calculated according to the formulas:

when the mass fraction of rhodium to 15%.

;

when the mass fraction of rhodium in excess of 15%

,

where a  — optical density of the analyzed solution;

 — optical density of standard solution;

 — the mass of rhodium in the standard solution, g;

 — weight of alloy, suitable aliquote part of the solution, g;

the difference between the mass of rhodium in the standard solution and the comparison solution, g;

 — mass fraction of rhodium in the solution comparison, %.

5.2. Allowable absolute discrepancies in the results of parallel measurements (the rate of convergence) at a confidence probability of 0.95, should not exceed the values given in table.4.

Absolute differences average results of determinations obtained in two different laboratories (a measure of reproducibility) shall not exceed the values specified in table.4.

Table 4

5.1, 5.2. (Changed edition, Rev. N 1).

5.3. Control of the correctness of the results of determining the mass fraction of rhodium is playing its mass fraction in the artificial mixtures the chemical composition close to the composition of the analyzed alloy, drawn through the entire course of the analysis.

The results of the analysis of samples considered correct if the absolute difference between the maximum and minimum values of the mass fraction of rhodium in the artificial mixture does not exceed about 0.17% when the mass fraction of rhodium from 4.5 to 10.0%, to 0.22% when the mass fraction of rhodium in excess of 10.0 to 25.0% and 0.28% for the mass concentration of rhodium in excess of 25.0 to 40.5%.

(Added, Rev. N 1).