GOST 26876-86
GOST 26876−86 (ST SEV 5016−85) sintered hard Alloys. General requirements for methods of chemical analysis
GOST 26876−86
(ST CMEA 5016−85)
Group B59
STATE STANDARD OF THE USSR
SINTERED HARD ALLOYS
General requirements for methods of chemical analysis
Cemented carbides. General requirements for methods of chemical analysis
AXTU 1709
Valid from 01.01.87
to 01.01.97*
_______________________________
* Expiration removed
Protocol N 7−95 Interstate Council
for standardization, Metrology and certification
(IUS N 11, 1995). — Note the manufacturer’s database.
DEVELOPED by the Ministry of nonferrous metallurgy of the USSR
PERFORMERS
N.Kudrya, S. N. Suvorov, S. V. Romanov, A. A. Zaluzhny
INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
Member Of The Board Of A. P. Snurnikov
APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
1. This standard establishes General requirements for methods of chemical analysis of solid sintered alloy, carbide carbide mixtures and complex carbides.
The standard fully complies ST SEV 5016−85.
2. The selection and preparation of samples is carried out according to GOST 20559−75.
A sample of the sintered hard alloy has to be ground into powder and sifted through a sieve with a nominal mesh size of not more than 0,160 mm according to ST SEV 2644−80.
If the sample contains a plasticizer, it should be removed.
3. Laboratory volumetric glassware should meet the requirements of GOST 1770−74.
4. All reagents used should have a purity not lower than «pure for analysis» (h. e. a.), if not provided the other requirements in the standards on methods of determination of elements.
5. For the preparation of aqueous solutions and the analysis used distilled water according to GOST 6709−72 or deionized water, if no other requirements in the standards on methods of determination of elements.
6. In the expression «diluted 1:1, 1:2», etc. the first digits denote the volume part of the diluted reagent, the second volume of the used solvent.
7. The concentration of solutions Express:
the relative density ();
the mass of the substance in grams per unit volume of solution (mass concentration, g/cm);
mass of substance in grams referred to 100 g of solution (mass fraction, expressed in percent);
the volume of material in cubic centimeters, is related to 100 cmof solution (volume ratio, expressed in percent);
the amount of substance in moles, contained in unit volume of solution (molar concentration, mol/DM).
8. For the preparation of standard solutions used, the metals content of the base element not less than 99.9%, unless otherwise prescribed in the standards methods for the determination of the elements.
9. Weighing the sample sample precipitation and substances for the preparation of standard solutions is carried out on an analytical balance with an accuracy of 0.0002 g. no more than the Required accuracy of weighing and measuring the volume change in the standards on methods of determination of elements by specifying the number of decimal places.
10. Terms related to the degree of heating of water (solution) and the duration of any operation — according to ST SEV 804−77.
11. The titer of the solutions must be installed not less than three batches of the starting material. The titer is expressed in grams of ingredient per 1 cmof the solution, count up to the sixth decimal place and rounded to the fourth significant digit.
12. The contents of elements determined in three parallel batches.
Discrepancies in the results of parallel definitions should not exceed the permissible differences given in the relevant standards on methods of determination of elements at confidence probability of 0.95.
If discrepancies in the results exceed the permitted, the analysis is repeated.
13. Simultaneously with the analysis under the same conditions is carried out at least three control experiments for inclusion in the definition of the amendments, taking into account the content of the element in the reactants. The arithmetic average of the results of the control experiments is subtracted from the values obtained when determining the content of the element in the sample.
14. The result of the analysis taking arithmetic mean value of results of parallel measurements. Rounding numeric values is carried out according to ST SEV 543−77.
15. When photometric definitions used cuvettes with a thickness of the light absorbing layer, in which the measurements were carried out at the optimum optical density.
16. The calibration graph should be constructed in the system of rectangular coordinates: the x-axis to delay the numeric value of the concentration or mass of the element in the specified amount, and the ordinate is the measured value, or a function of it.
To build a calibration curve requires at least three calibration points, each point should be based on the average results of three parallel measurements.
The calibration points should be evenly distributed across the measuring range. The first and last points must correspond to the limits of the measuring range, or cover the range of measurements.
Preparation of solutions for constructing the calibration curve performed prior to analysis. You can define and apply the calibration function.
17. In determining the method of atomic absorption set wavelength, the composition of the gas flame, a reducing or oxidizing action of the flame, other conditions of the measurement such that an optimum sensitivity and accuracy for the corresponding element, and applied device.
18. Control of the correctness of the results of determination of total and free carbon is carried out using standard samples (GEO, CCA, or SOP). The results of the analysis are correct if the difference between received the contents of the controlled component and its validated contents in the standard sample does not exceed the permissible differences at the level of the certified values.
19. Control of the correctness of the results of determination of cobalt is carried out by the method of additives, which carry out finding the content of the analyte in the test material after adding an appropriate sample of pure metal or aliquote part of a standard solution of this component to the sample of analyte prior to analysis.
20. Control of the correctness of the results of the determination of titanium is carried out by varying batches, which carry out finding the contents defined components in different batches of the same analyte.
21. The amount of additive (amount of a standard solution) is chosen so that the analytical signal of the designated component increased 1.5−2 times compared with the analytical signal of this component in the absence of additives in the previous linkage. We should also maintain the optimal conditions of analysis provided by a particular standard on method of analysis.
22. The results of the analysis are correct if the value found differs from that given additive content of more than 0.5
and
— the permissible discrepancy of the results of parallel measurements of the component in the sample and in the sample with the additive, the previous and subsequent batches.
