GOST 20068.1-79

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  ГОСТ 20068.1-79

GOST 20068.1−79 Bronze without tin. Method of spectral analysis on a metal standard samples with photographic registration of spectra (with Amendments No. 1, 2)

GOST 20068.1−79

Group B59

INTERSTATE STANDARD

BRONZE WITHOUT TIN

Method of spectral analysis on a metal standard
specimens with photographic registration of spectra

Tinless bronze. Method of spectral analysis of metal
standard specimens with spectrum photographic record

AXTU 1709

Date of introduction 1980−07−01

INFORMATION DATA

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

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 29.10.79 N 4102

3. REPLACE GOST 20068.1−74

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 with Amendments No. 1, 2 approved in June 1984, November 1989 (IUS 9−84, 2−90)


This standard applies to bronze without tin stamps Bra5, Bra7, Bramc9−2, Bramc10−2, Brazh9−4, Brazhmc10−3-1,5, Brazhn10−4-4, Brazhnmc9−4-4−1, Brkmc3−1, Brb2, Brbnt1,7, Brbnt1,9 and Brkn1−3 according to GOST 18175 and sets the method of spectral analysis for a metal with photographic registration of spectrum.

The method is based on the excitation spectrum of the arc discharge AC followed by registration of it on the plate with a spectrograph. Mass fraction of detectable elements find for the calibration graphics using the measured values of the difference of optical densities of the analytical lines and «internal standards» in the spectrograms of the sample.

The method allows to determine without tin in the bronze, iron, Nickel, manganese, zinc, tin, lead, arsenic, aluminum, antimony, beryllium and silicon in the range of mass fraction, indicated in the table.1.

Table 1

The range of detectable concentrations of the elements according to
the grade of alloy

The precision and reproducibility of the results is characterized by the values of the permissible differences given in table.2, at a confidence level =0,95.

Table 2

Notes:

1. When verifying compliance with established standards of permissible differences of the two results of parallel measurements for the taking the arithmetic mean of the first () and second () results of parallel measurements of the impurities in the same sample.

2. When checking the established norms of permissible differences of the two results of the analysis for taking the arithmetic mean of the two matched analyses.


(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 25086.

1.2. The systematic examination of the reproducibility of the analysis of samples according to GOST 18242*.
__________________
* In the Russian Federation GOST R 50779.71−99.

(Added, Rev. N 2).

2. APPARATUS, REAGENTS AND SOLUTIONS

Spectrograph for photographing the ultraviolet region of the spectrum with medium-resolution type ICP-30.

Excitation source is alternating current arc (of type generator UGE-4).

Microphotometer type MF-2 or IPV-460.

Spectromancer PS-18 or other type.

Electrodes of copper, M-1 or from coal in the form of bars with diameter 6−7 mm, grade-3, sharpened to a hemisphere or truncated cone.

A device for sharpening copper and carbon electrodes machine model CP-35.

Standard samples, manufactured in accordance with GOST 8.315.

Lathe for sharpening and analyzed samples on the plane of the type of TV 16.

Photographic plates of the spectral types 1, 2, «Micro», ES, UPS sensitivity from 0.5 to 60 units.

Metol (para-metilaminofenazon) according to GOST 25664.

Hydroquinone (paradoxians) according to GOST 19627.

Sanitarily anhydrous sodium GOST 195.

The anhydrous sodium carbonate according to GOST 83.

Potassium bromide according to GOST 4160.

Chernovetskiy crystalline sodium (thiosulfate) according to GOST 244.

Acetic acid according to GOST 61.

Distilled water according to GOST 6709.

Developer for photographic plates of the spectral types 1, 2, «Micro», ES prepared by mixing equal volumes of solution 1 and 2 before use.

Solution 1; prepared as follows: 2.5 g of metol 12 g of hydroquinone and 100 g of sodium semitecolo dissolved in 500−700 cmof water and add water to 1 DM.

Solution 2; is prepared as follows: 100 g of sodium carbonate and 7 g of potassium bromide dissolved in 500−700 cmof water and add water to 1 DM.

You can also use other contrasting working developers.

Developer for photographic plates of the spectral type UFS; prepared as follows: 2.2 g of metol, 8.8 grams of hydroquinone, 96 g of sodium semitecolo, 48 g of sodium carbonate and 5 g of potassium bromide dissolved in 500−700 cmof water and add water to 1 DM.

Fixing solution; prepared as follows: 300 g of sodium thiosulfate, 25 g of sodium semitecolo and 8 cmof acetic acid are dissolved in 1 DMdistilled water. Allowed the use of other fixing solutions.

Allowed to use other equipment, equipment, materials and reagents, subject to obtaining the metrological characteristics are not worse than specified in this standard.

Measuring instruments must be certified in accordance with GOST 8.326*.
___________________
* In the Russian Federation there are PR 50.2.009−94.

(Changed edition, Rev. N 1, 2).

3. PREPARATION FOR ASSAY

3.1. The preparation of analyzed samples and

Preparation of the analyzed samples and analysis must be the same type for each series of measurements. The sample is templet or a piece of molded samples of arbitrary shape. The sample mass and should not differ by more than two times.

Sample preparation is carried out with a sweep of one of its faces on a plane with a file or cutting tool (the machine) without coolant and lubricant. When photographing each of a spectrum of the stripped surface should be a flat pad with a diameter of not less than 10 mm without holes, scratches, cracks, and slag inclusions. Before photographing spectra for removing surface contamination of the analyzed samples and wipe with ethanol.

(Changed edition, Rev. N 2).

4. ANALYSIS

4.1. The sample (or CO) is clamped in the lower clamp of the tripod and fed by coal (or copper) electrode so that the distance from ubeskrivelig plot to the edge of the sample was not less than the sparking spots (2−5 mm).

Between the ends of the electrodes, separated by 1.5−2.5 mm, light arc AC power 3−8 A.

The interelectrode gap is set at a template, or micrometer screw. The arc length and the source position on the optical axis is controlled through the aperture located on the middle lens being lighting systems.

The spectra photographed with a quartz spectrograph medium dispersion type of ISP-30. The slit of the spectrograph — 0,015 mm.

With the aim of reducing the exposure time and obtaining high resolution of the spectrograph used astigmatic coverage of the gap with complete filling of the collimator lens. This applies to a single-lens spherical condenser with a focal length of 75 mm, located at a distance of 300 mm from the slit, and 72 mm from the light source.

It is also allowed to use any other lighting system that provides uniform intensity of the line in the focal plane of the instrument.

For each sample (samples and) take pictures of the two spectrograms.

Exposure time and distance from the light source to the slit of the spectrograph is adjusted depending on the sensitivity of the used photographic plates, ensuring the normal optical density of the background of the continuous spectrum. An increase in the density of the background due to the veils, lighting, etc. is not allowed.

Pre-firing is 15 s. the exposure Time should be not less than 15 s.

4.2. Processing of photographic plates. A manifestation of photographic plates depending on the type carried out in the respective developer (see section 2) at a temperature of 18−20 °C.

After washing photographic plates in running water they are fixed in fixing solution, washed in running water and dried.

4.1, 4.2. (Changed edition, Rev. N 2).

5. PROCESSING OF THE RESULTS

The optical densities of the analytical lines and «internal standards» in the spectrograms are measured with the aid of microphotometer.

The wavelengths of the analytical lines and «internal standards» are shown in table.3.

Table 3

The wavelengths of the analytical lines and «internal standards»

Indicated in the table Background-1 means the value of optical density of weak molecular lines 235,08 nm; Background-2 — the maximum value of the optical density of the background near the line on the far side; the Background 3 — minimum value of the optical density of the background near the line on the high side.

Allowed the use of other analytical lines and «internal standards», provided that they ensure the convergence of the re-analysis results and the lower boundary of the designated contents of the elements satisfying the requirements of this standard.

In the spectrogram, using microphotometry measure the blackening of analytical lines of the determined elements of the lines and «internal standard» (background) . Calculate a value . Find the arithmetic mean of the results obtained on the two spectrograms of each standard sample (), and build a calibration curve in the coordinates where  — mass fraction of impurities in the standard samples, %. According to the obtained calibration chart find the content of impurities for each of the two spectrograms obtained for one sample.

The main method is the method of «three standards». Allowed the use of other methods of graphing, such as the solid calibration curve, a method of control of a «standard», etc.

The final result of the analysis taking the arithmetic mean of the results of two parallel measurements obtained on the same photographic plate.

Permissible differences of two parallel definitions, and two results of sample analysis shall not exceed the values given in table.2.

If the difference between parallel determinations exceeds the value , the photographing of the spectra is repeated on the second photographic plate.

Control of accuracy of analysis results is carried out according to GOST 25086 using state, industry standard samples or standard samples of the enterprise.

(Changed edition, Rev. N 2).