GOST 20068.3-79

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  ГОСТ 20068.3-79

GOST 20068.3−79 Bronze without tin. Method of spectral analysis of oxide standard specimens with photographic registration of spectrum (with Amendments No. 1, 2)

GOST 20068.3−79

Group B59

INTERSTATE STANDARD

BRONZE WITHOUT TIN

Method of spectral analysis of oxide standard
specimens with photographic registration of spectrum

Tinless bronze. Method of spectral analysis of oxide
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 20068.3−74

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 9−82, 2−90)


This standard applies to the tin-free bronze 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 on the oxide samples with photographic registration of spectrum.

The method is based on using as a test samples and standard samples (CO) oxide powders of bronze, obtained by dissolving the metal in nitric acid followed by thermal decomposition of salts. Compressed into tablets powder of bronze or graphite base is introduced into the arc DC. Spectra produced by the spectrograph. The method provides the possibility to analyze samples in any form.

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

Table 1

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.


Method of spectral analysis of oxide standard specimens is arbitration.

(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.

(Added, Rev. N 2).

2. APPARATUS, REAGENTS AND SOLUTIONS

The quartz spectrograph or diffraction medium, or large variance. Allowed the use of spectral apparatus with photoelectric registration of spectrum, if it ensures the convergence of the results of the analysis indicated in table.2.

A constant current source to power the arc, providing a voltage of 200−400 V and currents up to 10 A.

Device for high-frequency ignition of the DC arc from the generator of any system (PS-39, DG, IG).

Microphotometer designed for measuring optical densities of spectral lines.

Kit for pressing powders

Damn.1

Oil press, hydraulic or any other, providing a pressure of 1.5−2 t

Mould alloy steel (e.g. CVH), a punch with a diameter of 4−6 mm, a height of 50−80 mm (see the devil.1). The plunger and the inner surface of hardened cement matrix and then carefully sanded and brought to the surface.

Muffle furnace of any type with thermocouple, which allows to obtain and maintain temperatures up to 800 °C.

Platinum, porcelain or quartz varicellae cups for dissolving and evaporation of samples (dissolution, you can also use flasks or in the glasses heat resistant glass).

Graphite electrodes-stand with a diameter of 8−10 mm with a spherical hole, the diameter of the electrodes to a depth of (2±0,2) mm (see hell.2).

The location of the electrodes with the samples when taking spectrograms

and — the location and size of the electrodes and of the briquette before the exposure;
b — shot in the anode mode; in shooting in the cathode mode. 1 — graphite stand; 2 — briquette; 3 — melt; 4 — a front electrode

Damn.2

Spectral coals brand-3 diameter of (6±0,2) mm.

Standard samples, manufactured in accordance with GOST 8.315.

Drying Cabinet.

The hotplate.

The machine with a set of shaped cutters for sharpening carbon electrodes and electrode-holders.

Spectrographic plates type 1 or type 2 sensitivity 0,5−5 units., «Micro» sensitivity 10−60 units and plate type UFS.

Analytical scale 200 g with weights of type ADV-200.

Mortar agate or from glass.

Boxy storage of the briquettes.

Tweezers for gripping of briquettes.

Glass or plastic caps to protect from dust sharpened electrodes.

Magnet type MVM 63.

A stopwatch or timer.

Nitric acid according to GOST 4461, diluted 1:1 or 1:3.

The technical rectified ethyl alcohol according to GOST 18300.

Metalpar-metilaminofenazon according to GOST 25664.

Hydroquinone (paradoxians) according to GOST 19627.

Sodium sanitarily according to 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 plates the spectral type 1, 2, «Micro», is prepared by mixing equal volumes of solutions 1 and 2 before use.

Solution 1; prepared as follows: 2.5 g of metol 12 g of hydroquinone and 100 g of sodium sulfate 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 high contrast developers.

Developer for plates 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. Sample ofmagnesium and cleaned from surface contamination by etching in nitric acid, diluted 1:3, 5−10 C, then washed with water, ethyl alcohol and dried at 105 °C. an Average sample weight of not less than 3 g is placed in myprivatekey Cup, poured nitric acid (1:1) at the rate of 10−15 cmof acid per 1 g of the metal is dissolved with moderate heating. The resulting solution was evaporated to dryness, a Cup of dry salt is placed in a muffle furnace, calcined at (700±20) °C for 15−20 min until the termination of allocation of oxides of nitrogen and the resulting oxides are ground in a mortar.

3.2. WITH turning chips after removing the contaminated surface layer on a lathe. Training FROM the analysis are as indicated in claim 3.1.

3.3. The obtained powders selected from three sample weighing (0,30±0,01) g and briquetted in a steel mould. Prepared to shoot the tablets were stored in buksh.

4. ANALYSIS

4.1. Tablets were placed in a recess on the end face of the graphite electrode, mounted in the lower elektrodvigateli. As the second electrode set coal or copper core, strengthening it in the upper elektrodvigateli so that the distance from the bottom edge to the top of the pills totaled (3,0±0,1) mm.

The shape and size of the electrodes and their arrangement in the exposure time given on features.2.

The light source is DC-arc at a current of 6−3 A. tablet on the stand include the graphite anode of the arc. Each tablet should be used for only one spectrogram. When the current is switched on prior to fusing the preform arc lights between the dummy electrode and the stand, and only after melting part of the briquette the anode spot of the arc moves onto the formed melt of oxides. This transition is accelerating because after a few seconds of arc current is turned off and again turn it on, until the melt has not yet had time to cool down. Getting exposure is considered after the transition of the anode spot of the arc on the briquettes. The exposure time of 30−40 s. during the entire exposure time must be adjusted initially established arc gap around the magnified image of the arc on the screen of the objective lens of the lighting system or with a special short throw projection lens.

The shooting conditions of the spectrograms:

The width of the slit of a spectrograph — 0,010−0,015 mm.

The light slit of a spectrograph with three-lens Achromat condenser.

Aperture on the middle of the condenser lens is 5 mm.

Spectra of standard samples and samples are photographed three times on a single photographic plate.

The shortwave part of the spectrum photographed on the plates UPS, and wavelengths on the plates of type 1, 2 or «Micro».

Allowed to determine the mass percent of iron, Nickel and silicon in the cathode mode, using the trial and WITH kinglets, remaining after combustion at the anode.

(Changed edition, Rev. N 2).

4.2. In those cases, when the shooting conditions of the spectra differ from those recommended, such as a slit illuminated by a single-lens condenser, used a different power current, the other plate sensitivity, etc., you should choose the conditions to select optimal interval the optical densities of the lines.

Note. The exposure time is adjusted depending on the sensitivity of the used photographic plates, ensuring the normal blackening of the background of the continuous spectrum; otherwise, you have to build the characteristic curve. The increase in optical density of the background due to the veils, lighting, etc. is not permitted as this reduces the sensitivity of the analysis.

4.3. 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 the plates in tap water they are fixed in fixing solution, washed in running water and dried.

(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 slot width of the photocell shall be 0.10−0.25 mm; gap width between the green cheeks, as measured on the screen in front of the cell is 0.3−1.0 mm.

The wavelengths of the analytical lines given in table.3.

Table 3

As «internal standard» is measured by the optical density of the continuous background in the spectrogram is close to the analytical lines.

Allowed the use of other analytical lines and «internal standards» subject to receipt of the metrological characteristics are not worse than specified in this standard.

Calibration graphs constructed in the coordinates: .

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

Mass fraction of detectable elements in the sample find the schedule for the calibration value found in the table of mandatory application calculated for the same spectrogram where .

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.

When finding the mass fraction of the element close to the rejection limit number of concurrent measurements is doubled, i.e., 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 enterprises.

Sec. 5. (Changed edition, Rev. N 2).

APP (mandatory)

APP
Mandatory

THE TABLE VALUES CORRESPONDING TO
MEASURED VALUES

A. Explanations to the tables

The tables below are used to transfer the measured values to values . The tables contain the results of the calculation according to the formula

.

This formula is obtained as follows.

We denote the total intensity of the line with background through , the intensity of the background under the high line in the absence of a line through . Since , the ratio of line intensity to the background intensity is determined by the expression

. (a)

If the conditions of photographing the spectrum chosen so that the optical density of the line background and the background in the absence of the line are in the normal range,

, (b)

where ;  — contrast ratio. Hence, using the expression (a), it is easy to

.

The tables include most important to the practice of analytical work values from 0.05 to 1.99.

In its construction of the table is divided into two parts: the part covering values from 0.05 to 0,999 and part of the covering values from 1.00 to 1.99.

Consider the first part of the table (0,050,999)…

In the first left column of the table under the heading printed values : 0,05; 0,06; 0,07;… 0,99. To the right of the column headers are printed numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, depicting the third after the decimal point, the sign of the value .

Having a certain value , for example =0,537, find the line of 0.53 corresponding to the first two decimals and in column 7, read the respective value =0,388. Similarly, for =0,143 0,14 in the row in column 3 to read the respective value =1,591.

The second part of the table, covering values from 1.00 to 1.99, built in a similar way, with the difference that in the first left column the value is shown only with one decimal place, and printed numbers 0, 1, 2, 3,… 9 the column headings represent the second after the decimal point, the sign of the value . So, having value =1,36, in the line of 1.3 in column 6 read =1,341.

For values smaller than had 0.301, feature  — negative, denoted by a minus sign over the characteristic (, …) .

As considered in the table can be used to find the values , corresponding values , however they were not measured.

In routine analytical work it is permissible to omit the measurement taking a =1. This is a simplification of several curves calibration curve, if different from unity, but does not lead to significant errors in the analysis, since the same effect on the values obtained for WITH and samples.

B. Value corresponding measured values