GOST 25278.15-87
GOST 25278.15−87 Alloys and alloys of rare metals. X-ray fluorescence method for the determination of zirconium, molybdenum, tungsten and tantalum in alloys on the base of niobium
GOST 25278.15−87
Group B59
STATE STANDARD СОЮ3А SSR
ALLOYS AND ALLOYS OF RARE METALS
X-ray fluorescence method for the determination of zirconium, molybdenum, tungsten and tantalum in alloys on the base of niobium
Alloys and foundry alloys of rare metals. X-ray fluorescence method for determination of zirconium, molybdenum, tungsten and tantalum in alloys on the base of niobium
AXTU 1709
Valid from 01.07.88
to 01.07.93*
________________________________
* Expiration removed
according to the Protocol of the Intergovernmental Council
for standardization, Metrology and certification
(IUS N 2, 1993). — Note the manufacturer’s database.
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
PERFORMERS
E. G. Nembrini, G. N. Andrianov, A. P. Popov, S. L. Shvartsman, V. A. Shestakov
2. APPROVED AND promulgated by the Decree of the State Committee USSR on standards on 29 October 1987 N 4091
3. The period of examination — 1993
The frequency of inspection is 5 years.
4. INTRODUCED FOR THE FIRST TIME
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Section number, paragraph |
| GOST 3760−79 |
2 |
| GOST 3769−78 |
2 |
| GOST 4204−77 |
2 |
| GOST 5556−81 | 2 |
| GOST 5712−78 |
2 |
| GOST 7172−76 |
2 |
| GOST 9428−73 |
2 |
| GOST 9656−75 |
2 |
| GOST 10929−76 |
2 |
| GOST 18300−72 |
2 |
| GOST 23620−79 |
2 |
| GOST 26472.0−85 |
2 |
| GOST 26473.0−85 |
1.1 |
This standard specifies x-ray fluorescence method for the determination of zirconium (0.2 to 2.5%), molybdenum (0.5 to 6%), tungsten (from 2 to 12%) and tantalum (from 0.15 to 1.5%) in the alloys based on niobium.
The method is based on excitation of atoms of the sample with primary x-radiation, registration of fluorescence x-ray spectra comparison of samples and the unknown samples and the determination of elements by multiple regression equations.
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis and safety requirements according to GOST 26473.0−85.
2. APPARATUS, MATERIALS AND REAGENTS
X-ray fluorescence spectrometer of the type SRM-18, SRM-20, PV 1400 company «Philips» (the x-ray tube with palladium or silver anode) or similar with the metrological characteristics are not inferior to the characteristics of the mentioned spectrometers.
The management computing machine with a RAM of at least 16 K and a set of peripherals.
Hydraulic press NTR-40 company «the Duke» (Germany), P-10 or similar with a force of at least 10 t
Mould steel or hard alloy.
Mold made of aluminum with a diameter of 40 mm.
The mixer is Electromechanical type 8000−11 Spex (USA), Pulverisette-7 of the company Fritsch (Germany) or similar.
Muffle furnace with thermostat providing temperatures up to 1100 °C.
Analytical scale.
Libra technical.
Tile electrical with closed spiral.
The quartz crucibles high capacity of 40 or 50 cm.
High platinum crucibles with a capacity of 25 cm.
Beakers, glass, laboratory with a capacity of 50 cm.
Conical flasks with a capacity of 250 cm.
Funnels, glass, conical.
Volumetric flasks with a capacity of 100, 250 cm.
Pipettes with a capacity of 5 cmwith divisions.
Pipettes with a capacity of 25 cmwith no divisions.
Microburette with a capacity of 10 cmwith a scale division of 0.02 cm
.
Potassium preservatory according to GOST 7172−76.
Sulfuric acid according to GOST 4204−77.
Hydrogen peroxide according to GOST 10929−76.
Ammonium oxalate according to GOST 5712−78, a solution of 40 g/DM.
Ammonia water according to GOST 3760−79.
Ammonium sulfate according to GOST 3769−78.
The technical rectified ethyl alcohol according to GOST 18300−72*.
_________________
* On the territory of the Russian Federation GOST 18300−87. — Note the manufacturer’s database.
Medical absorbent cotton wool GOST 5556−81.
Boric acid according to GOST 9656−75.
Lithium tetraborate anhydrous (lithium tetraborate).
Molybdenum metal powder or fine shavings, containing at least 99.95% of molybdenum.
Molybdenum (VI) oxide for spectral analysis.
Tungsten metal in the form of powder or slices that contain at least 99.95 percent tungsten.
Tungsten (VI) oxide, OS.h.
Niobium metal in the form of powder or fine chips containing not less than 99.9% niobium.
Of niobium pentoxide according to GOST 23620−79.
Tantalum (V) oxide, OS.h.
Zirconium (IV) oxide, OS.h.
The zirconium metal in the form of powder or fine chips containing not less than 99.95% zirconium.
Silicon dioxide according to GOST 9428−73.
A standard solution of molybdenum containing 1 mg/cmof molybdenum: 0.1 g of molybdenum metal is placed in a conical flask with a capacity of 250 cm
and dissolve in low heat (about 200 °C) in 20 cm
of hydrogen peroxide, cover the flask conical funnel glass. After complete dissolution of the sample is added cautiously, drop by drop, 2 cm
of ammonia solution and again heated to a decolorizing solution. The resulting solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
, adjusted to the mark with water, mix.
A standard solution of tungsten containing 5 mg/cmtungsten: 0.5 g metal tungsten is placed in a conical flask with a capacity of 250 cm
and dissolve in low heat (about 200 °C) in 30 cm
of hydrogen peroxide, cover the flask conical funnel glass. After complete dissolution of the sample is added cautiously, drop by drop, 4 cm
of ammonia solution and again heated to a decolorizing solution. The resulting solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
, adjusted to the mark with water, mix.
Standard solution of zirconium containing 0.5 mg/cmZirconia: 0.05 g of metallic zirconium is placed in a beaker with a capacity of 50 cm
and dissolved at a moderate heat (about 300 °C) in 6 cm
of concentrated sulfuric acid with 1 g of ammonium sulfate, covered with a glass watch glass.
After complete dissolution of the sample add 0.5 cmof hydrogen peroxide solution, dilute with water to 30 cm
, was stirred until complete dissolution of the salts; the resulting solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
, adjusted to the mark with water, mix.
Standard solution tantalum containing 0.5 mg/cmtantalum: 0,061 g of tantalum pentoxide is placed in a quartz crucible with a capacity of 50 cm
, add 2 g of potassium persulfate, a few drops (about 0.5 cm
) concentrated sulphuric acid and fused in a muffle furnace at a temperature of 900−950 °C. If the melting takes place incompletely, and the melt is cooled, add 1 cm
of sulfuric acid and re-fused to obtain a liquid transparent water. The smelt is cooled and dissolved by heating in 15−20 cm
of a solution of ammonium oxalate; transfer the solution into a volumetric flask with a capacity of 100 cm
; adjusted to the mark with water.
3. ANALYSIS
3.1. Sample preparation comparison (OS)
Six quartz crucible is introduced from microburette consistently different volumes of standard solutions of zirconium, molybdenum, tungsten and tantalum (table.1) and carefully evaporated (avoiding splashing!) to a volume of 0.3−0.5 cm. When the mass of the elements in the samples compare more than 10 mg allowed the introduction of the sample metal (tab.1).
Table 1
| The designation of the reference sample |
The volume of a standard solution of the element, see |
The mass of an element in the reference sample, mg |
Estimated value of the mass fraction, defined by the alloy components in the reference sample, % | |||||||||||
| Zr |
Mo |
W |
The |
Zr |
Mo |
W |
The | Nb |
Zr |
Mo |
W |
The |
Nb | |
| OC1 |
10,0 |
10,0 |
4,0 |
15,0 |
5,0 |
10,0 |
20,0 |
7,5 | At the rate of 457.5 |
1,0 |
2,0 |
4,0 |
1,5 |
91,5 |
| OC2 |
5,0 |
30,0 |
8,0 |
4,0 |
2,5 |
30,0 |
40,0 |
2,0 | 420,5 |
0,5 |
6,0 |
8,0 |
0,4 |
85,1 |
| ОС3 |
25,0 |
5,0 |
12,0 |
6,0 |
12,5 |
5,0 |
60,0 |
3,0 | 419,5 |
2,5 |
1,0 |
12,0 |
0,6 |
83,9 |
| ОС4 |
7,5 |
25,0 |
10,0 |
10,0 |
3,75 |
25,0 |
50,0 |
5,0 | 416,25 |
0,75 |
5,0 |
10,0 |
1,0 |
83,25 |
| ОС5 |
2,0 |
2,5 |
2,0 |
1,5 |
1,0 |
2,5 |
10,0 |
0,75 | 485,75 |
0,2 |
0,5 |
2,0 |
0,15 |
97,15 |
| ОС6 |
15,0 |
17,5 |
6,0 |
5,0 |
7,5 |
17,5 |
30,0 |
2,5 | 442,5 |
1,5 |
3,5 |
6,0 |
0,5 |
88,5 |
Then introduced into crucibles of various by weight of niobium — based alloy (tab.1) add 10 g of potassium peacemaking, a few drops of concentrated sulfuric acid, place the crucibles in a muffle furnace and conduct alloying at a temperature of 750−800 °C to produce a clear float.
The crucible was cooled to room temperature, the melt out of the crucible, crushed and milled into an Electromechanical mixer until the particle diameter of 71 microns (grinding time ~1 min). Before chopping mixer chamber wiped with a cotton swab moistened with alcohol. Consumption of wool — 2 grams of alcohol and 1 cmin a single operation.
The procedure of preparation of the sample comparison conducted at least two times, thereby obtaining at least two independently prepared samples of each of the six compositions listed in table.1.
3.2. Preparation of the emitters from the samples of comparison
Approximately 4−5 g of boric acid are poured into a mold and compressed at a force of 10−20 kN (1−2 TS), then the core mold is removed, poured on compacted substrate of boric acid of at least 6 g OS and compressed at a force of 100 kN (10 TF). It is allowed to compress the emitters of the OS without backing. For this 8 g OS poured into a mold and pressed to the radiator at the force of 100 kN (10 TF). The emitters of the OS, pressed without backing, is allowed to use instead of the emitters from the OS, pressed on a substrate.
Before each subsequent pressing of the radiator parts mold wipe with a cotton swab moistened with alcohol. The consumption of wool — 2 grams of alcohol and 1 cmin a single operation.
The mass of substrate material and crushed going samples for the preparation of tablets of the emitters is weighed with an error not more than 0.5 g.
3.3. Preparation of the emitters of the reference and test samples
Preparing a single reference sample (RO) glass-based (silicon dioxide and lithium tetraborate): 25 g of lithium tetraborate, 3 g silicon dioxide, 2 g of niobium pentoxide, 1 g of tungsten trioxide, 0.4 g of molybdenum trioxide, 0.1 g zirconium dioxide, 0.2 g of tantalum pentoxide is placed in a platinum crucible and fused in a muffle furnace at a temperature of 1000−1050 °C for 30−40 min After fusing the contents of the crucible is poured into a mold made of aluminum, cooled in air to room temperature, remove from the mold and mark.
Prepare two test samples: N 1 and N 2. As test samples using samples of alloys in which the content of the determined elements are listed in table.2 intervals.
Table 2
| The number of test samples |
Mass fraction of zirconium, % |
Mass fraction of molybdenum, % |
Mass fraction of tungsten, % |
The mass fraction of tantalum, % |
| 1 |
0,75−1,0 |
2.0 to 2.5 |
4.5 to 5.5 |
0,2−0,4 |
| 2 |
Of 1.25−1.5 |
4.5 to 5.5 |
10,5−11,5 |
1.1 to 1.4 |
The emitters of the test samples prepared in the same way as the emitters from the samples of comparison (see p.3.2) after receiving pyrasulfotole float according to claim 3.1.
The emitters of the reference sample and test samples in the absence of mechanical damages (scratches, nicks, etc.) is considered suitable as long as the error related with their heterogeneity, does not exceed the sum of the main instrumental and theoretical statistical errors are more than 1.3 times.
Quantitative assessment of biases associated with the heterogeneity of the sample, is carried out according to industry documents.
3.4. Preparing the appliance for use
Preparation of instrument control computer for work and maintenance carried out in accordance with the instructions for operation and maintenance. The mode of operation of the x-ray tube is 40 kV, 50 mA.
3.5. Calibration of the instrument
When calibrated using the same emitter prepared from a reference sample, and one emitter prepared from each OS. Each emitter is placed in a cuvette (pre-wiped with cotton wool soaked in alcohol at the rate of 1 g of wool and 0.5 cmalcohol), then the cell with the emitters sequentially loaded into the x-ray spectrometer.
The dimension of each emitter is produced once at an exposure of 100 s. the intensity Counts are automatically displayed on the printing device and the memory of the computer.
The calibration is carried out with the help of computers and appropriate software. According to the instruction manual of the software complex find the coefficients of regression equations. For this purpose, the computer memory enter calibration information: received as specified in paragraph 3 above.5, the counts of the intensities of the analytical lines for the reference sample and sample comparison, the values of the elements content in OC1-ОС6 table.1 and the multiple regression equation for each analyzed element are given below:
where — determine the mass fraction (percent) zirconium, molybdenum, tungsten or tantalum;
— coefficients of regression equations;
— counting intensity — the number was for a set exposure time of the pulses characterizing the intensity of the analytical line of zirconium, molybdenum, tungsten, tantalum, respectively, measured for the emitter prepared from a sample test portion or sample of the test sample;
— the same for the emitter prepared from a sample reference of the sample.
After the calibration the computer prints the values of the coefficients of the calibration equations.
The calibration of an instrument on samples comparison OC1-ОС6 is carried out with the purpose of updating the coefficients of the calibration equations, 1 time per month.
3.6. Preparation of samples for analysis
A portion of the sample weighing 0.5 g was placed in a quartz crucible, add 10 g of potassium peacemaking, a few drops of concentrated sulfuric acid, place the crucible in a muffle furnace and conduct alloying at a temperature of 750−800 °C to produce a clear float. The crucible was cooled to room temperature, the melt out of the crucible, weigh and add preservatory potassium to total weight of 10.5 g, crushed and milled to a particle diameter of ~71 µm (milling time on the mechanical mixer — 1 min).
3.7. Certification emitters of the test samples
The emitters of the reference and test samples placed in the cuvette. The cell with the transducers is loaded into the spectrometer and performs the measurements according to the instructions for operation and maintenance. Expect on a computer the content of the identified elements corresponding to the measured line intensity for the emitters of the test samples # 1 and 2. Details of the procedure of measurements and processing of the results of the analysis are described below in sec. 4 and 5.1. The values of the mass fraction of detectable elements (in percent) assigned to the emitters of the test samples No. 1 and 2, find the multiple analysis (20).
4. ANALYSIS
From each sample, prepare two transmitters. For the preparation of a single emitter sample crushed with a mass of not less than 6 g poured into the mold and pressed the emitter when the force of the vehicle 10. The emitters are pressed on a backing of boric acid or other similar bonding material, as indicated in paragraph 3.2.
Radiators, pressed from the analyzed samples placed in the cuvette, pre-wiped with cotton wool soaked in alcohol (1 gram of cotton and 0.5 cmof ethanol). In the same cuvette is placed one emitter, made of a reference sample, and two emitter made of the test sample No. 1 or No. 2 (depending on the alloy composition).
Cells with the emitters sequentially loaded into the spectrometer and performs the measurements according to the instructions for the operation and maintenance of the device.
Prior to the measurement to produce a measurement of the intensity of the analytical lines of the determined elements for the emitter of the reference sample. Thus make two measurements of the intensity each analytical line for a single emitter with exposure of 100 and the results averaged and then do as specified in clause 5.2.
While meeting the requirements of section 5.2 make measurements of the intensity of the analytical lines of the determined elements for the remaining emitters. Measurements are performed in automatic or Autonomous mode.
Thus, for each emitter the measurement of intensity of analytical lines of the determined elements to produce at an exposure of 100 s.
5. PROCESSING OF THE RESULTS
5.1. Processing of information carried out on electronic computing machine, using the appropriate software system. To do this, in the memory of the computer enter the calibration information (in the form of regression equations for each of the element and the numerical values of the coefficients of these equations) when operating in the automatic mode or the calibration information, the counts of the intensities of the lines from reference, analyze, and test samples (on tape) when working in offline mode. After work the computer prints on the form the results of parallel measurements obtained for the first and second emitters analyze and test samples.
The stability control the conditions of analysis of the contents of the determined elements in the test sample is carried out as specified in clause 5.3 of this standard. While meeting the requirements of section 5.3 find and correlate with each other, the first and second results of parallel measurements of the content of each element as specified in clause 5.4. While meeting the requirements of section 5.4 find each of the element analysis result.
5.2. Control the stability of the equipment by the intensities of the lines defined elements from the reference sample
Control the stability of the equipment by the intensities of the analytical lines of the determined elements from the reference sample is performed to account for instrumental drift using the emitter prepared according to section 3.3. Control is carried out according to the instruction manual of the spectrometer.
5.3. The stability control the conditions of analysis of the contents of the determined elements in the test sample
5.3.1. The stability control the conditions of analysis of the contents of the determined elements are on the test sample N 1 and 2 depending on the content of determined elements in the sample. This control is carried out in the analysis of each sample (or group of samples) products. Thus use of two transmitters of the respective test samples prepared according to claim 3.3.
5.3.2. For the first of two results of parallel measurements of each of the elements in the test sample taking the mass fraction of the corresponding element (%) found for the first emitter and the second the result of taking the mass fraction of the element found for the second emitter, made from the same test sample. The difference between the two results of parallel measurements with a confidence probability of 0.95 should not exceed the values permitted by the divergence of the two results of parallel measurements (
), is given in table.3.
Table 3
| The designated element |
Mass fraction, % |
The allowable discrepancy of the two results of parallel measurements |
The allowable discrepancy of the two results of the analysis |
| Cubic Zirconia |
0,20 |
0,02 |
0,03 |
| Of 1.00 |
0,07 |
0,1 | |
| 2,50 |
0,13 |
0,2 | |
| Molybdenum |
0,50 |
0,04 |
0,06 |
| 3,0 |
0,2 |
0,3 | |
| 6,00 |
0,35 |
0,5 | |
| Tungsten |
Of 2.00 |
0,15 |
0,25 |
| 7,0 |
0,5 |
0,8 | |
| 12,0 |
0,7 |
1,1 | |
| Tantalum | 0,15 |
0,02 |
0,03 |
| 0,70 |
0,05 |
0,08 | |
| 1,50 |
0,1 |
0,15 |
5.3.3. If the discrepancy between the results of the parallel determinations do not exceed the values given in table.3, then calculates the result of analysis — the arithmetic average of the first and second of the parallel definitions of this element in the test sample. The difference between the found result of the analysis of test samples and accepted the content of this element in the validation sample, with confidence probability of 0.95 does not exceed in absolute value, equal to 0.7
, where
is the permissible divergence of the results of the analysis for this tier of content, taken at the table.3.
5.3.4. If the discrepancy between the results of parallel measurements exceed the permitted values (see table.3), the analysis of groups of samples and test samples, repeat or find out and eliminate the causes of unsatisfactory analysis.
5.4. Retrieving results of parallel measurements and result analysis
5.4.1. While meeting the requirements established in clause 5.2 and 5.3, in the first of two results of parallel measurements each item in the sample accept its mass fraction, was found for the first emitter and the second mass fraction, was found for the second emitter, made from the same sample.
The difference between the larger and the smaller of the two results of parallel measurements with a confidence probability of 0.95 should not exceed the values permitted by the divergence of the two results of parallel measurements (
), is given in table.3.
5.4.2. If the discrepancy of the two results of parallel measurements exceed the values specified in table.3, check the quality of the preparation of the emitters from the sample and repeat the determination.
5.4.3. The difference of two analysis results with a confidence probability of 0.95 does not exceed the permissible values of the differences (
) are shown in table.3.
