This standard is applicable to the determination of oxygen content in nickel-based alloy powder. Determination range: 0.01% to 0.20%. This standard complies with GB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". GB/T 8638.13-1988 Chemical analysis method for nickel-based alloy powder - Determination of oxygen content by pulse heating inert gas fusion coulometric titration GB/T8638.13-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of nickel base alloy powder
Pulse heating inert gas fusion
Coulometric titrimetric method
Nickel base alloy powder— Determination of oxygen content- Pulse heating inert gas fusion coulometric titrimetric method This standard is applicable to the determination of oxygen content in nickel base alloy powder. Determination range: 0.01%～0.20%UDC 669.245-492.2
GB 8638.13 - 88
This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is wrapped with metal foil and put into a graphite crucible directly heated by low-voltage alternating current in an argon gas flow, and melted at about 2500C. The oxygen in the sample is precipitated as carbon monoxide, which is converted into carbon dioxide by copper oxide and absorbed by the barium perchlorate solution with a pH value of about 9.5, which reduces the pH value of the solution. At the same time, the alkali generated by electrolysis is used to restore the pH value of the solution to the original given value. The amount of oxygen is calculated based on the pulse count of the electricity consumed by electrolysis.
2 Reagents and materials
Fluorine gas, purity greater than 99.99%.
Copper oxide, linear.
2.3 Barium carbonate
2.4 Perchloric acid solution (1+19).
2.5 Solution in cathode pool (main cup): weigh 100g barium perchlorate (Ba(C10, 3H, 0) and dissolve it in 2000mL water, add 60mL isopropanol and mix. Store in a ground-mouth bottle for later use. 2.6 Solution in anode pool (secondary cup): weigh 100g barium perchlorate [Ba(C10), 3H, 0] and dissolve it in 500mL water, mix. Store in a ground-mouth bottle for later use.
2.7 Solution in reference electrode pool (small cup): weigh 5g barium perchlorate [Ba(C10.), 3H, 0) and 3g sodium chloride, dissolve in 100ml. water, add a few drops of silver nitrate solution (5%) after complete dissolution, heat to 60~～70℃, cool and mix. Store in a ground-mouth bottle for later use. 2.8 Magnesium perchlorate or phosphorus pentoxide.
2.9 Carbon tetrachloride.
2.10 Acetone.
Metal foil: nickel foil or iron-nickel foil, oxygen content less than 0.02%, thickness ≤0.05mm. Alkali asbestos.
Glass wool.
Stone crucible, made of high-purity, dense, fine-grained graphite with sufficient strength at high temperature. Its shape and size are shown in Figure 1.2.14
Approved by China Nonferrous Metals Industry Corporation on January 11, 1988 and implemented on D1-01, 1989
GB8638.13.88
Figure 1 Graphite crucible
Other shapes and sizes of crucibles that can completely precipitate oxygen are allowed to be used, and the heating conditions are selected separately. 3 Instruments
Pulse heating coulometric oxygen analyzer should meet the following technical indicators: a.
Measurement upper limit not less than 500g;
Sensitivity: 0.5ug;
Heating temperature higher than 3000℃;
d. Blank test value less than 5ug;
Precision: ±2% or 2ppm (whichever is greater). The gas circuit system of pulse heating coulometric oxygen analyzer is shown in Figure 2. 15
Figure 2 Gas circuit system of pulse heating coulometric oxygen analyzer 1-nitrogen cylinder; 2-pressure reducing valve; 3 pressure gauge; 4-copper oxide purification furnace, 5 alkali asbestos purifier 6, 10, 16 electromagnetic valves; 7.9, 22-needle valve; 8-magnesium perchlorate or phosphorus pentoxide dryer; 11-pH electromagnetic valve, 12-pulse furnace; 13-degassing air flow meter: 14-buffer equal volume: 15-dust collector; 17-steel oxide converter, 18, 19-stop valve; 20-analysis air flow meter; 21-absorption cell; 23-fluorine screen air flow meter 216
4 Sample
GB8638.13
Sample oxidation and contamination should be avoided when storing the sample. The sample should be fully mixed before weighing. 5 Analysis steps
5.1 Number of determinations
Measure twice in parallel and take the average value.
5.2 Sample amount
0≤0.02%Weigh 0.500~1.000g of sample. 0>0.02%Weigh 0.200~~0.700g of sample. 5.3 Sample
5.3.1 The metal box (2.11) used to wrap the sample should be cleaned with silk cloth dipped in carbon tetrachloride (2.9) before use, cut into small pieces of equal size and appropriate size, and washed with carbon tetrachloride (2.9) and acetone (2.10) in turn, air-dried, and weighed. 5.3.2 The sample should be wrapped with treated metal foil (5.3.1). The wrapped sample should be handled with clean utensils and should not leak during the process of being transferred into the crucible.
5.3.3 The cleaned metal foil and wrapped samples in accordance with 5.3.1 should be picked up with clean tweezers. Do not touch them with your hands or with unclean utensils.
5.4 Preparation of instruments
5.4.1 Check the various reagents or materials used for purification, conversion, dust removal and absorption of the instrument and update or add them in time. 5.4.2 Open the gas valve and adjust the flow rate of the analytical gas flow to 100-150mL/min and the flow rate of the argon screen gas flow to 100-200mL/min. 5.4.3 Check and turn on the power supply, heat the purification furnace and conversion furnace to 580C, and start the coulometric analyzer. 5.5 Calibration test
5.5.1 Use a constant current source device to calibrate the charge of the coulometric titration electrolytic pulse. 5.5.2 Use standard substances for inspection when necessary.
5.6 Blank test
Carry out the blank test several times according to the test conditions of sample (5.3), and take the average value as the blank value. After a certain number of sample analyses or after the analysis heating conditions are changed, the blank value should be checked or re-determined. 5.7 Determination of oxygen content of metal foil
Carry out the oxygen content of metal foil several times according to the test conditions of sample (5.3), and calculate the oxygen content of the metal according to formula (1): 1(Ct-B+ ... +Cn= B) × . 5 × 10-Q
Where: Q-
Oxygen content of metal foil;Www.bzxZ.net
Count value obtained from the blank test;
Count value of oxygen content measurement of the i-th metal box;
Mass of the i-th metal foil;
Number of measurements.
5.8 Determination
5.8.1 Correct the endpoint pH value of the cathode pool (main cup) solution (2.7) to about 9.5. 5.8.2 Pass cooling water through the pulse furnace.
5.8.3 Use a special copper brush to clean the sample inlet channel and the pulse furnace chamber, load new into the furnace, and load the wrapped sample (5.3.2) into the sampler.
5.8.4 Carry out crucible degassing under the following conditions:
Degassing heating current 950~1000A;
Degassing air flow rate not less than 1000mL/min; b.
Degassing time 10~608.
GB 8638.13-88
5.8.5 Switch the instrument to the analysis state, add the sample (5.8.3) in the sampler into the graphite crucible, and reset the coulomb count to zero. 5.8.6 The sample analysis heating is carried out in two stages, first at low temperature and then at high temperature. Low temperature stage: heating current 400~500A (about 1300℃) heating time 5~10s. High temperature stage: heating current 850~950A (about 2500℃); heating time 15~25s. In continuous analysis, the analysis heating conditions should remain relatively stable. 5.8.7 Read the analysis count value. The time interval from the start of analysis to the reading of the count value should remain stable in the analysis of the same batch of samples. The same time interval should also be taken for the blank test. 5.8.8 In continuous analysis, continue to proceed according to 5.8.3~5.8.7. 5.8.9 When temporarily interrupting the analysis, the pulse furnace cooling water should be turned off in time. When continuing the analysis, proceed according to 5.8.2 to 5.8.7. 6 Calculation of analysis results
Calculate the percentage of oxygen according to formula (2):
(A- B -C) X 0.5× 10-
Wherein:
Count value obtained when analyzing the sample;
Count value obtained from the blank test;
C-calculated count value of the metal foil used to wrap the sample; m. --sample weight, g.;
0.5 X 10-
count value equivalent to oxygen, uranium.
The count value of the metal foil used to wrap the sample is calculated according to formula (3): Q·m
C 0.3x10--
Where:
Q is the oxygen content of the metal foil;
m, - the mass of the metal foil used to wrap the sample, g; 0.5 X 10-6 --
7 Allowable difference
… oxygen content equivalent to one count, 8.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
Oxygen content
0. 0 1～0. 050
0.050 ~-0. 100
>0. 100 ~0. 200
Additional remarks:
This standard was drafted by the Iron and Steel Research Institute of the Ministry of Metallurgical Industry. This standard was drafted by the Iron and Steel Research Institute of the Ministry of Metallurgical Industry. The main drafters of this standard are Du Xueqiang and Cao Honglu. 218
Allowable difference
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