This standard is applicable to the determination of silicon content in nickel-based alloy powder. Determination range: 0.10% to 6.00%. This standard complies with GB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products". GB/T 8638.3-1988 Chemical analysis method for nickel-based alloy powder Determination of silicon content by perchloric acid dehydration gravimetric method GB/T8638.3-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of nickel-based alloy powder
Determination of silicon content by gravimetric method after dehydration by perchloric acid
Nickel base elloy powder- Determination of silicon content. Gravimetric method after dehydration by perchloric acid
This standard is applicable to the determination of silicon content in nickel-based alloy powder. Determination range: 0.10%～6.00%. UDC 669. 245-492. 2
GB 8638. 3 - 88
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
After the sample is acidified by alkali fusion (or dissolved by acid), the silicic acid is dehydrated by fuming with perchloric acid, filtered and washed, and then burned to silicon dioxide. It is treated with sulfuric acid and hydrofluoric acid to volatilize silicon tetrafluoride and remove it. The percentage of silicon is calculated from the mass difference before and after silicon removal. 2 Reagents
2.1 Sodium peroxide.
2.2 Hydrochloric acid (g1.19 g/mL).
2.3 Perchloric acid (p1.67 g/mL).
2.4 Nitric acid (p1.42 g/mL).
2.5 Hydrofluoric acid (g1.15 g/mL).
2.6 Hydrochloric acid (5+95).
2.7 Sulfuric acid (1+1).
2.8 Ammonium thiocyanate solution (5%).
2.9 Methanol.
3 Apparatus
Muffle furnace.
4 Analysis steps
4.1 Number of determinations
Measure twice in parallel and take the average value.
4.2 Sample quantity
Weigh 0.5000~1.000g of sample.
4.3 Blank test
Carry out a blank test together with the sample.
4.4 Determination
4.4.1Put the sample (4.2) in a graphite crucible, add 5g of sodium peroxide (2.1), melt it in a blowtorch or muffle furnace (600~700C), wait for the sample to decompose, remove and cool. Put it in a 200mL plastic cup, add 20mL of hot water to soak it, wash the crucible and transfer the solution into a 400mL beaker containing 20mL of hydrochloric acid (2.2), wash the plastic cup with water, and add the washing liquid into the beaker. Add 20~30ml pernitrogen acid (2.3), heat and evaporate until smoke appears, cover surface III, and continue heating to reflux perchloric acid smoke for 15~20min. 4.4.2 For samples that can be dissolved in hydrochloric acid and nitric acid, place the sample (4.2) in a 400mL beaker, heat and dissolve the sample with an appropriate amount of acid, concentrate to a volume of about 10mL, add 40mL methanol (2.9), remove surface III and leave a small gap, evaporate slowly at low temperature to less than 10ml, add 5mL nitric acid (2.4), 20~30ml perchloric acid (2.3), heat and evaporate until gastric smoke appears. 4.4.3 Remove and cool slightly, moisten the salts with 5mL hydrochloric acid (2.2), add 100mL hot water, and heat again (but do not boil) to dissolve the soluble salts, add a small amount of paper pulp, and immediately filter with medium-speed quantitative filter paper. Use a glass rod with a rubber head to carefully wipe off the precipitate adhering to the wall of the cup, and wash the beaker with hot hydrochloric acid (2.6) and wash the precipitate until there is no iron ion [check with ammonium thiocyanate solution (2.8)]. Then wash three times with hot water: 4.4.4 Transfer the filtrate and washing solution into the original beaker, heat and evaporate until gastric perchloric acid smoke, and reflux for 15~20min, and proceed as in 4.1.3.
Put the precipitate obtained in 4.4.3 and 4.4.4 together with the filter paper in a platinum volute, dry, ashed, cool slightly, add hydrochloric acid (2.2) dropwise to moisten the precipitate in 4.4.5
, add 2mL of medium alcohol (2.9), and drive out the boron at low temperature (acid-soluble samples have already been driven out of the boron, so this operation can be omitted). Continue evaporating the precipitate until the day. Cover part of the tower with a platinum volute cover, burn in a muffle furnace at 1000-1050℃ for 30-10min, take out, cool slightly, place in a desiccator, cool to room temperature, weigh, and repeatedly burn until constant weight. 4.4.6 Add 4-5 drops of sulfuric acid (2.7) and 5 mL of hydrofluoric acid (2.5) along the inner wall of the crucible, heat at low temperature until the sulfuric acid smoke is completely emitted, and then place the platinum in a muffle furnace at 1000-1050℃ and burn for 20 minutes (samples containing tungsten and molybdenum should be burned at 800℃), take out, cool slightly, place in a desiccator, cool to room temperature, weigh, and repeatedly burn to a constant weight. 5 Calculation of analysis results
Calculate the percentage of silicon according to formula (1):
Si(%) = [(m - m.) = (m= m)2× 0. 67 4. × 100me
Wherein: m,
Mass of crucible and precipitate before hydrofluoric acid treatment, 8;Mass of crucible and precipitate after hydrofluoric acid treatment, 8;Mass of crucible and reagent blank before hydrofluoric acid treatment, 8;Mass of crucible and reagent blank precipitate after hydrofluoric acid treatment, g.Weighing weight, g:
0. 4674.--
6 Allowable difference
Coefficient of converting silicon dioxide into silicon.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table
0.10~~0.50Www.bzxZ.net
>0. 50～1. 00
≥1. 00~3. 00
>3. 00 ~6. 00
Additional Notes:
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 drafter of this standard is Yang Qiuping.
Additional Notes:
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.