GB/T 4699.2-1984 Chemical analysis methods for silicon-chromium alloys - Alkali fusion-ammonium persulfate oxidation volumetric method for determination of chromium content

GB/T 4699.2-1984 Chemical analysis methods for silicon-chromium alloys - Alkali fusion-ammonium persulfate oxidation volumetric method for determination of chromium content GB/T4699.2-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of silicochromiumIhe alkaline fusion-ammonlum persulfateoxidation volumetric method for the determinationof chromium+contellt
Introduction to the standard: Determination of chromium+content in silicon-chromium alloys. Determination range: 25.00~50.0°C: UDC 669.782.5' 26
543.24:546
GB 4699.2-84
A The standard complies with GB 1467-78 General Principles and Regulations for Chemical Analysis of Metallurgical Products". Method Summary
The sample is dissolved in sodium hydroxide, dissolved in hot water, acidified with sulfuric acid: oxidized with ammonium sulfate, high-energy acid is distinguished by acidification, reduced with standard ammonium sulfate solution, and reversed with high-energy acid standard solution. Reagents
2.1 Sodium hydroxide: analytical grade,
hydrochloric acid (1+3)
sodium phosphate (specific gravity 1.70).
vitriol acid (0.5)
manganese sulfate solution: 100g manganese sulfate (MnSOH,O) is dissolved in water, diluted to 1000ml, mixed with 2.6 ||tt ||2.7 Ammonium persulfate solution (20%): Prepare when needed. 2.8 Potassium permanganate solution (0.3%)
2.9 Standard ammonium ferric sulfate solution (n.IN) 2.9.1 Preparation
Add 30ml sulfuric acid (specific gravity 1.84) to 305ml water, add 40g ammonium ferric sulfate, wait for it to dissolve completely, then add about 700ml water and mix.
2.9.2 Calibration wwW.bzxz.Net
Take 25.00ml of standard ammonium ferric sulfate solution (2.9.1), add 25ml, 5ml phosphoric acid (2.4). Add potassium permanganate standard solution (2.10.1) dropwise until it turns slightly red. 2.10 Standard manganese acid solution (3.1N) 2.10.1
Take 3.3g potassium manganate, add 1050ml water, heat to a low temperature, keep for 1-2h, let the filtered body be slightly filtered, transfer to a brown plate that has been washed with steam for 3 hours, and store it for about 2 hours.
2.10.2 International
National Bureau of Standards 19841004 Issued
1985 09 01 Implementation
GH 499.2—84
Weigh about 22.5g (refined to 0.0001g) sodium oxalate standard reagent dried at 150-200℃. Dissolve in water and transfer to a 250ml volumetric flask to dilute to 25ml. Filter evenly. Take 25.00ml of this solution and add 200ml of water and 10ml of sulfuric acid (specific gravity 1.84) to make the solution temperature reach 25-30℃. Stir slowly while completely raising the burette. Add the required amount (about 2937ml) of permanganate standard solution (2.10.1) dropwise to about 2ml. Wait until the red color disappears and heat to 5%. ～60, continue to slowly titrate with potassium permanganate standard solution until it turns slightly red, and keep it for 30s without fading as the end point (0.5-1ml should be added drop by drop before the end point, and the previous drop should be added later.
In addition: slowly add 10ml of liquid (specific gravity 1.42) into 1200ml water, heat to 5-60 (:, do a blank test to calibrate 2.11-sodium sulfonate solution (0.1)
The sample should pass through 0.125m dry..
Analysis steps
4.1 Test volume
Weigh 1.5000g of sample.
4.2 Determination
4.2.1 Place the sample (4.1) in 30 ml of alumina or oxidizing agent, add 10 g of sodium peroxide (2.1), stir thoroughly, and heat the sample on a hot plate with a flux of 350-400% to melt it. Stir it with a needle under a low-temperature flame to avoid deflagration. Operate for about 5 minutes at about 7 °C until it melts.
4.2.2 Cool naturally. Place the sample in a 50 mm beaker, add 100 mm of hot water to remove the melt, cool it, and add 6 ml of hot water. Take out the mixture (2.3), wash with water for about 10 minutes, cool it down, transfer it into a 500ml container, dilute it with 120ml water to 60ml, mix it well, take 100ml of the liquid, transfer it into 500ml of boiling water, add 55ml of phosphate (2.1) and 120ml of sulfuric acid (2.3), dilute it with warm water to about 200ml4.2.4 Add 0.5ml of potassium manganate solution (2.8), 1Uml of nitric acid solution (2.5) and 5-25ml of ammonium persulfate solution (2.7), boil it to oxidize it into heavy acid, when a reddish layer of manganese acid appears, boil it for 5 minutes again to decompose the excess ammonium persulfate, add 5ml of hydrochloric acid (2.2) and 51ml of manganese sulfate (2.6) and boil it. After the high-chain acid is decomposed, continue to boil it for 2-3 minutes, cool it to room temperature, and then dilute it with 25ml of water.
Task: It can also be replaced by polarization of ammonium aldehyde, that is, the solution will be heated to nearly the limit, and the acid will be added at a rate of 23 drops each time, and then continued for 5min to completely oxidize the chromium. If the precipitation of manganese dioxide (2.2) and manganese sulfate (2.6) is still sensitive to hydrochloric acid or (organic manganese), add 2-3 ml of salt solution (3.2) and boil to completely decompose it. 4,2.5 titrate with ammonium ferric sulfate standard solution (2.4.1) to the heavy acid solution: then add 5-10 ml and immediately titrate with potassium permanganate standard solution (2.11.1) until the solution turns purple as the end point (when the end point is unclear, add 2-3 drops of sodium aniline sulfonate (2.11) solution):
5 Calculation of analysis results
According to the calculation of the complex mass:
Cr R%) - (1- 2: 9173 v 100
Formula: [: The first-class rubber length iron desire standard non-group density (2.0.]), [; F, the volume of the high potassium standard solution consumed when full, m: K-: The volume of the standard solution of manganese and potassium, m: C-: The concentration of the standard solution of slightly acidic industry, Nm
Chen sample volume,;
GB 4699.2-B4
1V The amount of chromium equivalent to the standard solution of ammonium ferric sulfate, g/nlt test solution ratio.
The analysis results are expressed to two decimal places. The difference between the analysis results of the laboratories should not be greater than the allowable difference listed in the following table.
≥25.00- 50.00
Additional Notes:
This standard is issued by the Ministry of Metallurgy of the People's Republic of China: This standard is issued by Shanghai Ferroalloy! Responsible for the implementation of this standard, the original standard of the Ministry of Metallurgy is YB577-65 "Chemical Analysis Method of Alloys", the price absorption, %
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.