JB/T 3168.3-1999 Chemical composition analysis method for spray welding alloy powder
Some standard content:
ICS25.160.20
Mechanical Industry Standard of the People's Republic of China
JB/T3168.3-1999
Chemical Composition Analysis Methods
Alloy Powder for Welding-Chemical analys is methodsPublished on 1999-06-24
National Bureau of Machinery Industry
Implementation on 2000-01-01
JB/T3168.3—1999
This standard is a revision of JB317082 "Chemical Composition Analysis Methods for Alloy Powder for Welding". Only editorial changes were made to the original standard during the revision, and its main technical content remained unchanged. This standard replaces JB3170—82 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Welding Standardization. The responsible drafting units of this standard are Harbin Welding Research Institute and Tianjin General Company Metrology Station. The main drafters of this standard are Sun Yujiu and Zhao Xingru. This standard was issued in 1982, and this revision is the first revision. 1
1 Scope
Machinery Industry Standard of the People's Republic of China
Alloy powder for welding-Chemical analysis methods This standard specifies the analysis method of the chemical composition of alloy powder for welding. This standard is applicable to alloy powder for plasma welding and oxyacetylene flame welding. 2 Referenced standards
JB/T3168.3-1999
Replaces JB3170—82
The provisions contained in the following standards constitute the provisions of this standard by being cited in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards: GB/T223.1-1981
JB/T3168.1-1999
3 General provisions
Determination of carbon content in steel and alloys
Technical conditions for spray welding alloy powder
The powder sample should be clean and oil-free, and the sampling method in 5.2.2 of JB/T3168.1-1999 should be followed, and the sample should be stored in a desiccator. The sensitivity of the analytical balance used should reach 0.1 mg. 3.2
The water used for reagent preparation and analysis should be distilled water or ion exchange water. 3.3
Unless otherwise specified, reagents should be analytically pure or guaranteed reagents. 3.4wwW.bzxz.Net
The solutions contained in the standard are all aqueous solutions except those with specified solvents. 3.5
The solution (1+2) in the standard, for example, refers to a solution of 1 part (in terms of volume) of hydrochloric acid (specific gravity 1.19), sulfuric acid (specific gravity 1.84), nitric acid (specific gravity 1.42) 3.6
phosphoric acid (specific gravity 1.70), perchloric acid (70%) or ammonium hydroxide (specific gravity 0.90) and 2 parts of water. 3.7 The percentage concentration in the standard refers to the number of grams of solute contained in 100mL of solution. For example, 10% sodium chloride solution means that 10g of sodium chloride is contained in 100mL of solution.
3.8 The hot water or hot solution in the standard refers to a temperature of 70-80℃. 3.9 The instruments and measuring tools used in the standard must be calibrated. Determination of carbon content
According to the determination of carbon content in GB/T223.1. Alloy powder and steel belong to two types of materials, so there are slight modifications and supplementary instructions in terms of sample weighing, furnace temperature, flux and preheating time as follows: a) Sample weighing 0.25kg;
b) The furnace temperature should be maintained at about 1250℃ for testing; c) The flux should be 0.5~1g of vanadium pentoxide, and a blank test should be performed. If there is a blank, it should be subtracted from the result: d) The preheating time is 2.5~3min
Approved by the State Machinery Industry Bureau on June 24, 1999 and implemented on January 1, 2000
5 Determination of silicon content
Glycerol dehydrated animal glue precipitated silicon weight method. JB/T3168.3—1999
Note: Methanol can also be used to remove boron, and the perchloric acid dehydration weight method. 5.1 Method Summary
The sample is boiled and dehydrated with glycerol in an acidic solution, silicon is precipitated with animal glue, filtered and washed, and then burned to silicon dioxide. Silicon is volatilized and removed with sulfuric acid and hydrofluoric acid to form silicon tetrafluoride. The percentage content is calculated from the weight difference before and after silicon removal. Arbitration range: 0.60% 4.50%
5.2 Reagents
Saturated hydrochloric acid with bromine: Add bromine saturated to hydrochloric acid (specific gravity 1.19). Nitric acid (specific gravity 1.42).
Hydrochloric acid (specific gravity 1.19), (1+1).
Sulfuric acid (1+2).
Hydrofluoric acid (40%).
Glycerol.
Gelatin solution: Dissolve 25g gelatin in 450mL hot water, dilute to 500mL and place in a cold place. It can be used for 4 days. 5.3 Analysis steps
Weigh 0.5000g or 1.0000g of the sample, place it in a 400mL beaker, add 50mL of bromine-saturated hydrochloric acid, heat on a hot plate to dissolve, until most of the sample is dissolved, then add 10mL of bromine-saturated hydrochloric acid to dissolve until the reaction stops, add 5mL of nitric acid until the sample is completely dissolved, boil at high temperature until the volume is 15~20mL, carefully add 15mL of glycerol, shake well, boil carefully, and shake the beaker to avoid burning, until small bubbles are generated, remove from the heat, cool slightly, add 20mL of hydrochloric acid (specific gravity 1.19), boil for 5min, cool to 90℃, add 5~6mL of heated gelatin solution (5%) while stirring continuously, stir for 2min, and let it stand for at least 5min. Add 100mL of hot water containing 10mL of 5% gelatin solution, stir well, filter after cooling, carefully use a glass rod with a rubber head to transfer the sediment to the filter paper, wash with hydrochloric acid (1+1) solution 3 times, and then wash with hot water containing 5% gelatin solution 6~10 times. First dry and carbonize, then burn in a high-temperature furnace at 1000~1050℃ for 30min, take out, place in a desiccator to cool to room temperature, weigh, this weight is A. Add 3~5 drops of water along the inner wall of platinum to moisten the residue, add 2~3 drops of sulfuric acid (1+2), 3~5mL of hydrofluoric acid, evaporate at low temperature until all sulfuric acid fumes are emitted, then place the platinum glass at 800℃17 and burn 15~20mm, cool, weigh, and repeatedly burn to constant weight, this weight is B.
The percentage of silicon is calculated according to formula (1):
Si=(4-B)x0.4675 ×10%
Wherein: A—weight before hydrofluoric acid treatment, 9; B—weight after hydrofluoric acid treatment, g
0.4675-The coefficient of silicon dioxide converted to silicon W-the weight of the sample, g.
5.4 Allowable difference
1) Samples containing molybdenum, tungsten and molybdenum-tungsten are burned to constant weight at 550℃ (containing molybdenum), 800℃ (containing tungsten) and 600℃ (containing tungsten-molybdenum) respectively. 2
See Table 1 for the allowable difference.
Determination of boron content
Silicon content
0.501-4.00
Acid-base titration volumetric method.
6.1 Method Summary
JB/T3168.3—1999
Allowance
The sample is melted with sodium peroxide, leached with water, and elements such as iron and nickel are separated. The chromium is separated by precipitation with barium carbonate. p-nitrophenol is used as an indicator, neutralized with hydrochloric acid, and then mannitol is added to make it form a strong complex acid with boric acid. Phenol is used as an indicator, titrated with sodium hydroxide standard solution, and back-titrated with hydrochloric acid standard solution. Arbitration range: 0.50%~5.00%
6.2 Reagents
Sodium peroxide.
Hydrochloric acid (1+1).
Anhydrous sodium sulfite solution (10%).
Barium carbonate.
p-nitrophenol indicator (0.2%) solution. Phenol indicator (1%) ethanol solution.
Mannitol (or glycerol).
Sodium hydroxide standard solution (Q05N): Weigh 2g of sodium hydroxide, put it in a small beaker, add 50~60mL of water to dissolve it, then add 2~3mL of 10% barium chloride solution to precipitate carbonate, let it stand to make the solution clear, transfer it to a 1000mL volumetric flask, and then dilute it to the scale with boiled distilled water, and use it after calibration (store in a plastic bottle). Calibration of sodium hydroxide standard solution: Weigh 0.1500g of 105℃ dried standard potassium hydrogen phthalate (3 portions) are placed in 250mL conical flasks, dissolved with 20mL ethanol, added with about 50mL neutral water, and 23 drops of phenol. Titrate with sodium hydroxide standard solution until it turns pink. The extreme difference in the milliliters of sodium hydroxide standard solution consumed by the 3 solutions shall not exceed Q05mL, and the average value is taken. The equivalent concentration of sodium hydroxide standard solution is calculated according to formula (2): G×1000
Where: N-equivalent concentration of sodium hydroxide standard solution: G weight of potassium hydrogen phthalate, g
204.22-equivalent of potassium hydrogen phthalate: V volume of standard sodium hydroxide solution consumed, mL. Hydrochloric acid standard solution (0.05N): Take 4.2mL of hydrochloric acid (specific gravity 1.19) and dilute to 1000mL with water. (2)
JB/T3168.3—1999
Calibration of the volume ratio of hydrochloric acid standard solution to sodium hydroxide standard solution: Take three portions of 20 mL of hydrochloric acid standard solution and place them in three 200 mL conical flasks. Add 2 to 3 drops of phenolic indicator to each portion and use sodium hydroxide standard solution until it turns light red. The extreme difference in the milliliters of sodium hydroxide standard solution consumed by the three portions of solution shall not exceed 0.05 mL, and the average value shall be taken. The volume ratio of hydrochloric acid standard solution to sodium hydroxide standard solution is calculated according to formula (3): KV
Where: K is the volume ratio of hydrochloric acid standard solution to sodium hydroxide standard solution; V is the volume of sodium hydroxide standard solution consumed, mL. 6.3 Analysis steps
Weigh 0.5000g of the sample (to be used as a reagent blank during the operation), place it in a nickel crucible containing 4g of sodium peroxide, mix it well and bake it on an electric furnace, then melt it at 750℃ for 15min, cool it, place it in a 250mL beaker, add 70mL of boiling water to leach the melt, wash it, heat it to boil, transfer it to a 250mL volumetric flask after cooling, dilute it to the scale with water, and shake it well. Dry filter, take 50mL of the filtrate, place it in a 250mL beaker, put in a small piece of Congo red test paper, add hydrochloric acid (1+1) until the Congo red test paper turns blue, a few drops in excess, then add sodium sulfite solution (10%) until the solution turns blue-green of trivalent chromium, 1~2 drops in excess, boil it, add solid carbonate lock until the Congo red test paper turns red, and a little in excess, boil it for 2min, and drive off carbon dioxide. Filter it with fast filter paper and wash it with hot water 5 times.
Add 1~2 drops of p-nitrophenol indicator to the filtrate. The solution is yellow. Titrate with hydrochloric acid (0.05N) standard solution until the yellow turns to colorless. Regardless of the amount, add 2g of mannitol (or 20~25mL of glycerol). Add 2~3 drops of phenolphthalein indicator and titrate with sodium hydroxide standard solution (0.05N) until it turns pink. Then add 0.5g of mannitol. If the red color does not disappear, continue to add 0.5mL of sodium hydroxide standard solution. Then use a microburette to titrate the hydrochloric acid standard solution (0.05N) until the red turns to yellow. This is the end point. The percentage of boron is calculated according to formula (4):
0.01082×V-VK)×N×100%x
Wherein: V-the volume of sodium hydroxide standard solution consumed, mL: V2-the volume of hydrochloric acid standard solution consumed by back-titration of excess sodium hydroxide solution, mL; K-the volume ratio of hydrochloric acid solution to sodium hydroxide standard solution: N-the equivalent concentration of sodium hydroxide standard solution: W-the weight of the sample taken, g:
0.01082 milligram equivalent of boron;
X-the percentage of boron equivalent to reagent blank.
6.4 Allowable difference
See Table 2 for the allowable difference.
Boron content
0.10-0.50
0.51~1.00
Allowable difference
7 Determination of chromium content
Ammonium persulfate silver salt volumetric method.
7.1 Method Summary
JB/T3168.3—1999
The sample is dissolved in sulfuric and phosphoric acid mixture, and silver nitrate is used as catalyst. Ammonium persulfate oxidizes trivalent chromium to hexavalent chromium, and manganese is also oxidized to permanganate. Sodium chloride is used to remove the interference of permanganate, and then N-phenyl anthranilic acid is used as an indicator. Ammonium ferrous sulfate standard solution is used for titration to reduce hexavalent chromium to trivalent chromium. For samples containing vanadium, ferrous o-phenanthroline is used as an indicator, excess ammonium ferrous sulfate standard solution is added, and potassium permanganate is used for back titration.
Arbitration range: 2.00% 50.00% g
7.2 Reagents
Hydrochloric acid (1+1)
Nitric acid (specific gravity 1.42).
Hydrogen peroxide (30%).
Phosphoric acid (specific gravity 1.70).
Hydrofluoric acid (40%).
Sulfuric acid (specific gravity 1.84).
Sulfur-phosphorus mixed acid: sulfuric acid + phosphoric acid + water = (320 + 160 + 520). Silver nitrate solution (2.0%): weigh 2g of silver nitrate and dissolve it in 100mL of water, add a few drops of nitric acid and store it in a brown bottle. Ammonium persulfate solution (25%).
Sodium chloride solution (5%).
Manganese sulfate solution (4%).
Anhydrous sodium acetate or crystalline sodium acetate (CH,COONa·3H,O). N-phenylated anthranilic acid solution: 0.2%, weigh 0.2g of reagent in a 300mL conical flask, add 0.2g of anhydrous sodium carbonate, add 20mL of water, heat to dissolve, cool, dilute to 100mL, and shake to hook. Ferrous-o-phenanthroline indicator: Weigh 1.49g o-phenanthroline, 0.7g ferrous sulfate (FeSO4·7HO) or 0.98g ammonium ferrous sulfate [(NH4)2Fe(SO4)26HO], place in a 300mL conical flask, add 50mL water, heat to dissolve, cool, dilute to 100mL and shake well.
Potassium dichromate standard solution:
a) Weigh 5.6578g of the reference reagent that has been pre-dried at 150℃ for 1h, dissolve it in water, transfer it to a 1000mL volumetric flask, dilute to the mark with water, and shake well. This solution contains 2.00mg chromium in 1mL. This solution is standard solution A. b) Take 50.00mL of the standard solution and place it in a 100mL volumetric flask, dilute to the mark with water, and shake well. This solution contains 1.00mg chromium in 1mL. This solution is standard solution B.
Ammonium ferrous sulfate standard solution (0.06N): Weigh 24g of ammonium ferrous sulfate [(NH4)Fe(SO4)2·6HO), dissolve in sulfuric acid (5+95), dilute to 1000mL with this acid, and shake well. Ammonium ferrous sulfate standard solution (0.1N): Weigh 40g of ammonium ferrous sulfate [(NH4),Fe(SO4)2·6HO, dissolve in sulfuric acid (5+95), dilute to 1000mL with this acid, and shake well. Calibration of the titer of ammonium ferrous sulfate to chromium: Take three portions of potassium dichromate standard solution (its content should be close to the chromium content in the sample), place them in 500mL conical flasks, add 25mL sulfur-phosphorus mixed acid, 4 drops of manganese sulfate solution, dilute with water to 200mL, add 3mL5
JB/T3168.3—1999
silver nitrate solution, 20mL ammonium persulfate solution, and boil. The following is the analysis procedure for samples without vanadium. The extreme difference in the number of milliliters of ammonium ferrous sulfate standard solution consumed by three portions of potassium dichromate standard solution shall not exceed 0.05mL, and the average value is taken. The titration degree of ammonium ferrous sulfate standard solution on chromium is calculated according to formula (5): 7=VC
Wherein: T—the titration degree of ammonium ferrous sulfate standard solution on chromium, g/mL; V—the volume of potassium dichromate standard solution, mL; C—the chromium content of potassium dichromate standard solution, gmL; V—the volume of ammonium ferrous sulfate standard solution consumed in titration, mL. (5)
Potassium permanganate solution (0.06N): Weigh 1.9g potassium permanganate, place it in a 300mL conical flask, add a small amount of water to dissolve it, pour it into a dark glass bottle, add 5~10mL phosphoric acid, dilute it to 1000mL with water, and shake it well. Place it in a cool place for 3~4 days and filter it with glass before use.
Calibration of the volume ratio of potassium permanganate to ammonium ferrous sulfate standard solution: Take 25.00mL of ammonium ferrous sulfate standard solution in three portions, place them in 200mL conical flasks respectively, and titrate with equivalent potassium permanganate solution until the solution turns light red and does not disappear within 1~2 minutes. The extreme difference of the milliliters of potassium permanganate consumed in the three portions shall not exceed 0.05mL, and the average value is taken. The volume ratio of potassium permanganate solution to ammonium ferrous sulfate standard solution is calculated according to formula (6): K=25.00
Where: K The volume ratio of potassium permanganate solution to ammonium ferrous sulfate standard solution: V2 The volume of potassium permanganate solution consumed, mL. 7.3 Analysis steps
Weigh 0.Place 1000g in a 300mL conical flask, add 15mL hydrochloric acid (1+1), a few drops of hydrogen peroxide, heat at low temperature to dissolve (add a few drops of hydrofluoric acid to assist dissolution; if the sample is not completely dissolved and the acid has evaporated, add more hydrochloric acid and hydrogen peroxide). After dissolution, add 25mL of sulfur-phosphorus mixed acid, heat and evaporate until smoking, then add nitric acid to oxidize. When the sample contains vanadium or tungsten, add 10mL of phosphoric acid (specific gravity 1.70)2, and continue to evaporate until sulfuric acid smoke appears for 2 minutes, remove, cool slightly, dilute with water to 200mL, add 3mL of silver nitrate solution, 20mL of ammonium persulfate solution, shake well, and heat until the solution is stable rose red (if the manganese content in the sample is low, add a few drops of manganese sulfate and boil until the solution is stable rose red), continue to boil for 5 minutes, remove, add 7mL of sodium chloride solution, boil until the pink color disappears, continue to boil until the silver chloride precipitate condenses and sinks, cool rapidly, and titrate with ammonium ferrous sulfate standard solution for 3. until the solution is light yellow, add 3 drops of N-phenyl tauryl benzoic acid and continue to titrate until the rose color changes to bright green as the end point. The percentage of chromium is calculated by formula (7):
VT×100%
1) When the sample is cobalt-based powder, dissolve the sample with sulfur-phosphorus mixed acid [carefully add 300mL sulfuric acid (specific gravity 1.84) to 400mL water, cool and add 300mL phosphoric acid (specific gravity 1.70) and 20mL to dissolve by heating. After dissolution, evaporate until white sulfur trioxide smoke emerges, add nitric acid (specific gravity 1.42) dropwise to oxidize, decompose the carbide completely, cool, and dilute to 200mL with water. Follow the analysis steps below. 2) When tungsten and vanadium coexist, add 200mL phosphoric acid (specific gravity 1.70) to the dissolved sample. Add 20g of anhydrous sodium acetate during titration. 3) When the chromium content is greater than 25%, titrate with 0.1N ammonium ferrous sulfate standard solution. 6
JB/T3168.3-1999
Wherein: V is the volume of ammonium ferrous sulfate standard solution consumed in titration, mL; T is the titer of ammonium ferrous sulfate standard solution to chromium, g/mL: W is the sample weight, g.
The vanadium-containing powder is titrated according to the following steps: first, titrate with ammonium ferrous sulfate standard solution until the yellow color of hexavalent chromium turns to bright green, add 5 drops of ferrous-o-phenanthroline 1, and titrate until the solution is stable red, and the excess is 5mL. Back-titrate with potassium permanganate solution until the red color disappears for the first time, add 10g of anhydrous sodium acetate (1g of anhydrous sodium acetate is equivalent to 1.66g of crystalline sodium acetate), shake the conical flask until the sodium acetate dissolves, and continue to slowly titrate with potassium permanganate solution until the light blue color (blue-green when the chromium content is high) is the end point. The percentage of chromium is calculated according to formula (8):
(4-V,K)×T
Wherein: V4
The volume of ammonium ferrous sulfate standard solution consumed, mL; X100%
.......
V—The volume of potassium permanganate solution consumed by the excess ammonium ferrous sulfate standard solution minus the volume corrected by ferrous-o-phenanthroline indicator, mL:
K—The volume ratio of potassium permanganate solution to ammonium ferrous sulfate standard solution: T—The titer of ammonium ferrous sulfate standard solution to chromium, g/mL; w——The weight of the sample, g.
7.4 Allowable difference
The allowable difference is shown in Table 3.
Chromium content
5.01~10.00
10.01~14.00
14.01~18.00
1801-30.00
3Q01~50.00
8 Determination of iron content
Hydroxide separation-potassium dichromate titration method 8.1 Method summary
After decomposing the sample with acid, precipitate iron with ammonia water. Allowable difference
1) Ferrous iron-o-ferrous iron The consumption of potassium permanganate solution by the phenanthroline indicator must be corrected. The steps are as follows: %
After the calibration of the volume ratio of potassium permanganate solution to ammonium ferrous sulfate standard solution, add 5 drops of indicator to one of the two solutions and 10 drops of indicator to the other. Titrate with potassium permanganate solution of the same concentration as the titration sample. The difference in the consumption of potassium permanganate solution is equivalent to the correction value of 5 drops of indicator. This value should be subtracted from the milliliters of potassium permanganate solution consumed by the excess ammonium ferrous sulfate standard solution. 7
JB/T3168.3—1999
In hydrochloric acid solution, tin dichloride is used to reduce trivalent iron to divalent iron, and excess stannous chloride is oxidized with high mercuric chloride. In the presence of phosphoric acid and sulfuric acid, sodium diphenylamine sulfonate is used as an indicator to titrate with standard potassium dichromate solution. The interference of nickel and cobalt can be separated with ammonia water in the presence of ammonium chloride. Arbitration range: 1.00%-8.00%
8.2 Reagents
Bromolybdenum saturated hydrochloric acid.
Perchloric acid (70%).
Ammonium hydroxide (specific gravity 0.90), (2%). Ammonium chloride.
Hydrochloric acid (1+1), (specific gravity 1.19).
Sulfuric acid (specific gravity 1.84).
Tin dioxide solution (5%): Dissolve 5g of tin dichloride in 20mL of hydrochloric acid (specific gravity 1.19), add water to 100mL, and add 2~5g of metal tin particles.
Mercuric dichloride solution (2.5%).
Sulfur-phosphorus mixed acid: Add 15mL each of sulfuric acid (specific gravity 1.84) and phosphoric acid (specific gravity 1.70) into 70mL of water. Sodium diphenylamine sulfonate indicator (0.3%): add 1-2 drops of sulfuric acid (specific gravity 1.84) to every 100 mL. Potassium dichromate standard solution (0.02N): weigh 0.9807 g of the standard potassium dichromate dried at 150-160 °C in advance, dissolve in a small amount of water, transfer to a 1000 mL volumetric flask, dilute to scale with water, and mix well. 8.3 Analysis steps
Weigh 0.5000 g of the sample and place it in a 300 mL beaker, add 50 mL of bromine-saturated hydrochloric acid and heat. After the action stops, add 15 mL of perchloric acid and continue to dissolve. After dissolution, continue to heat until white smoke appears, add 20 mL of water until the soluble salt is completely dissolved, transfer to a 50 mL volumetric flask, dilute to scale with water, and shake well.
Dry filter, take 20mL of the filtrate, put it in a 400mL beaker, add water to 200mL, add 3g of ammonium chloride, neutralize with ammonia water until the iron hydroxide is completely precipitated, then add 5mL of excess, heat and boil for 1~2min, let it stand until the precipitate sinks, filter it with fast filter paper, and wash the precipitate with hot ammonia water (2%) 7-8 times.
Use 20mL hot hydrochloric acid (1+1) to dissolve the precipitate, and wash the iron ions alternately with hot water and hot hydrochloric acid (1+1), and then wash with hot water 3~4 times. Collect the filtrate in the original beaker, evaporate on a hot plate to a volume of about 20mL, add tin dichloride solution (5%) while hot until the yellow color disappears, add 1 drop of excess, quickly cool with running water, add 5mL of mercuric dichloride solution (2.5%), let stand for 2~3min, add 120mL of water, 10mL of sulfur-phosphorus mixed acid, 5~6 drops of sodium diphenylamine sulfonate indicator, and titrate with potassium dichromate standard solution (0.02NM) until it turns from green to purple.
The percentage of iron is calculated according to formula (9):
Fe-NV×0.05585×100%
Wherein: N is the equivalent of potassium dichromate standard solution: V—volume of potassium dichromate standard solution consumed in titration, mL; W—weight of sample taken, g:
0.05585 is the milligram equivalent of iron.
8.4 Tolerance
The tolerance is shown in Table 4.
Iron content
Determination of tungsten content
Thiocyanate photometric method.
9.1 Summary of the method
JB/T3168.3-1999
Tolerance
The sample is dissolved in bromine-saturated hydrochloric acid and perchloric acid, evaporated until white perchloric acid smoke is emitted, add cinchonine to completely precipitate the tungsten, filter and wash. Dissolve the precipitate in sodium hydroxide, add nitric acid and mixed acid, and heat to decompose the filter paper. After adding stannous chloride to reduce tungsten, add thiocyanate to make tungsten into thiocyanate complex of tungsten, and measure its absorbance. Arbitration range: 0.50%-6.00%.
9.2 Reagents
Bromolybdenum saturated hydrochloric acid.
Perchloric acid (70%).
Sulfuric acid (specific gravity 1.84).
Phosphoric acid (specific gravity 1.70).
Nitric acid (specific gravity 1.42).
Hydrochloric acid (specific gravity 1.19).
Cinchonine solution (12.5%): Take 12.5g of cinchonine and dissolve it in 100mL of hydrochloric acid (1+1) solution. Cinchonine wash solution: Take 30mL of cinchonine solution (12.5%) and dilute it to 1000mL with water. Sodium hydroxide solution (10%): Prepare when needed. Mixed acid: perchloric acid + sulfuric acid + phosphoric acid + water = (1+1+1+1). Stannous chloride solution: Dissolve 7g of stannous chloride in an appropriate amount of hydrochloric acid, and dilute to 100mL with hydrochloric acid. Ammonium thiocyanate solution: Dissolve 20g of ammonium thiocyanate in an appropriate amount of water, dilute to 100mL with water, and prepare when needed. Tungsten standard solution: Weigh 1.7960g of sodium tungstate (Na,WO·2HO), dissolved in appropriate amount of water, transferred to a 1000mL volumetric flask, diluted to scale with water, and shaken. This solution contains 1mg of tungsten in 1mL, and is calibrated by weight method. 9.3 Analysis steps
Weigh 0.2000g of sample, place in a 500mL beaker, add 20mL of bromine-saturated hydrochloric acid, heat to dissolve, after the action stops, add 20mL of perchloric acid, continue heating for 1, evaporate until white smoke appears, oxidize chromium to dichromic acid, and continue to smoke for 3~5min. After cooling, add 100mL of water to dissolve the salts, add 5mL of cinchonine solution, slowly boil for about 10min, let it stand for a while, filter the precipitate with filter paper with a small amount of filter paper pulp, and wash it thoroughly with cinchonine washing solution. Transfer the precipitate and filter paper into the original beaker together, add 20mL of sodium hydroxide solution, slightly heat to dissolve the precipitate, add 30mL of nitric acid1): If the sample is not completely dissolved, 5-6 drops of hydrofluoric acid can be added. 9
JB/T3168.3—1999
and 20mL of mixed acid, heat to decompose filter paper, etc. Continue to heat and evaporate white smoke until the solution becomes transparent. After cooling, add 50mL of water, cool again, transfer to a 100mL volumetric flask, and dilute with water to the scale. Take 5mL, place it in a 100mL volumetric flask, add 40mL of stannous chloride solution, immerse it in a water bath (about 60℃) for about 10min, cool it with running water, add 10mL of ammonium thiocyanate solution, cool again, dilute it with water to the scale, shake it thoroughly, let it stand for 10min, use water as a blank, and measure its absorbance at a wavelength of 400nm. Drawing of the standard curve: weigh several portions of 0.2g of pure iron, place each in a 500mL beaker, add 0~15.0mL of tungsten standard solution, add dissolved acid and follow the operating steps to measure its absorbance. Draw the curve. 9.4 Allowable difference
See Table 5 for the allowable difference.
Tungsten content
0.50-1.50
1.51-3.00
3.01-6.00
10 Determination of nickel content
Ion exchange separation--dimethylacetyl nickel gravimetric method. Note: The determination of nickel in iron-based powder is carried out by dimethylacetyl separation-EDTA volumetric method. 10.1 Method summary
Allowable difference
In hydrochloric acid solution, cobalt, iron and other elements are separated by ion exchange chromatography. After separation, nickel is precipitated into dimethylacetyl nickel by dimethylacetyl alcohol solution. The precipitate is dried and weighed. Arbitration range: 2.00%~35.00%
10.2 Apparatus
Ion exchange column, diameter about 25mm, column length 300mm (see Figure 1). Ion exchange resin, using domestic 717 type (alkyl quaternary amine type) chloride anion exchange resin, crosslinking degree 8%, particle size 0.180~0.154mm.
Take an appropriate amount of resin, put it in a 400mL beaker, soak it in water until the resin reaches maximum expansion, pour out most of the water, add 200mL hydrochloric acid (1+19) and stir vigorously, let it stand for 4~6min, let the resin sink, pour out the upper suspension and discard it. Repeat the treatment with hydrochloric acid (1+19) for more than 2 times, and keep the coarser resin for column loading. The preparation of the ion exchange column is as follows: fill the bottom of the column with 10~20mm glass wool, fill it with the treated resin to a height of about 150mm, and put about 20mm of glass wool on the top to prevent the resin from being stirred when the solution is added. After loading, rinse it once with 50mL hydrochloric acid (1+19), and saturate it with 80mL hydrochloric acid (3+1) before use. 10.3 Reagents
Bromine saturated hydrochloric acid.
Perchloric acid (70%).
Hydrochloric acid 12M, 9M, 4M, 0.6M, (1+19), (3+1), (1+2), (specific gravity 1.19). 10
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