Method for chemical analysis of Nickel and Nickel alloy for vacuum tubes
Some standard content:
Standard of the Ministry of Electronics Industry of the People's Republic of China Chemical Analysis Method for Nickel and Nickel Alloys for Vacuum Devices SJ 1542~87
replaced SJ1542-79
The method is applicable to the analysis of carbon, phosphorus, iron, manganese, nickel, tungsten, cobalt and silicon in nickel and nickel alloys for vacuum devices. 1 General Matters The reagents used in the method are analytically pure unless otherwise specified. 1.1 The water used in the new method is specified as deionized water or deionized water. The main reagent solution is expressed in grams of the reagent contained in the solution. The solvent used in the analysis is not specified. Water is used, and the analytical instrument is used. The sensitivity is 0.1m≤, and the weighing should be accurate to 0.2m. The so-called "constant weight" in the method means that the difference between the two weighing pans does not exceed 1.2m. The concentration and conversion coefficient of the standard solution are all retained. The selection of effective effect shall be carried out according to G.1-8? "General Regulations for the Preparation of Standards for Standardization Work" Attached to the Six-Person-Single-Double Method: 1.9 Standard temperature is 20℃. Room temperature is 1-85℃. Warm water is 40-60℃. Hot water is above 0℃ and cold water is below 1C.
2 Determination of carbon and sulfur
Method 1: Carbon and sulfur are measured by induction method
2, 1, 1 Key points of the method:
Test the mixture with oxygen to oxidize it into carbon dioxide and sulfur dioxide, respectively, and absorb them by potassium dichromate solution: Determine the change in the conductivity of the potassium dichromate solution before and after the absorption of carbon dioxide and sulfur dioxide.
21.2 Reagents
2.1.2.1 Remove the water and make sure that the resistance is greater than 800, boil it to 101 and cool it for use. 2.1.2.2 Potassium chromate solution
Weigh 0.15% potassium chromate solution and dissolve it in 5% water, add 1% sulfuric acid to reduce the resistance to about 1112Ω, such as 201 di-n-butanol, shake well and use it. This solution needs to be left for 10 days and cannot be used continuously (not for more than one week in summer). This solution can be 0.0020%~0.0050%, with an absolute error of 0.0005%. 2.1.2.3 Barium hydroxide solution
Ministry of Electronics Industry of the People's Republic of China 7987:-02-10 issued 1987--12-01 implementation
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Ba(OHD2) solution concentration
Carbon analysis range
0.008-0.05%
0.05~0. 56%
2.1.2.4 Solvent, pot granules, purity above 99.9% (low total carbon content) 2.1.3 Instruments and devices (refer to Figure 1)
3, flow meter; 4, buffer bottle,
1, oxygen bottle: 2. partial pressure gauge,
5, 7, air washing bottle: 6, washing bottle, 8, drying tower! 10, porcelain boat, 11. Porcelain tube, 12. Conductivity 9, tube furnace,
21.4 Analysis steps
2, 1, 4.1 Sample treatment: wash with ether, divide, and set aside after drying. 2, 1, 4, 2 When the combustion furnace humidity is raised to 1800℃, add 2~5ml of oxygen, start the instrument, first burn empty for blank test, confirm that there is no carbon and sulfur in the pipeline, accurately weigh 1,0000 points of nickel sample on the porcelain convex ( The porcelain boat can be used after being burned in a furnace at about 1800C for 2 minutes with oxygen before use). Add about 1 person, turn on the oxygen switch, and adjust the oxygen flow rate to 8B/m to keep it constant. After the above work is completed, press the instrument exchange key to make the heavy potassium carbonate and sodium hydroxide flow into the absorber respectively, press the magnetic adjustment zero point, and then press the support to adjust the zero point, and then push the porcelain boat into the high temperature zone. After that, plug the rubber stopper and let the oxygen burn. Press the stirring button, and the stirring will stop automatically after about 60~90S. Turn off the oxygen, press the carbon bond and sulfur bond, and record their readings respectively. When making the second sample, just press the exchange key again. The rest of the operations are the same.
Weigh different standard samples, draw the standard curve according to the above operation, and then calculate the carbon and sulfur contents according to the standard reading according to the following formula.
(,-D, ×
Carbon or sulfur [%]
Where:
--the indicated value of the recorder in the formal sample;
|f--the carbon or sulfur content (more or less) equivalent to the indicated value of each scale of the recorder;
2.1.5 Precautions
Prevent drowning.
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b The furnace temperature cannot be lower than 1800℃.
e The oxygen flow must be constant.
d Pay attention to the blanks caused by the furnace tube, porcelain boat, and solvent etching. . After making the sample with relatively high sulfur and carbon content, it should be burned once. f. Pay attention to whether the surface is smooth and free of bubbles after melting, otherwise redo it. 2.2 Method 2, Combustion - Iodine Potassium Volumetric Method for Sulfur Determination 2.21 Key points of the method
The test is conducted at a high temperature of more than 1300℃ and oxygen is passed through the test tube to burn the sulfur, so that the sulfur is oxidized and the sulfur dioxide is absorbed by the acid starch solution to generate sulfuric acid. The blue color is titrated with iodine potassium standard solution as the end point, and the standard steel is used as the titration to calculate the sulfur content.
Determination range
2.2.3 Reagents
0.008%~0.10%
2.2-3.1 Hydrochloric acid (density 1.19)
Strong solvent The purity of the tin particles is above 0.9%, and the sulfur content should be low. 2.2.3.3
Starch absorption liquid Weigh 10 soluble starch, add a little water to make a paste, add 500ml water, stir evenly, heat to boiling, then cool, add 500ml water, add 10ml hydrochloric acid (density 1.19), stir evenly and clarify. When using, take 25=1 of the second layer of clear liquid, add 15ml hydrochloric acid (density 1.19), dilute to 1 with water, and shake well.
2.2.3.4 Iodine iodide standard solution (0.015) Weigh 0.86≤ potassium iodate, dissolve it in water, transfer it to a 1L volumetric flask, and dilute to the scale with water.
2.2.3,5 Potassium iodate standard solution (0.0005) Take 50ml of 0.01N potassium iodate standard solution, place it in a 1L volumetric flask, add 1ml potassium iodide to dissolve it, dilute to the scale with water, and shake well. 22.4 Instrumentation See Figure
The gas washing bottle is filled with slurry (density 184), and the amount filled is about one-third of the height of the bottle. The upper layer of the drying tower is filled with alkali asbestos, the lower layer is filled with anhydrous calcium chloride, the middle layer is glass wool, and the bottom and top are also covered with glass wool.
Drying tube, with degreasing ladder inside
Aizhou 87, 88mm are both OK, burn at 1000℃ for 1~2 hours or in a tubular furnace at 1800℃, burn for 2 hours with oxygen, and put it into a grease-free dryer with calcium chloride inside after cooling. ~3
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1. Cover gas bottle, 2. Oxygen meter! 8. Buffer bottle: 4. Gas washing throat; 5. Drying tower; 6. Tubular furnace, 8. SCR temperature automatic controller (or rumor pressure), 9. Spherical drying tube: 10. Absorption cup, 10, fixed tube, 11, porcelain, 12, Aizhou 11, daylight (8)
2.2.5 Analysis steps
2.2.5.1 Preparation before analyzing samples
Raise the furnace temperature to 100°C, check whether the instrument cover is leaking, and burn several waste samples according to the analysis steps to make the pipeline reach equilibrium.
Prepare for absorption core of starch test, add 51ml starch solution to the absorption cup, and drive it (the flow rate is 1500~2000=1/m1). Use potassium iodate standard solution (0.000) to fill it until the light blue color does not fade, as the blank end color, and turn off the gas.
0. 0.5% potassium iodate standard solution is used for titration of sulfur. Weigh three portions of standard steel sample and measure according to the analytical steps. The difference in milliliters of the three portions of potassium iodate standard solution consumed is less than 0.2 μm. Take the average value and use it together for blank test of porcelain boat and flux. The titration degree of potassium iodate standard solution on sulfur is calculated by the following formula: S standard (%) × W
vV. Let potassium iodine standard solution be equivalent to sulfur (titer). S standard (%) - the content of sulfur in standard steel sample. Weight of standard steel (kg): double average volume of potassium iodate standard solution consumed by standard steel.
The average value of the copper iodate standard solution consumed by a titration is 2.2.52 Sample analysis
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Weigh 1.0000 μl of the sample and place it in a porcelain boat. Add an appropriate amount (usually 2) of flux. Open the rubber case and place the porcelain boat in the porcelain tube. Push it into the temperature zone with a long hook. Immediately plug it with a rubber stopper. Preheat for 1 Ⅱ ml and then pass the load (the flow rate is 1.5～2.0L/min). The gas after combustion is passed into the light blue absorption cup with 50Ⅲ1 absorption liquid in advance, so that the blue color of the powder absorption liquid begins to fade, and then it is immediately titrated with 0.0005 potassium iodate standard solution, and the initial color is maintained. The speed of titration depends on the speed of the blue color disappearance of the absorption liquid. After the last hydrogen is passed, the color does not change, which is the end point. The gas is closed, the stopper is opened, and the porcelain boat is taken out with a long hook. According to the milliliters of potassium iodine consumed by the titration, the percentage of sulfur in the sample is calculated. 2.2.6 Calculation of results
In the formula: T—titration degree (/m)
V—milliliters of potassium iodate consumed by the sample:
V. - milliliters of potassium iodate consumed by the blank
W.—sample weight (unit).
2.27 Precautions
Replace the starch absorption liquid every time to make the titration result stable. b. Observe the melting condition of the porcelain sample. If the slag is not flat and there are bubbles on the cross section, re-measurement is required. c. If more than ten samples are made continuously, calibration with standard steel is required to remove oxides. d. If the sulfur content increases, the sample weighing plate can be reduced for adjustment (at least 0.25 samples can be weighed) 3 Determination of phosphorus
3.1 Method - Saddle beryllium precipitation separation Phosphomolybdenum blue colorimetric method 3.1.1 Key points of the method
In 0.65~1.3 nitric acid medium, phosphorus reacts with ammonium molybdate to form phosphomolybdic heteropoly acid, which can be extracted by n-butanol-trichloromethane, reduced with stannous fluoride, and extracted into the aqueous phase for colorimetric determination. 3.12 Range: 0.002%～0.01%
3.1.3 Reagents
Nitric acid 11
Ammonia water: (density 0,90) (1:50)
Gamic acid (70%)
Copper ammonium (10%)
Sodium nitrite (10%)
N-butanol-chloroform mixture (n-butanol: chloroform) Methane = 18) EDTA 10%
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3.1, 3, 8 Ag-cured argentum, 1% (weigh 1 tin chloride, add 6 ml concentrated hydrochloric acid and dilute to 100 ml with water (freshly prepared when methane is used).
3.1.3.9 Beryllium vegetate solution: 2% (weigh 205 beryllium sulfate in 800 ml beaker and dissolve in water, add 80 ml 1:2 of sulfuric acid, transfer to a 1/2 volumetric flask after cooling, and dilute to the mark with water. 3.1.3.10 Phosphorus standard solution (1) Weigh 0.4893g of potassium dihydrogen phosphate that has been dried to constant weight at 105℃ in a beaker, dissolve it with an appropriate amount of water, transfer it to a 1/2 volumetric flask, add 50ml nitric acid (density 1.42): After cooling, dilute to the mark with water, and shake (100F/m1). 3.1,3,11 Phosphorus standard solution (P) Take 50=1 (A) solution in a 500ml volumetric flask, add 10㎡ nitric acid (density 1.42), cool and dilute to 1/2 with water, shake well (1/3). 3.1.4 Analysis steps
Weigh 0.5000 of the sample and dissolve it in 20ml nitric acid by heating. After dissolving, add 81 high nitrogen to evaporate until white smoke appears, and reflux ~, remove and cool, add 2 water to dissolve the salt, Add 1 % sulfur solution, 10% EDTA40, water (specific gravity 0.90) to adjust to P=B~4 and water to about 100ml. Boil for 2~9=in, remove the cold, add 10ml water, 10ml ammonia water (specific gravity 0.90) and boil for 1min. Cool in running water for 9min. Filter with medium-speed filter paper, wash the sediment and beaker with ammonia water (1:50) 5~7 times. Put the funnel containing the sediment into 2 0ml warm nitric acid is dissolved and filtered into the original beaker. The filter paper is washed with water and then removed. 1-2ml sodium nitrite solution is added to the solution, and nitrous oxide is removed by boiling. After cooling, it is transferred to a 10ml volumetric bottle and diluted to the scale with water.
Absorb 15ml of the specific solution, add 20ml of butyl alcohol-triiron methane condensate into a 125ml separatory mixing bucket, add 3ml of ammonium molybdate, and shake vigorously for 40-50S. After static separation, the organic layer was placed in another dry 125 μm separating funnel, 15 ml of chlorinated sodium solution was added, and the mixture was shaken vigorously for 15-20 seconds to static separate. The organic phase layer was discarded, and the aqueous layer was placed in a 23 μm dry colorimetric plate. At a wavelength of 680 μm, the reagent blank was taken as zero, and the photometric intensity was measured. The phosphorus content was found from the standard curve. 31.5 Drawing of standard curve
Several portions (0, 1, 2, 8, 4, 5 1) of phosphorus standard solution (B) were taken and placed in 100 μl volumetric flasks, 15 ml of boiled nitraldehyde was added, and diluted to the mark with water. After shaking, 15 1 of the solution was divided into 6 125 μl funnels, 20 ml of n-butanol-chloroform mixture was added, and 8 ml of ammonium molybdate solution was added. The following steps were carried out according to the sample. The absorbance was measured and the standard curve was drawn. 3.1.6 Calculation of results
A×100
——From the standard curve, find the maximum phosphorus content in the sample. G——Weigh the sample (5)
3, 1, 7 Notes
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a For samples that do not contain enough phosphorus, add 1 5ml 1 1 nitric acid to dissolve the chromium and manganese after the ionized acid fumes have been cooled for 5 ~ 6 minutes, add sodium nitrite to reduce chromium and manganese, add 1~ drops of excess, boil to remove nitrogen oxides, cool and dilute to 100ml in a volumetric flask, and operate as follows. b: If the temperature is too low, in order to make the phosphoric acid extraction complete and quickly stratify, the extraction liquid can be appropriately increased in temperature and the extraction time can be extended.
, 2-diphosphomolybdate blue colorimetric method
3.2.1 Key points of the method
The sample is dissolved in nitric acid, and ammonium persulfate is used to further oxidize phosphorus to orthophosphoric acid. At a certain acidity, phosphorus reacts with ammonium molybdate to form phosphopolyacid, which is extracted with n-butanol-nitroform solution and reduced with tin chloride and back-extracted in water for colorimetric analysis:
3.2.2 Reagents
Nitric acid: 11
Ammonium persulfate 15% (prepared on the same day)
Ammonium molybdate 5%,
N-butyl chloroform 1:8
Titanium chloride: 1% (1 tin chloride is dissolved in 6-nitrogen concentrated hydrochloric acid and made up to 100 ml with water)
(prepared freshly when used)
3.2.2, 6-phosphorus standard solution 0.01m /m1
3.2,3 Instrument Spectrophotometer
3-2.4 Analysis steps
Weigh 1,0000 samples in a 250ml conical flask, add 15ml of .111 nitric acid, heat to dissolve completely, add 51 of ammonium persulfate, boil, remove and cool, transfer to a 100Ⅲ volumetric flask, dilute to scale with water, shake well, draw 26ml into a 1251 separatory funnel, add 4ml of 5% ferric zirconate, add 20ml of n-butanol-trioxane mixture, vibrate 40 times, let stand and separate. Put the organic phase into another separatory funnel with 10ml of tibialis chloride solution accurately pre-vibrated, vibrate 20 times, let stand and separate, remove the organic phase, and heat at 680℃, adjust to zero with reagent blank. Use 1℃m colorimetric. Colorimetric water phase, calculate the percentage of tibialis in the sample from the standard curve.
3.2, 5 Drawing of standard curve
Add 0, 0.250, 6, 1.0, 2.0, 8.0ml of phosphorus standard solution to 6 125ml separatory funnels, add 25ml of 1N nitric acid and 4ml of 5% ammonium aluminate bath solution. 20ml of n-butanol-fluoroform mixed solution, measure the extinction value according to the sample operation, and draw the standard curve. 3.2.6 Calculation of results
A×100
Wherein: Phosphorus content (g) obtained from the standard curve G——sample weight (g).
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4 Determination of phosphorus in diamond alloy-complexometric titration 4.1 Key points of the method t
In an oxygen solution with a pH of 8-12, use ammonium adenosine as an indicator and titrate with E-waste A. The interference of large amounts of cobalt can be eliminated by oxidizing cobalt to a high concentration in a solvent with hydrogen peroxide. 4.2 Reagents
4.2.1 Nitric acid 1.1
4.2.2 Hydrogen peroxide 80%
Hydrogen water (density 0.89)
Triethanolammonium 1:1
Ammonium pyrochloreate indicator, 1&Ammonium pyrochloreate mixed with 100% titanium chloride. 3DTA standard solution: 0.01M (use lock and pure combination to form sample or standard steel according to the mixing requirements, and obtain the titer.)
4.3 Analysis steps
Weigh 0.000g sample in a 2501 conical flask, add 10ml 1:1 nitric acid, heat and dissolve, drive out fluorine oxides, transfer to a volumetric flask, add 1ml water, 2~80% water, slowly add 20Ⅱ1 hydrogen peroxide, after the reaction is complete, dilute with water to the scale, shake the hook. Pipette 10ml of this solution into the original conical flask, add 20㎡1 water, 5ml triethanolamine, add a little purple adenosine, and use standard EDTA to determine that the solution is tight red as the end point,
4.4 Calculation of results
1×V×25
-×100
Wherein: T——Titer of ETA standard solution (㎡1)-Volume of FTA standard solution consumed by titrating sample (㎡): G-Weighing amount of sample (g).
5 Determination of cobalt in alloy-potentiometric titration 5.1 Key points
Use potassium ferric oxide to oxidize in ammonia solution, titrate with excess potassium ferric oxide and cobalt solution, and determine the boiling point by the sudden change of the electric meter.
5.2 Reagents
5.2,1 Nitric acid 111
5.2.2 Ammonium citrate solution: 50%,
Water: (density 0.89)
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5.2.4 Cobalt sulfate 0.025M#
5.2.5 Potassium ferrocyanide 0.05M (16g potassium ferrocyanide dissolved in 1000ml water.)#5.2.6 Cobalt standard solution 1m2g/ml (weigh 1.000g pure cobalt and 1.5000g pure cobalt in 10ml nitric acid, remove nitrogen oxides, transfer to a 1L volumetric flask, dilute to scale, shake well), 5.3 Analysis steps
Weigh 0.5000g sample in a conical flask, add 10ml 1:1 nitric acid to dissolve, remove nitrogen oxides, cool, transfer to a 250ml volumetric flask, dilute to scale with water. Shake well. Take 10ml of this solution and inject it into a 500ml beaker containing 50ml ammonium citrate, 10ml potassium ferric chloride, 50ml ammonia water and 80ml water under electromagnetic stirring. Operate the titrator with 0.025ml cobalt sulfate solution until the potential suddenly changes as the end point. 5.4 Calculation of results
T×(VV,)×25
Where T is the titration degree of potassium ferrocyanide to cobalt (V/ml) and K is the number of milliliters of potassium ferrocyanide per milliliter of cobalt sulfate solution. The K value is obtained by dividing the number of milliliters of cobalt sulfate solution consumed in the blank titration by the number of liters of potassium ferrocyanide solution added, V is the number of milliliters of potassium ferrocyanide added!
V, m is the number of liters of cobalt sulfate consumed in the sample titration! G is the amount of sample weighed (maximum).
Calibration of cobalt titer with standard solution of potassium chloride 55
Take the standard solution of cobalt and the air solution similar to that in the sample and put them into 150 processing beakers respectively (ratio is to be determined) and operate according to the analysis step 5,3.
g—grams of standard cobalt added
V, millikelvin of standard cobalt sulfate solution consumed (K means the same as soil). 6 Determination of iron in cobalt and cobalt alloys
6.1 Method—sulfate spectrophotometry with methyl isobutyl ketone extraction 6.1.1 Key points of the method
Use nitric acid to decompose the sample, add hydrochloric acid, extract and separate iron with methyl isobutyl ketone, wash it with hydrochloric acid, and then use thiocyanate iron to generate thiocyanate iron complex and adjust its absorbance. 6.1.2 Analysis model (0.001~0.2%)
6.1.3 Reagents
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6.1.6.7 Hydrochloric acid: 2, 2t1
6.1.3.2 Nitric acid 1 1
6.1.3,3 Cobalt standard solution 10mg/m1 (Weigh 10000g of pure cobalt and dissolve it in 10m1:1 nitric acid. After driving out the hydrogen dioxide, transfer it to a 100m1 volumetric flask and dilute it to the mark with water) 6.1.3.4 Cobalt standard solution 10m/m (Weigh 1.0000g of pure cobalt and dissolve it in 10m1:1 nitric acid. After driving out the nitrogen dioxide, transfer it to a 100m1 volumetric flask and dilute it to the mark with water) 6.1.3.5 Ammonium thiocyanate solution: 80% aqueous solution 6.1.3.6 Methyl isobutyl ketone (B)
6.1.3,7 Iron standard solution: 10μm/m1 [Weigh 0.1000g of pure iron, dissolve it in hydrochloric acid (10m), transfer it to a 100m1 volumetric flask, dilute it to the mark with water, and shake well (100%/m1). Pipette 10ml of this solution into a 100ml volumetric flask, dilute to the mark with water, add (10μ/ml) B, 1.4 Analysis steps
Weigh 0.2500~0.5000 sample into an 800ml beaker, add 10:1 nitric acid and heat to dissolve to drive off nitrogen oxides, cool to room temperature and pour into a 100ml volumetric flask, dilute to the mark with 2:1 nitric acid, take 10ml into a 150ml separatory pot, add 10:121 hydrochloric acid to make the liquid volume 20ml, add 20ml of I B and shake vigorously for 1min, let it stand and separate, remove water, add salt (B:) 10ml, shake for 30S and let it stand and separate, remove water, add 10l of thioguanidine to the organic phase and shake for 10S and let it stand and separate, remove the aqueous phase, and pour the organic phase into a 5% equalizer. Dilute to the mark, filter the organic phase with dry filter paper and place it in a 1°C colorimetric trough, and measure the photometry at a wavelength of 50 nm. Plotting the standard curve
In a series of 150 ml separating funnels, add ml of nickel standard solution and 2 cobalt standard solution, then add iron standard solution, and dilute to 20 ml with 2:1 hydrochloric acid for No. 0, 5, 10, 15, 20, and 80. The same operation is performed for the following samples, and the absorbance is measured to plot the standard curve. 6.1, 5 Calculation
A×100
Where: A-the content of iron in the sample (unit) G——the amount of the sample weighed (unit).
If necessary, press the button, press the return button, and place it in the separating funnel, add the desired amount, and discard the organic phase.
6.2 Method: Spectrophotometric elimination of dicarbonate 6.2.1 Key points of the method: In an acidic narrow solution, iron reacts with liquid salt to form a red complex for colorimetric determination. The additional color of nickel and cobalt ions can be eliminated by using a cobalt synthetic solution as the substrate. 6.2.2 Determination range 0.08~0.5%
6.2.3 Reagents
6.2.31 Nitrate 1111#4
6.2,3.2 Ammonium fluoride: 12%
6.2,3.3 Standard solution 10g/ml
6.23.4 Cobalt standard solution 10mg/ml
6,2,5 Iron standard solution, weigh 0.4000% pure iron (99.9% %) in a 200ml beaker, add 10% nitric acid in a ratio of 1:1, heat to dissolve, remove all the carbon dioxide, cool, transfer to a 100ml volumetric flask, dilute to the mark with water, shake. Pipette 10ml into a 100ml volumetric flask, dilute to the mark with water, and place evenly. This solution contains 0.04 mg of iron per milliliter.
6.2.4 Analysis steps
Take 0.200~.000 milliliters of sample in a 15-liter beaker, add 10 μl of 1:1 nitric acid, heat and dissolve, and drive out all the nitrogen oxides, remove and cool, add a small amount of water, transfer to a 100 μl volumetric flask, dilute to the mark with water, and shake.
Pull 10 ml of the above solution into a 6-liter volumetric flask, add 1 μl of water, 1 μl of thiourea, dilute to the mark with water, and shake. At the same time, take 3 μl of nickel and 1 μl of cobalt standard solution as a blank test, use the blank solution as a reference, and measure the absorbance on a spectrophotometer. The colorimetric blood is 530 μl and 3 μl, and the iron content is obtained from the standard curve. 6.2.5 Drawing of standard curve
Add 0, 0.5, 1.0, 1.5, 2.0, 2.5 ml of iron standard solution to 6 0.1 ml volumetric flasks respectively, add 3 ml of tin and 1 ml of cobalt standard solution and add water to make the volume about 15 ml. After measuring the absorbance with the same sample, draw the standard curve. 6.2.6 Calculation of results
Where: A-iron content (g) obtained from the curve; G-sample weight (g).
7 Determination of silicon in cobalt alloy
1.1 Method-silicon dioxide gravimetric method
7.1.1 Key points of the method
The sample is dissolved in nitric acid, dehydrated with high nitrogen acid, and the silicon is made to produce insoluble silicic acid, which is separated by filtration. The precipitate is calcined, weighed, and treated with fluorine acid to volatilize the silicon dioxide. 7.1.2 Determination range 0.1～6%
1.1.3 Reagents
7.1..1 Nitric acid 11
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7, 1.3.2 High-density acid (density 1.67)
7.1.3.3 Hydrofluoric acid (density 115) 1
7.1.3.4 Disodium iodide 1:10
7.1.3.5 Thialdehyde 118
7.1.4 Analysis steps
Accurately weigh 80000 ml of sample and put it in a 4:10 beaker, add 40 ml of 1:1 nitric acid, heat to dissolve, add 20 ml of perhydrogen acid and continue heating until white smoke is produced and maintained for 2 to 8 minutes, cool, add 20 to 800 ml of hot water and stir to dissolve the salt, then filter it with medium-speed filter paper. Use a glass rod with a rubber head to pick up the precipitate attached to the beaker and put it on the filter paper. First wash the precipitate with hot water, then wash it with 1:10 hot fluorescent acid, and finally wash it with hot water until there is no nitrogen ion. Put the precipitate and filter paper into a constant weight crucible (be careful to ash it), and then calcine it in a muffle furnace at 1000°C until it is constantly blue. Record the weight. Add 1.8 pounds of acid ions and 8-6 ml of hydrofluoric acid to the weighed platinum, and evaporate carefully until the fumes are exhausted. Then burn in a muffle furnace at 1000℃ to constant weight, and record the weight G2. 7.1.5 Calculation of results
(G,-G) X0,46T4
-×100
In the formula, G,-weight before hydrochloric acid treatment (name) G2-weight after hydrochloric acid treatment (number) G-weight of sample (name) 3
white. 46 4-coefficient of converting silicon dioxide into silicon. 7.2 Silicon dioxide blue colorimetric method
72.1 Key points
After the sample is decomposed by nitric acid, at pH 1~2, silicon reacts with saw acid to form chain-pin heteropoly acid, which is reduced to chain-pin molybdenum blue by ammonium ferrous sulfate and then colorimetric determination is performed. 7.22 Determination range 0.06~0.95%
7, 2, 3. Reagents
7.23.1 Nitric acid 1:118
7, 2, 3.2 Ammonium molybdate, 8% (filtered and stored in a plastic bottle). 2..3 Ammonium ferrous phosphate (F05H4) 6% (0.6) ammonium ferrous carbonate was decomposed with water and transferred to a 100 volume bottle, and diluted to 100% by volume with 11 acid. 17, 2, 3.4 Sulfuric acid and oxalic acid were mixed by equal volumes: 113 magnetic acid and 8% ammonium oxalate were mixed). 7.2.3.5 Standard solution 10㎡%/ml
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