GB/T 4698.2-2011Methods for chemical analysis of titanium sponge,titanium and titanium alloys - Determination of iron content (English PDF)

4.1 Measurement range

The measurement range of iron is 0.005% ~ 2.00% (mass fraction).

4.2 Method principle

The sample is dissolved by hydrochloric acid-hydrofluoric acid. The titanium oxide nitric acid is added. The boric acid, tartaric acid, ammonium acetate, hydroxylamine hydrochloride is added. The 1,10-phenanthroline is added, to form 1,10-phenanthroline iron complex; the iron content is measured by spectrophotometer.

4.3 Reagents

4.3.4 Boric acid.

4.3.5 Tartaric acid (200 g/L).

4.3.6 Ammonium acetate (500 g/L).

4.3.7 Hydroxylamine hydrochloride solution (100 g/L).

4.3.8 The 1,10-phenanthroline solution (2 g/L). Dissolve 2.0 g of 1,10-phenanthroline in 100 mL of ethanol (volume percentage not less than 95%). Use water to dilute it to 1000 mL.

4.3.9 Iron standard solution.

4.4 Instruments

4.4.1 Analytical balance. Accurate to 0.1 mg.

4.4.2 Spectrophotometer.

4.5 Specimens

4.6 Analytical procedures

4.6.1 Number of measurements

Carry out two measurements, independently. Take the average value.

4.6.2 Blank test

Do a blank test with the sample.

4.6.3 Drawing of working curve

4.6.3.3 After standing at room temperature for 20 min, pipette part of the solution into a 1 cm absorption dish. Use water as a reference, to measure the absorbance of the standard solution. Use the mass concentration of iron (mg/100 mL) as the abscissa AND the absorbance as the ordinate, to draw the working curve. Make sure that, the linear correlation coefficient is better than 0.999. Move the relevant curve in parallel, so that it passes through the coordinate origin.

4.6.4 Measurement

4.6.4.1 Place the sample (4.5.2) in a 200 mL polytetrafluoroethylene beaker.

4.7 Calculation of analysis results

The iron content is calculated in terms of the mass fraction of iron, wFe; the value is expressed in %; it is calculated according to formula (1).

4.8 Precision

The tolerance of this method is represented by formula (2), formula (3), formula (4). Repeatability limit.

5.1 Measurement range

The measurement range of iron is 0.01% ~ 2.00% (mass fraction).

5.2 Principle

The specimen is dissolved with hydrochloric acid and hydrofluoric acid. The nitric acid titanium oxide, iron and other elements are added. Then boric acid is added; the iron concentration in the test solution is measured, by atomic absorption spectrometer.

5.3 Reagents

5.3.1 Hydrochloric acid (1 + 1). Slowly add 500 mL of hydrochloric acid (rho 1.16 g/mL ~ 1.19 g/mL) to 500 mL of water.

5.3.2 Nitric acid (1 + 1). Slowly add 500 mL of nitric acid (rho 1.42 g/mL) to 500 mL of water.

5.3.3 Hydrofluoric acid (1 + 1). Slowly add 100 mL of hydrofluoric acid (rho 1.14 g/mL) to 100 mL of water.

5.3.4 Boric acid.

5.3.5 Pure titanium wTi >= 99.95%; the iron content is known AND shall be as low as possible. If the iron content is unknown, it shall use the method 1 for accurate measurement.

5.3.6 Iron standard solution.

5.4 Instruments

5.4.1 Analytical balance. Accurate to 0.1 mg.

5.4.2 Flame atomic absorption spectrometer. It uses air/acetylene flame; the wavelength is 248.3 nm.

5.5 Specimen

5.6 Analytical procedures

WARNING. Air-acetylene burners shall be ignited and extinguished, in accordance with atomic absorption spectrometry instrumentation procedures, to avoid a possible explosion hazard.

5.6.1 Number of measurements

Two samples are measured independently. Take the average value.

5.6.2 Blank test

Carry out the blank test, by the use of pure titanium (5.3.5), along with the sample.

5.6.3 Preparation of standard solutions

5.6.3.3 wFe > 0.1%

5.6.3.3.1 Weigh 6 parts of pure titanium (5.3.5), 0.50 g per each part. Place them in a 200 mL polyethylene beaker.

5.6.3.3.2 Add 10 mL of hydrochloric acid (5.3.1) and 5 mL of hydrofluoric acid (5.3.3).

Cover a polyethylene watch glass. Heat in a water bath to dissolve it. Add 3 mL of nitric acid (5.3.2). Continue to heat to drive off nitrogen oxides. Add 3 g of boric acid (5.3.4). Stir to dissolve it. Cool it to room temperature.

5.6.3.3.3 Transfer the solution into a 100 mL volumetric flask.

5.6.3.3.4 Pipette part of the solution, according to Table 2, into six 100 mL volumetric flasks. Add hydrochloric acid (5.3.1). Add 0.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, 10.00 mL of iron standard solution (5.3.6.2), respectively. Use water to dilute it to the mark. Mix well.

5.6.4 Preparation of test solution

5.6.5 Measurement

5.6.5.1 General

The instrument shall be equipped with an iron hollow cathode lamp, which is recommended by the manufacturer. The wavelength shall be set at 248.3 nm. The measurement shall be carried out, by an air-acetylene lean flame. When the equipment has a computer system control function, THEN, the establishment of the working curve, the calibration (drift correction, standardization, recalibration), the measurement of iron content shall be carried out, in accordance with the requirements of the computer software's operating instructions.

5.7 Calculation of analysis result

5.7.1 wFe <= 0.1%

The iron content is calculated in terms of the mass fraction of iron wFe; the value is expressed in %; it is calculated according to formula (5).

5.8 Precision

The tolerance of this method is represented by formula (7), formula (8), formula (9). Reproducibility limit.

6.1 Measuring range

The measurement range of iron is 0.01% ~ 3.0% (mass fraction).

6.2 Method principles

The sample is dissolved by nitric acid and hydrofluoric acid or sulfuric acid and hydrofluoric acid. The content of iron in the sample is measured, by inductively coupled plasma (ICP)-atomic emission spectrometer.

6.3 Reagents

6.3.1 Hydrochloric acid (1 + 1). Slowly add 500 mL of hydrochloric acid (rho 1.16 g/mL ~ 1.19 g/mL), into 500 mL of water.

6.3.2 Nitric acid (rho 1.42 g/mL).

6.3.10 Lanthanum solution (1 mg/mL). Accurately weigh 1.17 g of lanthanum trioxide (wLa2O3 >= 99.5%), into a 300 mL beaker. Add 20 mL of hydrochloric acid (6.3.1). Heat to dissolve it. Cool and transfer it into a 1000 mL volumetric flask. Use water to dilute it to the mark. Mix well.

6.3.11 Iron standard solution (1.000 mg/mL). Accurately weigh 1.0000 g of metallic iron (wFe >= 99.9%), into a 500 mL beaker. Add 60 mL of hydrochloric acid (6.3.1). Heat to dissolve it. Then add 10 mL of nitric acid (6.3.3), to oxidize iron from low valence to high valence. Heat it until no brown nitrogen and oxygen fumes are produced. Cool and transfer it into a 1000 mL volumetric flask. Use water to dilute it to the mark. Mix well.

6.4 Instruments

6.5 Specimen

6.5.1 Sampling

Sampling of sponge titanium, titanium, titanium alloys shall be carried out, in accordance with published standard methods.

6.5.2 Sample

Weigh 0.500 g of sample, accurate to 0.0001 g.

6.6 Analytical procedures

6.6.4.2).

6.6.3.2.1 Weigh 4 parts of pure titanium (6.3.7), 0.50 g per each part. Transfer them into a 200 mL polyethylene beaker.

6.6.3.2.2 Add 50 mL of nitric acid (6.3.3) and 10 mL of hydrofluoric acid (6.3.4). Cover a polyethylene watch glass. Heat it in a water bath to dissolve it completely. Continue to heat and boil it, to drive off nitrogen oxides. Cool to room temperature.

6.6.3.2.3 Remove the watch glass. Pipette 0.00 mL, 5.00 mL, 10.00 mL, 15.00 mL of iron standard solution (6.3.11), respectively. Transfer the solution into a 100 mL volumetric flask.

6.6.3.3.6 Add 0.00 mL, 5.00 mL, 10.00 mL, 15.00 mL of iron standard solution (6.3.11), respectively. Transfer the solution into a 100 mL volumetric flask.

6.6.3.3.7 Add 5.0 mL of cobalt (6.3.8), yttrium (6.3.9) or lanthanum (6.3.10) internal standard solution. Use water to dilute it to the mark. Mix well.

6.6.3.4 Dissolution of specimen by sulfuric acid (applicable to 6.6.4.4).

6.6.3.4.1 Weigh 4 parts of pure titanium (6.3.7), 0.50 g per each part. Place them in a 100 mL conical flask.

6.6.3.4.2 Add 40 mL of sulfuric acid (6.3.6). Slowly heat it, until the titanium is completely dissolved (add water to keep the volume constant). Add nitric acid (6.3.2) dropwise, to oxidize titanium. Continue heating, until the solution emits white smoke. Cool to room temperature.

6.6.3.4.3 Remove the watch glass. Add 0.00 mL, 5.00 mL, 10.00 mL, 15.00 mL of iron standard solution (6.3.11), respectively. Transfer the solution into a 100 mL volumetric flask. Use water to dilute it to the mark. Mix well.

6.6.4 Preparation of test solution

6.6.4.3.1 Put the sample in a 200 mL polytetrafluoroethylene beaker.

6.6.4.3.2 Add 20 mL of sulfuric acid (6.3.5) and 4 mL of hydrofluoric acid (6.3.4). Cover a polytetrafluoroethylene watch glass.

6.6.4.3.3 Remove the watch glass. Continue to heat until white smoke is emitted, for about 3 min ~ 5 min. Cool to room temperature.

6.6.4.3.4 The amount of sulfuric acid remaining in the beaker will affect the emission intensity. Therefore, it is recommended that the residual sulfuric acid volume shall be kept constant. The internal standard method can also be used, to eliminate the influence.

6.6.4.3.5 Cool to room temperature. Add 20 mL of hydrochloric acid (6.3.1) and a small amount of water, to dissolve the salts.

6.6.4.3.6 After cooling to room temperature, transfer it into a 100 mL volumetric flask. […]