Method for measuring content of trace boron in ferrotitanium alloy

Abstract

The invention belongs to the technical field of chemical analysis, and particularly relates to a method for measuring the content of trace boron in ferrotitanium alloy, which comprises the following steps: 1) sample decomposition: leaching and dissolving a ferrotitanium alloy sample in the presence of mannitol by using mixed acid of nitric acid and hydrofluoric acid, and fixing the volume to obtain a sample to be measured; and 2) determination of boron content: setting working parameters of an ICP-AES spectrometer, setting a detection spectral line of boron, preparing and drawing a calibration curve, and determining the boron content in the sample to be detected obtained in the step 1). The detection method disclosed by the invention has the advantages of high efficiency, safety, low cost, rapidness and the like, the detection result is stable and meets the production detection requirements by adding mannitol and protecting boron in the decomposition process, and the sample can be ensured to be completely dissolved and the accuracy of trace boron detection can be ensured by adopting mixed acid consisting of nitric acid and hydrofluoric acid.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical analysis, and particularly relates to a method for determining the trace boron content in ferro-titanium alloy. Background Art

[0002] The presence of trace boron in steel can increase the hardenability of steel. As the boron content increases, the mechanical properties, corrosion resistance and ductility of steel will decrease significantly. Boron can affect graphitization in cast iron, thus increasing the depth of white cast iron. When the boron addition amount exceeds 0.01%, it has an obvious effect of stabilizing carbides, so the wear resistance of cast iron can be improved. The boron content in cast iron rolls is 0.02% - 0.1%, which can improve the surface hardness and white solidification. When the boron content in malleable cast iron reaches 0.001% - 0.005%, it is beneficial to form nodular graphite. At the same time, it can also increase the particles of graphite and improve its distribution. This effect is beneficial to annealing treatment. In recent years, ferro-titanium has been widely used in metallurgical production and can be used as a deoxidizer, denitrifier and alloy additive. Among them, boron element is called the vitamin of metal materials. Adding a small amount of boron to titanium alloy can refine grains and improve the properties of the alloy.

[0003] During the smelting process of ferro-titanium, in order to ensure the production quality, it is necessary for testers to accurately test the trace boron components in ferro-titanium alloy. At present, there are various methods for determining the boron content in titanium alloy, such as spectrophotometry. In these traditional methods, the easy volatility of boron has not been well solved, and the accurate determination of trace boron cannot be achieved.

[0004] Therefore, how to detect the trace boron content in ferro-titanium alloy has become an urgent technical problem to be solved. Summary of the Invention

[0005] To solve the drawbacks of the above-mentioned prior art, the present invention discloses a method for determining the trace boron content in ferro-titanium alloy, and adopts the following technical means:

[0006] A method for determining the trace boron content in ferro-titanium alloy, comprising the following steps:

[0007] 1) Sample decomposition: Dissolve the ferro-titanium alloy sample by leaching with a mixed acid of nitric acid and hydrofluoric acid in the presence of mannitol, and then make up the volume to obtain a sample to be tested.

[0008] 2) Determination of boron content: Set the working parameters of the ICP-AES spectrometer, set the detection spectral line of boron, prepare and draw a calibration curve, and determine the boron content in the sample to be tested obtained in step 1).

[0009] Inductively coupled plasma atomic emission spectrometry (ICP-AES) has the advantages of a wide linear range, high precision, strong traceability, and can flexibly select spectral lines according to the content level of the analyzed element and spectral interference, so as to achieve the synchronous analysis of elements with conventional and low contents. It has been widely adopted in national or industry standard systems. With the popularization and application of ICP-AES, more and more units are using it. This invention is of great significance. By protecting boron during the decomposition process, the detection results are stable and meet the requirements of production detection. Combined with ICP-AES, the detection results are more accurate.

[0010] Further, in step 1), the ratio of ferro-titanium alloy sample: mannitol: nitric acid: hydrofluoric acid is 0.2: 4.5 - 5.5: 14 - 16: 3.5 - 4.5, where the measurement unit of the ferro-titanium alloy sample is g, and the measurement units of mannitol, nitric acid, and hydrofluoric acid are ml.

[0011] Further, step 1) is specifically: place the ferro-titanium alloy sample in a polytetrafluoroethylene beaker, add nitric acid, mannitol, and hydrofluoric acid in sequence, place it on a hot plate at 165 - 175 °C and shake well until the ferro-titanium alloy sample is completely dissolved, make up the volume to obtain the sample to be tested.

[0012] Further, in step 2), the working parameters of the ICP-AES spectrometer are set as follows:

[0013] The pump speed is 48 - 51 r.min -1 , the RF power is 1145 - 1155 W, the nebulizer gas flow rate is 0.48 - 0.51 L / min, the cooling gas flow rate is 11.5 - 12.5 L / min, the auxiliary gas flow rate is 0.48 - 0.51 L / min, the exposure and light-taking time of the visible light chamber is 4 - 6 s, and the exposure time of the ultraviolet light chamber is 14 - 16 s.

[0014] Further, in step 2), the detection spectral line of boron is 182.641 nm. In this invention, the detection wavelength of boron is set at 182.641 nm, and there is no spectral interference in the spectral peak and background.

[0015] Further, in step 2), the preparation and drawing method of the calibration curve is:

[0016] Weigh 5 portions of 0.2000 g of ferrotitanium standard samples. In the presence of mannitol, after leaching and dissolving with a mixed acid of nitric acid and hydrofluoric acid, transfer them into 5 100-ml volumetric flasks respectively. Add 0.0 ml, 0.5 ml, 1.0 ml, 2.0 ml, and 3.0 mL of boron standard stock solution with a concentration of 20.00 μg / ml respectively, and make up the volume to obtain working curve solutions. These working curve solutions are equivalent to containing 0%, 0.005%, 0.010%, 0.020%, and 0.030% of boron in 0.2000 g of the sample; when the boron content in the sample exceeds this range, the addition amount of the boron standard stock solution can be adjusted to make the working curve range cover the sample content.

[0017] Under the working parameters of the ICP-AES spectrometer and the detection spectral line conditions of boron set in step 2), measure the spectral intensities of the working curve solutions in sequence. Take the percentage content of boron in the working curve solutions as the abscissa and the measured spectral intensities as the ordinate to establish a calibration curve.

[0018] The present invention uses the standard addition method to fill the blank of no method for the determination of trace boron in ferrotitanium alloy, which is an important innovation and has good application prospects and great social benefits.

[0019] Furthermore, in step 2), the sample introduction system of the ICP-AES spectrometer is a hydrofluoric acid-resistant sample introduction system.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The present invention fully decomposes the sample with a mixed acid of nitric acid and hydrofluoric acid in the presence of mannitol, and then uses the ICP to draw a working curve by the standard addition method to determine the content of trace boron in ferrotitanium alloy. It is a technical innovation, and the measurement results are rapid and accurate.

[0022] The detection method of the present invention has the advantages of high efficiency, safety, low cost, rapidity, etc. By adding mannitol, boron in the decomposition process is protected, making the detection results stable and meeting the production detection requirements. By using a mixed acid composed of nitric acid and hydrofluoric acid, it can ensure complete dissolution of the sample and ensure the accuracy of trace boron detection. Specific embodiments

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below.

[0024] The nitric acid, hydrofluoric acid, mannitol, hydrochloric acid, ferrotitanium standard samples, and boron standard stock solution used in the embodiments and comparative examples of the present invention are all ordinary commercially available products.

[0025] The manufacturer and model of the ICP-AES spectrometer used in the embodiments and comparative examples of the present invention for detection are: THERMOFISHER Icap7400 type, and the sample introduction system is hydrofluoric acid-resistant.

[0026] When detecting the boron content in the examples and comparative examples of the present invention, the detection spectral line is set to 182.641 nm, and the working parameters of the ICP-AES spectrometer are set as follows:

[0027]

[0028] Example 1

[0029] 1) Sample decomposition: Weigh 0.2000 g of ferrotitanium sample 1 (accurate to 0.0001 g), place it in a 150 mL clean polytetrafluoroethylene beaker, add 15 mL of nitric acid, 5 mL of mannitol, and 4 mL of hydrofluoric acid in sequence, place it on a low-temperature hot plate at 170 °C and shake well to completely dissolve the sample, make the volume up to 100 mL, and wait for measurement.

[0030] 2) Prepare and plot the calibration curve:

[0031] The calibration curve is established by the standard addition method. Weigh 5 portions of 0.2000 g of ferrotitanium standard samples, dissolve them according to the sample decomposition method described in step 1), transfer them into 100 mL volumetric flasks after dissolution, and use a pipette to respectively add 0.0 mL, 0.5 mL, 1.0 mL, 2.0 mL, and 3.0 mL of 20.00 μg / mL boron standard stock solution to prepare working curve solutions. These solutions respectively correspond to 0%, 0.005%, 0.010%, 0.020%, and 0.030% boron content in 0.2000 g of the sample. Under the set measurement conditions, measure the intensities of the analysis spectral lines of the standard series solutions in sequence. Taking the percentage content of the standard series solutions as the abscissa and the measured spectral intensity as the ordinate, establish a regression curve, and calculate the regression coefficient, detection limit, background equivalent concentration, correlation coefficient, etc.

[0032] 3) Under the set measurement conditions, use the calibration curve plotted in step 2) to detect the boron component content in the ferrotitanium sample 1 decomposed in step 1), and the results are shown in Table 1.

[0033] Example 2

[0034] 1) Sample decomposition: Weigh 0.2000 g of ferrotitanium sample 2 (accurate to 0.0001 g), place it in a 150 mL clean polytetrafluoroethylene beaker, add 15 mL of nitric acid, 5 mL of mannitol, and 4 mL of hydrofluoric acid in sequence, place it on a low-temperature hot plate at 170 °C and shake well to completely dissolve the sample, make the volume up to 100 mL, and wait for measurement.

[0035] 2) Detect using the calibration curve prepared in Example 1, and the results are shown in Table 1.

[0036] Example 3

[0037] 1) Sample decomposition: Weigh 0.2000 g of ferrotitanium sample 3 (accurate to 0.0001 g), place it in a 150 mL clean polytetrafluoroethylene beaker, successively add 15 mL of nitric acid, 5 mL of mannitol, and 4 mL of hydrofluoric acid, place it on a low-temperature hot plate at 170 °C and shake well to completely dissolve the sample, make up the volume to 100 mL, and wait for measurement.

[0038] 2) Detection was carried out using the calibration curve prepared in Example 1, and the results are shown in Table 1.

[0039] Example 4

[0040] 1) Sample decomposition: Weigh 0.2000 g of ferrotitanium sample 4 (accurate to 0.0001 g), place it in a 150 mL clean polytetrafluoroethylene beaker, successively add 15 mL of nitric acid, 5 mL of mannitol, and 4 mL of hydrofluoric acid, place it on a low-temperature hot plate at 170 °C and shake well to completely dissolve the sample, make up the volume to 100 mL, and wait for measurement.

[0041] 2) Detection was carried out using the calibration curve prepared in Example 1, and the results are shown in Table 1.

[0042] Table 1 Detection results of boron content in Examples 1 - 4

[0043]

[0044] Comparative Example 1

[0045] 1) Sample decomposition: Weigh 0.2000 g of ferrotitanium sample 1 (accurate to 0.0001 g), place it in a 150 mL clean polytetrafluoroethylene beaker, successively add 19 mL of aqua regia and 5 mL of mannitol, place it on a low-temperature hot plate at 170 °C and shake well. The heating time is the same as that in Example 1, and the sample was not completely dissolved. Continuing to heat, it was found that the sample could never be completely dissolved.

[0046] Comparative Example 2

[0047] 1) Sample decomposition: Weigh 0.2000 g of ferrotitanium sample 1 (accurate to 0.0001 g), place it in a 150 mL clean polytetrafluoroethylene beaker, successively add 15 mL of aqua regia, 4 mL of hydrofluoric acid, and 5 mL of mannitol, place it on a low-temperature hot plate at 170 °C and shake well. The heating time is the same as that in Example 1, and the sample was not completely dissolved. Continuing to heat, it was found that the sample could never be completely dissolved.

[0048] As can be seen from Table 1, the detection accuracy of the detection method of the present invention is relatively high. In addition, it was found during the decomposition process that by using the combination of nitric acid and hydrofluoric acid of the present invention, the sample can be completely digested, while by using aqua regia or the combination of aqua regia and hydrofluoric acid in Comparative Example 1 and Comparative Example 2, the sample can never be completely digested.

Claims

1. A method for determining trace boron content in titanium-iron alloy, characterized in that: The steps include: 1) Sample decomposition: The titanium-iron alloy sample is leached and dissolved in a mixed acid of nitric acid and hydrofluoric acid in the presence of mannitol, and then the volume is fixed to obtain a sample to be tested; 2) Determination of boron content: set the working parameters of the ICP-AES spectrometer, set the detection spectrum of boron, prepare and draw a calibration curve, and determine the boron content in the sample obtained in step 1).

2. The method according to claim 1, characterized in that: In step 1), the ratio of ferrotitanium alloy sample: mannitol: nitric acid: hydrofluoric acid is 0.2: 4.5-5.5: 14-16: 3.5-4.5, wherein the measurement unit of the ferrotitanium alloy sample is g, and the measurement units of mannitol, nitric acid and hydrofluoric acid are ml.

3. The method according to claim 1 or 2, characterized in that: Step 1) is specifically as follows: placing a titanium-iron alloy sample in a polytetrafluoroethylene beaker, adding nitric acid, mannitol and hydrofluoric acid in sequence, placing it on a hot plate at 165-175° C. and shaking it fully until the titanium-iron alloy sample is completely dissolved, and then constant volume is obtained to obtain a sample to be tested.

4. The method according to claim 1, characterized in that: In step 2), the operating parameters of the ICP-AES spectrometer are set as follows: Pump speed is 48~51r.min -1 , RF power is 1145~1155W, nebulizer gas flow rate is 0.48~0.51L / min, cooling gas flow rate is 11.5~12.5L / min, auxiliary gas flow rate is 0.48~0.51L / min, visible light chamber exposure and light capture time is 4~6s, and ultraviolet light chamber exposure time is 14~16s.

5. The method according to claim 1, characterized in that: In step 2), the detection spectrum line of boron is 182.641 nm.

6. The method according to claim 1, characterized in that: In step 2), the preparation and drawing method of the calibration curve is: Weigh 5 portions of 0.2000g titanium iron standard sample, dissolve them with nitric acid and hydrofluoric acid mixed acid in the presence of mannitol, transfer them into 5 100ml volumetric flasks respectively, add 0.0ml, 0.5ml, 1.0ml, 2.0ml and 3.0ml of 20.00μg / ml boron standard stock solution respectively, make up to volume, and prepare working curve solution, which is equivalent to 0.2000g sample containing 0%, 0.005%, 0.010%, 0.020% and 0.030% boron; Under the ICP-AES spectrometer working parameters and boron detection spectrum conditions set in step 2), the spectral intensity of the working curve solution is measured in turn, and a calibration curve is established with the percentage of boron in the working curve solution as the horizontal axis and the measured spectral intensity as the vertical axis.

7. The method according to claim 1, characterized in that: In step 2), the sample introduction system of the ICP-AES spectrometer is a hydrofluoric acid resistant sample introduction system.

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