Method for detecting carbon content in titanium-aluminum alloy

Abstract

The invention relates to a method for detecting the carbon content in a titanium-aluminum alloy, which comprises the following steps: (1) carrying out mixed acid treatment on a titanium-aluminum alloy sample to obtain a sample to be detected; (2) carrying out heat treatment on the to-be-detected sample and a fluxing agent to obtain to-be-detected gas; the fluxing agent comprises a tungsten-tin mixed fluxing agent, a pure iron fluxing agent and a pure copper fluxing agent; and (3) analyzing the carbon content of the gas to be detected to obtain the carbon content in the titanium-aluminum alloy. According to the detection method provided by the invention, a mixed acid treatment process is combined with a sample detection process for mutual cooperation, on one hand, impurities and oxides on the surface of the titanium-aluminum alloy sample are removed by adopting mixed acid treatment, and on the other hand, a fluxing agent is introduced in the heat treatment process, and the variety of the fluxing agent is optimized; therefore, complete melting of the titanium-aluminum alloy sample and full release of carbon are promoted, and the detection result has the advantages of good repeatability, excellent stability and high accuracy.

Description

Technical Field

[0001] This invention relates to the technical field of alloy material composition analysis, and in particular to a method for detecting the carbon content in titanium-aluminum alloys. Background Technology

[0002] Titanium-aluminum (TiAl) alloys have become important materials in many high-tech fields due to their excellent physical and mechanical properties. Their high specific strength, good high-temperature resistance, and oxidation resistance make them promising for aerospace, automotive, and other high-temperature applications. Significant research has been conducted both domestically and internationally on the microstructure, deformation characteristics, influence of additive elements, and preparation techniques of TiAl alloys.

[0003] The carbon content in titanium-aluminum alloys is a crucial standard for evaluating product quality, as its level significantly impacts the alloy's performance. Currently, there are no specific standards for detecting the carbon content in titanium-aluminum alloys. Existing technologies for detecting carbon content in metals or alloys generally employ gravimetric methods, infrared absorption methods, chromatographic methods, or electrochemical methods. Among these, infrared absorption methods are a primary choice for researchers due to their simplicity, high sensitivity, reliable results in determining carbon content in metals or alloys, wide testing range, and fast analysis speed. Existing technology CN107153045A discloses a method for determining the carbon content in ultra-low carbon intermediate coating agents using infrared absorption. This method first establishes a linear relationship using infrared absorption, and then obtains the carbon content of the test sample based on the sample analysis.

[0004] However, while infrared absorption spectroscopy offers improved accuracy compared to other methods for detecting carbon content in metals or alloys, direct application of infrared absorption to determine carbon content results in poor repeatability and stability due to dust, oxides, and other impurities present in the metals or alloys. Existing technology GB / T 4698.7-2011, "Chemical Analysis Methods for Determination of Oxygen and Nitrogen Content in Sponge Titanium, Titanium and Titanium Alloys," uses a 3:1 mass ratio of nitric acid to hydrofluoric acid solution for cleaning. At room temperature, the highly reactive nature of aluminum causes the reaction to be too rapid, leading to unstable results when directly applying infrared absorption spectroscopy to detect carbon content in the sample.

[0005] Therefore, providing a method for detecting the carbon content in titanium-aluminum alloys, while also possessing the advantages of good repeatability and high stability of the detection results, has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a method for detecting the carbon content in titanium-aluminum alloys. The detection method provided by the present invention combines a mixed acid treatment process with a sample detection process. On the one hand, the mixed acid treatment removes impurities and oxides from the surface of the titanium-aluminum alloy sample. On the other hand, a flux is introduced during the heat treatment process, and the type of flux is optimized, thereby promoting complete melting of the titanium-aluminum alloy sample and full release of carbon. This results in detection results that simultaneously possess the advantages of good repeatability, excellent stability, and high accuracy.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for detecting the carbon content in titanium-aluminum alloys, the method comprising the following steps:

[0009] (1) The titanium-aluminum alloy sample was subjected to mixed acid treatment to obtain the sample to be tested;

[0010] (2) The sample to be tested and the flux are heat-treated to obtain the gas to be tested; the flux includes tungsten-tin mixed flux, pure iron flux and pure copper flux;

[0011] (3) Analyze the carbon content of the gas to be tested to obtain the carbon content in the titanium-aluminum alloy.

[0012] The detection method provided by this invention combines a mixed acid treatment process with a sample detection process. On the one hand, the mixed acid treatment removes impurities and oxides from the surface of the titanium-aluminum alloy sample, making the results of detecting the carbon content in the titanium-aluminum alloy sample more stable and accurate. On the other hand, a flux is introduced during the heat treatment process, and the type of flux is optimized to ensure the complete melting of the titanium-aluminum alloy sample and the full and complete release of carbon content in the melt product, thereby further improving the repeatability, stability, and accuracy of the detection results.

[0013] The flux used in this invention is a compound of tungsten-tin mixed flux, pure iron flux, and pure copper flux, which can ensure complete melting of the titanium-aluminum alloy sample during heat treatment without the generation of dust splashes, and can fully release the carbon content in the sample. The resulting detection curve is flat without tailing peaks, thus obtaining detection results of the carbon content of titanium-aluminum alloy samples with good repeatability, excellent stability, and more accurate results.

[0014] Specifically, in tungsten-tin fluxes, although tungsten has a high melting point, it is extremely easy to oxidize, reaching tungsten trioxide (WO3) at 900℃. This oxidation process releases a large amount of heat, resulting in a significant fluxing effect. Furthermore, the WO3 formed is an acidic oxide that promotes the escape of the analyte gas, facilitating the full release of carbon. However, due to the high melting point of pure tungsten (3400℃), tin, with a melting point of only 231℃, needs to be added to lower the flux's melting point. Simultaneously, the introduction of tin improves the fluidity of the slag, enabling a rapid reaction. In the electromagnetic induction heating process of a carbon-sulfur analyzer, pure iron flux generates a thermal effect under the influence of a magnetic field, rapidly increasing the temperature inside the crucible. Furthermore, pure iron flux increases the sample's magnetic permeability and fluidity, and lowers the melting point of the entire combustion system. Pure copper introduced into the flux oxidizes during heat treatment, releasing a large amount of heat. During the reaction, it inhibits the volatilization of tin oxides, reduces the viscosity of the molten oxide or slag, and facilitates gas release.

[0015] Preferably, the titanium-aluminum alloy sample in step (1) is pretreated before the mixed acid treatment.

[0016] Preferably, the pretreatment includes: preparing several small titanium-aluminum alloy samples from the titanium-aluminum alloy sample.

[0017] Preferably, the unit mass of the titanium-aluminum alloy sample is 0.05-0.08g, such as 0.05g, 0.055g, 0.06g, 0.065g, 0.07g, 0.075g, or 0.08g.

[0018] Optionally, the titanium-aluminum alloy sample described in this invention is first prepared into a rod-shaped sample by mechanical processing, and then made into several small titanium-aluminum alloy samples with a unit mass of 0.05-0.08g by a cutting process.

[0019] This invention cuts the titanium-aluminum alloy sample into several smaller titanium-aluminum alloy samples, which can further improve the removal of impurities and oxides from the sample during the mixed acid treatment process, thereby making the results of detecting the carbon content in the titanium-aluminum alloy sample more stable and more accurate.

[0020] Preferably, the mixed acid treatment in step (1) uses a mixed acid solution.

[0021] Preferably, the mixed acid solution includes a first acid solution, a second acid solution, and a solvent.

[0022] Preferably, the first acid solution comprises a nitric acid solution.

[0023] Preferably, the second acid solution comprises a hydrofluoric acid solution.

[0024] Preferably, the concentration of the first acid solution is 62-68 wt%, such as 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, or 68 wt%.

[0025] Preferably, the concentration of the second acid solution is 30-60 wt%, such as 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, or 60 wt%.

[0026] Preferably, the volume ratio of the first acid solution to the second acid solution is (0.9-1.2):(0.8-1.4), for example, 0.9:1.4, 1:1.4, 1.1:1.4, 1.2:1.4, 0.9:1.3, 1:1.3, 1.1:1.3, 1.2:1.3, 0.9:1.2, 1:1.2, 1.1:1.2, 0.9:1.1, 1:1, 1:1.2, 0.9:0.8, or 1.2:0.8, etc.

[0027] Preferably, the volume ratio of the first acid solution to the solvent is 1:(3-6), such as 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5 or 1:6, etc.

[0028] As a preferred technical solution of the present invention, the mixed acid treatment process includes: mixing the pretreated titanium-aluminum alloy sample with a mixed acid solution, and then washing and drying it to obtain the sample to be tested.

[0029] Preferably, the mixing method includes any one of ultrasound, oscillation, or stirring, with ultrasound being the preferred method.

[0030] The present invention further optimizes the ultrasonic process, which can more effectively remove impurities and oxides adhering to the surface of the titanium-aluminum alloy sample.

[0031] In this invention, the drying method is not specifically limited, including but not limited to drying under heating lamps or drying under nitrogen, and those skilled in the art can choose according to their needs.

[0032] Preferably, the mass-to-volume ratio of the titanium-aluminum alloy sample to the mixed acid solution is (0.01-0.05) g:1 mL, such as 0.01 g:1 mL, 0.02 g:1 mL, 0.03 g:1 mL, 0.04 g:1 mL, or 0.05 g:1 mL.

[0033] Preferably, the mixing time between the titanium-aluminum alloy sample and the mixed acid solution is 0.5-5 min, such as 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, or 5 min.

[0034] Preferably, the mass ratio of the sample to be tested to the flux in step (2) is 1:(10-18), such as 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17 or 1:18, and preferably 1:(10-14).

[0035] This invention further regulates the mass ratio of the sample to be tested and the flux. If the mass ratio is too small, the amount of flux added will be too large, which will result in a large amount of dust splashing and affect the detection effect of the carbon content of the sample. If the mass ratio is too high, the amount of flux added will be too small, which will result in the inability to effectively promote the complete melting of the sample and affect the accuracy of the analysis results.

[0036] Preferably, the mass ratio of tungsten to tin in the tungsten-tin mixed additive is (2-5):1, such as 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, and more preferably (3-4.5):1.

[0037] This invention regulates the mass ratio of tungsten to tin in the tungsten-tin mixed flux. If the mass ratio of tungsten to tin is too small, the tungsten content will be too low, resulting in poor fluxing effect and failure to promote the escape of the gas to be tested, thus affecting the accuracy of carbon content detection in the sample. If the mass ratio is too large, the tungsten content will be too high, resulting in a large amount of dust generated during the heat treatment of the sample to be tested, affecting the subsequent detection effect.

[0038] Preferably, based on a total flux mass of 100wt%, the mass percentage of the tungsten-tin mixed flux is 20-32wt%, such as 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, or 32wt%.

[0039] In this invention, if the mass ratio of the tungsten-tin mixed flux is too small, the fluxing effect will be poor, the sample will not be completely melted, and the test results will be affected; if the mass ratio of the tungsten-tin mixed flux is too large, a large amount of dust splash will be generated, which will affect the detection effect of the carbon content of the sample to be tested.

[0040] Preferably, based on a total flux mass of 100wt%, the mass percentage of the pure iron flux is 40-60wt%, such as 40wt%, 44wt%, 48wt%, 52wt%, 56wt%, or 60wt%.

[0041] In this invention, if the mass ratio of pure iron flux is too small, it will lead to incomplete reaction, such as pits, in the molten solid in the crucible after the reaction is completed; if the mass ratio of pure iron flux is too large, it will lead to a large amount of dust after melting and increase costs.

[0042] Preferably, based on a total flux mass of 100wt%, the mass percentage of the pure copper flux is 20-35wt%, such as 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, 32wt%, 34wt%, or 35wt%, with 22-35wt% being the most preferred.

[0043] In this invention, if the mass ratio of pure copper flux is too small, the fluxing effect will be poor and the sample will not be completely melted; if the mass ratio of pure copper flux is too large, a large amount of copper oxide (CuO) will be generated. CuO is an alkaline substance and will affect the release of carbon dioxide during the reaction.

[0044] As a preferred technical solution of the present invention, during the heat treatment in step (2), the flux is applied to the sample to be tested.

[0045] This invention employs a method of coating the sample to be tested with a flux, which encapsulates the sample beneath it. During heat treatment, the flux melts preferentially to achieve a fluxing effect, thereby allowing the sample to be fully melted.

[0046] In this invention, the order in which the three fluxes are added to the sample to be tested has little effect on the test results. The fluxes can be added to the sample to be tested in any order, including but not limited to the following order: adding tungsten-tin mixed flux, pure iron flux, and pure copper flux to the surface of the sample to be tested in sequence.

[0047] Preferably, the amount of sample to be tested in step (2) is 0.2-0.5g, such as 0.2g, 0.25g, 0.3g, 0.35g, 0.4g, 0.45g or 0.5g.

[0048] This invention regulates the injection volume of the test sample to avoid the titanium-aluminum alloy test sample being too large, which would prevent complete melting during heat treatment and affect the detection effect. At the same time, it avoids the subsequent carbon content detection results from being too light.

[0049] Preferably, the heat treatment in step (2) is carried out in an oxygen atmosphere.

[0050] Preferably, the purity of the oxygen atmosphere is 99.6% or higher, such as 99.6%, 99.7%, 99.8% or 99.9%.

[0051] Preferably, the heat treatment in step (2) includes: under the heating condition of oxygen atmosphere, the sample to be tested covered with flux melts, and the carbon in the melted product reacts with the oxygen in the reaction atmosphere to obtain the gas to be tested.

[0052] Preferably, the heating power of the heat treatment in step (2) is 4.0-5.0kW, such as 4.0kW, 4.1kW, 4.2kW, 4.3kW, 4.4kW, 4.5kW, 4.6kW, 4.7kW, 4.8kW, 4.9kW or 5.0kW.

[0053] In this invention, if the heating power of the heat treatment is too low, the sample to be tested will not be completely melted, affecting subsequent detection. Furthermore, it will also cause incomplete combustion of carbon in the sample and oxygen in the reaction atmosphere, affecting the accuracy of the detection. If the heating power is too high, it will lead to excessive energy consumption and affect the service life of the instrument.

[0054] Preferably, the heat treatment time in step (2) is 15-25s, such as 15s, 17s, 19s, 21s, 23s or 25s.

[0055] Preferably, the gas to be tested in step (2) includes carbon dioxide.

[0056] Preferably, the heat treatment in step (2) and the analysis in step (3) are both performed in a carbon-sulfur analyzer.

[0057] Preferably, the heat treatment in step (2) is carried out in the graphite crucible cavity of the carbon-sulfur analyzer.

[0058] Preferably, step (3) of analyzing the carbon content of the gas to be tested is carried out in the infrared detection cell of a carbon-sulfur analyzer.

[0059] Preferably, the gas to be tested is delivered to the infrared detection cell via a carrier gas.

[0060] Preferably, the carrier gas is oxygen.

[0061] Preferably, the pressure of the carrier gas is 30-40 psi, such as 30 psi, 31 psi, 32 psi, 33 psi, 34 psi, 35 psi, 36 psi, 37 psi, 38 psi, 39 psi or 40 psi.

[0062] Preferably, during the transport process, the integration delay time of the carbon flow analyzer is 20-30s, such as 20s, 22s, 24s, 26s, 28s or 30s.

[0063] Preferably, the analysis time in step (3) is 40-60s, such as 40s, 44s, 48s, 52s, 56s or 60s.

[0064] Preferably, the carbon-sulfur analyzer needs to be purged before the sample is injected.

[0065] In this invention, a purging process is performed before the carbon-sulfur analyzer is used to remove dust or other impurities from the analyzer.

[0066] Preferably, the purging process takes 10-30 seconds, such as 10 seconds, 14 seconds, 18 seconds, 22 seconds, 26 seconds, or 30 seconds.

[0067] As a further preferred technical solution of the present invention, the detection method includes the following steps:

[0068] (1) Prepare several small titanium-aluminum alloy samples with a unit mass of 0.05-0.08g. Mix the small titanium-aluminum alloy samples and the mixed acid solution at a mass-volume ratio of (0.01-0.05)g:1mL for 0.5-5min. Then, after washing and drying, the sample to be tested is obtained.

[0069] The mixed acid solution comprises a first acid solution with a concentration of 62-68 wt%, a second acid solution with a concentration of 30-60 wt%, and a solvent. The volume ratio of the first acid solution to the second acid solution is (0.9-1.2):(0.8-1.4), and the volume ratio of the first acid solution to the solvent is 1:(3-6).

[0070] (2) The carbon-sulfur analyzer is purged for 10-30 seconds. 0.2-0.5 g of the sample to be tested is placed in the graphite crucible chamber of the carbon-sulfur analyzer. The flux is applied to the sample to be tested according to the mass ratio of the sample to the flux of 1:(10-18). The sample is then subjected to heat treatment for 15-25 seconds in an oxygen atmosphere with a purity of 99.6% or higher. The heating power of the heat treatment is 4.0-5.0 kW. During the heating process of the heat treatment, the sample to be tested covered with flux melts. The carbon in the melted product reacts with the oxygen in the reaction atmosphere to produce a test gas containing carbon dioxide.

[0071] The flux comprises 20-32 wt% tungsten-tin mixed flux, 40-60 wt% pure iron flux and 20-35 wt% pure copper flux, wherein the mass ratio of tungsten to tin in the tungsten-tin mixed flux is (2-5):1.

[0072] (3) Using oxygen with a gas flow rate of 2-4 L / min as the carrier gas, and setting the gas pressure of the carrier gas to 30-40 psi, the gas to be tested is transported to the infrared detection cell of the carbon-sulfur analyzer through the carrier gas. The integration delay time of the carbon flow analyzer is 20-30 s. The carbon content of the gas to be tested is analyzed in the infrared detection cell for 40-60 s to obtain the carbon content in the titanium-aluminum alloy.

[0073] Compared with the prior art, the present invention has at least the following beneficial effects:

[0074] (1) The detection method provided by the present invention combines the mixed acid treatment process with the sample detection process. On the one hand, the mixed acid treatment removes impurities and oxides from the surface of the titanium-aluminum alloy sample, making the results of detecting the carbon content in the titanium-aluminum alloy sample more stable. On the other hand, flux is introduced during the heat treatment process and the type of flux is optimized to ensure the complete melting of the titanium-aluminum alloy sample and the full release of carbon content in the melt product, thereby further improving the repeatability, stability and accuracy of the detection results.

[0075] (2) The flux used in this invention is a mixture of tungsten-tin flux, pure iron flux and pure copper flux, which can ensure that the titanium-aluminum alloy sample is completely melted and no dust splashes are generated during the heat treatment process, and can fully release the carbon content in the sample. The resulting detection curve is flat and without tailing peaks, thus obtaining a carbon content determination process with high accuracy, good repeatability and excellent stability. Detailed Implementation

[0076] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0077] The carbon and sulfur analyzer used in the following examples is from Lexco, Inc., USA, and its model is CS844.

[0078] Example 1

[0079] This embodiment provides a method for detecting the carbon content in titanium-aluminum alloys, the method comprising the following steps:

[0080] (1) A mixed acid solution was prepared by mixing 65wt% nitric acid solution and 45wt% hydrofluoric acid solution in a volume ratio of 1:1 and nitric acid solution and deionized water in a volume ratio of 1:4. The titanium-aluminum alloy sample was cut into several small titanium-aluminum alloy samples with a unit mass of 0.05g. The small titanium-aluminum alloy samples and the mixed acid solution were ultrasonically mixed for 1min at a mass-volume ratio of 0.02g:1mL. Then, after washing with ethanol and drying under nitrogen conditions, the sample to be tested was obtained.

[0081] (2) The carbon-sulfur analyzer was purged for 20 seconds. 0.3g of the sample to be tested obtained in step (1) was placed at the bottom of the graphite crucible chamber in the carbon-sulfur analyzer. 1.2g of tungsten-tin mixed flux (where the mass ratio of W to Sn is 4:1), 2g of pure iron flux and 1g of pure copper flux were successively covered on the sample to be tested. The sample was heat-treated for 20 seconds in an oxygen atmosphere with a purity of 99.6%. The heating power of the heat treatment was 4.5kW. During the heat treatment, the sample to be tested covered with flux melted. The carbon in the melt product reacted with the oxygen in the reaction atmosphere to obtain the gas to be tested containing carbon dioxide.

[0082] (3) Using oxygen with a flow rate of 3L / min as the carrier gas, and setting the oxygen pressure to 35psi, the gas to be tested obtained in step (2) is transported to the infrared detection cell of the carbon-sulfur analyzer through the carrier gas. The integration delay time of the carbon-sulfur analyzer is 25s. The carbon content of the gas to be tested obtained in step (2) is analyzed in the infrared detection cell for 50s to obtain the carbon content in the titanium-aluminum alloy sample.

[0083] Example 2

[0084] This embodiment provides a method for detecting the carbon content in titanium-aluminum alloys, the method comprising the following steps:

[0085] (1) A mixed acid solution was prepared by mixing 63wt% nitric acid solution and 30wt% hydrofluoric acid solution in a volume ratio of 0.9:1.1 and nitric acid solution and deionized water in a volume ratio of 1:3. The titanium-aluminum alloy sample was cut into several small titanium-aluminum alloy samples with a unit mass of 0.07g. The small titanium-aluminum alloy samples and the mixed acid solution were ultrasonically mixed for 0.5min in a mass-volume ratio of 0.02g:1mL. Then, after washing with ethanol and drying under nitrogen conditions, the sample to be tested was obtained.

[0086] (2) The carbon-sulfur analyzer was purged for 15 seconds. 0.4g of the sample to be tested obtained in step (1) was placed at the bottom of the graphite crucible chamber in the carbon-sulfur analyzer. 0.8g of tungsten-tin mixed flux (where the mass ratio of W to Sn is 3:1), 2.3g of pure iron flux and 0.9g of pure copper flux were then placed on the sample to be tested. The sample was then heat-treated for 25 seconds in an oxygen atmosphere with a purity of 99.8%. The heating power of the heat treatment was 4.0kW. During the heat treatment, the sample to be tested covered with flux melted. The carbon in the melt product reacted with the oxygen in the reaction atmosphere to produce a test gas containing carbon dioxide.

[0087] (3) Using oxygen with a gas flow rate of 2.5 L / min as the carrier gas, and setting the oxygen pressure to 30 psi, the gas to be tested obtained in step (2) is transported to the infrared detection cell of the carbon-sulfur analyzer through the carrier gas. The integration delay time of the carbon-sulfur analyzer is 30 s. The carbon content of the gas to be tested in step (2) is analyzed in the infrared detection cell for 60 s to obtain the carbon content in the titanium-aluminum alloy sample.

[0088] Example 3

[0089] This embodiment provides a method for detecting the carbon content in titanium-aluminum alloys, the method comprising the following steps:

[0090] (1) A mixed acid solution was prepared by mixing 68wt% nitric acid solution and 60wt% hydrofluoric acid solution in a volume ratio of 1.2:0.8 and nitric acid solution and deionized water in a volume ratio of 1:6. The titanium-aluminum alloy sample was cut into several small titanium-aluminum alloy samples with a unit mass of 0.05g. The small titanium-aluminum alloy samples and the mixed acid solution were ultrasonically mixed for 5min in a mass-volume ratio of 0.02g:1mL. Then, the samples were washed with ethanol and dried with a heating lamp to obtain the sample to be tested.

[0091] (2) The carbon-sulfur analyzer was purged for 30 seconds. 0.5g of the sample to be tested obtained in step (1) was placed at the bottom of the graphite crucible chamber in the carbon-sulfur analyzer. 1.8g of tungsten-tin mixed flux (where the mass ratio of W to Sn is 4.5:1), 2.5g of pure iron flux and 1.7g of pure copper flux were then placed on the sample to be tested. The sample was then heat-treated for 16 seconds in an oxygen atmosphere with a purity of 99.8%. The heating power of the heat treatment was 5.0kW. During the heat treatment, the sample to be tested covered with flux melted. The carbon in the melt product reacted with the oxygen in the reaction atmosphere to produce a test gas containing carbon dioxide.

[0092] (3) Using oxygen with a gas flow rate of 3.5 L / min as the carrier gas, and setting the oxygen pressure to 40 psi, the gas to be tested obtained in step (2) is transported to the infrared detection cell of the carbon-sulfur analyzer through the carrier gas. The integration delay time of the carbon-sulfur analyzer is 30 s. The carbon content of the gas to be tested in step (2) is analyzed in the infrared detection cell for 60 s to obtain the carbon content in the titanium-aluminum alloy sample.

[0093] Example 4

[0094] The only difference between this embodiment and Embodiment 1 is that this embodiment omits cutting the titanium-aluminum alloy into several small samples with a unit mass of 0.05g. Instead, the titanium-aluminum alloy is ultrasonically mixed with the mixed acid solution at a mass-to-volume ratio of 0.02g:1mL for 1 minute. After washing with ethanol and drying under nitrogen conditions, a whole sample of 0.3g is obtained. In step (2), the whole sample of 0.3g is placed directly at the bottom of the graphite crucible chamber in the carbon-sulfur analyzer. The rest of the contents are the same as in Embodiment 1.

[0095] Example 5

[0096] The only difference between this embodiment and Embodiment 1 is that the flux used in step (2) consists of 1.5g of tungsten-tin mixed flux (W to Sn mass ratio of 4:1), 2.6g of pure iron flux, and 1.3g of pure copper flux. That is, the mass ratio of the sample to the total mass of the flux in step (2) is 1:18. The rest is the same as in Embodiment 1.

[0097] Example 6

[0098] The only difference between this embodiment and Embodiment 1 is that the flux used in step (2) consists of 0.7g of tungsten-tin mixed flux (W to Sn mass ratio of 4:1), 1.1g of pure iron flux, and 0.6g of pure copper flux. That is, the mass ratio of the sample to the total mass of the flux in step (2) is 1:8. The rest is the same as in Embodiment 1.

[0099] Example 7

[0100] The only difference between this embodiment and Embodiment 1 is that the flux used in step (2) consists of 1.7g of tungsten-tin mixed flux (W to Sn mass ratio of 4:1), 2.9g of pure iron flux, and 1.4g of pure copper flux. That is, the mass ratio of the sample to the total mass of the flux in step (2) is 1:20. The rest is the same as in Embodiment 1.

[0101] Example 8

[0102] The only difference between this embodiment and Embodiment 1 is that the mass ratio of W to Sn in the tungsten-tin mixed flux used in step (2) is 5:1. The rest is the same as in Embodiment 1.

[0103] Example 9

[0104] The only difference between this embodiment and Embodiment 1 is that in step (2), the mass ratio of W to Sn in the tungsten-tin mixed flux is 1:1. The rest is the same as in Embodiment 1.

[0105] Example 10

[0106] The only difference between this embodiment and Embodiment 1 is that in step (2), the mass ratio of W to Sn in the tungsten-tin mixed flux is 6:1. The rest is the same as in Embodiment 1.

[0107] Example 11

[0108] The only difference between this embodiment and Embodiment 1 is that the flux used in step (2) consists of 1.55g of tungsten-tin mixed flux (W to Sn mass ratio of 4:1), 1.7g of pure iron flux, and 0.95g of pure copper flux. That is, in step (2), based on a total flux mass of 100wt%, the mass percentage of tungsten-tin mixed flux is 36.9wt%. The rest is the same as in Embodiment 1.

[0109] Example 12

[0110] The only difference between this embodiment and Embodiment 1 is that the flux used in step (2) consists of 1.3g of tungsten-tin mixed flux (W to Sn mass ratio of 4:1), 1.5g of pure iron flux, and 1.4g of pure copper flux. That is, in step (2), the mass percentage of pure iron flux is 35.7wt% based on a total flux mass of 100wt%. The rest is the same as in Embodiment 1.

[0111] Example 13

[0112] The only difference between this embodiment and Embodiment 1 is that the flux used in step (2) consists of 1.3g of tungsten-tin mixed flux (W to Sn mass ratio of 4:1), 2.2g of pure iron flux, and 0.7g of pure copper flux. That is, in step (2), the total mass of flux is 100wt%, and the mass percentage of pure copper flux is 16.7wt%. The rest is the same as in Embodiment 1.

[0113] Example 14

[0114] The only difference between this embodiment and Embodiment 1 is that the heating power used in step (2) is 3.5kW. The rest is the same as in Embodiment 1.

[0115] Comparative Example 1

[0116] The only difference between this comparative example and Example 1 is that the detection method provided in this comparative example omits the mixed acid treatment process of the titanium-aluminum alloy sample in step (1), that is, the cut titanium-aluminum alloy sample is directly used as the sample to be tested. The rest is the same as in Example 1.

[0117] Comparative Example 2

[0118] The only difference between this comparative example and Example 1 is that, in the detection method provided in this comparative example, the pure iron flux is omitted from the flux used in step (2), and the mass fraction of the omitted pure iron flux is evenly distributed to the tungsten-tin mixed flux and the pure copper flux. The rest is the same as in Example 1.

[0119] Comparative Example 3

[0120] The only difference between this comparative example and Example 1 is that, in the detection method provided in this comparative example, the pure copper flux used in step (2) is omitted, and the mass fraction of the omitted pure copper flux is evenly distributed to the tungsten-tin mixed flux and the pure iron flux. The rest is the same as in Example 1.

[0121] Comparative Example 4

[0122] The only difference between this comparative example and Example 1 is that the flux covering the surface of the sample to be tested in step (2) is omitted in the detection method provided in this comparative example, and the sample to be tested in step (1) is directly placed in a carbon-sulfur analyzer for heat treatment. The rest is the same as in Example 1.

[0123] The detection methods provided in the above embodiments and comparative examples were performed three times in parallel without interruption. The measured carbon content and combustion status were recorded, and the average value and standard deviation of the parallel tests were calculated based on the measured values. The results are shown in Table 1.

[0124] Table 1

[0125]

[0126] The test results show that:

[0127] (1) As can be seen from Examples 1 to 3, the detection method provided by the present invention combines the mixed acid treatment process with the sample detection process. On the one hand, the mixed acid treatment removes impurities and oxides from the surface of the titanium-aluminum alloy sample. On the other hand, flux is introduced during the heat treatment process and the type of flux is optimized, thereby promoting the complete melting of the titanium-aluminum alloy sample and the full release of carbon, and improving the repeatability, stability and accuracy of the detection results.

[0128] (2) As can be seen from Examples 1 and 4, the present invention cuts the titanium-aluminum alloy sample into several small titanium-aluminum alloy samples, which can further improve the effect of removing impurities and oxides in the sample during the mixed acid treatment process, thereby making the results of detecting the carbon content in the titanium-aluminum alloy sample more stable and more accurate.

[0129] (3) As can be seen from Examples 1 and 5-7, the present invention further controls the mass ratio of the sample to be tested and the flux. If the mass ratio is too small and the amount of flux added is too large, dust will accumulate in the furnace and combustion tube, resulting in poor parallel stability and accuracy of the test results. If the mass ratio is too high and the amount of flux added is too low, it will be impossible to effectively promote the complete melting of the sample to be tested, affecting the detection effect of carbon content of the sample to be tested.

[0130] (4) As can be seen from Examples 1 and 8-10, the present invention further regulates the mass ratio of tungsten to tin in the tungsten-tin mixed flux. If the mass ratio of tungsten to tin is too small and the tungsten content is too small, the fluxing effect will be poor and the gas to be tested will not be able to escape, thus affecting the accuracy of the carbon content detection of the sample. If the mass ratio is too large and the tungsten content is too high, a large amount of dust will be generated during the heat treatment of the sample to be tested, affecting the subsequent detection effect.

[0131] (5) As can be seen from Examples 1 and 11-13, the present invention further regulates the mass ratio of tungsten-tin mixed flux, pure iron flux and pure copper flux in the flux, thereby improving the fluxing effect of the flux, so that the titanium-aluminum alloy sample can be completely melted during the heat treatment process without the generation of dust splashes, and promotes the full release of carbon in the sample and the escape of carbon dioxide gas obtained from combustion, thereby improving the accuracy and repeatability of carbon content detection in the sample.

[0132] (6) As can be seen from Examples 1 and 14, the present invention further regulates the heating power of heat treatment. If the heating power of heat treatment is too low, the sample to be tested cannot be completely melted, which will affect the subsequent detection. In addition, it will also cause the carbon in the sample to be tested to burn incompletely with the oxygen in the reaction atmosphere, which will affect the accuracy of the detection.

[0133] (7) As can be seen from Example 1 and Comparative Example 1, the present invention removes impurities and oxides from the surface of titanium-aluminum alloy samples by mixed acid treatment, making the results of detecting carbon content in titanium-aluminum alloy samples more stable. However, when the mixed acid treatment process is missing, the results of carbon content determination of the sample will be unstable and the accuracy will be affected.

[0134] (8) As can be seen from Example 1 and Comparative Examples 2-3, the flux of the present invention, through the mutual compounding of tungsten-tin mixed flux, pure iron flux, and pure copper flux, can ensure that the sample is completely melted during heat treatment without the generation of dust splashes, thereby allowing the carbon content in the sample to be fully released. The resulting detection curve is flat without tailing peaks, and a carbon content determination process with high accuracy and good repeatability is obtained. However, if the pure iron flux is lacking, it will lead to incomplete melting, poor fluidity of the sample during melting, and pits at the bottom of the crucible after the reaction; if the pure copper flux is lacking, it will also lead to incomplete melting and the melting temperature will not reach the required level.

[0135] (9) As can be seen from Example 1 and Comparative Example 4, if the flux is missing in the detection method of the present invention, the sample to be tested will not be able to undergo a melting reaction during the heat treatment process, resulting in a decrease in the accuracy and repeatability of the carbon content detection results.

[0136] In summary, the detection method provided by this invention combines a mixed acid treatment process with a sample detection process. On the one hand, the mixed acid treatment removes impurities and oxides from the surface of the titanium-aluminum alloy sample, making the results of detecting the carbon content in the titanium-aluminum alloy sample more stable. On the other hand, a flux is introduced during the heat treatment process, and the type of flux is optimized to ensure the complete melting of the titanium-aluminum alloy sample and the full release of carbon content in the melt product, thereby further improving the repeatability, stability, and accuracy of the detection results.

[0137] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for detecting the carbon content in titanium-aluminum alloys, characterized in that, The detection method includes the following steps: (1) The titanium-aluminum alloy sample was subjected to mixed acid treatment to obtain the sample to be tested; (2) The sample to be tested and the flux are heat-treated to obtain the gas to be tested; the flux includes tungsten-tin mixed flux, pure iron flux and pure copper flux; (3) Analyze the carbon content of the gas to be tested to obtain the carbon content in the titanium-aluminum alloy.

2. The detection method according to claim 1, characterized in that, The titanium-aluminum alloy sample described in step (1) is also pretreated before the mixed acid treatment; Preferably, the pretreatment includes: preparing several small titanium-aluminum alloy samples from the titanium-aluminum alloy sample; Preferably, the unit mass of the titanium-aluminum alloy sample is 0.05-0.08g.

3. The detection method according to claim 1 or 2, characterized in that, The mixed acid treatment in step (1) uses a mixed acid solution; Preferably, the mixed acid solution comprises a first acid solution, a second acid solution, and a solvent; Preferably, the volume ratio of the first acid solution to the second acid solution is (0.9-1.2):(0.8-1.4); Preferably, the volume ratio of the first acid solution to the solvent is 1:(3-6).

4. The detection method according to claim 2 or 3, characterized in that, The mixed acid treatment process includes: mixing the pretreated titanium-aluminum alloy sample with a mixed acid solution, washing and drying it to obtain the sample to be tested; Preferably, the mass-to-volume ratio of the titanium-aluminum alloy sample to the mixed acid solution is (0.01-0.05) g: 1 mL; Preferably, the mixing time between the titanium-aluminum alloy sample and the mixed acid solution is 0.5-5 minutes.

5. The detection method according to any one of claims 1-4, characterized in that, In step (2), the mass ratio of the sample to be tested to the flux is 1:(10-18), preferably 1:(10-14); Preferably, the mass ratio of tungsten to tin in the tungsten-tin mixed additive is (2-5):1, more preferably (3-4.5):1; Preferably, based on a total flux mass of 100 wt%, the mass percentage of the tungsten-tin mixed flux is 20-32 wt%. Preferably, based on a total flux mass of 100 wt%, the pure iron flux has a mass percentage of 40-60 wt%. Preferably, based on a total flux mass of 100 wt%, the mass percentage of the pure copper flux is 20-35 wt%, more preferably 22-35 wt%.

6. The detection method according to any one of claims 1-5, characterized in that, In step (2), the flux is applied to the sample to be tested; Preferably, the amount of sample to be tested in step (2) is 0.2-0.5g; Preferably, the heat treatment in step (2) is carried out in an oxygen atmosphere; Preferably, the purity of the oxygen atmosphere is 99.6% or higher; Preferably, the heat treatment in step (2) includes: under the heating condition of oxygen atmosphere, the sample to be tested covered with flux melts, and the carbon in the melted product reacts with the oxygen in the reaction atmosphere to obtain the gas to be tested.

7. The detection method according to any one of claims 1-6, characterized in that, The heating power for the heat treatment in step (2) is 4.0-5.0 kW; Preferably, the heat treatment time in step (2) is 15-25 seconds; Preferably, the gas to be tested in step (2) includes carbon dioxide.

8. The detection method according to any one of claims 1-7, characterized in that, The heat treatment in step (2) and the analysis in step (3) are both performed in a carbon-sulfur analyzer; Preferably, step (3) of analyzing the carbon content of the gas to be tested is carried out in the infrared detection cell of a carbon-sulfur analyzer; Preferably, the gas to be tested is delivered to the infrared detection cell via a carrier gas; Preferably, the carrier gas is oxygen; Preferably, the pressure of the carrier gas is 30-40 psi; Preferably, during the conveying process, the integration delay time of the carbon-sulfur analyzer is 20-30 seconds; Preferably, the analysis time in step (3) is 40-60 seconds.

9. The detection method according to claim 8, characterized in that, The carbon and sulfur analyzer needs to be purged before the sample is injected. Preferably, the purging process takes 10-30 seconds.

10. The detection method according to claim 1, characterized in that, The detection method includes the following steps: (1) Prepare several small titanium-aluminum alloy samples with a unit mass of 0.05-0.08g. Mix the small titanium-aluminum alloy samples and the mixed acid solution at a mass-volume ratio of (0.01-0.05)g:1mL for 0.5-5min. Then, after washing and drying, the sample to be tested is obtained. The mixed acid solution comprises a first acid solution with a concentration of 62-68 wt%, a second acid solution with a concentration of 30-60 wt%, and a solvent. The volume ratio of the first acid solution to the second acid solution is (0.9-1.2):(0.8-1.4), and the volume ratio of the first acid solution to the solvent is 1:(3-6). (2) The carbon-sulfur analyzer is purged for 10-30 seconds. 0.2-0.5 g of the sample to be tested is placed in the graphite crucible chamber of the carbon-sulfur analyzer. The flux is applied to the sample to be tested according to the mass ratio of the sample to the flux of 1:(10-18). The sample is then subjected to heat treatment for 15-25 seconds in an oxygen atmosphere with a purity of 99.6% or higher. The heating power of the heat treatment is 4.0-5.0 kW. During the heating process of the heat treatment, the sample to be tested covered with flux melts. The carbon in the melted product reacts with the oxygen in the reaction atmosphere to produce a test gas containing carbon dioxide. The flux comprises 20-32 wt% tungsten-tin mixed flux, 40-60 wt% pure iron flux and 20-35 wt% pure copper flux, wherein the mass ratio of tungsten to tin in the tungsten-tin mixed flux is (2-5):

1. (3) Using oxygen with a gas flow rate of 2-4 L / min as the carrier gas, and setting the gas pressure of the carrier gas to 30-40 psi, the gas to be tested is transported to the infrared detection cell of the carbon-sulfur analyzer through the carrier gas. The integration delay time of the carbon flow analyzer is 20-30 s. The carbon content of the gas to be tested is analyzed in the infrared detection cell for 40-60 s to obtain the carbon content in the titanium-aluminum alloy.

Images