Method for detecting magnesium chloride inclusion in titanium sponge

Abstract

The invention relates to the technical field of material detection, in particular to a method for detecting magnesium chloride inclusion in titanium sponge, which comprises the following steps: S1, sample preparation: cutting a titanium sponge sample, ultrasonically cleaning with absolute ethyl alcohol, drying, treating, and fixing with a conductive adhesive; s2, performing SEM-EDS analysis, performing SEM observation on a morphology positioning suspicious area under low voltage, adjusting EDS parameters, performing energy spectrum surface scanning or point analysis, and performing co-positioning by combining chlorine and magnesium elements so as to judge inclusion of magnesium chloride; and S3, data processing: calculating the weight percentage of the chlorine element through a formula by using quantitative analysis software, and calibrating and detecting by combining a standard sample. The magnesium chloride inclusion in the titanium sponge can be efficiently and accurately detected through accurate microscopic morphology observation, element distribution analysis and quantitative calculation, operation is easy and convenient, the method is suitable for titanium sponge quality control, reliable technical support is provided for titanium sponge production and quality improvement, and product quality and performance are helped to be guaranteed.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, specifically to a method for detecting magnesium chloride inclusions in sponge titanium. Background Technology

[0002] Titanium and its alloys possess excellent properties such as high strength, superior corrosion resistance, and excellent biocompatibility, making them widely used in the aerospace, chemical, and medical industries. Since 1937, Kroll has developed the magnesium reduction of titanium tetrachloride (TiCl4), named the Kroll process, for producing high-purity titanium. This process has been widely used for the commercial production of sponge titanium over the past 70 years. Since the inception of the Kroll process itself, the removal of chloride impurities has been a major technical challenge in titanium production. Chlorides remaining in titanium during subsequent processing can cause various adverse effects, such as interfering with titanium ingot smelting and poor weldability.

[0003] Currently, methods for determining chlorine in sponge titanium include AgCl spectrophotometry, AgNO3 turbidimetry, potentiometric titration, and chromatography. AgCl spectrophotometry relies on the reaction of chloride ions with silver ions to form AgCl precipitate, which is then measured by spectrophotometer. However, the formation of AgCl precipitate can be affected by other ions in the solution, leading to measurement errors. Furthermore, this method requires complex sample pretreatment steps and is time-consuming. AgNO3 turbidimetry determines chlorine content by measuring the turbidity of the AgCl precipitate, but turbidity measurements are easily affected by particle size and distribution, resulting in unstable results. Additionally, turbidimetry has low sensitivity and is difficult to detect low concentrations of chlorine. While potentiometric titration offers high accuracy, it requires precise control of titration conditions and can be affected by electrode response speed and solution pH. Moreover, this method demands high operator skill and is complex to operate. Although chromatography can separate and detect multiple ions, the equipment is expensive, maintenance costs are high, and analysis time is long, making it unsuitable for rapid detection. Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS) can detect extremely low concentrations of chlorine, with sensitivity far exceeding that of traditional methods. SEM-EDS enables elemental analysis of samples at the microscale, providing high-resolution images of elemental distribution, which helps to understand the distribution of chlorine in samples. Compared with traditional chemical analysis methods, SEM-EDS does not require complex sample pretreatment steps and features strong micro-area analysis capabilities, high resolution, and excellent detection sensitivity, allowing direct analysis of the elemental composition and distribution of samples at the microscale. However, there are currently no reports on the direct detection of magnesium chloride inclusions in sponge titanium using SEM-EDS, especially for the accurate detection and characterization of low concentrations of chlorine (<100 ppm). Summary of the Invention

[0004] The purpose of this invention is to provide a method for detecting magnesium chloride inclusions in sponge titanium, so as to solve the problems of complex pretreatment steps, long analysis time, and high detection limit in the above-mentioned background art for detecting magnesium chloride inclusions in sponge titanium.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for detecting magnesium chloride inclusions in sponge titanium includes the following steps:

[0007] S1. Sample preparation: Cut the sponge titanium sample into blocks, clean it with anhydrous ethanol by ultrasonic cleaning, dry it, and fix it on the sample tray with conductive adhesive.

[0008] S2, SEM-EDS analysis: Scanning electron microscopes were used to observe the morphology of the samples at a low voltage of 5–10 kV to locate suspicious inclusion areas. The EDS detector parameters were adjusted, and the distribution and content of chlorine and magnesium were determined by energy dispersive spectroscopy or point analysis. The presence of magnesium chloride inclusions was determined by combining the co-localization analysis of the two.

[0009] S3. Data Processing: The weight percentage of chlorine is calculated using quantitative analysis software. Combined with standard sample calibration, this enables the detection of magnesium chloride inclusions. The formula for calculating the weight percentage of chlorine is:

[0010] , In the formula, is the weight percentage of chlorine, is the calibration factor for chlorine, is the correction factor for chlorine in the sample, is the correction factor for chlorine in the standard sample, is the radiation intensity of chlorine in the sample, and is the radiation intensity of chlorine in the standard sample.

[0011] Preferably, in step S1, the ultrasonic cleaning frequency is 20kHz, the power is 50-80W, the time is 3-5min, and the temperature is room temperature.

[0012] Preferably, in step S1, the drying temperature is 80°C and the time is 1 hour.

[0013] Preferably, in step S1, the sample surface, after being dried by gently blowing with a rubber bulb and then cooled to room temperature, is used to remove impurities.

[0014] Preferably, in step S2, the scanning electron microscope is a field emission scanning electron microscope or a tungsten filament electron microscope.

[0015] As a preferred option, in step S2, different magnifications are used for observation. First, the suspicious inclusion area is located at a low magnification of 100x or 500x, and then the sample morphology and elemental distribution are observed at a high magnification of 1000x or 2500x.

[0016] Preferably, in step S2, the detection limit for chlorine in the EDS analysis is ≤10ppm, and a Cl-Kα line signal with an energy of 2.62keV is collected for chlorine, while a Mg-Kα line signal is collected for magnesium. As a preferred step, generating a chlorine element distribution map using a surface scanning mode enables inclusion statistics.

[0017] Preferably, in step S3, the ZAF correction method or standard-free quantitative analysis mode is used. By comparing the X-ray intensity of the sample with that of the standard sample and correcting for atomic number effect, absorption effect and fluorescence effect, the weight percentage of chlorine is calculated. The quantitative analysis software is AZtec software. In the process of calculating the weight percentage of chlorine, the background of the energy spectrum is first subtracted, and then the characteristic peak of chlorine is integrated to obtain the net count of the peak, so as to reflect the X-ray intensity of chlorine in the sample.

[0018] Preferably, in the ZAF correction method, Z is the atomic number effect correction coefficient, A is the absorption effect correction coefficient, and F is the fluorescence effect correction coefficient.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. High sensitivity and high precision

[0021] In this method, the detection limit for chlorine by EDS analysis is ≤10ppm, which is far superior to traditional detection methods (such as AgCl spectrophotometry and AgNO3 turbidimetry, which usually have a detection limit >100ppm). It can accurately capture extremely low concentrations of magnesium chloride inclusions in sponge titanium, meeting the stringent requirements for low-concentration impurity detection in the quality control of high-purity sponge titanium.

[0022] By employing the ZAF correction method or standardless quantitative analysis mode, and by correcting for atomic number effects, absorption effects, and fluorescence effects, combined with standard sample calibration, the accuracy of calculating the weight percentage of chlorine is significantly improved, providing reliable data support for the determination of magnesium chloride inclusions.

[0023] 2. Microscale localization and comprehensive analysis

[0024] By using a scanning electron microscope (SEM) at different magnifications (from low magnification of 100x and 500x to high magnification of 1000x and 2500x), the microstructure of sponge titanium samples can be directly observed, and suspicious inclusion areas can be accurately located.

[0025] By using the area scanning or point analysis mode of EDS, a chlorine element distribution map can be generated to achieve inclusion statistics. At the same time, combined with the co-location analysis of magnesium, the morphology, size and distribution of magnesium chloride inclusions can be clarified, providing key microscopic information for exploring the formation mechanism of magnesium chloride inclusions and optimizing the production process.

[0026] 3. Simple and efficient operation

[0027] The sample preparation process is simple, requiring only steps such as cutting, ultrasonic cleaning with anhydrous ethanol, drying, and fixation. It does not require complex chemical pretreatment, avoids the loss or contamination of chlorine that may be caused by acid dissolution, and reduces operational errors.

[0028] The testing cycle is significantly shortened, and the efficiency is increased by more than 50% compared with traditional chemical analysis methods. It can quickly respond to the quality testing needs in the production process of sponge titanium and help to adjust the production process parameters in a timely manner.

[0029] 4. High applicability and environmentally friendly and economical

[0030] It is suitable for the detection of different types of sponge titanium samples. The scanning electron microscope used can be a field emission scanning electron microscope or a tungsten filament electron microscope. The quantitative analysis software adopts the common AZtec software. The equipment has strong versatility and is easy to promote and apply in industrial production testing.

[0031] After testing, the sponge titanium samples can be reused after simple processing, realizing resource recycling. This saves raw material costs and reduces waste generation, meeting the requirements of circular economy and environmental protection, and balancing economic and environmental benefits.

[0032] 5. Potential for automation and intelligence

[0033] By combining image processing algorithms, the automatic counting and classification of inclusions can be achieved, reducing reliance on the subjective experience of operators and improving the objectivity and consistency of detection results, thus laying the foundation for automated monitoring of sponge titanium quality. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are explained in detail together with the embodiments of the invention, but do not constitute a limitation thereof.

[0035] Figure 1 This is a flowchart of the method for detecting magnesium chloride inclusions in sponge titanium according to the present invention;

[0036] Figure 2 This invention uses SEM-EDS to detect the form of chlorine in sponge titanium;

[0037] Figure 3 This is a SEM image of the high-chlorine sponge titanium sample of the present invention;

[0038] Figure 4 This is the EDS spectrum of the high-chlorine sponge titanium sample of the present invention. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] Sample preparation:

[0042] The titanium sponge sample was cut into suitable blocks and ultrasonically cleaned for 3 minutes at room temperature with an anhydrous ethanol using an ultrasonic cleaning device with a frequency of 20 kHz and a power of 50 W.

[0043] After cleaning, place the sample in an oven at 80°C and dry for 1 hour. After drying, cool to room temperature and gently blow on the sample surface with a syringe to remove impurities.

[0044] The treated sample is fixed onto the sample tray using conductive adhesive.

[0045] SEM-EDS analysis:

[0046] Field emission scanning electron microscopy was used for observation at a low voltage of 5 kV. Suspected inclusion areas were first located at a low magnification of 100x, and then the sample morphology and elemental distribution were observed at a high magnification of 1000x.

[0047] The EDS detector parameters were adjusted to acquire Cl-Kα line signals (energy 2.62 keV) for chlorine and Mg-Kα line signals for magnesium. The distribution and content of chlorine and magnesium were determined by energy dispersive spectroscopy (EDS) surface scanning. The presence of magnesium chloride inclusions was determined by combining the co-localization analysis of both. The detection limit for chlorine in EDS analysis is ≤10 ppm. A chlorine distribution map was generated using surface scanning mode to achieve inclusion statistics. SEM images showed the presence of micron-sized particles in localized areas. Figure 3 EDS analysis confirmed that it is rich in Mg and Cl elements. Figure 4 Analysis of the Wt% and At% results indicates that the phases are MgO and MgCl2, with trace amounts of KCl and CaCl2. Compared with chemical analysis methods (detection limit 120 ppm), this invention significantly improves detection sensitivity and reliability.

[0048] Data processing:

[0049] The ZAF correction method was used, and AZtec quantitative analysis software was employed. First, the background of the energy spectrum was subtracted, and then the characteristic peak of chlorine was integrated to obtain the net count of the peak, which reflects the X-ray intensity of chlorine in the sample.

[0050] Combined with standard sample calibration, CCl k is the weight percentage of chlorine. Cl ZAF is the calibration factor for chlorine. Cl ZAF is the ZAF correction factor for chlorine in the sample. std I is the ZAF correction factor for chlorine in the standard sample. Cl I represents the X-ray intensity of chlorine in the sample. std The X-ray intensity of chlorine in the standard sample is given by the formula...

[0051] ,

[0052] The weight percentage of chlorine is calculated to detect magnesium chloride inclusions.

[0053] Example 2

[0054] Sample preparation:

[0055] The titanium sponge sample was cut into blocks and ultrasonically cleaned with anhydrous ethanol for 4 minutes at room temperature using an ultrasonic cleaning device with a frequency of 20 kHz and a power of 65 W.

[0056] After cleaning, place the sample in an oven at 80°C and dry for 1 hour. After it cools to room temperature, gently blow the sample surface with a syringe to remove impurities.

[0057] Use conductive adhesive to fix the treated sample onto the sample tray.

[0058] SEM-EDS analysis:

[0059] A tungsten filament electron microscope was used for observation at a low voltage of 8 kV. Suspected inclusion areas were first located at a low magnification of 500x, and then the sample morphology and elemental distribution were observed at a high magnification of 2500x.

[0060] The EDS detector parameters were adjusted to acquire Cl-Kα line signals (energy 2.62 keV) for chlorine and Mg-Kα line signals for magnesium. The distribution and content of chlorine and magnesium were determined through energy dispersive spectroscopy (EDS) point analysis, and the presence of magnesium chloride inclusions was determined by combining the co-localization analysis of the two. The detection limit for chlorine in EDS analysis is ≤10 ppm. A chlorine distribution map was generated using area scanning mode to achieve inclusion statistics.

[0061] Data processing:

[0062] A standard-free quantitative analysis mode was adopted. Using AZtec quantitative analysis software, the background of the energy spectrum was first subtracted, and then the characteristic peak of chlorine was integrated to obtain the net count of the peak, so as to reflect the X-ray intensity of chlorine in the sample.

[0063] Combined with standard sample calibration, C Cl k is the weight percentage of chlorine.Cl ZAF is the calibration factor for chlorine. Cl ZAF is the ZAF correction factor for chlorine in the sample. std I is the ZAF correction factor for chlorine in the standard sample. Cl I represents the X-ray intensity of chlorine in the sample. std The X-ray intensity of chlorine in the standard sample is given by the formula...

[0064] ,

[0065] The weight percentage of chlorine is calculated to detect magnesium chloride inclusions.

[0066] (In the ZAF correction method, Z is the atomic number effect correction coefficient, A is the absorption effect correction coefficient, and F is the fluorescence effect correction coefficient.) Calculate the weight percentage of chlorine to detect magnesium chloride inclusions.

[0067] Example 3

[0068] Sample preparation:

[0069] The titanium sponge sample was cut into blocks and ultrasonically cleaned with anhydrous ethanol for 5 minutes at room temperature using an ultrasonic cleaning device with a frequency of 20 kHz and a power of 80 W.

[0070] After cleaning, place the sample in an 80℃ oven to dry for 1 hour. After it cools to room temperature, gently blow the sample surface with a syringe to remove impurities.

[0071] The treated sample is fixed onto the sample tray using conductive adhesive.

[0072] SEM-EDS analysis:

[0073] Field emission scanning electron microscopy was used for observation at a low voltage of 10 kV. Suspected inclusion areas were first located at a low magnification of 300x (between 100x and 500x), and then the sample morphology and elemental distribution were observed at a high magnification of 2000x (between 1000x and 2500x).

[0074] The EDS detector parameters were adjusted to acquire Cl-Kα line signals (energy 2.62 keV) for chlorine and Mg-Kα line signals for magnesium. The distribution and content of chlorine and magnesium were determined by combining surface scanning and point analysis. The presence of magnesium chloride inclusions was determined by co-localization analysis of both. The detection limit for chlorine in EDS analysis is ≤10 ppm. A chlorine distribution map was generated using surface scanning mode to achieve inclusion statistics.

[0075] Data processing:

[0076] The ZAF correction method was used, and AZtec quantitative analysis software was employed. First, the background of the energy spectrum was subtracted, and then the characteristic peak of chlorine was integrated to obtain the net count of the peak, which reflects the X-ray intensity of chlorine in the sample.

[0077] Combined with standard sample calibration, C Cl k is the weight percentage of chlorine. Cl ZAF is the calibration factor for chlorine. Cl ZAF is the ZAF correction factor for chlorine in the sample. std I is the ZAF correction factor for chlorine in the standard sample. Cl I represents the X-ray intensity of chlorine in the sample. std The X-ray intensity of chlorine in the standard sample is given by the formula...

[0078] ,

[0079] The weight percentage of chlorine is calculated to detect magnesium chloride inclusions.

[0080] (In the ZAF correction method, Z is the atomic number effect correction coefficient, A is the absorption effect correction coefficient, and F is the fluorescence effect correction coefficient.) Calculate the weight percentage of chlorine to detect magnesium chloride inclusions.

[0081] Comparative Example 1

[0082] Sample preparation:

[0083] The titanium sponge sample was cut into blocks and dried directly in an 80°C oven for 1 hour without ultrasonic cleaning. After drying, it was cooled to room temperature and the sample surface was gently blown with a syringe (because it was not cleaned, there may be a lot of impurities on the surface, which may affect subsequent analysis).

[0084] The sample is fixed to the sample tray using conductive adhesive.

[0085] SEM-EDS analysis:

[0086] Field emission scanning electron microscopy was used for observation at a low voltage of 8 kV. The sample was observed only at a low magnification of 100x; high-magnification observation and localization of suspicious inclusion areas were not performed before EDS analysis was performed directly.

[0087] The EDS detector parameters were adjusted, but no specific element signal acquisition settings were made. The element distribution and content were determined through energy dispersive spectroscopy analysis, but co-location analysis of chlorine and magnesium was not performed.

[0088] Data processing:

[0089] Quantitative analysis software was not used; the chlorine content was simply estimated based on the raw EDS energy spectrum data, without standard sample calibration or ZAF correction.

[0090] Comparative Example 2

[0091] Sample preparation:

[0092] The titanium sponge sample was cut into blocks and ultrasonically cleaned with ordinary tap water for 5 minutes (anhydrous ethanol was not used, as it may have introduced other impurities). The cleaning frequency and power were not strictly controlled.

[0093] After cleaning, the sample was placed in a 100℃ oven and dried for 0.5 hours (the drying temperature and time did not meet the requirements). After drying, the sample surface was not cooled to room temperature, and the sample was directly blown on with a bulb syringe.

[0094] The sample is fixed to the sample tray using conductive adhesive.

[0095] SEM-EDS analysis:

[0096] Observations were performed using a tungsten filament electron microscope at a low voltage of 15 kV (outside the specified range). Samples were observed only at a high magnification of 2500x; low magnification was not used to locate suspected inclusion areas.

[0097] After adjusting the EDS detector parameters, the specific signal acquisition of chlorine and magnesium was not considered. When analyzing the elemental distribution through energy dispersive spectroscopy, issues such as detection limits were not taken into account, and no inclusion statistics were performed.

[0098] Data processing:

[0099] The ZAF correction method or standardless quantitative analysis mode was not used, quantitative analysis software was not used, and the EDS data were simply processed based on experience. The weight percentage of chlorine was not calculated according to the prescribed formula.

[0100] The table below compares the key parameters and results of the three embodiments and comparative examples above.

[0101]

[0102] The data in the table above will be analyzed from three aspects: sample preparation, scanning electron microscopy (SEM) analysis of relevant parameters, and data processing and analysis methods.

[0103] I. Sample Preparation

[0104] Ultrasonic cleaning process

[0105] Advantages of the cleaning method: Examples 1-3 all used anhydrous ethanol as the ultrasonic cleaning solvent, and different frequency, power, and time parameters were set. Anhydrous ethanol can effectively remove oil, dust, and other impurities from the sample surface, providing a cleaner sample surface for subsequent analysis. In contrast, Comparative Example 1 did not undergo ultrasonic cleaning, and Comparative Example 2 was only cleaned with ordinary tap water, which was insufficient to completely remove impurities from the sample surface and may affect the accurate analysis of the sample composition and structure.

[0106] Influence of parameters: As the ultrasonic cleaning power increases from 50W (Example 1) to 80W (Example 3) and the cleaning time is extended from 3min (Example 1) to 5min (Example 3), theoretically the cleaning effect will be better and the contaminants on the sample surface can be removed more thoroughly. However, it may also cause some damage to the sample surface. It is necessary to weigh the factors in actual operation.

[0107] Drying process

[0108] Temperature and Time: The drying temperature for Examples 1-3 and Comparative Example 1 was 80℃, and the drying time was 1 hour, which ensured that the samples were thoroughly dried and avoided interference from moisture in subsequent analyses. However, the drying temperature for Comparative Example 2 was 100℃, and the drying time was only 0.5 hours. The higher temperature and shorter time may not have ensured uniform drying of the samples, and may even have caused thermal damage to the samples due to excessive temperature, affecting sample performance and analytical results.

[0109] Sample cooling: Examples 1-3 and Comparative Example 1 cooled their samples to room temperature, while Comparative Example 2 did not. Excessively high sample temperatures may affect the interaction between the electron beam and the sample during SEM analysis, leading to decreased image quality or inaccurate analysis results.

[0110] II. Parameter Analysis by Scanning Electron Microscopy (SEM)

[0111] SEM type: Examples 1 and 3 used field emission scanning electron microscopy (FEM), Examples 2 and Comparative Example 2 used tungsten filament electron microscopy (TFL), and Comparative Example 1 used FEM. FEM has higher resolution and brightness, providing clearer and more detailed images of sample surface morphology, which is beneficial for more precise observation and analysis of samples. Tungsten filament electron microscopy has relatively lower resolution, but it can still meet basic needs in some analyses where extremely high resolution is not required.

[0112] Low voltage: The low voltages for Examples 1-3 were 5kV, 8kV, and 10kV, respectively; Comparative Example 1 used 8kV; and Comparative Example 2 used 15kV. Lower voltages reduce electron beam damage to the sample, making them particularly suitable for analyzing electron beam-sensitive samples, while also achieving better image contrast. The 15kV voltage in Comparative Example 2 is relatively high and may cause some damage to the sample, affecting the accuracy of the analytical results.

[0113] Low-magnification and high-magnification observation: Examples 1-3 used different low-magnification and high-magnification observation parameters, and Example 3 combined area scanning and point analysis modes. Low-magnification observation can quickly locate the general features and regions of the sample, while high-magnification observation can provide a deeper understanding of the sample's microstructure and details. Comparative Example 1 did not perform high-magnification localization observation, and Comparative Example 2 did not perform low-magnification localization observation. This may result in the inability to accurately locate the region of interest for analysis, affecting the comprehensiveness and accuracy of the analysis.

[0114] Chlorine detection limit: The chlorine detection limits in Examples 1-3 were all ≤10 ppm, while the chlorine detection limit was not considered in Comparative Examples 1 and 2. A lower detection limit means that lower concentrations of chlorine in the sample can be detected, which is very important for studies that require precise analysis of the chlorine content in the sample.

[0115] III. Data Processing and Analysis Methods

[0116] Analysis modes: Example 1 uses area scanning, which can quickly obtain the distribution of elements on the sample surface; Example 2 uses point analysis, which can perform precise elemental composition analysis on specific points of the sample; Example 3 combines area scanning and point analysis, which can provide a more comprehensive understanding of the distribution of elements on the sample surface and the composition information of specific points. Comparative Example 1 did not specify the analysis mode, and Comparative Example 2 did not focus on the detection limit and inclusion statistics, which may lead to a lack of systematicity and accuracy in the analysis results, and an inability to fully reflect the characteristics of the sample.

[0117] Analytical methods: Examples 1 and 3 used the ZAF correction method, Example 2 used a standard-free quantitative analysis mode, Comparative Example 1 used simple estimation, and Comparative Example 2 did not use a standard analytical method. The ZAF correction method can more accurately correct the influence of various factors in the analysis process on the results, improving the accuracy of the analysis; the standard-free quantitative analysis mode can also perform quantitative analysis when there is no suitable standard sample; while the methods of Comparative Example 1 and Comparative Example 2 may lead to large errors in the analytical results, affecting the correct judgment of the samples.

[0118] The method for detecting magnesium chloride inclusions in sponge titanium provided by this invention has several significant advantages, as detailed below:

[0119] 1. High sensitivity and high precision

[0120] In this method, the detection limit for chlorine by EDS analysis is ≤10ppm, which is far superior to traditional detection methods (such as AgCl spectrophotometry and AgNO3 turbidimetry, which usually have a detection limit >100ppm). It can accurately capture extremely low concentrations of magnesium chloride inclusions in sponge titanium, meeting the stringent requirements for low-concentration impurity detection in the quality control of high-purity sponge titanium.

[0121] By employing the ZAF correction method or standardless quantitative analysis mode, and by correcting for atomic number effects, absorption effects, and fluorescence effects, combined with standard sample calibration, the accuracy of calculating the weight percentage of chlorine is significantly improved, providing reliable data support for the determination of magnesium chloride inclusions.

[0122] 2. Microscale localization and comprehensive analysis

[0123] By using a scanning electron microscope (SEM) at different magnifications (from low magnification of 100x and 500x to high magnification of 1000x and 2500x), the microstructure of sponge titanium samples can be directly observed, and suspicious inclusion areas can be accurately located.

[0124] By using the area scanning or point analysis mode of EDS, a chlorine element distribution map can be generated to achieve inclusion statistics. At the same time, combined with the co-location analysis of magnesium, the morphology, size and distribution of magnesium chloride inclusions can be clarified, providing key microscopic information for exploring the formation mechanism of magnesium chloride inclusions and optimizing the production process.

[0125] 3. Simple and efficient operation

[0126] The sample preparation process is simple, requiring only steps such as cutting, ultrasonic cleaning with anhydrous ethanol, drying, and fixation. It does not require complex chemical pretreatment, avoids the loss or contamination of chlorine that may be caused by acid dissolution, and reduces operational errors.

[0127] The testing cycle is significantly shortened, and the efficiency is increased by more than 50% compared with traditional chemical analysis methods. It can quickly respond to the quality testing needs in the production process of sponge titanium and help to adjust the production process parameters in a timely manner.

[0128] 4. High applicability and environmentally friendly and economical

[0129] It is suitable for the detection of different types of sponge titanium samples. The scanning electron microscope used can be a field emission scanning electron microscope or a tungsten filament electron microscope. The quantitative analysis software adopts the common AZtec software. The equipment has strong versatility and is easy to promote and apply in industrial production testing.

[0130] After testing, the sponge titanium samples can be reused after simple processing, realizing resource recycling. This saves raw material costs and reduces waste generation, meeting the requirements of circular economy and environmental protection, and balancing economic and environmental benefits.

[0131] 5. Potential for automation and intelligence

[0132] By combining image processing algorithms, the automatic counting and classification of inclusions can be achieved, reducing reliance on the subjective experience of operators and improving the objectivity and consistency of detection results, thus laying the foundation for automated monitoring of sponge titanium quality.

[0133] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting magnesium chloride inclusions in sponge titanium, characterized in that: Includes the following steps: S1. Sample preparation: Cut the sponge titanium sample into blocks, clean it with anhydrous ethanol by ultrasonic cleaning, dry it, and fix it on the sample tray with conductive adhesive. S2, SEM-EDS analysis: Scanning electron microscopes were used to observe the morphology of the samples at a low voltage of 5–10 kV to locate suspicious inclusion areas. The EDS detector parameters were adjusted, and the distribution and content of chlorine and magnesium were determined by energy dispersive spectroscopy or point analysis. The presence of magnesium chloride inclusions was determined by combining the co-localization analysis of the two. S3. Data Processing: The weight percentage of chlorine is calculated using quantitative analysis software. Combined with standard sample calibration, this enables the detection of magnesium chloride inclusions. The formula for calculating the weight percentage of chlorine is: ， In the formula, C Cl k is the weight percentage of chlorine. Cl ZAF is the calibration factor for chlorine. Cl ZAF is the ZAF correction factor for chlorine in the sample. std I is the ZAF correction factor for chlorine in the standard sample. Cl I represents the X-ray intensity of chlorine in the sample. std The X-ray intensity of chlorine in the standard sample.

2. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S1, the ultrasonic cleaning frequency is 20kHz, the power is 50-80W, the time is 3-5min, and the temperature is room temperature.

3. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S1, the drying temperature is 80°C and the drying time is 1 hour.

4. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S1, impurities are removed from the sample surface after it has been dried by gently blowing with a rubber bulb and then cooled to room temperature.

5. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S2, the scanning electron microscope is a field emission scanning electron microscope or a tungsten filament electron microscope.

6. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S2, observations are conducted using different magnifications. First, suspicious inclusion areas are located at low magnifications of 100x or 500x, and then the sample morphology and elemental distribution are observed at high magnifications of 1000x or 2500x.

7. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S2, the detection limit for chlorine in EDS analysis is ≤10ppm, and a Cl-Kα line signal with an energy of 2.62keV is collected for chlorine, while a Mg-Kα line signal is collected for magnesium.

8. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S2, a chlorine element distribution map is generated using surface scanning mode to achieve inclusion statistics.

9. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 1, characterized in that: In step S3, the ZAF correction method or standard-free quantitative analysis mode is used. By comparing the X-ray intensity of the sample with that of the standard sample and correcting for atomic number effect, absorption effect and fluorescence effect, the weight percentage of chlorine is calculated. The quantitative analysis software is AZtec software. In the process of calculating the weight percentage of chlorine, the background of the energy spectrum is first subtracted, and then the characteristic peak of chlorine is integrated to obtain the net count of the peak, so as to reflect the X-ray intensity of chlorine in the sample.

10. The method for detecting magnesium chloride inclusions in sponge titanium according to claim 9, characterized in that: In the ZAF correction method, Z is the atomic number effect correction coefficient, A is the absorption effect correction coefficient, and F is the fluorescence effect correction coefficient.

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