Method for detecting boron element in silicon carbide

Abstract

The invention belongs to the field of chemical analysis, and provides a method for detecting boron element in silicon carbide. The method comprises the following steps: (1) providing a sample to be detected; (2) carrying out burning treatment on the sample to be detected; (3) carrying out a melting reaction on the firing treatment product, calcium carbonate and an alkali solvent to obtain a melt; (4) mixing the melt, acid and mannitol to dissolve the melt so as to obtain a solution to be detected; and (5) detecting the signal intensity of boron in the solution to be detected through an inductively coupled plasma mass spectrometer, and obtaining the content of boron in the solution to be detected according to the standard curve. According to the method disclosed by the embodiment of the invention, silicon carbide can be thoroughly decomposed, and boron loss is hardly caused; the boron element (trace level) can be completely retained and leached in the whole sample melting and acidolysis leaching process; and the content of the boron element is accurately and rapidly detected by adopting ICP-MS or ICP-OES (Inductively Coupled Plasma Mass Spectrometry).

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical analysis, and particularly relates to a method for detecting boron in silicon carbide. BACKGROUND

[0002] Silicon carbide is a kind of refractory material made of quartz sand, petroleum coke (or coal coke) and wood chips as raw materials through high-temperature smelting of an electric resistance furnace, and the main components are SiC, FSi, SiO2 and FC. Since the trace impurity elements contained in silicon carbide can affect its performance, it is necessary to detect the content of impurity elements (such as boron) in silicon carbide. At present, it is difficult to detect boron in silicon carbide, and most of the analysis can only be performed on the surface composition of silicon carbide, and the analysis and detection effect of the internal crystal doping composition content of silicon carbide material is general. It can be seen that the detection of boron in silicon carbide still has the problem of inaccurate detection.

[0003] It should be noted that the above content is not necessarily prior art, and is not used to limit the patent protection scope of the present application. SUMMARY

[0004] The embodiment of the present application provides a method for detecting boron in silicon carbide to solve or alleviate one or more technical problems proposed above.

[0005] The method for detecting boron in silicon carbide provided by the embodiment of the present application comprises the following steps: (1) providing a sample to be measured; (2) performing a burning treatment on the sample to be measured; (3) performing a melting reaction on the product of the burning treatment, calcium carbonate and an alkali flux to obtain a melt; (4) mixing the melt, an acid and mannitol to dissolve the melt to obtain a solution to be measured; (5) detecting the signal intensity of boron in the solution to be measured by an inductively coupled plasma mass spectrometer, and obtaining the boron content in the solution to be measured according to a standard curve.

[0006] The method of the embodiment of the present application can completely decompose silicon carbide and hardly cause boron loss; the whole sample melting and leaching process can completely retain and leach out boron element (trace level); and ICP-MS or ICP-OES is used to realize accurate and rapid detection of the boron element content. Specifically, the burning treatment can eliminate the influence of volatile matter and free carbon in the cubic silicon carbide sample on the detection accuracy; the boron element in the silicon carbide mainly exists in the form of covalent bond inside the silicon carbide crystal, and the boron atom forms a covalent bond by replacing the silicon atom or carbon atom in the silicon carbide lattice, so that the decomposition of the silicon carbide and the stable retention of the boron are realized after high-temperature melting to destroy the covalent bond; the melting treatment can promote the boron element in the silicon carbide to be almost completely dissolved into the to-be-detected solution; mannitol and acid are used to dissolve the melt together, the mannitol inhibits the volatilization of boron, and ICP-MS or ICP-OES can be used to realize accurate and rapid detection of the boron element content in the silicon carbide. In addition, the method is simple, has high detection efficiency, is strong in operability, has low requirements on laboratory conditions and instrument equipment, and is strong in applicability.

[0007] According to the embodiment of the present application, the temperature of the burning treatment in step (2) is 650-850℃; and the time of the burning treatment is 30-90min.

[0008] According to the embodiment of the present application, the melting reaction of the product of the burning treatment, calcium carbonate and an alkali flux includes: After the product of the burning treatment and the calcium carbonate are dried, the dried product is subjected to the melting reaction with the alkali flux.

[0009] According to the embodiment of the present application, after the product of the burning treatment and the calcium carbonate are dried, the dried product is subjected to the melting reaction with the alkali flux, which includes: after the dried product and the alkali flux are mixed, the alkali flux is covered on the surface of the mixture.

[0010] According to the embodiment of the present application, the drying is performed at a temperature of 100-120℃ for 1-3h.

[0011] According to the embodiment of the present application, the alkali flux includes sodium hydroxide and sodium peroxide; and the mass ratio of the product of the burning treatment, the calcium carbonate and the alkali flux is 1:(5-15):(1-5).

[0012] According to the embodiment of the present application, the mass ratio of the sodium hydroxide and the sodium peroxide is 1:(1-3).

[0013] According to the embodiments of the present application, the melting reaction comprises a temperature rising stage and a temperature holding stage, the temperature rising stage is rising from 200-400℃ to 500-700℃ at a temperature rising rate of 8-15℃ / min; the time of the temperature holding stage is 10-30min.

[0014] According to the embodiments of the present application, the mass ratio of the melt, the acid and mannitol is 1:(7-10):(0.004-0.01).

[0015] According to the embodiments of the present application, the acid comprises hydrochloric acid; the concentration of the hydrochloric acid is 10-30wt%; the dissolving temperature is 100-150℃. BRIEF DESCRIPTION OF DRAWINGS

[0016] In the drawings, like reference numerals refer to like elements throughout the various drawings. The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the application. It should be understood that the drawings are merely depictions of some embodiments of the application and should not be construed as limiting the scope of the application.

[0017] Figure 1 is a flowchart of a method for detecting boron element in silicon carbide according to some embodiments of the present application. DETAILED DESCRIPTION

[0018] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the embodiments of the application are shown as examples. In the drawings, the size of layers, regions, elements, and the relative sizes of the layers, regions, elements, and the like can be exaggerated for clarity. The same or similar reference numerals are used throughout the drawings to refer to the same or like elements or elements having the same or similar functionality. The embodiments described below are exemplary and are intended to be illustrative of the present application, and are not to be construed as limiting the present application. It is noted that the embodiments and features of the present application can be combined with each other, if not in conflict.

[0019] It will be understood that when an element or layer is referred to as being "on", "adjacent", "connected" or "coupled" to another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on", "directly adjacent", "directly connected", or "directly coupled" to another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application and, similarly, a second element, component, region, layer or section discussed below could be termed a first element, component, region, layer or section without departing from the teachings of the present application.

[0020] It should be noted that the terms "first", "second", and the like, herein do not necessarily have an ordinal meaning. Rather these terms are used herein, inter alia, to distinguish a certain feature from another feature. It should be noted that where a term is used in the singular, it is also intended to encompass the plural unless the context clearly indicates otherwise. It should be further noted that the terms "comprise", "comprising", "comprises", "include", "including", and "includes" are used herein to indicate the presence of stated features, integers, steps, processes, acts, elements, or components, but not to the exclusion of one or more other features, integers, steps, processes, acts, elements, components, or groups thereof. Furthermore, it is understood that the word "comprising" does not exclude the presence of other elements or steps than those listed and the word "a" or "an" preceding the usage of an element does not exclude the presence of two or more such elements than that which is directly stated. It is further understood that the use of the term "about" in relation to a given numerical value x describes and supports the meaning of "x ± 10 %". The use of the term "in the range" is meant to describe and support the meaning of "between any stated value (min) and any stated value (max)". It is further understood that the terms "including", "including", "includes" when used in the specification, including claims, are used to mean "including but not limited to". Furthermore, terms such as binary, true and false, on and off, and the like, are used in connection with the disclosure herein merely to indicate different states, regions, and values except in their ordinary sense, such as is made very clear by the disclosure itself.

[0021] In the present application, when a numerical interval (i.e. a numerical range) is referred to, the distribution of the selectable values within the numerical interval is considered to be continuous and includes both numerical end points (i.e. the minimum and maximum values) of the numerical interval and every value between the two numerical end points, unless otherwise specified. When a numerical interval refers only to integers within the numerical interval, including both end point integers and every integer between the two end point integers, each integer is considered to be directly enumerated, unless otherwise specified. When multiple numerical ranges are provided to describe a characteristic or property, the numerical ranges can be combined. In other words, unless otherwise indicated, a numerical range disclosed herein is to be understood to include any and all sub-ranges of the same. A "value" in a numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. A "numerical interval" is intended to broadly include quantitative intervals, such as percentage intervals, ratio intervals, value intervals, etc.

[0022] The existing silicon carbide related detection standard and the method for detecting boron element in the literature report is GB / T 41153-2021 "Determination of boron, aluminum and nitrogen impurities in silicon carbide single crystal - Secondary ion mass spectrometry", other detection methods related to silicon carbide such as GB / T 3045-2017 "Silicon carbide surface free carbon, free silicon, ferric oxide, aluminum oxide, calcium oxide, magnesium oxide", GB / T 16555-2008 "Chemical analysis method of carbon-containing, silicon carbide and nitride refractory materials" and the report of ICP-AES method for determining impurities such as iron, aluminum, calcium, magnesium, potassium oxide, sodium oxide, titanium, phosphorus and vanadium on the surface of silicon carbide in the related literature all do not report the detection method of boron element. GB / T 41153-2021 "Determination of boron, aluminum and nitrogen impurities in silicon carbide single crystal - Secondary ion mass spectrometry" is to detect boron element by using secondary ion mass spectrometer, which is a surface analysis instrument for detecting materials, that is, the ion beam is used to sputter the material to be analyzed from the surface, and then the ion composition is detected and mass analyzed. Since the secondary ion mass spectrometer is a high-end scientific research equipment, it is expensive and the audience is relatively professional, and it is mainly used in the field of high-precision surface analysis, and it is less equipped in ordinary laboratories and scientific research institutions, so it is difficult for the detection laboratory to detect boron element in silicon carbide by using GB / T 41153-2021 "Determination of boron, aluminum and nitrogen impurities in silicon carbide single crystal - Secondary ion mass spectrometry", and the method is good for surface composition analysis, and the analysis and detection effect of the content of the internal crystal doping components of the silicon carbide material is general.

[0023] Therefore, the embodiment of the present application provides a method for detecting boron element in silicon carbide. Referring to Figure 1 , the method comprises the following steps: (1) providing a sample to be measured; (2) performing a calcination treatment on the sample to be measured; (3) performing a melting reaction on the product of the calcination treatment, calcium carbonate and an alkali flux to obtain a melt; (4) mixing the melt, an acid and mannitol to dissolve the melt to obtain a solution to be measured; (5) detecting the signal intensity of boron in the solution to be measured by an inductively coupled plasma mass spectrometer, and obtaining the content of boron in the solution to be measured according to a standard curve.

[0024] The method of the embodiments of the present application can completely decompose silicon carbide and hardly cause boron loss; the whole sample melting and leaching process can completely retain and leach out the boron element (trace level); and ICP-MS or ICP-OES is used to realize accurate and rapid detection of the boron element content. Specifically, the burning treatment can eliminate the influence of the existence of volatile matter and free carbon in the silicon carbide sample on the detection accuracy; the boron element in the silicon carbide mainly exists in the form of a covalent bond inside the silicon carbide crystal, and the boron atom forms a covalent bond by replacing the silicon atom or the carbon atom in the silicon carbide lattice, and high-temperature melting is needed to destroy the covalent bond to realize decomposition of the silicon carbide and stable retention of the boron; the melting treatment can promote the boron element in the silicon carbide to almost completely dissolve into the to-be-detected solution; mannitol and acid are used to dissolve the melt together, the mannitol inhibits the volatilization of boron, and ICP-MS or ICP-OES can be used to realize accurate and rapid detection of the boron element content in the silicon carbide. In addition, the method is simple, has high detection efficiency, is strong in operability, has low requirements on laboratory conditions and instrument equipment, and has strong applicability.

[0025] According to the embodiments of the present application, in step (1), a to-be-detected sample is provided. The to-be-detected sample refers to a silicon carbide sample.

[0026] According to the embodiments of the present application, in step (1), the to-be-detected sample is subjected to burning treatment. The burning treatment can eliminate the interference of the existence of volatile matter and free carbon in the silicon carbide sample on the final inspection result.

[0027] In some embodiments, the temperature of the burning treatment is 650-850℃, for example, 650℃, 700℃, 750℃, 800℃, 850℃, etc. The effect of the burning treatment is further improved.

[0028] Further, if the content of the silicon carbide in the to-be-detected sample is greater than 80%, the burning temperature is 650-750℃; if the content of the silicon carbide in the to-be-detected sample is less than 80%, the burning temperature is 750-850℃. This helps to reduce the burning time, because the free carbon content in high-purity silicon carbide is low, and the required burning temperature can be relatively low. It can be understood that the content of the silicon carbide in the to-be-detected sample can be tested in a semi-quantitative manner.

[0029] In some embodiments, the time of the burning treatment is 30-90min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min, etc. The effect of the burning treatment is further improved.

[0030] According to the embodiments of the present application, in step (3), the product of the calcination treatment, calcium carbonate, and an alkali flux are subjected to a melting reaction to obtain a melt. Boron in silicon carbide mainly exists in the form of a covalent bond inside a silicon carbide crystal. Boron atoms form covalent bonds by replacing silicon atoms or carbon atoms in the silicon carbide crystal lattice. High-temperature melting is required to break the covalent bonds, and then the decomposition of silicon carbide and the stable retention of boron are achieved. Melting treatment can promote almost all of the boron in the silicon carbide to dissolve into the to-be-tested solution. During the melting process, the addition of calcium carbonate can efficiently control the volatilization of boron. Excess CaO obtained by the decomposition of calcium carbonate reacts with Na3BO3 to generate calcium metaborate (Ca(BO2)2). The stable calcium metaborate is formed by the combination of boron and calcium, the form of boron is changed, and the volatilization of boron in the form of B2O3, which is easy to volatilize, is avoided. The volatilization of calcium metaborate is extremely low at high temperatures, and the loss of boron can be significantly reduced.

[0031] In some embodiments, the melting reaction of the product of the calcination treatment, calcium carbonate, and an alkali flux includes: drying the product of the calcination treatment and calcium carbonate, and then subjecting the dried product to a melting reaction with the alkali flux. In this way, if the product of the calcination treatment or calcium carbonate contains water, the volatilization rate of B2O3 generated during the melting reaction will increase. Water vapor is easy to react with liquid B2O3 generated during the reaction to form metaboric acid, thereby promoting the volatilization of boron. Pre-drying the product of the calcination treatment and calcium carbonate can further reduce the volatilization of boron, and thus the detection result of the boron element in the to-be-tested sample is more accurate.

[0032] Further, the drying is performed at a temperature of 100-120°C for 1-3h. Optionally, the drying equipment is a drying box.

[0033] In other embodiments, the melting reaction of the dried product of the calcination treatment and the alkali flux includes: mixing the dried product and the alkali flux, and then covering the surface of the mixture with the alkali flux. This has the advantage of reducing the volatilization of boron during the sample melting process.

[0034] In some embodiments, the alkali flux includes sodium hydroxide and sodium peroxide. The sodium hydroxide can reduce the temperature during the melting process, thereby greatly reducing the decomposition temperature of silicon carbide and reducing the energy consumption of the melting process. The sodium peroxide is a strong oxidizing agent that can directly release oxygen without decomposition, and can oxidize C in silicon carbide to CO3 2- and Si to SiO3 2-; strong oxidant (Na2O2) and low melting temperature (NaOH) synergistic effect, but also can make SiC completely decomposed time reduction; sodium hydroxide and sodium peroxide are both cheap, in the case of melting temperature does not need to be too high can achieve good melting effect, less corrosion of the nickel crucible used in the melting process and the sample after melting can be used more easily leaching, so as to further promote the dissolution of boron. In general, sodium hydroxide-sodium peroxide as a mixed alkali flux can completely decompose silicon carbide matrix, and excess calcium carbonate is added during the melting process to ensure that the volatilization loss of boron element does not occur. The main equations involved in the melting process are as follows: SiC + 3Na2O2 = Na2SiO3 + Na2CO3 + 2Na2O; BO3 3- + Na + → Na3BO3; CaCO3 = CaO + CO2↑; CO2 + 2NaOH = Na2CO3 + H2O; Na2SiO3 + CaO = CaSiO3 + Na2O; 2Na3BO3 + 3CaO = 3Ca(BO2)2 + 6Na2O.

[0035] Further, the mass ratio of the calcination product, calcium carbonate, and the alkali flux is 1:(5-15):(1-5). Thus, the melting reaction is further promoted.

[0036] Further, the mass ratio of sodium hydroxide and sodium peroxide is 1:(1-3). Thus, the melting reaction is further promoted.

[0037] In some embodiments, the melting reaction includes a heating stage and a holding stage, the heating stage is from 200℃-400℃ to 500℃-700℃ at a heating rate of 8℃ / min-15℃ / min; the holding stage is 10min-30min. The alkali flux and calcium carbonate reduce the melting temperature and melting time of the calcination product, and complete decomposition occurs at 500℃-700℃ for 10min-30min; wherein the heating stage is slow, which can reduce the volatilization of boron components caused by spattering during the heating process.

[0038] Further, the spattering in the heating stage and the holding stage, on the one hand, reduces the spattering by gradually increasing the temperature, and on the other hand, a crucible cover can be placed on the crucible containing the calcination product, calcium carbonate, and the alkali flux.

[0039] In some embodiments, the crucible for containing the product of the calcination process, calcium carbonate, and the alkali flux is a nickel crucible, which can reduce impurity interference compared to an iron crucible, and is less expensive than a platinum crucible.

[0040] According to embodiments of the present application, in step (4), the melt, the acid, and mannitol are mixed to dissolve the melt, to obtain a test solution. Mannitol can form a stable complex with borate, greatly increasing the molecular weight, and effectively inhibiting the volatilization of boron during the dissolution and leaching of the melt, so that the acid and mannitol completely decompose the melt.

[0041] In some embodiments, the mass ratio of the melt, the acid, and mannitol is 1:(7-10):(0.004-0.01). Thus, the melt is further completely decomposed.

[0042] Further, the acid includes hydrochloric acid. Thus, calcium metaborate (Ca(BO2)2) is easily soluble in hydrochloric acid and can be quickly dissolved in dilute acid, i.e., Ca(BO2)2+2HCl+2H2O=CaCl2+2H3BO3, and after dissolution, a clear Ca 2+ containing solution of H3BO3 is formed.

[0043] Further, the concentration of the hydrochloric acid is 10wt%-30wt%.

[0044] Further, the temperature of the dissolution is 100°C-150°C.

[0045] In other embodiments, in step (4), the melt, the acid, water, and mannitol are mixed to dissolve the melt, to obtain a test solution. Mannitol can form a stable complex with borate, greatly increasing the molecular weight, and effectively inhibiting the volatilization of boron during the dissolution and leaching of the melt, so that the acid and mannitol completely decompose the melt.

[0046] In some embodiments, the mass ratio of the melt, the solute in the acid, water, and mannitol is 1:(5-10):(4-10):(0.005-0.1). Thus, the melt is further completely decomposed.

[0047] According to embodiments of the present application, in step (5), the signal intensity of boron in the test solution is detected by inductively coupled plasma mass spectrometry, and the boron content in the test solution is obtained according to a standard curve.

[0048] In this step, (5-6) effective period of certified reference material is selected for processing with the sample, the content range of the reference material covers the conventional detection content, if there is no suitable standard sample, the same grade silicon carbide standard sample without boron can be selected, and the standard curve is prepared according to the approximate content of boron in the silicon carbide to be measured. The emission intensity of the boron standard solution series is measured under the optimal working condition of the instrument. The standard curve is drawn with the mass concentration of boron as the abscissa and the emission intensity as the ordinate. Among them, the preparation of the standard curve according to the approximate content of boron in the silicon carbide to be measured includes the semi-quantitative estimation of boron in silicon carbide.

[0049] After the standard curve is drawn, the solution to be measured is detected, the content of boron in the solution to be measured is measured under the optimal working condition of the instrument, and the emission intensity of boron is detected by ICP or ICP-MS according to the content of boron in the sample to be tested. The content of boron in the solution to be measured is obtained by comparing the standard curve, and the content of boron in the sample to be measured is obtained.

[0050] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments can be implemented in various manners, and should not be interpreted as being limited to the embodiments set forth herein.

[0051] Example 1 A silicon carbide sample is provided, which includes, after semi-quantitative, SiC (70%), SiO2 (7%), Al2O3 (7%), CaO (2%), CF (free carbon 7%), and Fe2O3 (4%) in terms of mass fraction.

[0052] The method for testing boron content in silicon carbide includes: using an alkali flux with a mass ratio of sodium hydroxide to sodium peroxide of 1:2, using a nickel crucible for alkali fusion, weighing 2g of mixed flux and 0.2g of sample, 0.4g of calcium carbonate in the nickel crucible and fully mixing, then covering 1g of alkali flux, covering the crucible cover, and placing the crucible into a muffle furnace at about 300°C, gradually increasing the temperature from 300°C to about 700°C, and taking out after heating and melting at 700°C for 20min, gently shaking, slightly cooling, and rinsing the bottom of the crucible with deionized water, placing the crucible and cover into a 250mL plastic cup, and covering the surface dish. 20mL of hydrochloric acid (20wt% mass fraction), 30mL of water, 5ml of 2.5g / L mannitol, low-temperature heating to melt the solubles, fully washing the crucible and cover, and continuing to boil on the electric stove for 2-3min (the temperature during the dissolution process is controlled at 120°C), taking out and cooling, transferring into a 250ml volumetric flask, diluting the scale, mixing, using dry filtration to test the solution, taking part of the filtrate for ICP analysis and detection, and then comparing with the standard curve (using an alkali flux with a mass ratio of sodium hydroxide to sodium peroxide of 1:2, using a nickel crucible for alkali fusion, weighing 2g of mixed flux and 0.2g of silicon carbide standard sample without boron, 0.4g of calcium carbonate in the nickel crucible and fully mixing, then covering 1g of alkali flux, covering the crucible cover, and preparing according to the method for testing boron in silicon carbide, transferring a series of 100μg / ml boron standard solutions into a 250ml volumetric flask, diluting, mixing, and obtaining a standard solution series with a boron mass percentage (%) of 0, 0.005, 0.01, 0.02, 0.04, 0.07, and 0.10, obtaining y=217616x+1110 (R 2 =0.999), obtaining the boron content in the test solution, and then obtaining the boron content in the test sample as 0.024%.

[0053] Example 2 A silicon carbide sample identical to that of Example 1 is provided.

[0054] The method for testing the boron content in silicon carbide comprises the following steps: using an alkali flux with a mass ratio of sodium hydroxide to sodium peroxide being 1:2, using a nickel crucible for alkali fusion, weighing 2g of mixed flux and 0.2g of the sample in the nickel crucible, and fully mixing, then covering 1g of the alkali flux, covering the crucible cover, and placing the crucible into a muffle furnace at about 300 DEG C, gradually increasing the temperature from 300 DEG C to about 500 DEG C, and taking out after heating and melting at 500 DEG C for 20 minutes, gently shaking, slightly cooling, and washing the bottom of the crucible with deionized water, placing the crucible and the cover into a 250mL plastic cup, and covering the surface dish. 20mL of hydrochloric acid (20wt%) is added, 30mL of water is added, 5ml of mannitol with a concentration of 2.5g / L is added, low-temperature heating is performed until the melt is dissolved, the crucible and the cover are fully washed, boiling is continued on the electric furnace for 2-3 minutes, and then the sample is taken out, cooled, and transferred into a 250ml capacity bottle, the dilution scale is marked, and mixing is performed. The test solution is dried and filtered, part of the filtrate is used for ICP analysis and detection, the boron content in the test solution is obtained by comparing the standard curve, and then the boron content in the test sample is obtained as 0.026%.

[0055] Comparative Example 1 The same silicon carbide sample as in Example 1 is provided.

[0056] The method for testing the boron content in silicon carbide comprises the following steps: using an alkali flux with a mass ratio of sodium hydroxide to sodium peroxide being 1:2, using a nickel crucible for alkali fusion, weighing 2g of mixed flux and 0.2g of the sample in the nickel crucible, and fully mixing, then covering 1g of the alkali flux, covering the crucible cover, and placing the crucible into a muffle furnace at about 300 DEG C, gradually increasing the temperature from 300 DEG C to about 500 DEG C, and taking out after heating and melting at 500 DEG C for 20 minutes, gently shaking, slightly cooling, and washing the bottom of the crucible with deionized water, placing the crucible and the cover into a 250mL plastic cup, and covering the surface dish. 20mL of hydrochloric acid (20wt%) is added, 30mL of water is added, 5ml of mannitol with a concentration of 2.5g / L is added, low-temperature heating is performed until the melt is dissolved, the crucible and the cover are fully washed, boiling is continued on the electric furnace for 2-3 minutes, and then the sample is taken out, cooled, and transferred into a 250ml capacity bottle, the dilution scale is marked, and mixing is performed. The test solution is dried and filtered, part of the filtrate is used for ICP analysis and detection, the boron content in the test solution is obtained by comparing the standard curve, and then the boron content in the test sample is obtained as 0.026%.

[0057] Comparative Example 2 The same silicon carbide sample as in Example 1 is provided.

[0058] The method for testing the boron content in silicon carbide comprises the following steps: using an alkali flux with a mass ratio of sodium hydroxide to sodium peroxide being 1:2, using a nickel crucible to perform alkali fusion, weighing 2g of mixed flux and 0.2g of the sample in the nickel crucible and fully mixing, then covering 1g of the alkali flux, covering the crucible cover, placing the crucible into a muffle furnace at about 300 DEG C, gradually increasing the temperature from 300 DEG C to about 700 DEG C, taking out after heating and melting at 700 DEG C for 20 minutes, gently shaking, slightly cooling, washing the bottom of the crucible with deionized water, placing the crucible and the cover into a 250mL plastic cup, covering the surface dish, adding 20mL of hydrochloric acid (20wt%) and 30mL of water, heating to dissolve the melt, fully washing the crucible and the cover, continuing to boil on the electric furnace for 2-3 minutes, taking out and cooling, moving into a 250ml volumetric flask, diluting the scale, mixing, using dry filtration of the test solution, taking part of the filtrate to perform ICP analysis, comparing with the standard curve to obtain the boron content in the test solution, and then obtaining the boron content in the test sample as 0.016%.

[0059] Comparative Example 3 The same silicon carbide sample as in Example 1 is provided.

[0060] The method for testing the boron content in silicon carbide comprises the following steps: using an alkali flux with a mass ratio of sodium hydroxide to sodium peroxide being 1:2, using a nickel crucible to perform alkali fusion, weighing 2g of mixed flux and 0.2g of the sample in the nickel crucible and fully mixing, then covering 1g of the alkali flux, covering the crucible cover, placing the crucible into a muffle furnace at about 300 DEG C, gradually increasing the temperature from 300 DEG C to about 700 DEG C, taking out after heating and melting at 700 DEG C for 20 minutes, gently shaking, slightly cooling, washing the bottom of the crucible with deionized water, placing the crucible and the cover into a 250mL plastic cup, covering the surface dish, adding 20mL of hydrochloric acid (20wt%) and 30mL of water, heating to dissolve the melt, fully washing the crucible and the cover, continuing to boil on the electric furnace for 2-3 minutes, taking out and cooling, moving into a 250ml volumetric flask, diluting the scale, mixing, using dry filtration of the test solution, taking part of the filtrate to perform ICP analysis, comparing with the standard curve to obtain the boron content in the test solution, and then obtaining the boron content in the test sample as 0.013%.

[0061] The test solution is tested as follows, and the test data are shown in Table 1: Precision test Test method: according to the experimental method of the above examples and comparative examples, each measurement is repeated for 7 times, and the precision of the test results and the melting effect in the experimental process are counted; Recovery rate experiment Test method: when the experiment is carried out according to the experimental method of the above examples and comparative examples, the sample is weighed as 0.2 g of test sample and 0.0025 g of high-purity borax (Na2B4O7·10H2O), and the other experimental steps remain unchanged Table 1

[0062] From the above table 1, it can be seen that the amount of boron element in silicon carbide is tested by the method of the present application, and the result of the example is more accurate than that of the comparative example. If the amount of calcium carbonate or mannitol added in the sample preparation process is too small, the volatilization of boron element cannot be effectively inhibited, which will also cause the detection result to deviate from the standard value, the precision is poor, and the recovery rate is too low.

[0063] It should be further noted that the "some embodiments", "other embodiments", "embodiments" and the like mentioned in the present application refer to the specific features, structures or characteristics described in conjunction with the embodiments, which are included in at least one embodiment described in the general description of the present application. The same expression appears in several places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the implementation of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of the present application.

[0064] In the above examples, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0065] It should be further noted that the above is only the preferred embodiment of the present application, and does not limit the patent protection scope of the present application. Any equivalent structure or equivalent process transformation using the content of the present application specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting boron element in silicon carbide, characterized by, The method comprises the following steps: (1) providing a sample to be tested; (2) performing a burning treatment on the sample to be tested; (3) performing a melting reaction on the product of the burning treatment, calcium carbonate and an alkali flux to obtain a melt; (4) mixing the melt, an acid and mannitol to dissolve the melt to obtain a solution to be tested; (5) detecting the signal intensity of boron in the solution to be tested by an inductively coupled plasma mass spectrometer, and obtaining the boron content in the solution to be tested according to a standard curve.

2. The detection method according to claim 1, characterized in that, The temperature of the burning treatment in step (2) is 650-850℃. The time of the burning treatment is 30-90 min.

3. The method of claim 1, wherein, The melting reaction on the product of the burning treatment, calcium carbonate and the alkali flux comprises: After drying the product of the burning treatment and calcium carbonate, the dried product is subjected to a melting reaction with the alkali flux.

4. The detection method according to claim 3, characterized in that, The melting reaction on the product of the burning treatment, calcium carbonate and the alkali flux comprises: After mixing the dried product and the alkali flux, the alkali flux is covered on the surface of the mixture.

5. The detection method according to claim 3 or 4, characterized in that, The drying is performed at a temperature of 100-120℃ for 1-3 h.

6. The detection method according to claim 1 or 3 or 4, characterized in that, The alkali flux comprises sodium hydroxide and sodium peroxide. The mass ratio of the product of the burning treatment, calcium carbonate and the alkali flux is 1:(5-15):(1-5).

7. The detection method according to claim 6, characterized in that, The mass ratio of sodium hydroxide and sodium peroxide is 1:(1-3).

8. The detection method according to claim 6, characterized in that, The melting reaction comprises a temperature rising stage and a temperature holding stage. The temperature rising stage is rising from 200-400℃ to 500-700℃ at a temperature rising rate of 8-15℃ / min. The time of the temperature holding stage is 10-30 min.

9. The method of claim 1, wherein, The mass ratio of the melt, the acid and mannitol is 1:(7-10):(0.004-0.01).

10. The detection method according to claim 1 or 9, characterized in that, The acid comprises hydrochloric acid. The concentration of the hydrochloric acid is 10-30 wt%. The temperature of the dissolution is 100-150℃.

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