Dissolution method and detection and analysis method of tungsten-silicon alloy

Abstract

The application provides a dissolving method and a detection and analysis method of tungsten-silicon alloy. The dissolving method comprises the following steps: mixing tungsten-silicon alloy and hydrofluoric acid in a reactor under ice bath environment to obtain a mixed solution, and then adding nitric acid dropwise into the mixed solution, and obtaining a clear and transparent solution after reaction. The dissolving method provided by the application realizes the full dissolution of the tungsten-silicon alloy by using hydrofluoric acid and nitric acid under ice bath environment, and the clear and transparent solution formed is used for subsequent detection and analysis, which helps to improve the accuracy of the detection result. The method is simple to operate, and the reagents and operations used are less, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of elemental analysis and testing technology, and relates to a solution method for tungsten-silicon alloys, and more particularly to a method for dissolving and analyzing tungsten-silicon alloys. Background Technology

[0002] Tungsten, as a metallic element, possesses stable chemical properties. At room temperature, it does not react with air or water. Without heating, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, and aqua regia of any concentration have no effect on tungsten. When the temperature rises to 80–100°C, all of these acids except hydrofluoric acid have a weak effect on tungsten. At room temperature, tungsten can rapidly dissolve in a mixture of hydrofluoric acid and concentrated nitric acid, but it has no effect in alkaline solutions. In the presence of air, molten alkali can oxidize tungsten to tungstates. The reaction to form tungstates is more vigorous in the presence of oxidizing agents (NaNO3, NaNO2, KClO3, or PbO2). At high temperatures, it can combine with oxygen, fluorine, chlorine, bromine, iodine, carbon, nitrogen, and sulfur, but not with hydrogen.

[0003] Silicon is chemically reactive, combining with various elements such as oxygen at high temperatures. It is insoluble in water, nitric acid, and hydrochloric acid, but soluble in hydrofluoric acid and alkaline solutions. Silicon is widely distributed in nature, rarely occurring in elemental form, primarily existing as silicon dioxide and silicates. It constitutes approximately 27.6% of the Earth's crust, making it the second most abundant element after oxygen.

[0004] Metallic elements or their compounds often require high purity in various applications, necessitating their analysis and detection. While methods for dissolving and detecting single metals or non-metals such as tungsten and silicon exist, there are no definitive methods for dissolving more complex composite oxides due to their more intricate crystal structures. Therefore, selecting appropriate methods for the dissolution and quantitative analysis of tungsten and silicon in compounds is crucial.

[0005] CN 109900679A discloses a method for determining the content of silicon, manganese, molybdenum, iron, and tungsten in cobalt-based alloys, comprising the following steps: 1) Sample pretreatment: Weigh a cobalt-based alloy sample, add a digesting agent, perform microwave digestion, cool, then add saturated benzoic acid solution for a sealed reaction, transfer, and dilute to obtain a sample solution; 2) Preparation of standard solutions: Select a matrix solution, add the elements to be measured, and prepare a standard solution; 3) Determination: Detect the standard solution prepared in step 2) and the sample solution from step 1) using inductively coupled plasma atomic emission spectrometry (ICP-AES), and quantify using a standard curve method to obtain the content of silicon, manganese, molybdenum, iron, and tungsten in the sample solution. This method dissolves the cobalt-based alloy sample and uses multiple types of acids while employing microwave-assisted digestion, making the process relatively complex.

[0006] CN 111307797A discloses a method for the joint determination of tungsten and silicon content in ferrotungsten. The method involves melting and decomposing the sample with sodium peroxide, acidifying it with hydrochloric acid, and oxidizing it with nitric acid to form an insoluble, pale yellow tungstic acid precipitate. To ensure more complete tungstic acid precipitation, an organic precipitant, cinchonine, is added. The precipitate is then filtered, washed, and ignited to remove impurities, yielding pure tungsten trioxide, from which the tungsten content is calculated. This method uses numerous auxiliary reagents in the digestion of ferrotungsten, making the process relatively complex.

[0007] In summary, existing technologies lack research on the simultaneous detection of tungsten and silicon components in tungsten-silicon alloys. For the dissolution of tungsten-silicon alloys, it is necessary to select appropriate combination processes and dissolving solutions based on the characteristics of the materials to ensure complete dissolution of the sample, facilitating subsequent content detection. At the same time, the dissolution process is relatively simple and low in cost. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for dissolving and analyzing tungsten-silicon alloys. The dissolution method utilizes hydrofluoric acid and nitric acid in an ice bath environment to achieve complete dissolution of the tungsten-silicon alloy. The resulting clear and transparent solution is used for subsequent analysis, which helps improve the accuracy of the test results. The method is simple to operate, requires fewer reagents and procedures, and has low cost.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a tungsten-silicon alloy sample for ICP-OES analysis, the method comprising the following steps:

[0011] In an ice bath environment, tungsten-silicon alloy and hydrofluoric acid are mixed in a reactor to obtain a mixed solution. Nitric acid is then added dropwise to the mixed solution, and a clear and transparent solution is obtained after the reaction.

[0012] In this invention, to accurately detect the elemental content in a tungsten-silicon alloy, it is necessary to fully dissolve it. Since tungsten and silicon have drastically different chemical properties, dissolving them is more difficult. Therefore, this invention first mixes the tungsten-silicon alloy and hydrofluoric acid in an ice bath to establish an HF environment for the subsequent reaction; then, nitric acid is added dropwise to further dissolve the alloy, resulting in a clear and transparent solution that meets the standards for instrumental analysis and can be used for ICP-OES detection. The method is simple to operate, requires no complex processes, and provides good sample dissolution, which helps improve the accuracy of subsequent detection, enables quantitative elemental analysis, and has low cost and wide applicability.

[0013] The tungsten-silicon alloy described in this invention can be in block or powder form, but the powder form of the tungsten-silicon alloy dissolves faster.

[0014] As a preferred embodiment of the present invention, the Si content in the tungsten-silicon alloy is 28-30 wt%, for example, it can be 28 wt%, 28.4 wt%, 28.8 wt%, 29.2 wt%, 29.6 wt%, or 30 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] As a preferred embodiment of the present invention, the temperature of the ice bath environment is -3 to 0°C, for example, it can be -3°C, -2.6°C, -2.2°C, -1.8°C, -1.4°C, -1°C, -0.6°C, -0.2°C or 0°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] It is worth noting that the mixing and dropwise addition reaction processes described in this invention are all carried out in an ice bath environment. The ice bath environment provides a low-temperature environment for the dissolution process. If the temperature is too high, it will cause the loss of silicon elements in the tungsten-silicon alloy.

[0017] As a preferred embodiment of the present invention, the solid-liquid ratio of the tungsten-silicon alloy and hydrofluoric acid is 1g:25-35mL, for example, it can be 1g:25mL, 1g:27mL, 1g:29mL, 1g:31mL, 1g:33mL or 1g:35mL, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0018] Preferably, the concentration of the hydrofluoric acid is 38-42 wt%, for example, it can be 38 wt%, 38.5 wt%, 39 wt%, 39.5 wt%, 40 wt%, 40.5 wt%, 41 wt%, 41.5 wt%, or 42 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] As a preferred embodiment of the present invention, the concentration of the nitric acid is 65-68 wt%, for example, it can be 65 wt%, 65.5 wt%, 66 wt%, 66.5 wt%, 67 wt%, 67.5 wt%, or 68 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] As a preferred embodiment of the present invention, the dropping rate is 10 to 20 min / drop, for example, it can be 10 min / drop, 12 min / drop, 14 min / drop, 16 min / drop, 18 min / drop or 20 min / drop, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0021] In this invention, the dropping rate of nitric acid is 10-20 min / drop (i.e., one drop of nitric acid is added every 10-20 min). If the dropping rate is too fast, the reaction will be too fast, the temperature in the system will rise, and the silicon element in the tungsten-silicon alloy will be lost. If the dropping rate is too slow, the reaction will be slow, increasing the time cost.

[0022] As a preferred embodiment of the present invention, the reaction time is 2 to 4 hours, for example, it can be 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours or 4 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] As a preferred embodiment of the present invention, the reactor comprises a polytetrafluoroethylene tube.

[0024] As a preferred embodiment of the present invention, the method for dissolving tungsten-silicon alloy provided in the first aspect of the present invention includes the following steps:

[0025] In an ice bath environment of -3 to 0°C, tungsten-silicon alloy and hydrofluoric acid with a concentration of 38 to 42 wt% are mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1 g: 25 to 35 mL to obtain a mixture. Then, nitric acid with a concentration of 65 to 68 wt% is added dropwise to the mixture at a rate of 10 to 20 min / drop. After reacting for 2 to 4 hours, a clear and transparent solution is obtained.

[0026] Secondly, the present invention provides a method for detecting and analyzing tungsten-silicon alloys, the method comprising: using ICP-OES to detect and analyze a clear and transparent solution obtained by the dissolution method provided in the first aspect.

[0027] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0028] The system refers to an equipment system, device system, or production device.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The dissolution method provided by the present invention achieves full dissolution of tungsten-silicon alloy in an ice bath environment using hydrofluoric acid and nitric acid. The resulting clear and transparent solution meets the standards for instrument testing and is convenient for subsequent testing.

[0031] (2) The dissolution method provided by the present invention is simple to operate, requires no complicated process, has a good sample dissolution effect, helps to improve the accuracy of detection, and has a low cost and wide applicability. Detailed Implementation

[0032] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0033] The present invention provides a method for dissolving a tungsten-silicon alloy, the method comprising the following steps:

[0034] In an ice bath environment of -3 to 0°C, tungsten-silicon alloy and hydrofluoric acid with a concentration of 38 to 42 wt% are mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1 g: 25 to 35 mL to obtain a mixture. Then, nitric acid with a concentration of 65 to 68 wt% is added dropwise to the mixture at a rate of 10 to 20 min / drop. After reacting for 2 to 4 hours, a clear and transparent solution is obtained.

[0035] The following are typical but non-limiting embodiments of the present invention:

[0036] Example 1

[0037] This embodiment provides a method for dissolving a tungsten-silicon alloy, the method comprising the following steps:

[0038] In an ice bath environment at -2℃, tungsten silicon alloy and 40wt% hydrofluoric acid were mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1g:30mL to obtain a mixture. Then, 66wt% nitric acid was added dropwise to the mixture at a rate of 15min / drop. After reacting for 3h, a clear and transparent solution was obtained.

[0039] The Si content in the tungsten-silicon alloy is 29.5 wt%.

[0040] Example 2

[0041] This embodiment provides a method for dissolving a tungsten-silicon alloy, the method comprising the following steps:

[0042] In an ice bath environment at -3°C, tungsten silicon alloy and 42wt% hydrofluoric acid were mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1g:25mL to obtain a mixture. Then, 68wt% nitric acid was added dropwise to the mixture at a rate of 20min / drop. After reacting for 2 hours, a clear and transparent solution was obtained.

[0043] The Si content in the tungsten-silicon alloy is 28 wt%.

[0044] Example 3

[0045] This embodiment provides a method for dissolving a tungsten-silicon alloy, the method comprising the following steps:

[0046] In an ice bath environment at 0°C, tungsten silicon alloy and 38wt% hydrofluoric acid were mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1g:35mL to obtain a mixture. Then, 65wt% nitric acid was added dropwise to the mixture at a rate of 10min / drop. After reacting for 4 hours, a clear and transparent solution was obtained.

[0047] The Si content in the tungsten-silicon alloy is 30 wt%.

[0048] Example 4

[0049] This embodiment provides a method for dissolving a tungsten-silicon alloy, the method comprising the following steps:

[0050] In an ice bath environment at -1℃, tungsten silicon alloy and 41wt% hydrofluoric acid were mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1g:32mL to obtain a mixture. Then, 67wt% nitric acid was added dropwise to the mixture at a rate of 18min / drop, and a clear and transparent solution was obtained after 3.5h of reaction.

[0051] The Si content in the tungsten-silicon alloy is 29 wt%.

[0052] Example 5

[0053] This embodiment provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and that of Embodiment 1 is:

[0054] In this embodiment, the solid-liquid ratio of the tungsten-silicon alloy and hydrofluoric acid is adjusted to 1g:20mL.

[0055] Example 6

[0056] This embodiment provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and that of Embodiment 1 is:

[0057] In this embodiment, the solid-liquid ratio of the tungsten-silicon alloy and hydrofluoric acid is adjusted to 1g:40mL.

[0058] Example 7

[0059] This embodiment provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and that of Embodiment 1 is:

[0060] In this embodiment, the dropping rate of the nitric acid is adjusted to 5 min / drop.

[0061] Example 8

[0062] This embodiment provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and that of Embodiment 1 is:

[0063] In this embodiment, the dropping rate of the nitric acid is adjusted to 25 min / drop.

[0064] Example 9

[0065] This embodiment provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and that of Embodiment 1 is:

[0066] In this embodiment, the concentration of nitric acid is adjusted to 30 wt%.

[0067] Comparative Example 1

[0068] This comparative example provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and Example 1 being:

[0069] In this comparative example, the ice bath environment is adjusted to a water bath environment with a temperature of 5°C.

[0070] Comparative Example 2

[0071] This comparative example provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and Example 1 being:

[0072] The hydrofluoric acid described in this comparative example was adjusted to a concentration of 40 wt% hydroiodic acid.

[0073] Comparative Example 3

[0074] This comparative example provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and Example 1 being:

[0075] The mixing of the hydrofluoric acid is omitted in this comparative example.

[0076] Comparative Example 4

[0077] This comparative example provides a method for dissolving a tungsten-silicon alloy, the only difference between this method and Example 1 being:

[0078] In this comparative example, the nitric acid was adjusted to hydrochloric acid with a concentration of 38 wt%.

[0079] The mass percentages of tungsten and silicon in the solutions provided in the above examples and comparative examples were determined by ICP-OES, and the results are shown in Table 1.

[0080] The deviation is calculated as follows: Deviation = |Actual value - Measured value| / Actual value × 100%.

[0081] Table 1

[0082]

[0083]

[0084] Based on the data in Table 1, the following points can be observed:

[0085] (1) Comprehensive analysis of Examples 1-4 shows that the dissolution method provided by the present invention can achieve a 100% dissolution rate for tungsten-silicon alloys. The ICP-OES method can quickly and accurately detect the element content in the dissolution solution and reduce the detection deviation to below 1.5%.

[0086] (2) Comprehensive analysis of Examples 1 and 5-6 shows that the amount of hydrofluoric acid used during the mixing process will affect the degree of dissolution of the tungsten-silicon alloy. If the amount of hydrofluoric acid added is too small (as in Example 5), the tungsten-silicon alloy will not be completely dissolved. If the amount of hydrofluoric acid added is too large (as in Example 6), it will not only damage the equipment, but also cause the loss of silicon elements due to excessive temperature.

[0087] (3) Comprehensive analysis of Examples 1 and 7-8 shows that the dropping rate of nitric acid affects the dissolution rate. If the dropping rate is too slow (as in Example 7), the dissolution rate will be too slow, thus increasing the time cost; if the dropping rate is too fast (as in Example 8), the temperature of the reaction system will be too high, thus causing the loss of silicon.

[0088] In addition, the concentration of nitric acid also affects the dissolution rate and degree of dissolution. If the concentration of nitric acid is too low (as in Example 9), the tungsten-silicon alloy will not be completely dissolved for a long time, or even not completely dissolved, making it impossible to detect the element content in the alloy.

[0089] (4) Comprehensive analysis of Example 1 and Comparative Example 1 shows that the ice bath environment can provide a low temperature environment for the dissolution process. If the water bath is adjusted to 5°C, the temperature of the reaction system will be too high, resulting in a large loss of silicon element in the tungsten-silicon alloy.

[0090] (5) Comprehensive analysis of Example 1 and Comparative Examples 2-4 shows that hydrofluoric acid of appropriate concentration can effectively and quickly dissolve tungsten-silicon alloy. If hydrofluoric acid is omitted or replaced, the tungsten-silicon alloy will not be completely dissolved, thus making it impossible to detect the element content in the tungsten-silicon alloy.

[0091] In summary, the dissolution method provided by this invention achieves complete dissolution of tungsten-silicon alloy in an ice bath environment using hydrofluoric acid and nitric acid. The resulting clear and transparent solution is used for subsequent detection and analysis, which helps to improve the accuracy of the detection results. The method is simple to operate, requires fewer reagents and operations, and has low cost.

[0092] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for dissolving a tungsten-silicon alloy, characterized in that, The dissolution method includes the following steps: In an ice bath environment, tungsten-silicon alloy and hydrofluoric acid are mixed in a reactor to obtain a mixed solution. Nitric acid is then added dropwise to the mixed solution, and a clear and transparent solution is obtained after the reaction. The temperature of the ice bath environment is -3~0℃; the dropping rate is 10~20 min / drop; The Si content in the tungsten-silicon alloy is 28-30 wt%. The solid-liquid ratio of the tungsten-silicon alloy and hydrofluoric acid is 1g:25~35mL; The concentration of the hydrofluoric acid is 38-42 wt%. The concentration of the nitric acid is 65-68 wt%.

2. The method for dissolving tungsten-silicon alloy according to claim 1, characterized in that, The reaction time is 2-4 hours.

3. The method for dissolving tungsten-silicon alloy according to claim 1, characterized in that, The reactor includes a polytetrafluoroethylene tube.

4. The method for dissolving tungsten-silicon alloy according to claim 1, characterized in that, The dissolution method includes the following steps: In an ice bath environment of -3 to 0°C, tungsten-silicon alloy and hydrofluoric acid with a concentration of 38 to 42 wt% are mixed in a polytetrafluoroethylene tube at a solid-liquid ratio of 1 g: 25 to 35 mL to obtain a mixture. Then, nitric acid with a concentration of 65 to 68 wt% is added dropwise to the mixture at a rate of 10 to 20 min / drop. After reacting for 2 to 4 hours, a clear and transparent solution is obtained.

5. A method for detecting and analyzing tungsten-silicon alloys, characterized in that, The detection and analysis method includes: using ICP-OES to detect and analyze the clear and transparent solution obtained by the dissolution method described in claim 1.

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