A cross-section sample preparation method of ultra-fine tungsten alloy wire

Abstract

The application belongs to the technical field of material detection and analysis, and particularly relates to a cross-section sample preparation method of superfine tungsten alloy wire, which comprises the following steps: fixing the tungsten alloy wire on a substrate made of the same material; then using epoxy resin and glass powder to perform hot embedding on the tungsten alloy wire, obtaining an embedded sample after cooling; then grinding and polishing the embedded sample under a pressure of 50-60 MPa; finally using a corrosion solution prepared from hydrogen peroxide, ammonia water and sodium dodecyl sulfonate to corrode the embedded sample, obtaining a tungsten alloy wire cross-section sample. The application uses a substrate made of the same material to fix the tungsten alloy wire, which is convenient for positioning the cross-section and avoids the occurrence of original cell reaction during corrosion; by accurately controlling key process parameters such as grinding pressure and polishing disc rotating speed, the cross-section micro-crack defects are effectively eliminated; by selecting a suitable type of corrosion agent and a suitable corrosion treatment time, a standardized detection sample meeting the requirements of microscopic analysis such as metallographic microscope and scanning electron microscope is prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material detection and analysis, and particularly relates to a cross-section sample preparation method of superfine tungsten alloy wire. BACKGROUND

[0002] The tungsten alloy wire has found new applications due to the development of the photovoltaic industry in recent years. Influenced by the development of photovoltaic silicon wafers towards thinning and reducing raw material loss, the tungsten alloy wire used for cutting silicon wafers also develops towards thinning, and now has reached tens of microns. However, this puts forward higher requirements for the microscopic morphology detection of tungsten wire. The traditional tungsten wire sample preparation method generally involves folding the tungsten wire and then directly hot-embedding it in phenolic resin, and then grinding and polishing to obtain a sample that can be used for optical or electron microscopy. However, the current superfine tungsten wire cannot be prepared in this conventional way. Firstly, the tungsten alloy wire is too thin to be fixed by this method. Secondly, the tungsten wire is too thin and is prone to cracking during grinding and polishing. The traditional sample preparation method needs to be coarsely ground with a 250-micron grinding disc and then finely ground and polished. This sample preparation method is prone to cause the sample to crack and distort during the first step of coarse grinding. If the sample is corroded with conventional etching liquid and for a conventional etching time, the sample will be completely corroded, resulting in failure of the sample preparation. SUMMARY

[0003] The application optimizes the process in view of the technical defects such as difficulty in positioning the cross-section when the traditional sample preparation method is used to prepare the cross-section sample of superfine tungsten alloy wire, and develops a cross-section sample preparation method of superfine tungsten alloy wire.

[0004] The cross-section sample preparation method of superfine tungsten alloy wire provided by the application comprises the following steps:

[0005] S1, fixing the tungsten alloy wire on a base, wherein the tungsten alloy wire and the base are made of the same material, the base is a column, and the tungsten alloy wire is perpendicular to the bottom surface of the base;

[0006] S2, hot-embedding the base with the fixed tungsten alloy wire with embedding powder, wherein the embedding powder comprises epoxy resin and glass powder, and a sample is obtained after cooling;

[0007] S3, grinding and polishing the bottom surface of the sample to obtain a ground and polished sample, wherein the pressure during the grinding and polishing process is 50-60 MPa;

[0008] S4, corroding the ground and polished sample with etching liquid to obtain a tungsten alloy wire cross-section sample, wherein the etching liquid comprises hydrogen peroxide, ammonia water and sodium dodecyl sulfonate.

[0009] In the above technical solution, in step S1, the application explores the influence of different substrates on the sample. If the substrate and the sample material are different, the difference in electrical conductivity will produce a potential difference and cause the corrosion speed to accelerate, making it difficult to control the corrosion time. Therefore, selecting a substrate with the same material as the tungsten alloy wire can avoid this situation and make it easier to control the corrosion time. In step S2, adding glass powder to the epoxy resin can improve the hardness of the cured epoxy resin. The higher the hardness of the embedded powder, the less likely it is to produce cracks during polishing. In step S3, the rough polishing step is abandoned to avoid cracking and distortion during rough polishing. Instead, polishing is performed under high pressure to obtain a more complete cross-section. In step S4, the polishing sample is etched using an etching solution containing hydrogen peroxide, ammonia, and sodium dodecyl sulfate. Compared with traditional etching solutions, this etching solution acts more slowly and can more accurately control the degree of tungsten alloy wire corrosion. The polar groups in sodium dodecyl sulfate adsorb on the surface of the alloy metal, and the non-polar groups are oriented to hinder the reaction between the etchant and the metal, thereby selectively etching the grain boundaries and achieving the effect of selectively exposing the grain boundaries.

[0010] Further, in step S1, the side surface of the column is perpendicular to the bottom surface, and the tungsten alloy wire is fixed to the side surface of the substrate.

[0011] Further, the substrate is a cuboid.

[0012] Further, in step S1, the diameter of the tungsten alloy wire is 30-50 μm, and the strength is 4500-6500 MPa.

[0013] Further, in step S2, in the embedded powder, the mass fraction of the glass powder is 30-40%, and the particle size of the glass powder is 50-100 μm.

[0014] Further, in step S2, the temperature during the hot embedding process is 150-180°C, the pressure is 240-260 MPa, and the pressure holding time is 15-20 min.

[0015] Further, in step S3, the polishing includes: using a 54 μm polishing disc to polish the embedded sample, and then using 9 μm, 3 μm, and 1 μm diamond sprays to polish the embedded sample, respectively.

[0016] Further, the rotation speed of the polishing disc is 600-1000 rpm, the polishing time is 2-4 min, and the polishing time is 50-200 s.

[0017] Further, in the step S4, the concentration of the hydrogen peroxide is 20wt%-25wt%, the concentration of the ammonia is 26wt%-30wt%, and the volume ratio of the hydrogen peroxide to the ammonia is 2:1-4:1.

[0018] Further, in the step S4, the mass fraction of the sodium dodecyl sulfonate in the etching solution is 4%-8%.

[0019] Further, in the step S4, the etching time is 2-4 min.

[0020] The application provides a cross-section sample preparation method for superfine tungsten alloy wires, and has the following beneficial effects: the tungsten alloy wire is fixed by using a homogeneous matrix material, the cross section is conveniently positioned, and original cell reaction is avoided during etching; key process parameters such as grinding pressure and polishing disc rotating speed are accurately controlled, so that cross-section microcrack defects are effectively eliminated; appropriate etchant types and etching treatment time are selected, so that a standardized detection sample meeting the requirements of microscopic analysis such as a metallographic microscope and a scanning electron microscope is prepared; compared with a traditional process, the surface defects of the sample are significantly optimized, and the cross-section grain boundary definition is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings shown.

[0022] Figure 1 The metallographic graph of the tungsten alloy wire cross-section sample prepared for Example 1.

[0023] Figure 2 The electron microscope graph of the tungsten alloy wire cross-section sample prepared for Comparative Example 1.

[0024] Figure 3 The metallographic graph of the tungsten alloy wire cross-section sample prepared for Comparative Example 2.

[0025] Figure 4 The metallographic graph of the tungsten alloy wire cross-section sample prepared for Comparative Example 5.

[0026] Figure 5 The 3D model of the tungsten alloy wire cross-section sample of the present application.

[0027] Figure 6 The top view of the tungsten alloy wire cross-section sample model of the present application.

[0028] The object, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments will be described below clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0030] The present application is a cross-section sample preparation method of ultra-fine tungsten alloy wire, comprising the following steps:

[0031] S1, fixing the tungsten alloy wire on the base, the tungsten alloy wire and the base are made of the same material, the base is a cylinder, and the tungsten alloy wire is perpendicular to the bottom surface of the base;

[0032] Preferably, the side surface of the cylinder is perpendicular to the bottom surface, and the tungsten alloy wire is fixed on the side surface of the base. The way of fixing the tungsten alloy wire is not limited, as long as it can keep one end of the tungsten alloy wire perpendicular to the bottom surface of the base. The diameter of the tungsten alloy wire is 30-50 μm, and the strength is 4500-6500 MPa, such as Figure 5 and Figure 6 As shown in the model of the tungsten alloy wire cross-section sample, the tungsten alloy wire to be measured can be wound around the base for multiple turns to increase the fault tolerance rate during sample preparation.

[0033] Specifically, the diameter of the tungsten alloy wire can be any one of 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or a range between any two of them, and the strength can be any one of 4500 MPa, 5000 MPa, 5500 MPa, 6000 MPa, 6500 MPa or a range between any two of them.

[0034] S2, hot-embedding the base with the fixed tungsten alloy wire with inlay powder, the inlay powder comprising epoxy resin and glass powder, and obtaining the inlay sample after cooling;

[0035] Preferably, in the inlay powder, the mass fraction of the glass powder is 30%-40%, and the particle size of the glass powder is 50-100 μm. The temperature during the hot-embedding process is 150-180℃, the pressure is 240-260 MPa, and the pressure holding time is 15-20 min. When inlaying, the bottom surface of the base with the fixed tungsten alloy wire is placed downward into the mold to ensure that the cross-section of the tungsten alloy wire parallel to the bottom surface of the base can be exposed as much as possible, providing a basis for the next step of polishing the bottom surface of the inlay sample.

[0036] Specifically, in the inlay powder, the mass fraction of glass powder can be any one or any two of 30%, 32%, 34%, 36%, 38%, and 40%, and the particle size of the glass powder can be any one or any two of 50μm, 60μm, 70μm, 80μm, 90μm, and 100μm; the temperature during the hot inlay process can be any one or any two of 150℃, 160℃, 170℃, and 180℃, the pressure can be any one or any two of 240MPa, 245MPa, 250MPa, 255MPa, and 260MPa, and the holding time can be any one or any two of 15min, 16min, 17min, 18min, 19min, and 20min.

[0037] S3. Polish the bottom surface of the mounting to obtain a polished sample. The pressure during the polishing process is 50~60MPa.

[0038] Preferably, the grinding and polishing process includes: grinding the sample with a 54μm grinding disc, and then polishing the sample with diamond sprays of 9μm, 3μm and 1μm respectively; the grinding disc rotates at 600~1000rpm, the grinding time is 2~4min, and the polishing time is 50~200s.

[0039] Specifically, the pressure during the grinding and polishing process can be any one or any two of 50MPa, 52MPa, 54MPa, 56MPa, 58MPa, and 60MPa; the rotation speed of the grinding disc can be any one or any two of 600rpm, 700rpm, 800rpm, 900rpm, and 1000rpm; the grinding time can be any one or any two of 2min, 2.5min, 3min, 3.5min, and 4min; and the polishing time can be any one or any two of 50s, 100s, 150s, and 200s.

[0040] S4. Use an etching solution to etch the polished sample to obtain a tungsten alloy wire cross-section sample. The etching solution includes hydrogen peroxide, ammonia and sodium dodecyl sulfonate.

[0041] Preferably, the concentration of hydrogen peroxide is 20wt%~25wt%, the concentration of ammonia is 26wt%~30wt%, and the volume ratio of hydrogen peroxide to ammonia is 2:1~4:1; the mass fraction of sodium dodecyl sulfonate in the corrosion solution is 4%~8%; and the corrosion time is 2~4 min.

[0042] Specifically, the concentration of hydrogen peroxide can be any one or any two of 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, and 25wt%; the concentration of ammonia can be any one or any two of 26wt%, 27wt%, 28wt%, 29wt%, and 30wt%; the volume ratio of hydrogen peroxide to ammonia can be any one or any two of 2:1, 2.5:1, 3:1, 3.5:1, and 4:1; the mass fraction of sodium dodecyl sulfonate in the corrosive solution can be any one or any two of 4%, 5%, 6%, 7%, and 8%; and the corrosion time can be any one or any two of 2 min, 2.5 min, 3 min, 3.5 min, and 4 min.

[0043] The technical solution of this application will be further described below with reference to specific embodiments.

[0044] Example 1

[0045] A method for preparing a cross-section sample of an ultrafine tungsten alloy wire includes the following steps:

[0046] S1. A 30μm diameter tungsten alloy wire is attached and fixed to a square substrate with conductive adhesive, keeping the tungsten alloy wire perpendicular to the bottom surface of the substrate. The tungsten alloy wire and the substrate are made of the same material.

[0047] S2. The substrate with the tungsten alloy wire fixed is placed into a hydraulic hot mounting machine and hot-mounted using mounting powder, which includes 70% epoxy resin and 30% glass powder. After cooling, the mounting sample is obtained. The glass powder has a particle size of 50 μm, the temperature during the hot mounting process is 150℃, the pressure is 240 MPa, and the holding time is 15 min.

[0048] S3. Polish the bottom surface of the mounting to obtain a polished sample. The pressure during the polishing process is 55 MPa. The polishing process includes: polishing the mounting with a 54 μm grinding disc for 3 minutes, and then polishing the mounting with diamond sprays of 9 μm, 3 μm and 1 μm for 50 seconds each. The rotation speed of the grinding disc is 600 rpm.

[0049] S4. The polished sample was etched with an etchant for 3 minutes to obtain a tungsten alloy wire cross-section sample. The etchant consisted of hydrogen peroxide, ammonia, and sodium dodecyl sulfonate. The concentration of hydrogen peroxide was 20 wt%, the concentration of ammonia was 26 wt%, the volume ratio of hydrogen peroxide to ammonia was 3:1, and the mass fraction of sodium dodecyl sulfonate in the etchant was 5%.

[0050] like Figure 1 As shown, this embodiment yields a tungsten alloy wire cross-section sample that is straight, clear, and free of cracks, with clearly exposed grain boundaries.

[0051] Example 2

[0052] A method for preparing a cross-section sample of an ultrafine tungsten alloy wire includes the following steps:

[0053] S1. A 50μm diameter tungsten alloy wire is attached and fixed to a square substrate with conductive adhesive, keeping the tungsten alloy wire perpendicular to the bottom surface of the substrate. The tungsten alloy wire and the substrate are made of the same material.

[0054] S2. The substrate with the tungsten alloy wire fixed is placed into a hydraulic hot mounting machine and hot-mounted using mounting powder, which includes 60% epoxy resin and 40% glass powder. After cooling, the mounting sample is obtained. The glass powder has a particle size of 100 μm, the temperature during the hot mounting process is 180℃, the pressure is 260 MPa, and the holding time is 20 min.

[0055] S3. Polish the bottom surface of the mounting to obtain a polished sample. The pressure during the polishing process is 60MPa. The polishing process includes: polishing the mounting with a 54μm grinding disc for 4 minutes, and then polishing the mounting with diamond sprays of 9μm, 3μm and 1μm for 200 seconds each. The rotation speed of the grinding disc is 1000rpm.

[0056] S4. The polished sample was etched with an etchant for 4 minutes to obtain a tungsten alloy wire cross-section sample. The etchant consisted of hydrogen peroxide, ammonia, and sodium dodecyl sulfate. The concentration of hydrogen peroxide was 25 wt%, the concentration of ammonia was 30 wt%, the volume ratio of hydrogen peroxide to ammonia was 2:1, and the mass fraction of sodium dodecyl sulfate in the etchant was 8%.

[0057] Example 3

[0058] A method for preparing a cross-section sample of an ultrafine tungsten alloy wire includes the following steps:

[0059] S1. A 40μm diameter tungsten alloy wire is attached and fixed to a square substrate with conductive adhesive, keeping the tungsten alloy wire perpendicular to the bottom surface of the substrate. The tungsten alloy wire and the substrate are made of the same material.

[0060] S2. The substrate with the tungsten alloy wire fixed is placed into a hydraulic hot mounting machine and hot-mounted using mounting powder, which includes 65% epoxy resin and 35% glass powder. After cooling, the mounting sample is obtained. The glass powder has a particle size of 70 μm. The temperature during the hot mounting process is 160℃, the pressure is 250 MPa, and the holding time is 18 min.

[0061] S3. Polish the bottom surface of the mounting to obtain a polished sample. The pressure during the polishing process is 50 MPa. The polishing process includes: polishing the mounting with a 54 μm grinding disc for 2 minutes, and then polishing the mounting with diamond sprays of 9 μm, 3 μm and 1 μm for 100 seconds each. The rotation speed of the grinding disc is 800 rpm.

[0062] S4. The polished sample was etched with an etchant for 2 minutes to obtain a tungsten alloy wire cross-section sample. The etchant consisted of hydrogen peroxide, ammonia, and sodium dodecyl sulfate. The concentration of hydrogen peroxide was 23 wt%, the concentration of ammonia was 28 wt%, the volume ratio of hydrogen peroxide to ammonia was 4:1, and the mass fraction of sodium dodecyl sulfate in the etchant was 4%.

[0063] Comparative Example 1

[0064] In step S1 of this comparative example, a pure copper substrate is used, and the other steps are the same as in Example 1.

[0065] like Figure 2 As shown, due to the inconsistency between the substrate material and the tungsten alloy wire, a galvanic cell reaction occurred during corrosion, resulting in an excessively fast corrosion rate. The tungsten alloy wire was almost completely corroded in the resin, leading to sample preparation failure.

[0066] Comparative Example 2

[0067] In step S2 of this comparative example, no glass powder was added to the embedding powder; only ordinary phenolic resin was used. The other steps were the same as in Example 1.

[0068] like Figure 3 As shown, due to the low hardness of phenolic resin and the large difference in hardness between the tungsten alloy wire and the inlay material, cracks appeared, resulting in sample preparation failure.

[0069] Comparative Example 3

[0070] In step S3 of this comparative example, conventional grinding and polishing parameters are used, and the pressure during the grinding and polishing process is 100 MPa. Other steps are the same as in Example 1.

[0071] Excessive pressure caused cracks in the tungsten alloy wire, resulting in sample preparation failure.

[0072] Comparative Example 4

[0073] In step S4 of this comparative example, a common etching solution, namely a 1:1 volume mixture of 20wt% potassium hydroxide solution and 20wt% potassium ferricyanide solution, was used to etch the sample. The other steps were the same as in Example 1.

[0074] The sample was corroded too quickly by the etchant, resulting in rapid corrosion that prevented accurate exposure of the grain boundaries and caused sample preparation failure.

[0075] Comparative Example 5

[0076] In step S4 of this comparative example, sodium dodecyl sulfonate was not added to the etching solution. Only a 3:1 mixture of hydrogen peroxide and ammonia was used to etch the sample. The other steps were the same as in Example 1.

[0077] like Figure 4 As shown, due to the non-selective corrosion of the sample by the etchant, the grain boundaries are not clearly exposed, resulting in poor sample quality.

[0078] This application proposes a method for preparing cross-section samples of ultrafine tungsten alloy wires, which yields the following beneficial effects: Using a homogeneous matrix material to fix the tungsten alloy wire facilitates cross-sectional positioning while avoiding galvanic reactions during corrosion; precise control of key process parameters such as grinding pressure and polishing disc rotation speed effectively eliminates microcrack defects in the cross-section; by selecting appropriate etchant types and corrosion treatment durations, standardized test samples meeting the requirements of microscopic analysis such as metallographic microscopy and scanning electron microscopy are prepared; compared with traditional processes, sample surface defects are significantly optimized, and the clarity of grain boundaries in the cross-section is also improved.

[0079] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing a cross-sectional sample of an ultrafine tungsten alloy wire, characterized in that, Includes the following steps: S1. Fix a tungsten alloy wire to a substrate. The tungsten alloy wire is made of the same material as the substrate. The substrate is a column, and the tungsten alloy wire is perpendicular to the bottom surface of the substrate. The diameter of the tungsten alloy wire is 30~50μm, and the strength is 4500~6500MPa. S2. The substrate with the tungsten alloy wire fixed is hot-mounted using inlay powder, which includes epoxy resin and glass powder. After cooling, the inlay sample is obtained. S3. Abandon rough grinding and polish the bottom surface of the inlay to obtain a polished sample. The pressure during the polishing process is 50~60MPa. S4. The polished sample is etched with an etching solution to obtain a tungsten alloy wire cross-section sample. The etching solution includes hydrogen peroxide, ammonia, and sodium dodecyl sulfonate. The concentration of hydrogen peroxide is 20wt%~25wt%, the concentration of ammonia is 26wt%~30wt%, the volume ratio of hydrogen peroxide to ammonia is 2:1~4:1, and the mass fraction of sodium dodecyl sulfonate in the etching solution is 4%~8%.

2. The method for preparing a cross-section sample of the ultrafine tungsten alloy wire according to claim 1, characterized in that, In step S1, the side of the column is perpendicular to the bottom surface, and the tungsten alloy wire is fixed to the side of the substrate.

3. The method for preparing a cross-section sample of the ultrafine tungsten alloy wire according to claim 1, characterized in that, In step S2, the glass powder in the embedded powder has a mass fraction of 30% to 40% and a particle size of 50 to 100 μm.

4. The method for preparing a cross-section sample of the ultrafine tungsten alloy wire according to claim 1, characterized in that, In step S2, the temperature during the hot mounting process is 150~180℃, the pressure is 240~260MPa, and the holding time is 15~20min.

5. The method for preparing a cross-section sample of the ultrafine tungsten alloy wire according to claim 1, characterized in that, In step S3, the polishing includes: grinding the mounting sample with a 54μm grinding disc, and then polishing the mounting sample with diamond sprays of 9μm, 3μm and 1μm respectively.

6. The method for preparing a cross-section sample of the ultrafine tungsten alloy wire according to claim 5, characterized in that, The grinding wheel rotates at 600-1000 rpm, the grinding time is 2-4 minutes, and the polishing time is 50-200 seconds.

7. The method for preparing a cross-section sample of the ultrafine tungsten alloy wire according to claim 1, characterized in that, In step S4, the corrosion time is 2-4 minutes.

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