CN114689631A - Preparation method of niobium and niobium alloy transmission electron microscope sample - Google Patents
Preparation method of niobium and niobium alloy transmission electron microscope sample Download PDFInfo
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- CN114689631A CN114689631A CN202210297050.5A CN202210297050A CN114689631A CN 114689631 A CN114689631 A CN 114689631A CN 202210297050 A CN202210297050 A CN 202210297050A CN 114689631 A CN114689631 A CN 114689631A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/2202—Preparing specimens therefor
Abstract
The invention discloses a preparation method of niobium and niobium alloy transmission electron microscope samples, which comprises the following steps: 1) obtaining a metal sheet, wherein the material of the metal sheet is pure niobium or a niobium-silicon alloy material containing more than 85 at.% of niobium element; 2) removing an oxide layer on the surface of the metal sheet obtained in the step 1), and then cleaning and drying; 3) dropwise adding mixed acid on the surface of the metal sheet, clamping the metal sheet at preset intervals, and measuring the thickness of the metal sheet after cleaning until the thickness of the metal sheet is 150-100 mu m; 4) preparing a metal sheet into a wafer, and polishing the wafer to a thickness of 80-60 microns by using sand paper; 5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample.
Description
Technical Field
The invention belongs to the field of metal materials, and relates to a preparation method of a niobium and niobium alloy transmission electron microscope sample.
Background
Niobium is a metal with excellent characteristics of high melting point, low density, high chemical stability, low neutron capture cross section and the like, and has great application potential in the aspects of aerospace engine hot parts, nuclear industry and the like. But the further application of niobium is restricted by the lower strength and the high-temperature oxidation phenomenon. Most people adopt an alloying method to improve the strength of niobium, but the method greatly reduces the excellent plasticity of the niobium; for the high-temperature oxidation phenomenon, a surface coating method is adopted, but the method has high cost and complicated manufacturing process, and when the surface coating is used as a structural material in a high-temperature environment, the surface coating can crack, so that the oxygen absorption and embrittlement of niobium are caused. The focus of the current research is how to improve the oxidation resistance of niobium without losing too much of its inherent good plasticity.
The silicon element is widely distributed in the earth crust, and researches show that when trace silicon (0-1 at.%) is added into niobium, the silicon exists in the matrix in the form of substitutional solid solution atoms, the phase composition is a single phase, so that the niobium can keep excellent plasticity, and the addition of the solid solution atoms can also cause the matrix to generate lattice distortion, so that the strength can be correspondingly improved. Compared with a niobium matrix, silicon atoms have stronger affinity with oxygen, so that solid solution oxygen atoms are more easily captured by the silicon atoms in the matrix, nucleation of niobium oxide is inhibited to a certain extent, and niobium added with solid solution silicon has certain oxidation resistance.
The characterization of niobium and niobium-silicon alloy by a transmission electron microscope is an important method for researching the microscopic behaviors of the niobium and niobium-silicon alloy, and the methods for preparing the conventional niobium and niobium-silicon alloy transmission sample comprise coarse grinding, fine grinding, electrolytic double spraying, coarse grinding, fine grinding, pit-ion thinning and focused ion beam sample extraction methods, and the three methods have the defects. For the rough grinding-fine grinding-electrolysis double-spraying sample preparation method, firstly, because niobium belongs to soft metal, the shearing force generated in the rough grinding stage can cause the material to generate defects in a certain thickness of the surface, and the sources of the defects are difficult to distinguish under a transmission electron microscope, namely the defects are introduced in the rough grinding stage or original in the material; secondly, at the present stage, the electrolyte of perchloric acid, n-butanol and methanol is adopted to carry out electrolytic double spraying on niobium, and the niobium reacts with perchloric acid to generate oxides which are attached to the surface of the material to block the electrolytic process, and the obtained thin area is small in area, poor in quality and multiple in amorphous layer. For the rough grinding-fine grinding-pit-ion thinning sample preparation method, besides dislocation is easily introduced in the sample grinding process, the pit stage also has the high possibility of causing plastic deformation of the sample and introducing defects in the material. Secondly, niobium has a large atomic number and a small thermal neutron capture cross section, so that the time cost for ion thinning is very high. For the focused ion beam sampling method, due to the special lattice structure of the body-centered cubic metal, when the ion beam acts on the metal, defects are often left, which affects the characterization effect under the transmission electron microscope, and secondly, the cost of the focused ion beam is very high, and the sampling process has high technical requirements and great failure risk.
In conclusion, although the methods can be used for preparing niobium and niobium-silicon alloy transmission electron microscope samples, the methods have certain limitations and disadvantages in the aspects of time cost, economic cost, sample preparation effect and the like, and the requirements for efficient and reliable sample preparation are difficult to meet.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of niobium and niobium alloy transmission electron microscope samples, which has the characteristics of excellent time cost, economic cost and sample preparation effect.
In order to achieve the above purpose, the preparation method of the niobium and niobium alloy transmission electron microscope sample comprises the following steps:
1) obtaining a metal sheet, wherein the material of the metal sheet is pure niobium or a niobium-silicon alloy material containing more than 85 at.% of niobium element;
2) removing an oxide layer on the surface of the metal sheet obtained in the step 1), and then cleaning and drying;
3) dropwise adding mixed acid on the surface of the metal sheet, clamping the metal sheet at preset intervals, and measuring the thickness of the metal sheet after cleaning until the thickness of the metal sheet is 150-100 mu m;
4) preparing a metal sheet into a wafer, and polishing the wafer to a thickness of 80-60 microns by using sand paper;
5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample.
The specific operation of the step 1) is as follows: cutting the material into metal sheets by using a wire cut electric discharge machine, wherein the material of the metal sheets is pure niobium or niobium-silicon alloy material containing more than 85 at.% of niobium element.
The specific operation of the step 2) is as follows: polishing the oxide layer on the surface of the metal sheet obtained in the step 1) by using sand paper until the surface of the metal sheet is exposed with metallic luster and has a flat surface, then placing the metal sheet in a cleaning machine for cleaning to remove organic pollutants attached to the surface, and then drying the surface of the metal sheet.
The specific operation of the step 3) is as follows:
putting the metal sheet into a beaker, sucking the mixed acid into a dropper, dropwise adding the mixed acid onto the surface of the metal sheet, clamping the metal sheet at preset intervals in the process, and measuring the thickness of the metal sheet after washing the metal sheet by using absolute ethyl alcohol until the thickness of the metal sheet is 150-100 mu m.
The specific operation of the step 4) is as follows:
preparing the metal sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the wafers to the thickness of 100-80 mu m by using 3000# water-mill sandpaper, and polishing the wafers to the thickness of 80-60 mu m by using 5000# water-mill sandpaper, so as to ensure that the surface of the metal sheet is flat and smooth.
The thin region of the TEM sample has a thickness less than 100nm and a width of about 5 μm.
The mixed acid in the step 3) is a solution formed by mixing 49% hydrofluoric acid, 95% -98% concentrated sulfuric acid and 65% -68% nitric acid in a volume ratio of 5:2:2, and the dropping speed of the mixed acid is 10 seconds per drop.
The electrolyte in the step 5) is a concentrated sulfuric acid solution with the concentration of 95% -98% and anhydrous methanol according to the volume ratio of 12.5: 87.5 the mixed solution has the electrolytic voltage of 20-40V, the current of 10-20mA and the temperature of the electrolyte of-40 ℃ to-30 ℃.
The invention has the following beneficial effects:
according to the preparation method of the niobium and niobium alloy transmission electron microscope sample, during specific operation, the material is not polished by using coarse sand paper in the chemical thinning stage, the internal structure of the material is represented under a transmission electron microscope, the chemical thinning efficiency is high, and the defect of long time consumption of physical thinning is avoided. In addition, the niobium and niobium-silicon alloy is polished by electrolytic double spraying, the reaction rate is higher than that of the traditional perchloric acid + n-butanol + methanol electrolyte, the surface of the niobium and niobium alloy does not react to generate an oxide film to block the electrolytic double spraying process in the electrolytic double spraying process, and the method has the advantages of simple preparation process, high speed, high success rate and low cost.
Furthermore, the niobium and niobium-silicon alloy transmission electron microscope sample obtained by using the anhydrous methanol solution containing 12.5% of sulfuric acid as the electrolyte has a thin area with large area and good quality, and is convenient for characterization and observation under a transmission electron microscope.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a metallographic structure diagram of a sample according to the first embodiment;
FIG. 3 is an energy spectrum of a sample of example one;
FIG. 4 is a schematic view illustrating a chemical thinning operation according to a first embodiment;
FIG. 5 is a schematic view illustrating an electrolytic double spray operation in the first embodiment;
FIG. 6a is an optical microscope photograph of a sample prepared with a conventional dual spray electrolyte;
FIG. 6b is an optical microscope photograph of the sample obtained in the first example;
FIG. 7a is a view of a thin area under a transmission electron microscope of a sample prepared by using a conventional double-spraying electrolyte;
FIG. 7b is an amorphous image under a transmission electron microscope of a sample prepared by using a conventional double-spraying electrolyte;
FIG. 7c is a sample image of a TEM obtained in the first example.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
There is shown in the drawings a schematic block diagram of a disclosed embodiment in accordance with the invention. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.
The preparation method of the niobium and niobium alloy transmission electron microscope sample comprises the following steps:
1) cutting a material into metal sheets with moderate sizes by using a wire cut electric discharge machine, wherein the metal sheets are made of pure niobium or niobium-silicon alloy materials containing more than 85 at.% of niobium element;
2) polishing the oxide layer on the surface of the metal sheet obtained in the step 1) by using abrasive paper until the surface of the metal sheet is exposed with metallic luster and is flat, then cleaning the metal sheet in a cleaning machine to remove organic pollutants attached to the surface, and then drying the surface of the metal sheet;
3) putting the metal sheet into a beaker, sucking the mixed acid into a dropper, slowly dropping the mixed acid on the surface of the metal sheet, clamping the metal sheet every minute in the process, and measuring the thickness of the metal sheet after cleaning by using absolute ethyl alcohol until the thickness of the metal sheet is 150-100 mu m;
4) preparing a metal sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the wafers to the thickness of 100-80 mu m by using No. 3000 water-milled sand paper, and polishing the wafers to the thickness of 80-60 mu m by using No. 5000 water-milled sand paper to ensure that the surface of the metal sheet is flat and smooth;
5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample, wherein the thickness of a thin area of the transmission electron microscope sample is less than 100nm, and the width of the thin area is about 5 mu m.
The thickness of the metal sheet in the step 1) is preferably 0.8-0.5mm, and the length multiplied by the width is more than or equal to 4mm multiplied by 4 mm;
the abrasive paper in the step 2) is No. 600 abrasive paper, the cleaning solution of the metal sheet is absolute ethyl alcohol, and ultrasonic cleaning is adopted for 3 minutes.
The mixed acid in the step 3) is a solution prepared by mixing 49% hydrofluoric acid, 95% -98% concentrated sulfuric acid and 65% -68% nitric acid in a volume ratio of 5:2:2, and the dropping rate of the mixed acid is 10 seconds per drop.
The electrolyte in the step 5) is a concentrated sulfuric acid solution with the concentration of 95% -98% and anhydrous methanol according to the volume ratio of 12.5: 87.5 the mixed solution has the electrolytic voltage of 20-40V, the current of 10-20mA and the temperature of the electrolyte of-40 ℃ to-30 ℃.
Example one
The preparation method of the niobium and niobium-silicon alloy transmission electron microscope sample comprises the steps of chemically thinning by using a mixed acid solution, electrolyzing the electrolyte used by double spraying and preparing various parameters in the sample preparation process.
The preparation method of the niobium and niobium-silicon alloy transmission electron microscope sample comprises the following steps:
1) cutting the niobium metal into sheets with moderate sizes by using a wire cut electric discharge machine;
2) polishing the oxide layer on the surface of the metal niobium in the step 1) by using abrasive paper until the material has metallic luster and a flat surface, cleaning the metal niobium sheet in a cleaning machine to remove organic pollutants attached to the surface, and drying the surface of the material;
3) putting the niobium metal sheet into a beaker, sucking the mixed acid into a dropper, slowly dropping the mixed acid on the surface of the niobium metal sheet, clamping the niobium metal sheet every minute during the process, cleaning the niobium metal sheet with absolute ethyl alcohol, and measuring the thickness of the niobium metal sheet until the thickness of the sample is 150 μm and 100 μm;
4) preparing the thinned metal niobium sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the metal niobium sheet to be 100-80 mu m by using 3000# water-milled sand paper, and polishing the metal niobium sheet to be 80-60 mu m by using 5000# water-milled sand paper, wherein the surface of the metal niobium sheet is smooth and smooth;
5) and carrying out electrolytic double-spraying operation on the niobium sheet polished by the sand paper to obtain the transmission electron microscope sample.
In the step 1), the thickness of the slice is preferably 0.8-0.5mm, and the length multiplied by the width is more than or equal to 4mm multiplied by 4 mm;
in the step 2), the abrasive paper is No. 600 water abrasive paper, the cleaning solution for the metal sheet is absolute ethyl alcohol, the cleaning method is ultrasonic cleaning, and the cleaning time is 3 minutes.
The chemical corrosive in the step 3) is a solution formed by mixing 49% hydrofluoric acid, 95% -98% concentrated sulfuric acid and 65% -68% nitric acid in a volume ratio of 5:2:2, and the dropping rate of corrosive liquid is 10 seconds per drop.
In the step 5), the electrolyte is a concentrated sulfuric acid solution with the concentration of 95% -98% and anhydrous methanol according to the volume ratio of 12.5: 87.5 the mixed solution has electrolytic voltage of 20-40V, current of 10-20mA and electrolyte temperature of-40 deg.C to-30 deg.C.
Referring to fig. 2, the original sample of pure niobium metal is shown, and the metallographic structure shows that the original material has no other impurity phase, and the crystal grains are equiaxed.
Referring to fig. 3, which is a spectrum diagram of a raw sample of metallic pure niobium, the result shows that the raw material is pure niobium without other impurity elements being evident.
Referring to FIG. 4, a schematic diagram of the chemical thinning operation is shown, wherein a thin sheet of niobium metal ground by sand paper is placed in a beaker according to the method shown in the figure, and HF is dropped onto the surface of niobium metal at a constant rate2SO4:HNO3Mixed acid solution at 5:2:2 until the sample thickness was 150-.
Referring to fig. 5, a chemically thinned and ground niobium metal sheet was placed in a sample holder and connected to a positive electrode, an electrolyte solution containing 12.5% sulfuric acid and 87.5% anhydrous methanol was poured into an electrolytic cell, and liquid nitrogen was poured into the electrolyte solution to maintain the temperature of the electrolyte solution between-40 ℃ and-30 ℃.
Referring to fig. 6a and 6b, which are optical micrographs of a conventional perchloric acid-containing electrolyte and the process after electrolytic double spraying, respectively, it can be found that the transmission electron microscope sample prepared by the process does not have an oxide film on the surface to hinder the electrolytic double spraying, and has a better polishing effect.
Referring to fig. 7a to 7c, compared with the conventional method for preparing samples of niobium and niobium-silicon alloy for transmission electron microscopy, the thin region of the metal pure niobium obtained by the above-mentioned preparation process is large in area and good in quality under the transmission electron microscopy, and a large amorphous layer is not formed.
It should be noted that the ratio of the acid solutions in the present invention is a volume ratio, and the concentrations of the original acid solutions are 49% of hydrofluoric acid, 95% -98% of sulfuric acid, and 65% -68% of nitric acid, respectively. In the electrolysis double-spraying step, the correct electrolysis voltage may be slightly different due to different models and specifications of the double-spraying instruments, and the electrolysis voltage should be adjusted correspondingly.
Example two
The preparation method of the niobium and niobium alloy transmission electron microscope sample comprises the following steps:
1) cutting a material into metal sheets with moderate sizes by using a wire cut electric discharge machine, wherein the metal sheets are made of pure niobium or niobium-silicon alloy materials containing more than 85 at.% of niobium element;
2) polishing the oxide layer on the surface of the metal sheet obtained in the step 1) by using abrasive paper until the surface of the metal sheet is exposed with metallic luster and has a flat surface, then placing the metal sheet in a cleaning machine for cleaning to remove organic pollutants attached to the surface, and then drying the surface of the metal sheet;
3) putting the metal sheet into a beaker, sucking the mixed acid into a dropper, slowly dropping the mixed acid on the surface of the metal sheet, clamping the metal sheet every minute in the process, and measuring the thickness of the metal sheet after washing the metal sheet by using absolute ethyl alcohol until the thickness of the metal sheet is 150 mu m;
4) preparing a metal sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the wafers to the thickness of 100 mu m by using 3000# water-mill abrasive paper, and polishing the wafers to the thickness of 80 mu m by using 5000# water-mill abrasive paper to ensure that the surface of the metal sheet is flat and smooth;
5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample, wherein the thickness of a thin area of the transmission electron microscope sample is less than 100nm, and the width of the thin area is about 5 mu m.
The thickness of the metal sheet in the step 1) is preferably 0.8mm, and the length × width is 4mm × 4 mm;
the abrasive paper in the step 2) is No. 600 abrasive paper, the cleaning solution of the metal sheet is absolute ethyl alcohol, and ultrasonic cleaning is adopted for 3 minutes.
The mixed acid in the step 3) is a solution prepared by mixing 49% hydrofluoric acid, 95% concentrated sulfuric acid and 65% nitric acid in a volume ratio of 5:2:2, and the dropping rate of the mixed acid is 10 seconds per drop.
The electrolyte in the step 5) is concentrated sulfuric acid solution with the concentration of 95% and anhydrous methanol according to the volume ratio of 12.5: 87.5 the mixed solution, the voltage of electrolysis was 20V, the current was 10mA, and the temperature of the electrolyte was-40 ℃.
EXAMPLE III
The preparation method of the niobium and niobium alloy transmission electron microscope sample comprises the following steps:
1) cutting a material into metal sheets with moderate sizes by using a wire cut electric discharge machine, wherein the metal sheets are made of pure niobium or niobium-silicon alloy materials containing more than 85 at.% of niobium element;
2) polishing the oxide layer on the surface of the metal sheet obtained in the step 1) by using abrasive paper until the surface of the metal sheet is exposed with metallic luster and has a flat surface, then placing the metal sheet in a cleaning machine for cleaning to remove organic pollutants attached to the surface, and then drying the surface of the metal sheet;
3) putting the metal sheet into a beaker, sucking the mixed acid into a dropper, slowly dropping the mixed acid on the surface of the metal sheet, clamping the metal sheet every minute in the process, and measuring the thickness of the metal sheet after washing the metal sheet by using absolute ethyl alcohol until the thickness of the metal sheet is 100 mu m;
4) preparing a metal sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the wafers to the thickness of 80 microns by using 3000# water-mill abrasive paper, and polishing the wafers to the thickness of 60 microns by using 5000# water-mill abrasive paper to ensure that the surface of the metal sheet is flat and smooth;
5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample, wherein the thickness of a thin area of the transmission electron microscope sample is less than 100nm, and the width of the thin area is about 5 mu m.
The thickness of the metal sheet in the step 1) is preferably 0.5mm, and the length × width is 5mm × 5 mm;
the abrasive paper in the step 2) is No. 600 abrasive paper, the cleaning solution of the metal sheet is absolute ethyl alcohol, and ultrasonic cleaning is adopted for 3 minutes.
The mixed acid in the step 3) is a solution in which 49% hydrofluoric acid, 98% concentrated sulfuric acid and 68% nitric acid are mixed in a volume ratio of 5:2:2, and the dropping rate of the mixed acid is 10 seconds per drop.
The electrolyte in the step 5) is a concentrated sulfuric acid solution with the concentration of 98 percent, and the volume ratio of the concentrated sulfuric acid solution to the anhydrous methanol is 12.5: 87.5 the mixed solution, the voltage of electrolysis was 40V, the current was 20mA, and the temperature of the electrolyte was-30 ℃.
Example four
The preparation method of the niobium and niobium alloy transmission electron microscope sample comprises the following steps:
1) cutting a material into metal sheets with moderate sizes by using a wire cut electric discharge machine, wherein the metal sheets are made of pure niobium or niobium-silicon alloy materials containing more than 85 at.% of niobium element;
2) polishing the oxide layer on the surface of the metal sheet obtained in the step 1) by using abrasive paper until the surface of the metal sheet is exposed with metallic luster and has a flat surface, then placing the metal sheet in a cleaning machine for cleaning to remove organic pollutants attached to the surface, and then drying the surface of the metal sheet;
3) putting the metal sheet into a beaker, sucking the mixed acid into a dropper, slowly dropping the mixed acid on the surface of the metal sheet, clamping the metal sheet every minute in the process, and measuring the thickness of the metal sheet after washing the metal sheet by using absolute ethyl alcohol until the thickness of the metal sheet is 120 mu m;
4) preparing a metal sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the wafers to the thickness of 90 mu m by using 3000# water-mill abrasive paper, and polishing the wafers to the thickness of 70 mu m by using 5000# water-mill abrasive paper to ensure that the surface of the metal sheet is flat and smooth;
5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample, wherein the thickness of a thin area of the transmission electron microscope sample is less than 100nm, and the width of the thin area is about 5 mu m.
The thickness of the metal sheet in the step 1) is preferably 0.6mm, and the length × width is 6mm × 6 mm;
the abrasive paper in the step 2) is No. 600 abrasive paper, the cleaning solution of the metal sheet is absolute ethyl alcohol, and ultrasonic cleaning is adopted for 3 minutes.
The mixed acid in the step 3) is a solution in which 49% hydrofluoric acid, 97% concentrated sulfuric acid and 67% nitric acid are mixed in a volume ratio of 5:2:2, and the dropping rate of the mixed acid is 10 seconds per drop.
The electrolyte in the step 5) is a concentrated sulfuric acid solution with the concentration of 97 percent, and the volume ratio of the concentrated sulfuric acid solution to the anhydrous methanol is 12.5: 87.5 the mixed solution, the voltage of electrolysis was 30V, the current was 15mA, and the temperature of the electrolyte was-35 ℃.
In addition, other modifications within the spirit of the invention may occur to those skilled in the art, and such modifications within the spirit of the invention are intended to be included within the scope of the invention as claimed.
Claims (8)
1. A preparation method of niobium and niobium alloy transmission electron microscope samples is characterized by comprising the following steps:
1) obtaining a metal sheet, wherein the material of the metal sheet is pure niobium or a niobium-silicon alloy material containing more than 85 at.% of niobium element;
2) removing an oxide layer on the surface of the metal sheet obtained in the step 1), and then cleaning and drying;
3) dropwise adding mixed acid on the surface of the metal sheet, clamping the metal sheet at preset intervals, and measuring the thickness of the metal sheet after cleaning until the thickness of the metal sheet is 150-100 mu m;
4) preparing a metal sheet into a wafer, and polishing the wafer to a thickness of 80-60 microns by using sand paper;
5) and carrying out electrolytic double-spraying operation on the wafer polished by the sand paper to obtain the transmission electron microscope sample.
2. The method for preparing niobium and niobium alloy transmission electron microscope samples according to claim 1, wherein the step 1) comprises the following specific operations: cutting the material into metal sheets by using a wire cut electric discharge machine, wherein the material of the metal sheets is pure niobium or niobium-silicon alloy material containing more than 85 at.% of niobium element.
3. The method for preparing niobium and niobium alloy transmission electron microscope samples according to claim 1, wherein the step 2) comprises the following specific operations: polishing the oxide layer on the surface of the metal sheet obtained in the step 1) by using sand paper until the surface of the metal sheet is exposed with metallic luster and has a flat surface, then placing the metal sheet in a cleaning machine for cleaning to remove organic pollutants attached to the surface, and then drying the surface of the metal sheet.
4. The method for preparing niobium and niobium alloy transmission electron microscope samples according to claim 1, wherein the specific operation of step 3) is:
putting the metal sheet into a beaker, sucking the mixed acid into a dropper, dropwise adding the mixed acid onto the surface of the metal sheet, clamping the metal sheet at preset intervals in the process, and measuring the thickness of the metal sheet after washing the metal sheet by using absolute ethyl alcohol until the thickness of the metal sheet is 150-100 mu m.
5. The method for preparing niobium and niobium alloy transmission electron microscope samples according to claim 1, wherein the step 4) comprises the following specific operations:
preparing the metal sheet into a plurality of wafers with the diameter of 3mm by using a sample punching device, polishing the wafers to the thickness of 100-80 mu m by using 3000# water-mill sandpaper, and polishing the wafers to the thickness of 80-60 mu m by using 5000# water-mill sandpaper, so as to ensure that the surface of the metal sheet is flat and smooth.
6. The method of claim 1, wherein the TEM sample has a thin area thickness of less than 100nm and a thin area width of about 5 μm.
7. The method for preparing samples of niobium and niobium alloys by transmission electron microscopy according to claim 1, wherein the mixed acid in step 3) is a solution of 49% hydrofluoric acid, 95% -98% concentrated sulfuric acid and 65% -68% nitric acid mixed in a volume ratio of 5:2:2, and the dropping rate of the mixed acid is 10 seconds per drop.
8. The method for preparing niobium and niobium alloy transmission electron microscope samples according to claim 1, wherein the electrolyte in the step 5) is a concentrated sulfuric acid solution with a concentration of 95-98% and anhydrous methanol in a volume ratio of 12.5: 87.5 the mixed solution has the electrolytic voltage of 20-40V, the current of 10-20mA and the temperature of the electrolyte of-40 ℃ to-30 ℃.
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