A metallographic preparation method for nanometer / submicron powder particle section

Abstract

The application provides a metallographic preparation method for nanometer / submicron powder particle sections and belongs to the technical field of superfine powder. The preparation method comprises the following steps: S1, preparing carbon-containing conductive inlay powder into submicron conductive inlay powder; S2, preparing conductive dispersion mixed glue by mixing electron microscope conductive silver glue, acetone and ethanol according to a certain proportion; S3, uniformly mixing submicron powder to be measured and the submicron conductive inlay powder according to a certain proportion, then adding the conductive dispersion mixed glue to sufficiently wet the submicron powder to be measured and the submicron conductive inlay powder, sufficiently stirring or kneading to obtain a mud-like mixture, and then using an inlay machine to prepare the mud-like mixture after vacuum drying into a submicron powder to be measured inlay sample; and S4, performing grinding and polishing treatment on the submicron powder to be measured inlay sample, then cleaning and drying the submicron powder to be measured inlay sample after polishing treatment to obtain a metallographic sample.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultrafine powder, and particularly relates to a metallographic preparation method for a nanometer / submicron powder particle section. BACKGROUND

[0002] Submicron is a new concept in the material industry, and is generally used to describe powder and belongs to the technical field of ultrafine powder. The detection and analysis of characterization is the combination of modern technologies such as microelectronics and scanning microscopy and computer technology, and is usually used to study the structure, properties and application of materials in the range of 100 nm-1000 nm. The preparation and detection of the submicron ultrafine powder section have the same technical features and difficulty as the detection and characterization in the nanometer scale. The observation of the submicron powder section characterization is usually carried out under magnification of tens of thousands to hundreds of thousands, and the submicron powder needs to be cut into two halves to expose the internal section to be observed. This requires extremely high processing and preparation technology, and requires high-precision professional equipment such as ion thinning and focused ion beam cutting (FIB) to achieve the cutting.

[0003] The key difficulty in the preparation of the nanometer / submicron powder section using conventional metallography is that:

[0004] First, the dispersion and fixation of the nanometer / submicron powder. The section of the nanometer / submicron powder needs to be processed, so the premise is that the sample preparation should have good dispersion and firm fixation of the submicron powder. Since the nanometer / submicron powder has a very small size, usually in the range of 100 nm-1000 nm, it has a small size effect and is easy to agglomerate. The particle size of the conventional conductive inlay powder (usually in the range of 40 microns-2 mm) and the inlay method is too different from that of the submicron powder, the inlay powder cannot play a dispersion role, the submicron powder is easy to agglomerate, the bonding force between the powders is poor, the fixation is not firm, the submicron powder is very easy to fall off, and the preparation and processing cannot be carried out. The use of conventional colloid / gum tape including conductive glue and conductive gum tape to bond the submicron powder has too large viscosity, the submicron powder cannot be dispersed, and the gumming belongs to elastic fixation with a large elastic deformation range, so the preparation and processing cannot be carried out. Both methods cannot meet the basic requirements of the sample preparation and processing of the submicron powder.

[0005] Second, the overall conductivity of the sample: after solving the dispersion and fixation of the nanometer / submicron powder sample, it is also necessary to ensure that the submicron powder sample has good conductivity, so as to meet the observation requirements of electron diffraction and scanning electron microscopy. The conventional conductive inlay material cannot disperse and fix the submicron powder; the conventional gold plating and carbon plating method can increase the conductivity, but the thickness of the formed plating film is about 10 nanometers, which is similar to the size level of the details of the submicron powder morphology, and is easy to cover the details of the submicron powder section characterization, so it is not suitable for the preparation of the submicron powder.

[0006] Third: Sub-micron processing preparation: after the preparation of the nano / sub-micron powder sample, the nano / sub-micron level processing is also solved. The conventional cutting and polishing method, the nano / sub-micron powder is easy to fall off and easy to remove excess, and the removal amount is even greater than the size of the nano / sub-micron powder, which cannot realize the "cutting" of the sub-micron powder and is not suitable for preparing the sub-micron powder sample. SUMMARY

[0007] To solve the above technical problems, the present application provides a metallographic preparation method for the cross section of nano / sub-micron powder particles. The porous framework formed by the sub-micron conductive inlay powder has good size matching with the sub-micron powder, and can well disperse and accommodate the sub-micron powder. Meanwhile, the present application provides a preparation method of a conductive dispersion mixed glue with strong adhesion, which has the ability to disperse sub-micron powder, adhere sub-micron powder and inlay powder framework, and conduct as a whole. A sub-micron level grinding and polishing process is provided, which has a removal amount in the sub-micron level, and realizes the preparation of the internal cross section of the sub-micron powder. Finally, a preparation method for the cross section of nano / sub-micron powder particles using conventional metallographic equipment and common materials is obtained.

[0008] The present application discloses a metallographic preparation method for the cross section of nano / sub-micron powder particles. The preparation method comprises:

[0009] Step S1, preparing carbon-containing conductive inlay powder into sub-micron conductive inlay powder;

[0010] Step S2, mixing electron microscope conductive silver glue, acetone and ethanol according to a certain proportion to prepare conductive dispersion mixed glue;

[0011] Step S3, uniformly mixing the to-be-tested sub-micron powder and the sub-micron conductive inlay powder prepared in step S1 according to a certain proportion, then adding the conductive dispersion mixed glue prepared in step S2 to fully wet the to-be-tested sub-micron powder and the sub-micron conductive inlay powder, fully stirring or kneading to obtain a mud-like mixture, and then using an inlay machine to prepare the mud-like mixture after vacuum drying into a to-be-tested sub-micron powder inlay sample;

[0012] Step S4, grinding and polishing the to-be-tested sub-micron powder inlay sample, then cleaning and drying the to-be-tested sub-micron powder inlay sample after polishing to obtain a metallographic sample.

[0013] According to the preparation method of the present application, the step S1 specifically comprises the following sub-steps:

[0014] Step S11, weighing 10-20g of the carbon-containing conductive inlay powder and placing it in an agate mortar for 20-30min of grinding to obtain uniform and delicate conductive inlay powder;

[0015] Step S12, the uniform fine conductive inlay powder is evenly scattered on the adhesive tape, whether the size of the conductive inlay powder is 0.6-5 μm is judged by means of a microscope, if yes, the uniform fine conductive inlay powder is used as the sub-micron conductive inlay powder; if no, the step S11 is returned to continue grinding.

[0016] According to the preparation method of the application, the step S2 specifically comprises the following sub-steps:

[0017] Step S21, 2 g of conductive silver glue for electron microscopy is weighed and placed in a first beaker; 10 ml of acetone is continuously added to the conductive silver glue for electron microscopy, and stirring is performed to uniformly dissolve the conductive silver glue for electron microscopy to obtain a first mixture;

[0018] Step S22, 20 ml of ethanol is measured and added to the first mixture, and stirring is uniformly performed to obtain a second mixture;

[0019] Step S23, after the second mixture is left to stand for 5-10 min, the first beaker is slowly tilted, the upper liquid is poured into a second beaker, and room temperature drying is performed until the liquid volume is reduced to half, to obtain the conductive dispersion mixed glue.

[0020] According to the preparation method of the application, the step S3 specifically comprises the following sub-steps:

[0021] Step S31, a certain amount of the sub-micron conductive inlay powder and a to-be-tested sub-micron powder are weighed and placed in a third beaker and stirred uniformly to obtain a third mixture; wherein the volume ratio of the to-be-tested sub-micron powder to the sub-micron conductive inlay powder is 1:5-1:3;

[0022] Step S32, a certain volume of the conductive dispersion mixed glue is measured and added to the third mixture to sufficiently wet the third mixture to obtain a fourth mixture; after the fourth mixture is sufficiently stirred or kneaded, a mud-like mixture is obtained;

[0023] Step S33, the mud-like mixture after vacuum drying is placed in an inlay machine to fill the carbon-containing conductive inlay powder, and conventional inlay processing is performed to obtain the to-be-tested sub-micron powder inlay sample.

[0024] According to the preparation method of the application, the volume ratio of the conductive dispersion mixed glue to the third mixture is 0.2-0.6.

[0025] According to the preparation method of the application, in the step S4, the grinding treatment specifically comprises the following sub-steps:

[0026] Step S411, M of the to-be-tested sub-micron powder mosaic samples are fixed on the polishing fixture, and then 400# silicon carbide sandpaper is used to grind the samples for 40-60s under a certain pressure, and then it is determined whether the to-be-tested sub-micron powder mosaic samples are ground flat, if not, the grinding is continued, if yes, step S412 is entered;

[0027] Step S412, the to-be-tested sub-micron powder mosaic samples and the polishing fixture are cleaned by tap water after the grinding by 400# silicon carbide sandpaper, and then 800# silicon carbide sandpaper is used to grind the samples for 40-60s under the same pressure, and then the to-be-tested sub-micron powder mosaic samples and the polishing fixture are cleaned again; 1000# silicon carbide sandpaper is used to grind the samples for 40-60s under the same pressure, and then the to-be-tested sub-micron powder mosaic samples and the polishing fixture are cleaned again.

[0028] In the grinding process, the pressure P1=M*10N, M is the number of the to-be-tested sub-micron powder mosaic samples ground at the same time, and N is the unit of pressure, Newton.

[0029] According to the preparation method, in step S4, the polishing process specifically includes the following sub-steps:

[0030] Step S421, the to-be-tested sub-micron powder mosaic samples after the grinding process are polished by 9μm diamond grinding liquid to obtain a first sample, the pressure of the first polishing process is P2=M*10N, the time of the first polishing process is 240-300s, M is the number of the to-be-tested sub-micron powder mosaic samples ground at the same time, and N is the unit of pressure, Newton.

[0031] Step S422, the first sample is polished by 3μm diamond grinding liquid to obtain a second sample, the pressure of the second polishing process is P3=M*10N+10N, the time of the second polishing process is 360-450s, M is the number of the to-be-tested sub-micron powder mosaic samples ground at the same time, and N is the unit of pressure, Newton.

[0032] Step S423, the second sample is polished by 1μm silicon oxide polishing liquid to obtain a third sample, the pressure of the third polishing process is P3=M*10N, the time of the third polishing process is 300-360s, M is the number of the to-be-tested sub-micron powder mosaic samples ground at the same time, and N is the unit of pressure, Newton.

[0033] According to the preparation method of the application, in the step S4, the third sample is first washed with pure water, then washed with ethanol again, and then dried by a hair dryer to obtain the metallographic sample.

[0034] In summary, the scheme provided by the application has the following technical effects:

[0035] In the application, the sub-micron conductive inlay powder is doped and mixed with the nano / sub-micron powder, the conductive dispersion mixed glue formed by the conductive silver glue, the acetone and the ethanol is mixed to form a surface modification dispersion for the sub-micron powder, the porous skeleton of the ordinary conductive inlay powder (i.e. the carbon-containing conductive inlay powder) is fixed and inlaid with the nano / sub-micron powder, and the conductive dispersion mixed glue is glued and fixed with the sub-micron powder.

[0036] In addition, the prepared nano / sub-micron powder inlay sample realizes good dispersion and firm fixation of the nano / sub-micron powder, and has the prerequisite for processing; the carbon particles in the sub-micron conductive inlay powder and the conductive particles in the conductive dispersion mixed glue constitute the conductive channel of the nano / sub-micron powder inlay sample, and meet the conditions for scanning electron microscope detection.

[0037] In addition, the application further realizes nano / sub-micron level processing of the nano / sub-micron powder inlay sample by using smaller pressure and fine grinding and polishing, and realizes "shearing" of the nano / sub-micron scale of the nano / sub-micron powder particles to obtain the internal cross section of the nano / sub-micron powder. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0039] Figure 1 is the scanning electron microscope picture of the metallographic sample in Example 1 of the application;

[0040] Figure 2 is the scanning electron microscope picture of the metallographic sample in Example 2 of the application. DETAILED DESCRIPTION

[0041] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. 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 protection scope of the present application.

[0042] The present application discloses a metallographic preparation method of nano / submicron powder particle section. The preparation method comprises:

[0043] In step S1, the carbon-containing conductive inlay powder is prepared into submicron conductive inlay powder.

[0044] In step S2, the conductive dispersion mixed glue is prepared by mixing the conductive silver glue for electron microscope, acetone and ethanol according to a certain proportion.

[0045] In step S3, the to-be-tested submicron powder and the submicron conductive inlay powder in step S1 are mixed uniformly according to a certain proportion, and then the conductive dispersion mixed glue in step S2 is added to fully wet the to-be-tested submicron powder and the submicron conductive inlay powder. After sufficient stirring or kneading, a mud-like mixture is obtained. Then, the mud-like mixture after vacuum drying is prepared into a to-be-tested submicron powder inlay sample by using an inlay machine.

[0046] In step S4, the to-be-tested submicron powder inlay sample is subjected to grinding and polishing treatment. Then, the to-be-tested submicron powder inlay sample after polishing treatment is cleaned and dried to obtain a metallographic sample.

[0047] In step S1, the carbon-containing conductive inlay powder is prepared into submicron conductive inlay powder.

[0048] In some embodiments, step S1 specifically comprises the following substeps:

[0049] In step S11, 10-20 g of the carbon-containing conductive inlay powder is weighed and placed in an agate mortar for grinding for 20-30 min to obtain uniform and fine conductive inlay powder.

[0050] In step S12, the uniform and fine conductive inlay powder is uniformly scattered on adhesive tape. Whether the size of the conductive inlay powder is 0.6-5 μm is judged by means of a microscope. If yes, the uniform and fine conductive inlay powder is used as the submicron conductive inlay powder. If no, the grinding in step S11 is continued.

[0051] Specifically, the purpose of controlling the size of the conductive inlay powder to be 0.6-5 μm is to ensure that the size of the conductive inlay powder is close to that of the to-be-tested submicron powder, so as to play a good mixing and dispersion role.

[0052] In step S2, the electrically conductive silver glue, acetone and ethanol are mixed in a certain proportion to prepare the conductive dispersion mixed glue.

[0053] In some embodiments, the step S2 specifically comprises the following sub-steps:

[0054] In step S21, 2g of the electrically conductive silver glue is weighed and placed in a first beaker; 10ml of acetone is added into the electrically conductive silver glue, and stirring is performed to dissolve the electrically conductive silver glue uniformly to obtain a first mixture;

[0055] In the present application, the adhesive aid in the conductive silver glue is dissolved in acetone, which can reduce the viscosity of the mixed solution, and make the conductive silver glue dissolve more uniformly. The ratio and the adding sequence in this step can quickly dissolve the conductive silver glue, obtain appropriate viscosity, and shorten the drying and baking time.

[0056] In step S22, 20ml of ethanol is measured and added into the first mixture to continue to dilute the mixed solution of the conductive silver glue and acetone, and stirring is performed uniformly to obtain a second mixture;

[0057] In the present application, the use of ethanol is to further dilute the first mixture, make the conductive silver glue further uniform, and reduce the viscosity of the mixed solution to a suitable level for preparing the inlaying powder mud; and the second mixture can be quickly volatilized during drying or baking, and the drying or baking time is shortened.

[0058] The ratio and the adding sequence of the conductive silver glue, acetone and ethanol in the present application can quickly dissolve the conductive silver glue, obtain appropriate viscosity, and shorten the drying or baking time.

[0059] In step S23, the second mixture is left to stand for 5-10min, then the first beaker is slowly tilted, the upper liquid is poured into a second beaker, and the liquid is dried at room temperature until the volume is reduced to half to obtain the conductive dispersion mixed glue.

[0060] The conductive dispersion mixed glue prepared by the method of the present application has conductive particles, dispersants and adhesive aids, wherein the conductive particles can construct a conductor channel and strengthen the conductivity of the inlaying powder and the sample powder; the dispersants can reduce the agglomeration tendency of the powder, facilitate the dispersion of the powder and the uniform mixing with the inlaying powder; and the adhesive aids can enhance the adhesion between the powder and the inlaying powder, and the powder is not easy to fall off during preparation.

[0061] In step S3, the to-be-tested submicron powder and the submicron conductive inlaying powder in step S1 are mixed uniformly in a certain proportion, then the conductive dispersion mixed glue in step S2 is added to fully wet the to-be-tested submicron powder and the submicron conductive inlaying powder, and stirring or kneading is performed to obtain a mud-like mixture, and then the mud-like mixture after vacuum drying is prepared into a to-be-tested submicron powder inlaying sample by using an inlaying machine.

[0062] In some embodiments, the step S3 specifically comprises the following sub-steps:

[0063] Step S31, a certain amount of the sub-micron conductive damascene powder and the to-be-tested sub-micron powder are taken and stirred uniformly in a third beaker to obtain a third mixture; wherein the volume ratio of the to-be-tested sub-micron powder and the sub-micron conductive damascene powder is 1:5-1:3.

[0064] The sub-micron conductive damascene powder can effectively disperse the to-be-tested sub-micron powder and make them uniformly mixed. However, too large proportion of the to-be-tested sub-micron powder will still cause self-agglomeration, and too large proportion of the sub-micron conductive damascene powder is not conducive to later observation, so the volume ratio of the to-be-tested sub-micron powder and the sub-micron conductive damascene powder is controlled to be 1:5-1:3.

[0065] In the present application, the sub-micron conductive damascene powder and the to-be-tested sub-micron powder with similar sizes are mixed with each other, which can play a good dispersion effect on the to-be-tested sub-micron powder.

[0066] Step S32, a certain volume of the conductive dispersion mixed glue is added into the third mixture to sufficiently wet the third mixture to obtain a fourth mixture; and the fourth mixture is sufficiently stirred or kneaded to obtain a mud-like mixture.

[0067] Specifically, the mud-like mixture is in the shape of block or cylinder.

[0068] In the present application, the addition of the conductive dispersion mixed glue into the third mixture composed of the sub-micron conductive damascene powder and the to-be-tested sub-micron powder can strengthen the electrical conductivity of the metallographic sample, strengthen the bonding ability, and further maintain the uniform dispersion of the nano / sub-micron powder.

[0069] Step S33, the mud-like mixture after vacuum drying is placed in a damascene machine to fill the carbon-containing conductive damascene powder, and conventional damascene processing is performed to obtain the to-be-tested sub-micron powder damascene sample.

[0070] Specifically, the carbon-containing conductive damascene powder contains three sizes of 1 μm, 10 μm and 50-100 μm. After the mud-like mixture and the carbon-containing conductive damascene powder are subjected to conventional damascene processing, a porous skeleton intercalation structure of three size powders of superfine powder, fine powder and coarse powder can be formed, the to-be-tested sub-micron powder is embedded in the porous skeleton, and is firmly bonded, so that the stability of the metallographic sample is stronger.

[0071] In some embodiments, the volume ratio of the conductive dispersion mixed glue and the third mixture is 0.2-0.6, so as to ensure that the mud-like mixture formed has appropriate dry and wet degree, is easy to shape and easy to dry.

[0072] In step S4, the to-be-tested sub-micron powder mosaic is subjected to grinding and polishing treatment, and then the to-be-tested sub-micron powder mosaic after polishing treatment is cleaned and dried to obtain a metallographic sample.

[0073] In some embodiments, the grinding treatment specifically includes the following sub-steps:

[0074] In step S411, the M to-be-tested sub-micron powder mosaics are uniformly fixed on a grinding and polishing fixture, and then 400# silicon carbide sandpaper is used to grind for 40-60s at a certain pressure, and whether the to-be-tested sub-micron powder mosaic is ground to be flat is determined. If not, the grinding with 400# silicon carbide sandpaper is continued. If yes, step S412 is entered.

[0075] Specifically, the specific operation of determining whether the to-be-tested sub-micron powder mosaic is ground to be flat is that whether the to-be-tested sub-micron powder mosaic is partially removed is visually observed. When the surface of the to-be-tested sub-micron powder mosaic presents a star point shape, the removal amount is tens of microns at this time, and step S412 can be entered.

[0076] In step S412, the to-be-tested sub-micron powder mosaic and the grinding and polishing fixture after grinding with 400# silicon carbide sandpaper are cleaned with tap water, and then 800# silicon carbide sandpaper is replaced to continue grinding the to-be-tested sub-micron powder mosaic for 40-60s at the same pressure, and then the to-be-tested sub-micron powder mosaic and the grinding and polishing fixture are cleaned again. After the to-be-tested sub-micron powder mosaic is ground again with 1000# silicon carbide sandpaper at the same pressure for 40-60s, the to-be-tested sub-micron powder mosaic and the grinding and polishing fixture are cleaned again and standby.

[0077] Wherein, the pressure P1 during the grinding treatment is M*10N; M is the number of to-be-tested sub-micron powder mosaics ground at the same time, and N is the unit of pressure, Newton.

[0078] Specifically, after the to-be-tested sub-micron powder mosaic is ground with 800# silicon carbide sandpaper, the removal amount is ten microns; after the to-be-tested sub-micron powder mosaic is ground with 1000# silicon carbide sandpaper, the removal amount is further reduced to the order of microns.

[0079] It should be noted that the selection of the type of sandpaper, pressure and time during the grinding treatment is based on the balance between the removal amount and the grinding efficiency. Generally, the coarser the sandpaper, the less the grinding time or pressure needs to be reduced to prevent the removal amount from being too large and causing excessive grinding of the sample powder. In the present application, the removal amounts of 400#, 800# and 1000# silicon carbide sandpaper form a difference under the same pressure and time, which is beneficial to the fine control of the removal amount of grinding preparation.

[0080] In some embodiments, the polishing treatment specifically includes the following sub-steps:

[0081] Step S421, using 9 μm diamond grinding fluid to the polished after the processing of the test sub-micron powder mosaic first polishing treatment to get the first sample, the first polishing treatment pressure P2 = M * 10N; the first polishing treatment time is 240-300s; wherein, M is the number of the same grinding test sub-micron powder mosaic, N is the pressure unit Newton. The test sub-micron powder mosaic after the first polishing treatment, can ensure that the removal of uniform micron level.

[0082] Step S422, using 3 μm diamond grinding fluid to the first sample for the second polishing treatment to get the second sample, the second polishing treatment pressure P3 = M * 10N + 10N; the second polishing treatment time is 360-450s; wherein, M is the number of the same grinding test sub-micron powder mosaic, N is the pressure unit Newton. The test sub-micron powder mosaic after the second polishing treatment, can ensure that the removal of uniform micron level below.

[0083] Step S423, using 1 μm silicon oxide polishing fluid to the second sample for the third polishing treatment to get the third sample, the third polishing treatment pressure P3 = M * 10N; the third polishing treatment time is 300-360s; wherein, M is the number of the same grinding test sub-micron powder mosaic, N is the pressure unit Newton. The test sub-micron powder mosaic after the third polishing treatment, can ensure that the removal of uniform nanometer / sub-micron level.

[0084] The polishing fluid particle size and time, pressure in the process of grinding are based on the balance of polishing efficiency and removal. 9 μm, 3 μm, 1 μm polishing fluid under the same pressure, time its removal difference, is beneficial to the preparation process of grinding removal fine control. Generally, the use of other size of polishing fluid, need to abide by the principle of size greater, pressure or time is smaller, to avoid removal and mechanical damage too large.

[0085] In the present application, each type of sandpaper grinding and polishing treatment of polishing fluid or polishing fluid, and time, pressure are based on the balance of polishing efficiency and removal. Each next pass is to remove the mechanical damage layer caused by the last pass, and remove some more; the removal of each next pass is different from the last pass, and the removal decreases significantly with the increase of the pass; each pass can fine-tune the pressure, time, to realize the fine degree of removal control is improved with the pass, finally reaches nanometer / sub-micron level of removal.

[0086] In some embodiments, in step S4, after rinsing the third sample with pure water for the first time, the third sample is rinsed with ethanol for the second time, and then the third sample is dried with a hair dryer to obtain the metallographic sample.

[0087] Example 1: Preparation of 600-1000 nm silver powder cross-section

[0088] (1) Weigh 10g of ordinary carbon conductive inlay powder and put it into an agate mortar. Grind it finely for 22 minutes until it is uniform and fine with a size of about 0.6-2μm. This will give you submicron conductive inlay powder. Set aside for later use.

[0089] (2) Weigh 2g of conductive silver paste for electron microscopy and put it into a 50ml beaker; add 10ml of acetone and stir with a spatula to dissolve it evenly to obtain the first mixture; continue to add 20ml of ethanol and continue to stir evenly to obtain the second mixture; let the second mixture stand for 10min to allow it to precipitate naturally, then pour the upper mixed liquid into a clean new beaker and dry it at room temperature until half of the volume remains, thus obtaining the conductive dispersion mixture; cover and set aside for later use.

[0090] (3) Weigh 4g of submicron conductive embedded powder and put it into a new beaker; separately weigh about 1 / 3 of the volume of the submicron conductive embedded powder and silver powder with a size of 600-1000nm, add it to the beaker and stir to mix the submicron conductive embedded powder and silver powder evenly to obtain a third mixture; measure 4ml of conductive dispersion mixture and add it to the third mixture to fully wet the third mixture to obtain a fourth mixture; continue to stir or knead the fourth mixture evenly to obtain a blocky mud-like mixture;

[0091] (4) After vacuum drying the blocky mud-like mixture at 100°C for 40 min, it is placed into a mounting machine, filled with ordinary carbon-containing conductive mounting powder, and subjected to conventional mounting treatment to obtain the submicron powder mounting sample to be tested.

[0092] (5) Take four prepared submicron powder mosaic samples to be tested, fix them evenly at intervals on the polishing fixture, and grind the four submicron powder mosaic samples to be tested for 40 seconds using 400#, 800# and 1000# silicon carbide sandpaper in sequence under a pressure of 40N. After each grinding, clean the submicron powder mosaic samples to be tested and the polishing fixture with tap water.

[0093] (6) According to the pressure and time in Table 1, the submicron powder mosaic sample to be tested after grinding was polished in sequence with 9μm and 3μm diamond polishing fluid and 1μm silicon oxide polishing fluid.

[0094] Table 1

[0095]

[0096] (7) The polished sample is taken out, first rinsed with pure water, then with ethanol, and then dried with a hair dryer to obtain the metallographic sample.

[0097] (8) The metallographic sample is observed using a scanning electron microscope, and as shown in FIG. 8, the image of the cross section and details of the silver powder at 80,000 times is clear. Figure 1

[0098] Example 2: Preparation of the cross section of 800-1000 nm beryllium aluminum powder

[0099] (1) 10 g of ordinary carbon-containing conductive inlay powder is weighed into an agate mortar and ground carefully for 20 min. The carbon-containing conductive inlay powder is ground to be uniform and fine, with a size of about 0.6-2 μm, to obtain sub-micron conductive inlay powder. It is placed for later use.

[0100] (2) 2 g of conductive silver glue for electron microscopy is weighed into a 50 ml beaker; 10 ml of acetone is added, and a medicine spoon is used to stir to dissolve it uniformly to obtain a first mixture; 20 ml of ethanol is continuously added, and stirring is continued to obtain a second mixture; the second mixture is left to stand for 10 min to allow it to naturally precipitate, and then the upper mixed liquid is poured into a clean new beaker and dried at room temperature to a volume of half, to obtain the conductive dispersion mixed glue; the lid is covered and placed for later use.

[0101] (3) 6 g of sub-micron conductive inlay powder is weighed into a new beaker; another 800-1000 nm beryllium aluminum powder with a volume of about 1 / 5 of the sub-micron conductive inlay powder is weighed, and both are added to the beaker and stirred to mix the sub-micron conductive inlay powder and the beryllium aluminum powder uniformly to obtain a third mixture; 6 ml of conductive dispersion mixed glue is measured and added to the third mixture to sufficiently wet the third mixture to obtain a fourth mixture, and the fourth mixture is continuously stirred or kneaded uniformly to obtain a blocky mud-like mixture;

[0102] (4) The blocky mud-like mixture is vacuum dried at 100°C for 30 min and then placed in an inlay machine to fill the ordinary carbon-containing conductive inlay powder, and conventional inlay processing is performed to obtain the sub-micron powder inlay sample to be tested;

[0103] (5) Three prepared sub-micron powder inlay samples to be tested are taken and fixed evenly on a grinding and polishing clamp, and 400#, 800#, and 1000# silicon carbide sandpaper is used in turn at a pressure of 30 N to grind the three sub-micron powder inlay samples to be tested for 60 s each time. The sub-micron powder inlay samples to be tested and the grinding and polishing clamp are washed with tap water after each grinding.

[0104] ​(6) According to the pressure and time in Table 2, the polished said to be measured sub-micron powder mosaic sample is sequentially polished by 9 μm and 3 μm diamond polishing liquid, 1 μm silicon oxide polishing liquid;

[0105] Table 2

[0106]

[0107] (7) The polished sample is taken out, first washed with pure water, then washed with ethanol, and dried with an electric hair dryer.

[0108] (8) The scanning electron microscope is used for observation, and the beryllium aluminum powder cross section and detail image under 80,000 times is clear, as shown in the figure. Figure 2

[0109] In summary, the technical scheme provided by the present application has the following technical effects:

[0110] In the present application, the sub-micron conductive mosaic powder is mixed and dispersed with the sub-micron powder, the conductive dispersion mixed glue formed by mixing the conductive silver glue, acetone and ethanol forms surface modification and dispersion of the sub-micron powder, the porous skeleton of the ordinary conductive mosaic powder (i.e. carbon-containing conductive mosaic powder) has the effect of embedding and fixing the sub-micron powder, and the conductive dispersion mixed glue forms glue fixing of the sub-micron powder.

[0111] In addition, the prepared to-be-measured sub-micron powder mosaic sample realizes good dispersion and firm fixation of the sub-micron powder, and has the prerequisite for processing; the carbon particles in the sub-micron conductive mosaic powder and the conductive particles in the conductive dispersion mixed glue constitute the conductive channel of the to-be-measured sub-micron powder mosaic sample, and meet the conditions of scanning electron microscope detection.

[0112] In addition, the present application further realizes sub-micron level processing of the to-be-measured sub-micron powder mosaic sample by using smaller pressure and fine grinding and polishing, and realizes "shearing" of the sub-micron scale of the sub-micron powder particles to obtain the internal cross section of the sub-micron powder.

[0113] Please note that the technical features of the above embodiments can be combined in any way, and in order to make the description simple, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the description. The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be interpreted as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.​

Claims

1. A metallographic preparation method for the cross-section of nano / submicron powder particles, characterized in that, The preparation method includes: Step S1: Prepare submicron conductive embedded powder from carbon-containing conductive embedded powder; Step S2: Prepare a conductive dispersion mixture by mixing conductive silver paste, acetone and ethanol in a certain proportion for electron microscopy. Step S3: Mix the submicron powder to be tested and the submicron conductive embedded powder in step S1 in a certain proportion until they are evenly mixed. Then add the conductive dispersion mixture in step S2 to fully wet the submicron powder to be tested and the submicron conductive embedded powder. After fully stirring or kneading, a mud-like mixture is obtained. Then, the mud-like mixture after vacuum drying is prepared into a submicron powder embedded sample to be tested using an embedded machine. Step S4: The submicron powder mosaic sample to be tested is ground and polished, and then the polished submicron powder mosaic sample to be tested is cleaned and dried to obtain a metallographic sample.

2. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 1, characterized in that, Step S1 specifically includes the following sub-steps: Step S11: Weigh 10-20g of the carbon-containing conductive inlay powder and place it in an agate mortar for grinding for 20-30 minutes to obtain a uniform and fine conductive inlay powder. In step S12, the uniform and fine conductive embedding powder is evenly sprinkled on the tape. The size of the conductive embedding powder is determined by a microscope. If the size is 0.6-5μm, the uniform and fine conductive embedding powder is used as the submicron conductive embedding powder. If not, return to step S11 to continue grinding.

3. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 1, characterized in that, Step S2 specifically includes the following sub-steps: Step S21: Weigh 2g of conductive silver paste for electron microscopy and place it in the first beaker; continue to add 10ml of acetone to the conductive silver paste for electron microscopy and stir to dissolve the conductive silver paste for electron microscopy evenly to obtain the first mixture; Step S22: Measure 20 ml of ethanol and add it to the first mixture, and stir until homogeneous to obtain the second mixture; Step S23: After letting the second mixture stand for 5-10 minutes, slowly tilt the first beaker, pour the upper liquid into the second beaker, and then dry it at room temperature until half of the liquid volume remains, to obtain the conductive dispersion mixture.

4. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 1, characterized in that, Step S3 specifically includes the following sub-steps: Step S31: Weigh a certain amount of the submicron conductive embedded powder and the submicron powder to be tested and place them in a third beaker and stir evenly to obtain a third mixture; wherein, the volume ratio of the submicron powder to be tested and the submicron conductive embedded powder is 1:5-1:

3. Step S32: A certain volume of the conductive dispersion mixture is measured and added to the third mixture to fully wet the third mixture to obtain a fourth mixture; after fully stirring or kneading the fourth mixture, a mud-like mixture is obtained. Step S33: The mud-like mixture after vacuum drying is placed in a mounting machine and filled with carbon-containing conductive mounting powder. Conventional mounting processing is performed to obtain the submicron powder mounting sample to be tested.

5. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 4, characterized in that, The volume ratio of the conductive dispersion mixture to the third mixture is 0.2-0.

6.

6. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 1, characterized in that, In step S4, the smoothing process specifically includes the following sub-steps: Step S411: Fix M of the submicron powder mosaic samples to be tested evenly on the polishing fixture, and grind them with 400# silicon carbide sandpaper under certain pressure for 40-60 seconds. Then determine whether the submicron powder mosaic samples to be tested have been ground flat. If not, continue grinding with 400# silicon carbide sandpaper. If so, proceed to step S412; Step S412: Clean the submicron powder mosaic sample and the polishing fixture after grinding with 400# silicon carbide sandpaper using tap water. Then, replace with 800# silicon carbide sandpaper and continue grinding the submicron powder mosaic sample with the same pressure for 40-60 seconds. Clean the submicron powder mosaic sample and the polishing fixture with tap water again. Then, replace with 1000# silicon carbide sandpaper and continue grinding the submicron powder mosaic sample with the same pressure for 40-60 seconds. Clean the submicron powder mosaic sample and the polishing fixture again before use. Wherein, the pressure P1 during the grinding process is M*10N; M is the number of the submicron powder mosaic samples to be tested being ground simultaneously, and N is the pressure unit Newton.

7. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 1, characterized in that, In step S4, the polishing process specifically includes the following sub-steps: Step S421: The submicron powder mosaic sample to be tested, after being ground and smoothed, is polished for the first time using 9μm diamond polishing slurry to obtain the first sample. The pressure of the first polishing is P2 = M * 10N; the time of the first polishing is 240-300s; where M is the number of submicron powder mosaic samples to be tested being ground at the same time, and N is the pressure unit Newton. Step S422: The first sample is polished a second time using 3μm diamond polishing slurry to obtain the second sample. The pressure of the second polishing process is P3 = M*10N+10N; the time of the second polishing process is 360-450s; where M is the number of the submicron powder mosaic samples to be tested being polished at the same time, and N is the pressure unit Newton. Step S423: The second sample is polished for the third time using 1μm silicon oxide polishing slurry to obtain the third sample. The pressure of the third polishing treatment is P3 = M * 10N; the time of the third polishing treatment is 300-360s; where M is the number of the submicron powder mosaic samples to be tested being polished at the same time, and N is the pressure unit Newton.

8. The metallographic preparation method for the cross-section of nano / submicron powder particles according to claim 7, characterized in that, In step S4, the third sample is rinsed with pure water for the first time, then rinsed with ethanol for the second time, and then dried with a hair dryer to obtain the metallographic sample.

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