A method for detecting tungsten carbide powder

Abstract

The present application belongs to the technical field of material analysis and detection, and particularly relates to a tungsten carbide powder detection method, which realizes the shaping of the tungsten carbide powder by mixing and sintering metal powder with tungsten carbide powder to form a large-volume tungsten carbide inlaid sample. The tungsten carbide metallographic sample is ground and polished to make the tungsten carbide grains appear, thereby reducing the difficulty of tungsten carbide sectioning and being conducive to the detection of various performance indicators of the tungsten carbide powder by using equipment, so as to effectively evaluate the quality of the tungsten carbide powder. The metal powder used in the present application can reduce the sintering temperature, prevent the tungsten carbide powder sample from appearing recovery recrystallization and defect elimination and being damaged at high temperature during the high-temperature sample preparation process, help to maintain the original morphology and structure of the tungsten carbide, and meet the industrial implementation.

Description

Technical Field

[0001] This invention belongs to the field of materials analysis and testing technology, specifically a method for detecting tungsten carbide powder. Background Technology

[0002] Tungsten carbide is a key raw material for preparing cemented carbide. The properties of tungsten carbide, especially its microscopic properties such as grain size, grain size uniformity, and microstructure, determine the performance of cemented carbide. Therefore, using reliable testing methods to analyze the microstructure of tungsten carbide helps to evaluate its quality and optimize the composition and properties of cemented carbide to improve the market competitiveness of the product.

[0003] In the production process of tungsten carbide powder, to evaluate its quality, it is necessary to observe the original particle morphology of the powder, analyze the presence of W2C, and the morphology, size, particle size distribution, and quantity of W2C. Traditional tungsten carbide samples used for microstructure analysis are powdery polycrystalline particles composed of numerous single crystals. Current testing methods can only evaluate the entire powder particle, while the morphology and internal structure of individual crystals are crucial to the performance of tungsten carbide. Due to the small size of tungsten carbide powder, it is difficult to cut the powder, making it difficult to detect the particles. Summary of the Invention

[0004] To address the problems existing in the prior art, the main objective of this invention is to propose a method for detecting tungsten carbide powder.

[0005] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0006] A method for detecting tungsten carbide powder includes the following steps:

[0007] S1. Tungsten carbide powder and metal powder are mixed by ultrasonic vibration to obtain a mixed powder, which is then pressed into a green blank; the metal powder is at least one of silver powder, gold powder, zinc powder, tin powder, and lead powder.

[0008] S2. Place the green blank into a hydrogen tube furnace and heat it to temperature T at a hydrogen flow rate of 50-300 mL / min and a heating rate of 5-20 °C / min. Temperature T is 10-200 °C higher than the melting point of the metal powder. Hold the temperature at T for 30-120 min to obtain a permeated sample.

[0009] S3. Embed the permeated sample into the resin to create an inlaid sample;

[0010] S4. Grind and polish the inlaid sample, observe the sample under a microscope, and detect tungsten carbide powder.

[0011] As a preferred solution of the method for detecting tungsten carbide powder according to the present application, in step S1, the weight ratio of tungsten carbide powder to metal powder is 1:2-10.

[0012] As a preferred solution of the method for detecting tungsten carbide powder according to the present application, in step S1, the FSSS particle size of tungsten carbide powder is 0.3-10 μm, and the specific surface area BET is 2.0-4.5 m 2 / g; the purity of metal powder is above 99.9%, and the FSSS particle size is 10-100 μm.

[0013] As a preferred solution of the method for detecting tungsten carbide powder according to the present application, in step S1, when the metal powder is lead powder, 0.1-0.15% of carbon powder in total mass of tungsten carbide powder and lead powder can be added.

[0014] As a preferred solution of the method for detecting tungsten carbide powder according to the present application, in step S2, the green body is placed in a graphite boat, a metal sheet or a metal green body is placed on top of the green body, and the green body is covered with metal powder, and then the green body is placed in the middle position of a hydrogen tube furnace, and the metal sheet, the metal green body and the metal powder have the same material as the metal powder in step S1.

[0015] As a preferred solution of the method for detecting tungsten carbide powder according to the present application, in step S2, the infiltration process is specifically:

[0016] S21, purging with any one of nitrogen, argon and helium at room temperature for 5-20 min;

[0017] S22, purging with hydrogen at room temperature for 1-5 min;

[0018] S23, heating to a temperature T at a heating rate of 5-20 ℃ / min under the condition that the hydrogen flow rate is 50-300 mL / min, the temperature T is 10-200 ℃ higher than the melting point of the metal powder, and the temperature T is kept for 30-120 min;

[0019] S24, cooling to room temperature in the furnace;

[0020] S25, purging with any one of nitrogen, argon and helium at room temperature for 1-5 min.

[0021] As a preferred scheme of the tungsten carbide powder detection method, in the step S2, when the metal powder is lead powder, the step S23 is to heat from room temperature to 300 DEG C at a heating rate of 15-20 DEG C / min, keep for 30 min, then heat to 360 DEG C at a heating rate of 2-10 DEG C / min, keep for 30-60 min.

[0022] As a preferred scheme of the tungsten carbide powder detection method, in the step S2, when the metal powder is silver powder, the step S23 is to heat from room temperature to 800 DEG C at a heating rate of 15-20 DEG C / min, keep for 30 min, then heat to 1000 DEG C at a heating rate of 2-10 DEG C / min, keep for 30-60 min.

[0023] As a preferred scheme of the tungsten carbide powder detection method, in the step S3, the resin is epoxy resin or phenolic resin.

[0024] As a preferred scheme of the tungsten carbide powder detection method, in the step S4, the grinding process is to grind the inlaid sample from both sides by using a grinder to obtain a metallographic inlaid sample with parallel upper and lower surfaces.

[0025] As a preferred scheme of the tungsten carbide powder detection method, in the step S4, the polishing process is to polish the inlaid sample after grinding by using a large-size diamond suspension on a polishing machine for 15-25 min, then use a small-size diamond suspension on the polishing machine for 10-20 min; the sample must be cleaned after each polishing and cleaned in an ultrasonic bath for 1-2 min.

[0026] As a preferred scheme of the tungsten carbide powder detection method, in the step S4, the sample is observed by using an amplification of 200-1000 times.

[0027] The present application has the following advantages:

[0028] The present application provides a tungsten carbide powder detection method, which mixes and sinters the metal powder and the tungsten carbide powder to form a tungsten carbide inlaid sample with a large volume, realizes the shaping of the tungsten carbide powder, grinds and polishes the tungsten carbide metallographic sample to make the tungsten carbide grains appear, reduces the cutting difficulty of the tungsten carbide, is conducive to the detection of various performance indexes of the tungsten carbide powder by using equipment, so as to effectively evaluate the quality of the tungsten carbide powder, and the metal powder used in the present application can reduce the sintering temperature, prevent the tungsten carbide sample from appearing recovery recrystallization and defect elimination in the high-temperature sample preparation process, and damage at high temperature, which is helpful to maintain the original morphology and structure of the tungsten carbide and can meet the industrial implementation. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and other drawings can also be obtained according to the structures shown in the drawings without any creative effort for those skilled in the art.

[0030] Figure 1 A metallographic phase diagram of the sample of the embodiment 1 of the present application;

[0031] Figure 2 A metallographic phase diagram of the sample of the embodiment 2 of the present application;

[0032] Figure 3 A metallographic phase diagram of the sample of the embodiment 3 of the present application;

[0033] Figure 4 A metallographic phase diagram of the sample of the comparative example 1 of the present application;

[0034] Figure 5 A metallographic phase diagram of the sample of the comparative example 2 of the present application;

[0035] Figure 6 A metallographic phase diagram of the sample of the comparative example 3 of the present application.

[0036] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments will be described clearly and completely 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 any creative effort belong to the protection scope of the present application.

[0038] The present application proposes a detection method of tungsten carbide powder, which has the following advantages:

[0039] (1) The present application mixes and sinters the metal powder and the tungsten carbide powder to form a large-volume tungsten carbide inlay sample containing resin, realizes the shaping of the tungsten carbide powder, grinds and polishes the tungsten carbide metallographic sample to make the tungsten carbide grains appear, reduces the difficulty of tungsten carbide sectioning, and is conducive to the detection of various performance indicators of the tungsten carbide powder by using equipment; so as to effectively evaluate the quality of the tungsten carbide.

[0040] (2) The present application uses at least one of silver, gold, zinc, tin and lead as a new binder, which can reduce the sintering temperature, prevent the tungsten carbide powder sample from appearing recovery recrystallization, defect elimination and high temperature damage in the high temperature sample preparation process, help to maintain the original morphology and structure of the tungsten carbide powder, and reduce the temperature by 100-600 DEG C compared with the traditional copper infiltration method (temperature 1100-1200 DEG C); reducing the sample preparation temperature can reduce the heating time, thereby improving the sample preparation efficiency, reducing the sample preparation cost and reducing the energy consumption.

[0041] (3) The binder of the present application has better plasticity and lower deformation resistance than the traditional copper powder binder, which can reduce the damage of compression and deformation to the original tungsten carbide powder, such as extrusion, crushing, rupture, deformation and bonding, so that the original morphology, structure and state of the tungsten carbide powder cannot be truly reflected.

[0042] (4) The tungsten carbide powder appears white, the carbon-deficient phase W2C appears bright white, and the binder appears dark, the contrast of the three phases is high, the color level is clear, and the phase interface is very clear and visible, which is more easy to present the appearance and boundary of the tungsten carbide powder, and the traditional copper powder binder appears light yellow and bright white, the contrast is low, and when the tungsten carbide powder is fine, the phase interface is difficult to distinguish.

[0043] (5) Since the lead powder is a powder material, it is oxidized on the surface at room temperature to become PbO (s), PbO is a hard and brittle phase, and the hard second phase particles will hinder the dislocation movement, affect the plastic deformation of lead, increase the resistance of pressing deformation, and is not conducive to the plastic deformation behavior of lead. At the same time, if PbO exists as a second phase, because PbO has poor wettability with Pb and tungsten carbide powder, it is easy to cause the generation of pores. The present application can also add a small amount of carbon powder, which can occur carbon thermal reduction reaction under certain vacuum degree and temperature: PbO (s) + C (s) = Pb (l) + CO (g) ; PbO (s) + CO (g) = Pb (l) + CO2 (g), the metallographic sample has high density and no second phase or other abnormal particles exist.

[0044] (6) The present application uses nitrogen, argon and helium to empty the residual air in the furnace tube, which can prevent the explosion hazard of the residual gas in the furnace tube.

[0045] (7) The present application places a metal sheet or a metal green body on the top of the green body and covers it with metal powder, and when liquid phase sintering, the metal sheet or the metal green body melts and penetrates into the sample, which improves the color purity of the metal, makes the binder phase color deeper, and can improve the contrast of the tungsten carbide powder and the binder phase powder, which is convenient for subsequent contrast analysis and observation of the tungsten carbide powder.

[0046] According to one aspect of the present application, the present application provides the following technical scheme:

[0047] A detection method of tungsten carbide powder, comprising the following steps:

[0048] S1, the tungsten carbide powder and the metal powder are mixed by ultrasonic vibration to obtain a mixed powder, and the mixed powder is pressed into a green body; the metal powder is at least one of silver powder, gold powder, zinc powder, tin powder and lead powder;

[0049] S2, the green body is put into a hydrogen tube furnace, and permeation is carried out under the condition that the hydrogen flow is 50-300 mL / min to obtain a permeated sample;

[0050] S3, the permeated sample is embedded in resin to obtain an inlaid sample;

[0051] S4, the inlaid sample is ground and polished, and the sample is observed by using a microscope to realize the detection of the tungsten carbide powder.

[0052] Preferably, in the step S1, the weight ratio of the tungsten carbide powder and the metal powder is 1:2-10; in the step S1, the FSSS particle size of the tungsten carbide powder is 0.3-10 μm, and the specific surface area BET is 2.0-4.5 m 2 / g; the purity of the metal powder is more than 99.9%, and the FSSS particle size of the metal powder is 10-100 μm; specifically, the weight ratio of the tungsten carbide powder and the metal powder can be, for example but not limited to, any one of 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or a range between any two of them;

[0053] Preferably, in the step S1, when the metal powder is lead powder, 0.1-0.15% of carbon powder based on the total mass of the tungsten carbide powder and the lead powder can be added. Since the lead powder belongs to a powder material, surface oxidation occurs at room temperature, becoming PbO(s), and PbO belongs to a hard and brittle phase. The hard second-phase particles hinder the dislocation movement, affect the plastic deformation of lead, increase the resistance of the pressing deformation, and are not conducive to the plastic deformation behavior of lead. At the same time, if PbO exists as a second phase, because PbO has poor wettability with Pb and tungsten carbide powder, it is easy to cause the generation of pores. A small amount of carbon powder is added in the present application, and carbon thermal reduction reactions occur under a certain vacuum degree and temperature: PbO(s)+C(s)=Pb(l)+CO(g); PbO(s)+CO(g)=Pb(l)+CO2(g), and the metallographic sample has high density and no second phase or other abnormal particles. Specifically, the added carbon powder can be, for example but not limited to, any one of 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15% or a range between any two of them based on the total mass of the tungsten carbide powder and the lead powder;

[0054] Preferably, in the step S2, the green body is placed in a graphite boat, a metal sheet or a metal green body is placed on the top of the green body, and the green body is covered with metal powder, and then it is placed in the middle position of a hydrogen tube furnace, and the metal sheet, the metal green body and the metal powder have the same material as the metal powder in the step S1. The metal sheet or the metal green body is placed on the top of the green body and covered with metal powder, and in the liquid phase sintering process, the metal sheet or the metal green body is melted and infiltrated into the sample, the color purity of the metal is improved, the color of the binder phase is deeper, the contrast between the tungsten carbide powder and the binder phase powder is improved, and the subsequent contrast analysis and observation and distinction of the tungsten carbide powder are facilitated.

[0055] Preferably, in the step S2, the infiltration process specifically comprises the following steps.

[0056] S21, purging with any one of nitrogen, argon and helium at room temperature for 5-20 min;

[0057] S22, purging with hydrogen at room temperature for 1-5 min;

[0058] S23, heating to a temperature T at a heating rate of 5-20 ℃ / min under the condition that the hydrogen flow is 50-300 mL / min, the temperature T is 10-200 ℃ higher than the melting point of the metal powder, and the temperature T is kept for 30-120 min;

[0059] S24, cooling to room temperature in the furnace;

[0060] S25, purging with any one of nitrogen, argon and helium at room temperature for 1-5 min.

[0061] The present application adopts nitrogen, argon and helium to exhaust the residual air in the furnace tube, so as to prevent the explosion hazard caused by the residual gas in the furnace tube.

[0062] Further preferably, in the step S2, when the metal powder is lead powder, the step S23 is heating from room temperature to 300 ℃ at a heating rate of 15-20 ℃ / min, keeping for 30 min, and then heating to 360 ℃ at a heating rate of 2-10 ℃ / min, keeping for 30-60 min.

[0063] Further preferably, in the step S2, when the metal powder is silver powder, the step S23 is heating from room temperature to 800 ℃ at a heating rate of 15-20 ℃ / min, keeping for 30 min, and then heating to 1000 ℃ at a heating rate of 2-10 ℃ / min, keeping for 30-60 min.

[0064] Preferably, in the step S3, the resin is epoxy resin or phenolic resin.

[0065] Preferably, in the step S4, the grinding process is: using a grinder to grind the embedded sample from both sides to obtain a metallographic embedded sample with upper and lower surfaces parallel to each other.

[0066] Preferably, in the step S4, the polishing process is: polishing the embedded sample after grinding on a polisher with a 54 μm diamond suspension for 15-25 min, and then polishing on a polisher with a 3 μm diamond suspension for 10-20 min; if there are scratches on the sample, the polishing time must be extended. The sample must be cleaned after each polishing and cleaned in an ultrasonic bath for 1-2 min.

[0067] Preferably, in the step S4, the sample is observed at a magnification of 200-1000 times, and the morphology, size and particle size distribution of the tungsten carbide powder, as well as the size and morphology of W2C, can be clearly seen.

[0068] The technical solutions of the present application are further described below in combination with specific embodiments.

[0069] Embodiment 1

[0070] A detection method of tungsten carbide powder, comprising the following steps:

[0071] S1, 2 g of WC30 powder with a Fisher particle size of 30.6 μm and 20 g of lead powder with a Fisher particle size of 26 μm and a purity of 99.9% are weighed and mixed in a mixing cup at a mass ratio of 1:10, and ultrasonic vibration mixing and dispersion is performed for 5 min to obtain a uniform state; the powder mixture is loaded into a mold cavity, and the green body is obtained by compression molding;

[0072] S2, the green body is placed in a graphite boat, a lead sheet is placed on the top of the green body and covered with lead powder, and then the green body is placed in the middle position of a hydrogen tube furnace, and the permeation sample is obtained under the condition that the hydrogen flow rate is 150 mL / min; the permeation process is as follows:

[0073] S21, nitrogen is blown for 10 min at room temperature;

[0074] S22, hydrogen is blown for 2 min at room temperature;

[0075] S23, heated to a temperature of 300 ℃ at a heating rate of 20 ℃ / min under the condition that the hydrogen flow rate is 150 mL / min, and then heated to 360 ℃ at a heating rate of 5 ℃ / min, and kept for 45 min.

[0076] S24, cool down to room temperature with the furnace;

[0077] S25, nitrogen is blown for 2 min at room temperature.

[0078] S3, embedding the infiltrated sample into phenolic resin to make an embedded sample;

[0079] S4, using a grinder to grind from both sides to obtain a metallographic embedded sample with upper and lower surfaces parallel to each other; polishing the embedded sample after grinding on a polisher with a 54 μm diamond suspension for 20 min, and then polishing on a polisher with a 3 μm diamond suspension for 15 min; after each polishing, the sample must be cleaned and cleaned in an ultrasonic bath for 2 min. After polishing the sample, wash with water and dry with a soft paper towel; analyze the sample using a microscope at a magnification of 500x (as shown in Figure 1 The metallographic microscope analysis shows that the binder phase is well solidified with WC powder, the density is high, no pores are found, the binder phase between the WC powders is dark, the color is relatively uniform, the WC particle morphology, size and particle distribution can be clearly seen, the W2C phase morphology can be seen, and the sample is not deformed.

[0080] Example 2

[0081] A detection method of tungsten carbide powder, comprising the following steps:

[0082] S1, weighing 2 g of WC30 powder with a Fisher particle size of 30.6 μm, 20 g of lead powder with a Fisher particle size of 26 μm and a purity of 99.9%, and mixing them in a mixing cup at a mass ratio of 1:10, adding 0.1% of carbon powder based on the total mass of the WC30 powder and the lead powder, and ultrasonic vibration mixing and dispersing for 5 min to a uniform state; loading the above-mentioned powder mixture into a mold cavity, and pressing it into a green body;

[0083] S2, placing the green body into a graphite boat, placing a lead sheet on the top of the green body and covering it with lead powder, and then placing it in the middle position of a hydrogen tube furnace, and performing infiltration under the condition of a hydrogen flow rate of 150 mL / min to obtain an infiltrated sample; the infiltration process is as follows:

[0084] S21, purging with nitrogen at room temperature for 10 min;

[0085] S22, purging with hydrogen at room temperature for 2 min;

[0086] S23, heating to a temperature of 300℃ at a heating rate of 20℃ / min under the condition of a hydrogen flow rate of 150 mL / min, and then heating to 360℃ at a heating rate of 5℃ / min, and holding for 30 min.

[0087] S24, cooling to room temperature with the furnace;

[0088] S25, purging with nitrogen at room temperature for 2 min.

[0089] S3, embedding the infiltrated sample into phenolic resin to make an inlaid sample;

[0090] S4, using a grinder to grind from both sides to obtain a metallographic inlaid sample with upper and lower surfaces parallel to each other; polishing the inlaid sample after grinding on a polisher with a 54 μm diamond suspension for 20 min, and then polishing on a polisher with a 3 μm diamond suspension for 15 min; after each polishing, the sample must be cleaned and cleaned in an ultrasonic bath for 2 min. After polishing, the sample is washed with water and dried with a soft paper towel; the sample is analyzed using a microscope at a magnification of 500x (as shown in Figure 2 The binder phase is well cured WC powder, the density is high, no pores are found, the binder phase between the WC powders is dark, the color is relatively uniform, the WC particle morphology, size and particle distribution can be clearly seen, the W2C phase morphology can be seen, and the sample is not deformed; and adding a certain amount of carbon powder helps to reduce the probability of the presence of lead oxide and improve the sample preparation and imaging effect.

[0091] Example 3

[0092] A method for detecting tungsten carbide powder, comprising the following steps:

[0093] S1, weighing 3g of WC30 powder with a Fisher particle size of 30.6 μm, 15g of silver powder with a Fisher particle size of 26 μm and a purity of 99.9%, and mixing and dispersing them in a mixing cup at a mass ratio of 1:5 for 5 min to a uniform state; loading the above-mentioned powder mixture into a mold cavity and pressing it into a green body;

[0094] S2, placing the green body into a graphite boat, and then placing it in the middle position of a hydrogen tube furnace, and performing infiltration under the condition that the hydrogen flow rate is 150 mL / min to obtain an infiltrated sample; the infiltration process is as follows:

[0095] S21, purging with nitrogen at room temperature for 10 min;

[0096] S22, purging with hydrogen at room temperature for 2 min;

[0097] S23, heating to a temperature of 800℃ at a heating rate of 20℃ / min under the condition that the hydrogen flow rate is 150 mL / min, and then heating to 1000℃ at a heating rate of 5℃ / min, and holding for 60 min.

[0098] S24, cooling to room temperature with the furnace;

[0099] S25, purging with nitrogen at room temperature for 2 min.

[0100] S3, embedding the infiltrated sample into phenolic resin to make an inlaid sample;

[0101] S4, grinding from both sides using a grinder to obtain a metallographic inlay sample with upper and lower surfaces parallel to each other; polishing the inlay sample after grinding on a polisher for 20 min using a 54 μm diamond suspension, and then polishing for 15 min using a 3 μm diamond suspension; after each polishing, the sample must be cleaned and cleaned in an ultrasonic bath for 2 min. After polishing the sample, wash with water and dry with a soft paper towel; analyze the sample using a microscope at a magnification of 500x (as shown in Figure 3 S4, grinding from both sides using a grinder to obtain a metallographic inlay sample with upper and lower surfaces parallel to each other; polishing the inlay sample after grinding on a polisher for 20 min using a 54 μm diamond suspension, and then polishing for 15 min using a 3 μm diamond suspension; after each polishing, the sample must be cleaned and cleaned in an ultrasonic bath for 2 min. After polishing the sample, wash with water and dry with a soft paper towel; analyze the sample using a microscope at a magnification of 500x (as shown in

[0102] Example 4

[0103] A method for detecting tungsten carbide powder, comprising the following steps:

[0104] S1, weighing 5 g of WC30 powder with a Fisher particle size of 30.6 μm, 10 g of silver powder with a Fisher particle size of 26 μm and a purity of 99.9%, and mixing them in a mixing cup at a mass ratio of 1:2, using ultrasonic vibration mixing and dispersing for 5 min to a uniform state; loading the above-mentioned powder mixture into a mold cavity, and pressing it into a green body;

[0105] S2, placing the green body into a graphite boat, placing a silver green body on top of the green body and covering it with silver powder, and then placing it in the middle position of a hydrogen tube furnace, and performing infiltration under the condition of a hydrogen flow rate of 300 mL / min to obtain an infiltrated sample; the infiltration process is as follows:

[0106] S21, purging with nitrogen at room temperature for 20 min;

[0107] S22, purging with hydrogen at room temperature for 1 min;

[0108] S23, heating to a temperature of 800℃ at a heating rate of 15℃ / min under the condition of a hydrogen flow rate of 300 mL / min, holding for 30 min, and then heating to 1000℃ at a heating rate of 10℃ / min, holding for 45 min.

[0109] S24, cooling to room temperature with the furnace;

[0110] S25, purging with nitrogen at room temperature for 5 min.

[0111] S3, embedding the infiltrated sample in epoxy resin to form an inlay sample;

[0112] S4, grinding from both sides using a grinder to obtain a metallographic mosaic with parallel upper and lower faces; polishing the ground mosaic sample on a polisher for 20 min using a 54 pm diamond suspension, and then polishing for 15 min using a 3 pm diamond suspension; after each polishing, the sample must be cleaned and washed in an ultrasonic bath for 1 min. After polishing, the sample is washed with water and dried with a soft paper towel; the sample is analyzed using a microscope at a magnification of 200x, and the metallographic microscope analysis shows that the binder phase is well solidified WC powder, the density is high, no pores are found, the binder phase between the WC powders is dark, the color is relatively uniform, the WC particle morphology, size and particle distribution can be clearly seen, the W2C phase morphology can be seen, and the sample is not deformed.

[0113] Comparative Example 1

[0114] A test method for a tungsten carbide powder, which is different from Example 1 in that,

[0115] S23, heating to 420°C at a heating rate of 10°C / min, and holding at 420°C for 60 min;

[0116] The sample is analyzed using a microscope at a magnification of 500x (as shown in Figure 4 the figure), and the metallographic microscope analysis shows that the binder phase is well solidified WC particles, there are individual pores, the density is general, the binder phase between the WC particles is dark and light, the WC particle morphology, size and particle distribution can be seen, and the W2C phase morphology can be seen.

[0117] Comparative Example 2

[0118] A test method for a tungsten carbide powder, which is different from Example 1 in that,

[0119] S23, heating to 300°C at a heating rate of 20°C / min, holding for 30 min; heating to 360°C at a heating rate of 5°C / min, and holding for 60 min;

[0120] The sample is analyzed using a microscope at a magnification of 500x (as shown in Figure 5 the figure), and the metallographic microscope analysis shows that the binder phase is well solidified WC particles, there are very few small pores, the density is very high, the binder phase between the WC particles is dark, the color is relatively uniform, the WC particle morphology, size and particle distribution can be clearly seen, and the W2C phase morphology can be seen, and the sample is deformed. The analysis is that the final temperature is too high, the liquid phase plastic flow is strengthened, and sintering creep is caused.

[0121] Comparative Example 3

[0122] A test method for a tungsten carbide powder, comprising the following steps:

[0123] S1. Weigh 3g of WC30 powder with a Fisher particle size of 30.6μm and 9g of copper powder with a Fisher particle size of 26μm and a purity of 99.9% and put them into a mixing cup at a mass ratio of 1:3. Mix and disperse the powder mixture using ultrasonic vibration for 5 minutes until it is uniform. Put the powder mixture into a mold cavity and press it into shape to obtain a green body.

[0124] S2. Place the green body into a graphite boat, then place it in the center of a hydrogen tube furnace, and perform permeation at a hydrogen flow rate of 150 mL / min to obtain a permeated sample; the permeation process is as follows:

[0125] S21. Purge with nitrogen gas for 10 minutes at room temperature;

[0126] S22. Purge with hydrogen gas for 2 minutes at room temperature;

[0127] S23. Heat to 1200℃ at a heating rate of 10℃ / min and hold for 60min;

[0128] S24. Cool to room temperature in the furnace;

[0129] S25. Purge with nitrogen gas for 2 minutes at room temperature.

[0130] S3. Embed the permeated sample into phenolic resin to create an embedded sample;

[0131] S4. Grind from both sides using a grinder to obtain a metallographic inlay sample with parallel top and bottom surfaces. Polish the ground inlay sample with a 54μm diamond suspension on a polishing machine for 20 minutes, then with a 3μm diamond suspension for 15 minutes. The sample must be cleaned after each polishing process and rinsed in an ultrasonic bath for 2 minutes. After polishing, wash the sample with water and wipe it dry with a soft paper towel. Analyze the sample using a microscope at 500x magnification (e.g., ...). Figure 6 As shown in the figure, metallographic microscopy analysis showed that the binder phase could solidify the WC particles, but black pores still existed. The internal morphology of the particles showed internal cracks, damage, and irregularities.

[0132] The tungsten carbide powder is mixed and sintered with the metal powder to form a large-volume tungsten carbide inlay sample, the tungsten carbide powder is shaped, the tungsten carbide metallographic sample is ground and polished to make the tungsten carbide grains appear, the cutting difficulty of the tungsten carbide is reduced, the performance indexes of the tungsten carbide powder are detected by using the equipment, the quality of the tungsten carbide powder is effectively evaluated, the sintering temperature can be reduced by using the metal powder, the tungsten carbide powder sample is prevented from appearing recovery recrystallization and defect elimination and high-temperature damage in the high-temperature sample preparation process, the original appearance and structure of the tungsten carbide are helped to be kept, and the industrial implementation can be met.

[0133] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made by using the content of the present application specification, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for detecting tungsten carbide powder, characterized in that, Includes the following steps: S1. Tungsten carbide powder, lead powder, and carbon powder are mixed using ultrasonic vibration to obtain a mixed powder, which is then pressed into a green body; the weight ratio of tungsten carbide powder to lead powder is 1:2~10; the mass of carbon powder accounts for 0.1~0.15% of the total mass of tungsten carbide powder and lead powder. S2. Place the green body into a hydrogen tube furnace and perform permeation at a hydrogen flow rate of 50~300mL / min to obtain a permeated sample; the permeation specifically involves: S21. Purge with any one of nitrogen, argon, or helium for 5-20 minutes at room temperature. S22. Purge with hydrogen gas for 1-5 minutes at room temperature; S23. Under the condition of hydrogen flow rate of 50~300mL / min, the temperature is increased from room temperature to 300℃ at a heating rate of 15~20℃ / min, held for 30min, and then increased to 360℃ at a heating rate of 2~10℃ / min, held for 30~60min. S24. Cool to room temperature in the furnace; S25. Purge with any one of nitrogen, argon, or helium for 1-5 minutes at room temperature. S3. Embed the permeated sample into the resin to create an inlaid sample; S4. Grind and polish the inlaid sample, observe the sample under a microscope, and detect tungsten carbide powder.

2. The method for detecting tungsten carbide powder according to claim 1, characterized in that, In step S1, the FSSS particle size of the tungsten carbide powder is 0.3~10μm, and the BET specific surface area is 2.0~4.5m². 2 / g; the purity of lead powder is above 99.9%, and the particle size of FSSS is 10~100μm.

3. The method for detecting tungsten carbide powder according to claim 1, characterized in that, In step S2, the green blank is placed in a graphite boat, a lead sheet or lead green blank is placed on top of the green blank, and the green blank is covered with lead powder. Then it is placed in the middle of the hydrogen tube furnace. The materials of the lead sheet, lead green blank, and lead powder are the same as those of the lead powder in step S1.

4. The method for detecting tungsten carbide powder according to claim 1, characterized in that, In step S3, the resin is epoxy resin or phenolic resin.

5. The method for detecting tungsten carbide powder according to claim 1, characterized in that, In step S4, the polishing process is as follows: polish the ground and inlaid sample with a large-sized diamond suspension on a polishing machine for 15-25 minutes, and then polish with a small-sized diamond suspension on a polishing machine for 10-20 minutes. The sample must be cleaned after each polishing and then cleaned in an ultrasonic bath for 1-2 minutes.

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