A WNiB ceramic and its preparation method

Abstract

The present invention provides a WNiB ceramic and a preparation method thereof, relating to the technical field of ceramics. The WNiB ceramic provided by the present invention is formed by ball milling, die pressing and sintering Ni powder, B powder and W powder, wherein the molar ratio of Ni powder, B powder and W powder is Ni:B:W = 1:(1.2 - 1.6):1. The preparation method of the WNiB ceramic provided by the present invention can prepare the above-mentioned WNiB ceramic. The WNiB ceramic provided by the present invention has good main mechanical property indexes, the highest flexural strength can reach 955 MPa, and the maximum fracture toughness can reach 9.8 MPa·m<supgt;1 / 2< / supgt>. It is not easy to break, so the safety during use is high and the service life is long. Moreover, the WNiB ceramic provided by the present invention uses W powder, Ni powder and B powder as raw materials and is prepared by processes such as ball milling, die pressing and sintering. Both the raw material cost and the preparation cost are relatively low, and the preparation process is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and in particular, to a WNiB ceramic and a preparation method thereof. Background Art

[0002] In the prior art, oxide and nitride ceramics are one of the main materials for indispensable important tools in metal processing, mining, oil drilling, national defense industry, etc., such as cutting tools, rock drilling, tooth restoration, ore crushing machinery, etc.

[0003] However, the ceramics in the prior art are prone to fracture during use and have a short service life, that is, their mechanical properties need to be further improved. Summary of the Invention

[0004] The first object of the present invention is to provide a WNiB ceramic to solve the technical problems of easy fracture and short service life of ceramics existing in the prior art.

[0005] The WNiB ceramic provided by the present invention is formed by ball milling, molding and sintering Ni powder, B powder and W powder. Among them, the molar ratio of the Ni powder, the B powder and the W powder is Ni:B:W = 1:(1.2 - 1.6):1.

[0006] Further, the particle sizes of the Ni powder, the B powder and the W powder are all not greater than 200 μm.

[0007] Further, the purities of the Ni powder, the B powder and the W powder are all not less than 99%.

[0008] The WNiB ceramic provided by the present invention can obtain the following beneficial effects:

[0009] The WNiB ceramic provided by the present invention has good main mechanical property indexes. The highest flexural strength can reach 955 MPa, and the maximum fracture toughness can reach 9.8 MPa·m1 / 2. It is not easy to fracture, so it has high safety and long service life during use. Moreover, the WNiB ceramic provided by the present invention uses W powder, Ni powder and B powder as raw materials and is prepared by processes such as ball milling, molding and sintering. Both the raw material cost and the preparation cost are relatively low, and the preparation process is simple.

[0010] The second object of the present invention is to provide a preparation method of a WNiB ceramic to solve the technical problems of easy fracture and short service life of ceramics existing in the prior art.

[0011] The preparation method of the WNiB ceramic provided by the present invention is used to prepare the above-mentioned WNiB ceramic, and includes the following steps:

[0012] Weigh the raw materials: Weigh Ni powder, B powder and W powder respectively, and the molar ratio of the three is Ni:B:W = 1:(1.2 - 1.6):1;

[0013] Ball-mill the B powder and the W powder: Add the weighed B powder and W powder into the ball-mill tank. After ball-milling for 10 - 30 h, stop the machine and cool it to room temperature;

[0014] Add the Ni powder for ball-milling: After the ball-mill tank is cooled to room temperature, open the ball-mill tank, add the weighed Ni powder into the ball-mill tank. After ball-milling for 1 - 5 h, stop the machine again and cool it to room temperature to obtain the mixed powder;

[0015] Molding by pressing: Fill the mixed powder obtained by ball-milling into a graphite mold and press it into a blank under a pressure of 50 - 180 MPa;

[0016] Sintering: Put the blank formed by pressing into a sintering furnace for sintering and heat preservation. The vacuum degree of the sintering furnace is not less than 10 -1 Pa, the sintering temperature is 1200 °C - 1500 °C, and the heat preservation time is 1 - 5 h; After reaching the heat preservation time, let the blank cool with the furnace to obtain the WNiB ceramic.

[0017] Further, the particle sizes of the Ni powder, the B powder and the W powder are all not greater than 200 μm.

[0018] Further, the purities of the Ni powder, the B powder and the W powder are all not less than 99%.

[0019] Further, in the step of ball-milling the B powder and the W powder, in addition to adding the B powder and the W powder into the ball-mill tank, 10% - 30% of absolute ethanol based on the total weight of the two is also added.

[0020] Further, before each time the ball-mill tank is loaded into the ball mill, the ball-mill tank is evacuated and filled with an inert gas.

[0021] Further, in the step of sintering, the heating rate of the blank is controlled to be 5 °C / s - 30 °C / s.

[0022] Further, the sintering furnace is a vacuum plasma activated sintering furnace.

[0023] The preparation method of the WNiB ceramic provided by the present invention, the prepared WNiB ceramic has all the above advantages of the WNiB ceramic, so it will not be elaborated here; In addition, the preparation method of the WNiB ceramic provided by the present invention uses W powder, Ni powder and B powder as raw materials, and is prepared by processes such as ball-milling, molding by pressing and sintering. The raw material cost and the preparation cost are both relatively low, and the preparation process is simple and the production cycle is short. Brief Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on the provided drawings.

[0025] Figure 1 This is a SEM (Scanning Electron Microscope) photo of the fracture morphology of the WNiB ceramic prepared in the first embodiment of the present invention. Specific Embodiments

[0026] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] This embodiment provides a WNiB ceramic, which is formed by ball milling, die pressing, and sintering Ni powder, B powder, and W powder. Among them, the molar ratio of Ni powder, B powder, and W powder is Ni:B:W = 1:(1.2 - 1.6):1; further, the molar ratio of the three can be Ni:B:W = 1:(1.3 - 1.5):1; specifically, the molar ratio of the three can be Ni:B:W = 1:1.4:1. Of course, it can also be 1:1.2:1, 1:1.3:1, 1:1.5:1, 1:1.6:1, etc.

[0028] The WNiB ceramic provided in this embodiment has good main mechanical property indexes. The highest flexural strength can reach 955 MPa, and the maximum fracture toughness can reach 9.8 MPa·m 1 / 2 , and it is not easy to break, so the safety during use is high and the service life is long. Moreover, the WNiB ceramic provided in this embodiment uses W powder, Ni powder, and B powder as raw materials and is prepared through processes such as ball milling, die pressing, and sintering. The raw material cost and the preparation cost are relatively low, and the preparation process is simple.

[0029] Specifically, in this embodiment, the particle sizes of Ni powder, B powder, and W powder are all not greater than 200 μm. Further, the particle sizes of Ni powder, B powder, and W powder can all be 100 - 200 μm. Preferably, the particle sizes of Ni powder, B powder, and W powder can all be 120 - 180 μm. More preferably, the particle sizes of Ni powder, B powder, and W powder can all be 140 - 160 μm. Specifically, the particle sizes of Ni powder, B powder, and W powder can be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, or the particle sizes between two value points. Selecting Ni powder, B powder, and W powder with an average particle size less than or equal to 200 μm as raw materials, the particle sizes of the raw materials are relatively small, which can quickly complete the mixing and obtain a mixed powder with a suitable particle size, thereby improving the ball milling efficiency and shortening the ball milling time. For example: the average particle sizes of Ni powder, B powder, and W powder can all be 150 μm, which can not only ensure that the ball milling time is not too long, thus shortening the preparation cycle and improving the production efficiency, but also maintain a low cost.

[0030] In addition, it should be noted that, in this embodiment, preferably, the particle sizes of Ni powder, B powder, and W powder are equal or basically equal. However, in other embodiments of the present application, the particle sizes of the three can also be unequal. For example: the average particle sizes of Ni powder, B powder, and W powder are 145 μm, 150 μm, and 155 μm respectively.

[0031] Specifically, in this embodiment, the purities of Ni powder, B powder, and W powder are all not less than 99%, specifically, they can be 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 100%, and the purities between two value points. The higher the purities of Ni powder, B powder, and W powder, the higher the purity of the obtained WNiB ceramic, thereby ensuring the wear corrosion resistance and mechanical properties of the WNiB ceramic. Preferably, the purities of Ni powder, B powder, and W powder are 99.5%, which can not only ensure that the prepared WNiB ceramic contains relatively low impurities, thus ensuring its good mechanical properties, but also effectively control the raw material cost.

[0032] This embodiment also provides a preparation method of WNiB ceramic for preparing the above-mentioned WNiB ceramic, including the following steps:

[0033] Weigh the raw materials: Weigh Ni powder, B powder and W powder respectively. The molar ratio of the three is Ni:B:W = 1:(1.2 - 1.6):1; further, the molar ratio of the three can be Ni:B:W = 1:(1.3 - 1.5):1; specifically, the molar ratio of the three can be Ni:B:W = 1:1.4:1. Of course, it can also be 1:1.2:1, 1:1.3:1, 1:1.5:1, 1:1.6:1, etc.

[0034] Ball-mill B powder and W powder: Add the weighed B powder and W powder into the ball-mill tank. After ball-milling for 10 - 30 h, stop the machine and cool it to room temperature; preferably, the ball-milling duration of B powder and W powder is 15 - 25 h, and further preferably, the ball-milling duration of B powder and W powder is 18 - 22 h. Specifically, the ball-milling duration of B powder and W powder can be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, 29 h, 30 h, or the ball-milling duration between two value points.

[0035] Add Ni powder for ball-milling: After the ball-mill tank is cooled to room temperature, open the ball-mill tank, add the weighed Ni powder into the ball-mill tank. After ball-milling for 1 - 5 h, stop the machine again and cool it to room temperature to obtain the mixed powder; preferably, the ball-milling duration after adding Ni powder is 2 - 4 h; specifically, the ball-milling duration after adding Ni powder can be 1 h, 2 h, 3 h, 4 h, 5 h, or any duration between two value points. Regarding the ball-milling duration, it can be determined according to the particle size of the raw materials, etc. For example, if the particle size of the raw materials is larger, the ball-milling duration should be appropriately longer; of course, if the performance requirements for the product are lower, the ball-milling duration can also be shortened.

[0036] Molding by pressing: Fill the mixed powder obtained by ball-milling into a graphite mold and press it into a blank under a pressure of 50 - 180 MPa; preferably, the molding pressure can be 80 - 150 MPa; further preferably, the molding pressure can be 100 - 120 MPa; specifically, the molding pressure can be 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, or the pressure between two value points.

[0037] Sintering: Put the blank formed by pressing into a sintering furnace for sintering and heat preservation. The vacuum degree of the sintering furnace is not less than 10 -1 Pa, the sintering temperature is 1200 °C - 1500 °C, and the heat preservation duration is 1 - 5 h; after reaching the heat preservation duration, let the blank cool with the furnace to obtain WNiB ceramics. Specifically, the vacuum degree of the sintering furnace can be 10-1 Pa, 10 -2 Pa, 10 -3 Pa, etc. The higher the vacuum degree, the smaller the possibility of the green body being oxidized. Regarding the sintering temperature, it can be further taken as 1250°C to 1400°C. Further still, it can be taken as 1300°C to 1350°C. Specifically, the sintering temperature can be 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, or the temperature between two value points. The holding time can be further taken as 2 to 4 h. Specifically, the holding time can be 1 h, 2 h, 3 h, 4 h, 5 h, or the time between two value points.

[0038] The preparation method of the WNiB ceramic provided in this embodiment, the prepared WNiB ceramic has all the advantages of the above-mentioned WNiB ceramic, so it will not be elaborated here; in addition, the preparation method of the WNiB ceramic provided in this embodiment uses W powder, Ni powder and B powder as raw materials, and is prepared by processes such as ball milling, molding and sintering. The raw material cost and the preparation cost are relatively low, and the preparation process is simple and the production cycle is short.

[0039] Specifically, in this embodiment, the particle sizes of the Ni powder, B powder and W powder are all not greater than 200 μm. Further, the particle sizes of the Ni powder, B powder and W powder can all be 100 to 200 μm. Preferably, the particle sizes of the Ni powder, B powder and W powder can all be 120 to 180 μm. More preferably, the particle sizes of the Ni powder, B powder and W powder can all be 140 to 160 μm. Specifically, the particle sizes of the Ni powder, B powder and W powder can all be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, or the particle sizes between two value points.

[0040] Specifically, in this embodiment, the purities of the Ni powder, B powder and W powder are all not less than 99%. Specifically, it can be 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 100%, and the purities between two value points.

[0041] Specifically, in this embodiment, in the step of ball-milling B powder and W powder, in addition to adding B powder and W powder into the ball-milling tank, 10% - 30% of absolute ethanol based on the total weight of the two is also added. Preferably, the addition amount of absolute ethanol is 15% - 25% of the total weight of B powder and W powder. Specifically, the addition amounts of absolute ethanol are 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% of the total weight of B powder and W powder, as well as the weight percentages between the two value points. During the ball-milling process, adding absolute ethanol can carry and disperse the powder materials, reduce the surface energy of the powder materials, and play a role in absorbing heat, making the powder materials distributed in a paste state on the spheres and the inner wall of the tank, and improving the powder refinement rate.

[0042] Specifically, in this embodiment, before each time the ball-milling tank is loaded into the ball mill, the ball-milling tank is evacuated and filled with an inert gas. Preferably, argon can be used. Of course, other inert gases such as krypton can also be filled. Evacuating the ball-milling tank and filling it with argon can effectively avoid the oxidation of raw materials, thereby ensuring the various properties of the prepared WNiB ceramic.

[0043] Specifically, in this embodiment, in the sintering step, the heating rate of the green body is controlled to be 5°C / s - 30°C / s. Further, the heating rate of the green body can be 10°C / s - 20°C / s. Specifically, the heating rates of the green body can be 11°C / s, 12°C / s, 13°C / s, 14°C / s, 15°C / s, 16°C / s, 17°C / s, 18°C / s, 19°C / s, 20°C / s.

[0044] Specifically, in this embodiment, the sintering furnace is a vacuum plasma activated sintering furnace. Through plasma activation, the heating rate can be accelerated, the sintering duration can be shortened, thereby shortening the preparation cycle and improving production efficiency. It can also reduce the sintering temperature and ensure uniform grains, thus being beneficial to controlling the microstructure of the sintered body to obtain excellent properties.

[0045] To further illustrate the present invention, the preparation method of the WNiB ceramic provided by the present invention and the WNiB ceramic will be described in more detail below with reference to the accompanying drawings and embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0046] Example 1

[0047] S100, Select Ni powder, B powder and W powder with a particle size of 150 μm and a purity of 99.5% as raw materials, and weigh them respectively according to the molar ratio Ni:B:W = 1:1.2:1.

[0048] S120: First, ball-mill the weighed B powder and W powder. Before ball-milling, weigh and add anhydrous ethanol accounting for 10% of the total weight of the two powders, load them into the ball-milling tank, evacuate and fill with argon. After ball-milling for 10 h, stop the machine and cool it to room temperature.

[0049] S130: Open the ball-milling tank, add the weighed Ni powder into the ball-milling tank, evacuate and fill with argon again, ball-mill for 5 h, stop the machine and cool it to room temperature again.

[0050] S140: Take out the mixed powder and directly fill it into the graphite mold, and press-mold it under 50 MPa.

[0051] S150: Put the press-molded green body into a vacuum plasma activated sintering furnace for sintering and heat preservation. The heating rate of the green body is 5 °C / s, the vacuum degree of the sintering furnace is 10 -1 Pa, the sintering temperature is 1500 °C, heat preservation for 1 h, and cool it with the furnace to obtain WNiB ceramics.

[0052] The flexural strength of the WNiB ceramics obtained through the above steps is 892 MPa, and the fracture toughness is 7.9 MPa·m 1 / 2 .

[0053] Example 2

[0054] S210: Select Ni powder, B powder and W powder with a particle size of 100 μm and a purity of 99.9% as raw materials, and weigh them according to the molar ratio of Ni:B:W = 1:1.6:1 respectively.

[0055] S220: First, ball-mill the weighed B powder and W powder. Before ball-milling, weigh and add anhydrous ethanol accounting for 30% of the total weight of the two powders, load them into the ball-milling tank, evacuate and fill with argon. After ball-milling for 20 h, stop the machine and cool it to room temperature.

[0056] S230: Open the ball-milling tank, add the weighed Ni powder into the ball-milling tank, evacuate and fill with argon again, ball-mill for 1 h, stop the machine and cool it to room temperature again.

[0057] S240: Take out the mixed powder and directly fill it into the graphite mold, and press-mold it under 180 MPa.

[0058] S250: Put the press-molded green body into a vacuum plasma activated sintering furnace for sintering and heat preservation. The heating rate of the green body is 15 °C / s, the vacuum degree of the sintering furnace is 10 -3 Pa, the sintering temperature is 1300 °C, heat preservation for 5 h, and cool it with the furnace to obtain WNiB ceramics.

[0059] The flexural strength of the WNiB ceramics obtained through the above steps is 955 MPa, and the fracture toughness is 6.7 MPa·m 1 / 2 .

[0060] Example 3

[0061] S310, Select Ni powder, B powder and W powder with a particle size of 200 μm and a purity of 99.5% as raw materials, and weigh them respectively according to the molar ratio Ni:B:W = 1:1.4:1.

[0062] S320, First, ball-mill the weighed B powder and W powder. Weigh and add 20% of absolute ethanol based on the weight of the two powders before ball-milling. Load them into the ball-milling tank, evacuate and fill with argon. After ball-milling for 30 h, stop the machine and cool to room temperature.

[0063] S330, Open the ball-milling tank, add the weighed Ni powder into the ball-milling tank, evacuate and fill with argon again, ball-mill for 2.5 h, stop the machine again and cool to room temperature.

[0064] S340, Take out the mixed powder and directly fill it into the graphite mold, and press-mold it under 100 MPa;

[0065] S350, Put the press-molded green body into a vacuum plasma activated sintering furnace for sintering and heat preservation. The heating rate of the green body is 30 °C / s, the vacuum degree of the sintering furnace is 10 -3 Pa, the sintering temperature is 1200 °C, heat preservation for 3 h, and cool with the furnace to obtain WNiB ceramics.

[0066] The flexural strength of the WNiB ceramics obtained through the above steps is 887 MPa, and the fracture toughness is 9.8 MPa·m 1 / 2 .

[0067] Table 1 Comparison table of mechanical properties of each example and comparative example

[0068] Flexural strength (MPa) <![CDATA[Fracture toughness (MPa·m 1 / 2 )]]> Example 1 892 7.9 Example 2 955 6.7 Example 3 887 9.8 Comparative Example 1 600.2 —— Comparative Example 2 612.75 5.88

[0069] Comparative example 1 is an invention patent application with the application number 202211538053.X and the name "A High-Temperature Wear-Resistant Mo-Si-B-Zirconium Boride Composite Material and Its Preparation Method". Comparative example 2 is an invention patent application with the application number 202210574955.2 and the name "A Core-Shell Nanoceramic Powder Coated with Graphene and Its Preparation Method". As can be seen from the above table, compared with the comparative examples, the flexural strength and fracture toughness of the WNiB ceramics provided by the examples of the present invention are significantly improved. In addition, Figure 1 Figure Figure 1 is the SEM photo of the fracture morphology of the WNiB ceramics prepared in Example 1. It can be seen from

[0070] In summary, the WNiB ceramic provided by this application has high flexural strength, good fracture toughness, and is not easily broken. Therefore, it has high safety and long service life during use; moreover, the preparation method is simple and the preparation cycle is short.

[0071] Finally, it should also be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0072] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to the embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A WNiB ceramic, characterized in that, it is made of Ni powder, B powder and W powder through ball milling, die pressing and sintering. Among them, before each ball milling, the ball milling tank is evacuated and filled with inert gas; During sintering, the molded green body is placed in a sintering furnace for sintering and heat preservation. The vacuum degree of the sintering furnace is not lower than 10 - 1 Pa, the sintering temperature is 1200°C to 1500°C, and the heat preservation time is 1 to 5 hours; the sintering furnace is a vacuum plasma activated sintering furnace; the molar ratio of the Ni powder, the B powder and the W powder is Ni:B:W = 1:(1.2 - 1.6):1; the particle sizes of the Ni powder, the B powder and the W powder are all not greater than 200 μm; the purities of the Ni powder, the B powder and the W powder are all not less than 99%.

2. A method for preparing a WNiB ceramic, used for preparing the WNiB ceramic according to claim 1, characterized in that, it includes the following steps: Weighing raw materials: Weigh Ni powder, B powder and W powder respectively, and the molar ratio of the three is Ni:B:W = 1:(1.2 - 1.6):1; the particle sizes of the Ni powder, the B powder and the W powder are all not greater than 200 μm, and the purities of the Ni powder, the B powder and the W powder are all not less than 99%; Ball milling the B powder and the W powder: Add the weighed B powder and W powder into the ball milling tank. After ball milling for 10 - 30 h, stop the machine and cool it to room temperature; Adding the Ni powder for ball milling: After the ball milling tank is cooled to room temperature, open the ball milling tank, add the weighed Ni powder into the ball milling tank. After ball milling for 1 - 5 h, stop the machine again and cool it to room temperature to obtain a mixed powder; Die pressing: Fill the mixed powder obtained by ball milling into a graphite mold and press it into a blank under a pressure of 50 - 180 MPa; Sintering: Put the molded green body into a sintering furnace for sintering and heat preservation. The vacuum degree of the sintering furnace is not less than 10 - 1 Pa, the sintering temperature is 1200°C to 1500°C, and the heat preservation time is 1 to 5 hours; after reaching the heat preservation time, let the green body cool with the furnace to obtain the WNiB ceramic.

3. According to the method for preparing a WNiB ceramic according to claim 2, characterized in that, in the step of ball milling the B powder and the W powder, in addition to adding the B powder and the W powder into the ball milling tank, 10% - 30% of absolute ethanol based on the total weight of the two is also added.

4. According to the method for preparing a WNiB ceramic according to claim 2, characterized in that, in the step of sintering, the heating rate of the blank is controlled to be 5 °C / s - 30 °C / s.

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