A fiber-reinforced cemented carbide, its preparation method and application

Abstract

The present invention provides a fiber-reinforced cemented carbide, a preparation method and an application thereof, belonging to the technical field of cemented carbides. The fiber-reinforced cemented carbide described in the present invention includes a cemented carbide matrix and cemented carbide fibers dispersed in the cemented carbide matrix; the raw materials for preparing the cemented carbide fibers include a first WC powder, a first Co powder and a modifier; the raw materials for preparing the cemented carbide matrix include a second WC powder and a second Co powder. The present invention uses cemented carbide fibers as toughening materials and disperses them in a cemented carbide matrix of the same system to obtain a fiber-reinforced cemented carbide, which can achieve the co-densification of two cemented carbides. The fiber-reinforced cemented carbide has both high hardness and good toughness, solves the contradiction between hardness and toughness existing in fine and medium-grained cemented carbides, and can be applied to fields such as geological and mineral drilling and mold forming under certain impact conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of cemented carbides, and particularly relates to a fiber-reinforced cemented carbide, a preparation method thereof, and an application thereof. Background Art

[0002] According to the definition of the classification of the crystal grain size of cemented carbides by the German Cemented Carbide Branch, the cemented carbide with a WC grain size of 0.8 - 1.3 μm is a fine-grained cemented carbide, and the cemented carbide with a WC grain size of 1.3 - 2.5 μm is a medium-grained cemented carbide. These two types of cemented carbides are widely used in fields such as geological and mining drilling and die forming. However, there is a certain contradiction between the hardness and toughness of the above two types of cemented carbides, that is, when the hardness increases, the toughness decreases, and vice versa. When the hardness and toughness of the cemented carbide do not match, it will directly affect the processing efficiency and quality. Moreover, in the process of geological and mining drilling or die forming, etc., the tools or dies made of cemented carbides need to withstand greater pressure and friction. If the hardness is too high and the toughness is insufficient, the tools or dies are prone to cracking, resulting in damage and reducing the service life; on the contrary, if the toughness is too high and the hardness is insufficient, the wear resistance is poor, and the tools or dies will also be quickly worn. Therefore, how to solve the contradiction between the hardness and toughness of fine- and medium-grained cemented carbides is an urgent problem to be solved in this field. Summary of the Invention

[0003] The purpose of the present invention is to provide a fiber-reinforced cemented carbide, a preparation method thereof, and an application thereof. The present invention uses cemented carbide fibers as toughening materials and disperses them in a cemented carbide matrix of the same system to obtain a fiber-reinforced cemented carbide, which can achieve the co-densification of the two cemented carbides. The fiber-reinforced cemented carbide has both high hardness and good toughness, solves the contradiction between the hardness and toughness of fine- and medium-grained cemented carbides, and can be applied in fields such as geological and mining drilling and die forming under certain impact conditions.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a fiber-reinforced cemented carbide, comprising a cemented carbide matrix and cemented carbide fibers dispersed in the cemented carbide matrix;

[0006] The preparation raw materials of the cemented carbide fibers include a first WC powder, a first Co powder, and a modifier;

[0007] The preparation raw materials of the cemented carbide matrix include a second WC powder and a second Co powder.

[0008] Preferably, the mass fraction of the cemented carbide fibers in the fiber-reinforced cemented carbide is 3% - 30%; the diameter of the cemented carbide fibers is 0.05 - 0.5 mm, and the aspect ratio is 2 - 10.

[0009] Preferably, in terms of mass percentage, the content of the second Co powder in the raw materials for preparing the cemented carbide matrix is 4.5% - 10%.

[0010] Preferably, the mass fraction of carbon in the second WC powder is 6.12% - 6.15%; the particle size of the second WC powder is 0.8 - 3.5 μm; the particle size of the second Co powder is 1.0 - 1.5 μm.

[0011] Preferably, in terms of mass percentage, the content of the first Co powder in the raw materials for preparing the cemented carbide fiber is 1% - 5% more than the content of the second Co powder in the raw materials for preparing the cemented carbide matrix; the modifier is a rare earth oxide.

[0012] Preferably, the modifier includes at least one of samarium oxide, yttrium oxide and dysprosium oxide; in terms of mass percentage, the content of the modifier in the raw materials for preparing the cemented carbide fiber is 0.5% - 1.2%.

[0013] Preferably, the mass fraction of carbon in the first WC powder is 0.02% - 0.04% higher than that in the second WC powder; the particle size of the first WC powder is more than 0.5 μm larger than that of the second WC powder; the particle size of the first Co powder is 1.0 - 1.5 μm.

[0014] The present invention provides a method for preparing the fiber - reinforced cemented carbide according to the above - mentioned technical solution, comprising the following steps:

[0015] Mix the cemented carbide fiber and the cemented carbide matrix and sinter them to obtain the fiber - reinforced cemented carbide.

[0016] Preferably, the sintering temperature is 1400 - 1450 °C, the heat - preservation time is 30 - 90 min, and the pressure is 1 - 4 MPa.

[0017] The present invention provides the application of the fiber - reinforced cemented carbide according to the above - mentioned technical solution or the fiber - reinforced cemented carbide obtained by the above - mentioned preparation method in geological drilling or die forming.

[0018] The present invention provides a fiber-reinforced cemented carbide, which comprises a cemented carbide matrix and cemented carbide fibers dispersed in the cemented carbide matrix; the raw materials for preparing the cemented carbide fibers include a first WC powder, a first Co powder and a modifier; the raw materials for preparing the cemented carbide matrix include a second WC powder and a second Co powder. In the present invention, WC powder and Co powder are essential components for preparing cemented carbide, and the function of the modifier is to purify the WC grain boundaries and strengthen the binder phase such as cobalt, which is beneficial to simultaneously improving the hardness and toughness of the obtained fiber-reinforced cemented carbide. The present invention uses cemented carbide fibers as toughening materials and disperses them in the cemented carbide matrix to obtain a fiber-reinforced cemented carbide; the cemented carbide fibers have high toughness and a fiber shape. When microcracks propagate in the cemented carbide matrix, crack deflection or termination will occur when encountering the cemented carbide fibers, that is, the cemented carbide fibers can hinder the expansion of cracks in the cemented carbide matrix and achieve toughening. At the same time, since both the cemented carbide fibers and the cemented carbide matrix belong to the WC-Co material system and have similar lattice constants, this similarity enables them to form a good lattice match at the interface, reducing the possibility of lattice distortion and stress concentration; in this case, preparing the fiber-reinforced cemented carbide will not affect the original carbon control system standard, can also solve the problem that the interface of dissimilar materials is mismatched and defects are likely to appear at the grain boundaries, can also improve the bonding force of the cemented carbide, reduce stress, and realize the co-densification of the cemented carbide fibers and the cemented carbide matrix. The fiber-reinforced cemented carbide of the present invention has both high hardness and good toughness, solves the contradiction between the hardness and toughness of cemented carbide, and further broadens the application field of traditional cemented carbide. The fiber-reinforced cemented carbide of the present invention can be applied to fields such as geological and mining drilling and mold forming under certain impact conditions.

[0019] Furthermore, the present invention uses cemented carbide fibers as toughening materials, which can reduce the dosage of the modifier in the fiber-reinforced cemented carbide to a certain extent. Moreover, since the cemented carbide fibers still belong to the WC-Co system, the original carbon control system standard can be not affected while promoting the hardness and toughness of the fiber-reinforced cemented carbide.

[0020] Furthermore, the present invention controls the interface composition gradient by adjusting the composition difference between the cemented carbide fibers and the cemented carbide matrix in the fiber-reinforced cemented carbide. Specifically, cemented carbide fibers and a cemented carbide matrix with relatively small differences in total carbon, WC particle size and Co content are used in combination, so that stress will not be generated at the interface due to excessive differences, and the co-densification and toughening of the two cemented carbides can also be achieved, avoiding the generation of pores. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is the preparation flow chart of the fiber-reinforced cemented carbide in the embodiment of the present invention;

[0023] Figure 2 It is the scanning electron microscope image of the fiber-reinforced cemented carbide obtained in Example 1;

[0024] Figure 3 It is the scanning electron microscope image of the fiber-reinforced cemented carbide obtained in Example 2. Specific embodiments

[0025] The present invention provides a fiber-reinforced cemented carbide, which includes a cemented carbide matrix and cemented carbide fibers dispersed in the cemented carbide matrix;

[0026] The preparation raw materials of the cemented carbide fibers include first WC powder, first Co powder and a modifier;

[0027] The preparation raw materials of the cemented carbide matrix include second WC powder and second Co powder.

[0028] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art or are prepared by methods well-known to those skilled in the art.

[0029] The fiber-reinforced cemented carbide of the present invention includes a cemented carbide matrix, and the preparation raw materials of the cemented carbide matrix include second WC powder and second Co powder.

[0030] In terms of mass percentage, the content of the second Co powder in the preparation raw materials of the cemented carbide matrix of the present invention can be 4.5% - 10%; in the specific embodiments of the present invention, the content of the second Co powder in the preparation raw materials of the cemented carbide matrix is 6% or 8%. The particle size of the second Co powder of the present invention can be 1.0 - 1.5 μm; in the specific embodiments of the present invention, the particle size of the second Co powder is 1.0 μm, 1.2 μm or 1.5 μm.

[0031] The raw materials for preparing the cemented carbide matrix of the present invention further include a second additive. The second additive of the present invention may include carbon black, a forming agent, and a dispersant; the forming agent may be paraffin wax; the dispersant may be absolute ethanol. In a specific embodiment of the present invention, the second additive includes carbon black, paraffin wax, and absolute ethanol. The present invention has no special requirements for the particle sizes of the carbon black and paraffin wax, and conventional carbon black and paraffin wax in the art can be used. In the present invention, the role of carbon black is to supplement carbon for the second WC powder; the forming agent is to improve the pressing performance of the material, so that the material forms a green compact with a certain strength after pressing, and has a certain impact on the shape and mechanical properties of the obtained cemented carbide matrix; the dispersant can improve the mixing uniformity between the materials, thereby promoting the improvement of the mechanical properties of the cemented carbide matrix.

[0032] In terms of mass percentage, the content of the second WC powder in the raw materials for preparing the cemented carbide matrix of the present invention can be 90% - 95.5%; in a specific embodiment of the present invention, the content of the second WC powder in the raw materials for preparing the cemented carbide matrix is 92% or 94%. The mass fraction of carbon in the second WC powder of the present invention can be 6.12% - 6.15%; in a specific embodiment of the present invention, the mass fraction of carbon in the second WC powder is 6.13% or 6.15%. The particle size of the second WC powder of the present invention can be 0.8 - 3.5 μm; in a specific embodiment of the present invention, the particle size of the second WC powder is 2.5 μm or 3 μm.

[0033] The fiber-reinforced cemented carbide of the present invention includes cemented carbide fibers, and the raw materials for preparing the cemented carbide fibers include a first WC powder, a first Co powder, and a modifier; in a specific embodiment of the present invention, the raw materials for preparing the cemented carbide fibers consist of a first WC powder, a first Co powder, and a modifier.

[0034] In terms of mass percentage, the content of the first Co powder in the raw materials for preparing the cemented carbide fibers of the present invention can be 1% - 5% more than the content of the second Co powder in the raw materials for preparing the cemented carbide matrix. In a specific embodiment of the present invention, when the content of the second Co powder in the raw materials for preparing the cemented carbide matrix is 6%, the content of the first Co powder in the raw materials for preparing the cemented carbide fibers is 12%. In another specific embodiment of the present invention, when the content of the second Co powder in the raw materials for preparing the cemented carbide matrix is 8%, the content of the first Co powder in the raw materials for preparing the cemented carbide fibers is 10%. The particle size of the first Co powder of the present invention can be 1.0 - 1.5 μm; in a specific embodiment of the present invention, the particle size of the first Co powder is 1.0 μm, 1.2 μm, or 1.5 μm.

[0035] In terms of mass percentage, the content of the modifier in the raw materials for preparing the cemented carbide fiber can be 0.5% - 1.2%; in specific embodiments of the present invention, the content of the modifier in the raw materials for preparing the cemented carbide fiber is 0.8%, 1% or 1.2%. In the present invention, the modifier can be a rare earth oxide; the modifier can include at least one of samarium oxide, yttrium oxide and dysprosium oxide. In specific embodiments of the present invention, the modifier can be samarium oxide, yttrium oxide or dysprosium oxide. In the present invention, the role of the modifier is to purify the WC grain boundary and strengthen the binder phase such as cobalt, which is beneficial to improving the hardness and toughness of the obtained fiber-reinforced cemented carbide simultaneously.

[0036] The raw materials for preparing the cemented carbide fiber of the present invention further include a first additive; the first additive can include carbon black, a forming agent and a dispersant. In the present invention, the forming agent can be paraffin wax; the dispersant can be absolute ethanol. The present invention has no special requirements for the specifications of the carbon black and paraffin wax, and conventional carbon black and paraffin wax in the art can be used.

[0037] In terms of mass percentage, the content of the first WC powder in the raw materials for preparing the cemented carbide fiber of the present invention can be 85% - 90%; in specific embodiments of the present invention, the content of the first WC powder in the raw materials for preparing the cemented carbide fiber is 88% or 89%. The mass fraction of carbon in the first WC powder of the present invention is 0.02% - 0.04% higher than the mass fraction of carbon in the second WC powder. In a specific embodiment of the present invention, when the mass fraction of carbon in the second WC powder is 6.13%, the mass fraction of carbon in the first WC powder is 6.16%. In another specific embodiment of the present invention, when the mass fraction of carbon in the second WC powder is 6.15%, the mass fraction of carbon in the first WC powder is 6.17%. The particle size of the first WC powder of the present invention can be more than 0.5 μm larger than the particle size of the second WC powder. In a specific embodiment of the present invention, when the particle size of the second WC powder is 3.0 μm, the particle size of the first WC powder is 6.0 μm. In another specific embodiment of the present invention, when the particle size of the second WC powder is 2.5 μm, the particle size of the first WC powder is 4.5 μm.

[0038] The diameter of the cemented carbide fiber of the present invention can be 0.05 - 0.5 mm, and the aspect ratio can be 2 - 10; in specific embodiments of the present invention, the diameter of the cemented carbide fiber is 0.08 mm, 0.1 mm, 0.2 mm or 0.4 mm; the length is 0.4 mm, 0.5 mm, 1 mm or 2 mm. In the fiber-reinforced cemented carbide of the present invention, the mass fraction of the cemented carbide fiber can be 3% - 30%; in specific embodiments of the present invention, the mass fraction of the cemented carbide fiber in the fiber-reinforced cemented carbide is 5%, 10%, 15%, 20% or 25%.

[0039] The present invention relies on cemented carbide fibers to achieve the toughening effect of the cemented carbide matrix. When microcracks propagate in the cemented carbide matrix and encounter the cemented carbide fibers, crack deflection or termination will occur, thereby achieving the fiber toughening effect. In a specific embodiment of the present invention, the hardness of the cemented carbide fibers is 88.7 - 90.5 HRA, the flexural strength is 3078 - 3126 MPa, and the fracture toughness is 15.5 - 16.2 MPa·m 1 / 2 。

[0040] The present invention uses cemented carbide fibers as toughening materials and disperses them in the cemented carbide matrix to obtain a fiber-reinforced cemented carbide. Since both the cemented carbide fibers and the cemented carbide matrix belong to the WC-Co material system, in this case, preparing the fiber-reinforced cemented carbide not only does not affect the original carbon control system standard but also can solve the problem of easy defects at the grain boundaries caused by the mismatch of dissimilar material interfaces, improve the bonding force of the cemented carbide, reduce stress, and achieve the co-densification of the two cemented carbides. The fiber-reinforced cemented carbide of the present invention simultaneously has high hardness and good toughness, solves the contradiction between the hardness and toughness of the cemented carbide, and further broadens the application field of traditional cemented carbides.

[0041] The present invention also provides a preparation method of the fiber-reinforced cemented carbide according to the above technical solution, including the following steps:

[0042] Mix the cemented carbide fibers and the cemented carbide matrix and sinter them to obtain the fiber-reinforced cemented carbide.

[0043] The raw materials for preparing the cemented carbide fibers are mixed and granulated to obtain the cemented carbide fibers. There are no special limitations on the mixing method of the raw materials for preparing the cemented carbide fibers in the present invention, and the conventional mixing methods in the art can be used. In the present invention, after the raw materials for preparing the cemented carbide fibers are mixed, the obtained material can be ball-milled and dried in sequence. In the present invention, the time of the ball milling can be 20-30 h; the drying can be vacuum drying, the temperature of the drying can be 80-100 °C, and the time can be 4-6 h. In a specific embodiment of the present invention, the time of the ball milling is 25 h; the temperature of the vacuum drying is 90 °C, and the time is 5 h. The present invention can granulate the material that has been ball-milled and dried, sieve the obtained material, and collect the particulate matter passing through the sieve; sinter the particulate matter to obtain the cemented carbide fibers. In the present invention, the granulation can be carried out in a rotary granulator. In the present invention, the aperture of the sieve of the rotary granulator can be 0.05-0.5 mm. The sintering in the present invention can be dewaxing sintering; the temperature of the dewaxing sintering can be 1050-1350 °C, and the holding time can be 0.5-1 h; in a specific embodiment of the present invention, the temperature of the dewaxing sintering is 1100 °C or 1200 °C; the holding time is 0.5 h, 0.8 h or 1 h.

[0044] The raw materials for preparing the cemented carbide matrix are mixed to obtain the cemented carbide matrix. There are no special limitations on the mixing method of the raw materials for preparing the cemented carbide matrix in the present invention, and the conventional mixing methods in the art can be used. In the present invention, after the raw materials for preparing the cemented carbide matrix are mixed, the obtained material can be ball-milled to obtain the cemented carbide matrix. In the present invention, the time of the ball milling can be 24-28 h. In a specific embodiment of the present invention, the time of the ball milling is 24 h, 26 h or 28 h.

[0045] After obtaining the cemented carbide fibers and the cemented carbide matrix, the present invention mixes the cemented carbide fibers with the cemented carbide matrix and performs sintering to obtain the fiber-reinforced cemented carbide. After mixing the cemented carbide fibers with the cemented carbide matrix, the present invention can successively ball-mill and dry the obtained material, sieve the obtained dried material, and collect the mixed material passing through the sieve mesh. In the present invention, the ball-milling time can be 2 to 8 h; the drying can be vacuum drying, the drying temperature can be 60 to 70 °C, and the time can be 5 to 7 h. In specific embodiments of the present invention, the ball-milling time is 2 h, 4 h, 6 h, or 8 h; the temperature of the vacuum drying is 60 °C, 65 °C, or 70 °C, and the time is 5 h, 6 h, or 7 h. After obtaining the mixed material, the present invention can mold the mixed material by pressing and sinter the obtained pressed material to obtain the fiber-reinforced cemented carbide. The present invention has no special requirements for the molding method and conditions of the pressing, and the conventional pressing methods in the art can be adopted. In the present invention, the sintering can be pressure sintering; the sintering temperature can be 1400 to 1450 °C, the holding time can be 30 to 90 min, and the pressure can be 1 to 4 MPa; in specific embodiments of the present invention, the sintering temperature is 1400 °C, 1410 °C, or 1420 °C; the holding time is 30 min, 45 min, 60 min, or 90 min, and the pressure is 1 MPa, 2 MPa, 3 MPa, or 4 MPa. The present invention prepares the fiber-reinforced cemented carbide by densification through sintering.

[0046] The present invention controls the interfacial composition gradient by designing the composition difference between the cemented carbide fibers and the cemented carbide matrix in the fiber-reinforced cemented carbide, so as to achieve the purpose of synergistic densification and toughening of the two cemented carbides.

[0047] The present invention also provides the application of the fiber-reinforced cemented carbide described in the above technical solution or the fiber-reinforced cemented carbide obtained by the preparation method described in the above technical solution in geological and mining drilling or die forming.

[0048] The present invention uses cemented carbide fibers as toughening materials, disperses them in the cemented carbide matrix of the same system to obtain a fiber-reinforced cemented carbide, and can achieve the synergistic densification of the two cemented carbides. The fiber-reinforced cemented carbide has both high hardness and good toughness, solves the contradiction between the hardness and toughness of the cemented carbide, and can be applied to fields such as geological and mining drilling and die forming under certain impact conditions.

[0049] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] Example 1

[0051] 890 g of WC powder (particle size of 6.0 μm, and the mass fraction of carbon in the WC powder was adjusted to 6.17% by carbon supplementation with carbon black), 100 g of Co powder (particle size of 1.2 μm), 10 g of samarium oxide, 30 g of paraffin wax, and 240 mL of absolute ethanol were added to the ball milling cylinder of a drum ball mill and ball milled for 25 h. After completion, the obtained material was vacuum dried at 90 °C for 5 h, poured into a rotary granulator with a sieve, and granulated. The particulate matter passing through the sieve was collected, and the particulate matter was dewaxed and sintered at 1200 °C for 0.5 h to obtain cemented carbide fibers (diameter of 0.08 mm and length of 0.4 mm).

[0052] 920 g of WC powder (particle size of 3.0 μm, and the mass fraction of carbon in the WC powder was adjusted to 6.15% by carbon supplementation with carbon black), 80 g of Co powder (particle size of 1.2 μm), 35 g of paraffin wax, and 280 mL of absolute ethanol were added to the ball milling cylinder of a drum ball mill with a ball-to-material ratio of 2:1 and ball milled for 28 h to obtain a cemented carbide matrix slurry after completion. The cover of the ball milling cylinder was opened, and the above-mentioned cemented carbide fibers (the mass ratio of the cemented carbide fibers to the cemented carbide matrix was 5:95) were put into the ball milling cylinder, and ball milling was continued for 4 h. After completion, the obtained material was vacuum dried at 70 °C for 6 h, and the obtained dried material was sieved through a sieve with a pore size of 0.375 mm, and the mixed material passing through the sieve was collected.

[0053] The above-mentioned mixed material was molded by die pressing, and then the obtained pressed material was sintered at a constant temperature of 1420 °C and 3 MPa for 45 min to obtain fiber-reinforced cemented carbide.

[0054] Figure 2 It is a scanning electron micrograph of the fiber-reinforced cemented carbide obtained in Example 1.

[0055] Example 2

[0056] 880 g of WC powder (particle size of 4.5 μm, and the mass fraction of carbon in the WC powder was adjusted to 6.16% by carbon supplementation with carbon black), 120 g of Co powder (particle size of 1.0 μm), 5 g of dysprosium oxide, 30 g of paraffin wax, and 240 mL of absolute ethanol were added to the ball milling cylinder of a drum ball mill and ball milled for 25 h. After completion, the obtained material was vacuum dried at 90 °C for 5 h, poured into a rotary granulator with a sieve, and granulated. The particulate matter passing through the sieve was collected, and the particulate matter was dewaxed and sintered at 1100 °C for 1 h to obtain cemented carbide fibers (diameter of 0.08 mm and length of 0.4 mm).

[0057] Add 940 g of WC powder (particle size: 2.5 μm, carbon mass fraction in WC powder adjusted to 6.13% by carbon supplementation with carbon black), 60 g of Co powder (particle size: 1.0 μm), 35 g of paraffin wax, and 280 mL of absolute ethanol into the ball-milling cylinder of a roller ball mill. The ball-to-material ratio is 1.5:1, and ball-mill for 24 h. After completion, a hard alloy matrix slurry is obtained. Open the cover of the ball-milling cylinder, put the above-mentioned hard alloy fibers (mass ratio of hard alloy fibers to hard alloy matrix is 20:80) into the ball-milling cylinder, continue ball-milling for 6 h. After completion, vacuum-dry the obtained material at 70 °C for 6 h, place the obtained dried material in a sieve with a pore size of 0.375 mm for sieving, and collect the mixed material passing through the sieve.

[0058] Mold the above-mentioned mixed material into shape by die pressing, and then isothermally sinter the obtained pressed material at 1410 °C and 4 MPa for 60 min to obtain fiber-reinforced hard alloy.

[0059] Figure 3 It is the scanning electron microscope image of the fiber-reinforced hard alloy obtained in Example 2.

[0060] Comparative Example 1

[0061] Add 920 g of WC powder (particle size: 3.0 μm, carbon mass fraction in WC powder adjusted to 6.15% by carbon supplementation with carbon black), 80 g of Co powder (particle size: 1.2 μm), 20 g of paraffin wax, and 240 mL of absolute ethanol into the ball-milling cylinder of a roller ball mill, ball-mill for 32 h. After completion, vacuum-dry the obtained material at 70 °C for 6 h, place the obtained dried material in a sieve with a pore size of 0.375 mm for sieving, and collect the mixed material passing through the sieve.

[0062] Mold the above-mentioned mixed material into shape by die pressing, and then isothermally sinter the obtained pressed material at 1420 °C and 3 MPa for 45 min to obtain hard alloy.

[0063] Comparative Example 2

[0064] Add 940 g of WC powder (particle size: 2.5 μm, carbon mass fraction in WC powder adjusted to 6.13% by carbon supplementation with carbon black), 60 g of Co powder (particle size: 1.0 μm), 20 g of paraffin wax, and 240 mL of absolute ethanol into the ball-milling cylinder of a roller ball mill, ball-mill for 30 h. After completion, vacuum-dry the obtained material at 70 °C for 6 h, place the obtained dried material in a sieve with a pore size of 0.375 mm for sieving, and collect the mixed material passing through the sieve.

[0065] Mold the above-mentioned mixed material into shape by die pressing, and then isothermally sinter the obtained pressed material at 1410 °C and 4 MPa for 60 min to obtain hard alloy.

[0066] The hardness, transverse rupture strength and fracture toughness of the fiber-reinforced cemented carbides obtained in Examples 1-2 and the cemented carbides obtained in Comparative Examples 1-2 were tested. Among them, the test method for hardness refers to GB / T 3849.1-2015 Cemented Carbides Rockwell Hardness Test (Scale A) Part 1: Test Method; the test method for transverse rupture strength refers to GB / T 3851-2015 Cemented Carbides - Method for Determination of Transverse Rupture Strength; the test method for fracture toughness refers to GB / T 23806-2009 Fine Ceramics - Test Method for Fracture Toughness - Single Edge Pre-Cracked Beam (SEPB) Method. The test results are shown in Table 1.

[0067] Table 1 Performance data of the fiber-reinforced cemented carbides obtained in Examples 1-2 and the cemented carbides obtained in Comparative Examples 1-2

[0068]

[0069] As can be seen from Table 1, compared with Comparative Examples 1-2, the transverse rupture strength and hardness properties of the fiber-reinforced cemented carbides obtained in Examples 1-2 are similar to those of Comparative Examples 1-2, but the fracture toughness is significantly improved. Obviously, the fiber-reinforced cemented carbides obtained in Examples 1-2 have both high hardness and good toughness, solving the contradiction between the hardness and toughness of cemented carbides.

[0070] Although the above embodiments have made a detailed description of the present invention, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A fiber reinforced cemented carbide, characterized in that: It comprises a WC-Co cemented carbide matrix and WC-Co cemented carbide fibers dispersed in the WC-Co cemented carbide matrix; The raw materials for preparing the WC-Co cemented carbide fiber include a first WC powder, a first Co powder and a modifier; the modifier is a rare earth oxide; The raw materials for preparing the WC-Co cemented carbide substrate include a second WC powder and a second Co powder; The mass fraction of carbon in the first WC powder is 0.02%-0.04% higher than that in the second WC powder; the particle size of the first WC powder is greater than that of the second WC powder by more than 0.5 μm; and the particle size of the first Co powder is 1.0-1.5 μm.

2. The fiber-reinforced cemented carbide according to claim 1, characterized in that: The mass fraction of the WC-Co cemented carbide fiber in the fiber-reinforced cemented carbide is 3%-30%; the diameter of the WC-Co cemented carbide fiber is 0.05-0.5 mm, and the aspect ratio is 2-10.

3. The fiber-reinforced cemented carbide according to claim 1, characterized in that: In terms of mass percentage, the content of the second Co powder in the raw material for preparing the WC-Co cemented carbide substrate is 4.5% to 10%.

4. The fiber-reinforced cemented carbide according to claim 1 or 3, characterized in that: The mass fraction of carbon in the second WC powder is 6.12%-6.15%; the particle size of the second WC powder is 0.8-3.5 μm; and the particle size of the second Co powder is 1.0-1.5 μm.

5. The fiber-reinforced cemented carbide according to claim 1, characterized in that: In terms of mass percentage, the content of the first Co powder in the raw material for preparing the WC-Co cemented carbide fiber is 1% to 5% more than the content of the second Co powder in the raw material for preparing the WC-Co cemented carbide matrix.

6. The fiber-reinforced cemented carbide according to claim 1 or 5, characterized in that: The modifier includes at least one of samarium oxide, yttrium oxide and dysprosium oxide; the content of the modifier in the raw material for preparing the WC-Co cemented carbide fiber is 0.5% to 1.2% by mass.

7. The method for preparing the fiber reinforced cemented carbide according to any one of claims 1 to 6, comprising the following steps: The WC-Co cemented carbide fiber is mixed with a WC-Co cemented carbide matrix and sintered to obtain the fiber-reinforced cemented carbide.

8. The preparation method according to claim 7, characterized in that: The sintering temperature is 1400-1450° C., the heat preservation time is 30-90 min, and the pressure is 1-4 MPa.

9. Use of the fiber-reinforced cemented carbide according to any one of claims 1 to 6 or the fiber-reinforced cemented carbide obtained by the preparation method according to claim 7 or 8 in mining drilling or mold forming.

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