In-situ generated Ti3SiC2 reinforced YT15 cemented carbide and preparation method thereof

Abstract

The present invention discloses a YT15 cemented carbide reinforced with in-situ generated Ti3SiC2 and a preparation method thereof, relating to the technical field of cemented carbide preparation. The method comprises ball-milling WC powder, Co powder, TiC powder, and Si powder as raw materials, adding anhydrous ethanol as a process control agent, pressing and forming after drying, and sintering in a pressure sintering furnace. Ti3SiC2 is synthesized within the YT15 cemented carbide through an in-situ reaction occurring during the sintering process, thereby obtaining the YT15 cemented carbide reinforced with in-situ generated Ti3SiC2. The in-situ reaction within the YT15 cemented carbide during the sintering process generates Ti3SiC2, which can improve its hardness, fracture toughness, density, thermal stability, and processing performance, thereby optimizing its overall performance.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, in particular to an in-situ generated Ti3SiC2 reinforced YT15 hard alloy and a preparation method thereof. Background Art

[0002] YT15, a tungsten-titanium-cobalt cemented carbide (WC-TiC-Co), has a titanium carbide content of 15%. It has high hardness (≥91HRA) and excellent wear resistance, making it suitable for semi-finishing and finishing of carbon steel and alloy steel, especially in continuous cutting scenarios. Compared with YG-type cemented carbide, the addition of titanium carbide to YT15 reduces its affinity with steel during high-speed cutting, reduces the formation of built-up edge, and thus improves the quality of the machined surface. However, YT15 is relatively brittle and has poor impact resistance, making it difficult to adapt to intermittent cutting or high-impact load conditions (such as casting processing); in addition, its high-temperature resistance is limited, and it is prone to oxidation and softening at high temperatures, resulting in shortened tool life.

[0003] Ti3SiC2 combines the properties of both metals and ceramics, such as high electrical conductivity (one-third that of copper), high thermal conductivity (37-43 W / cm·K), excellent thermal shock resistance (ΔT>1000°C), and high-temperature stability (oxidation resistance at 1200°C). It also exhibits self-lubricity and moderate strength (326-350 MPa), making it suitable for applications in high-temperature protective coatings, nuclear seals, and other fields. However, the current synthesis of Ti3SiC2 is limited by existing preparation techniques, resulting in the formation of impurity phases (such as TiC and SiC). Furthermore, the layered structure results in low interlaminar shear strength and significant macroscopic brittleness. Furthermore, the resulting Ti3SiC2 alloy has lower wear resistance than traditional cemented carbides, necessitating composite formation to enhance its performance.

[0004] Due to the contradiction between the high wear resistance of YT15 cemented carbide and its brittleness and insufficient temperature resistance, the above problems can be partially solved by introducing Ti3SiC2 reinforcement phase. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the deficiencies in the prior art, the present invention provides an in-situ generated Ti3SiC2-reinforced YT15 cemented carbide and a preparation method thereof. Ti3SiC2 is uniformly generated inside the YT15 cemented carbide through an in-situ reaction. During the in-situ reaction, the generated impurity phase is SiC with a content of approximately 0.1-0.9wt%. Ti3SiC2 and a small amount of SiC are introduced into the YT15 cemented carbide system as a composite reinforcement phase to play a role in interface strengthening. The layered structure of Ti3SiC2 can relieve stress concentration, while the high modulus particles of SiC can inhibit crack propagation. The two synergistically improve the fracture toughness of the cemented carbide.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] A method for preparing in-situ generated Ti3SiC2-reinforced YT15 cemented carbide is completed by the following steps:

[0010] S1, cemented carbide TiC powder and Si powder were mixed and ball-milled in a vacuum environment at a molar ratio of 3:1;

[0011] S2, in terms of mass percentage, WC powder, Co powder and TiC powder were weighed in a ratio of 79:6:15 and added to a ball mill for ball milling and mixing; it should be emphasized that the ratio of WC, Co and TiC in the raw material powder was always 79:6:15, and the mass percentages of the raw materials and components were changed by adding additional nano-silicon;

[0012] S3, taking 1-4 wt% of the total mass of the cemented carbide of the mixed powder obtained in S1 and 96-99 wt% of the mixed powder obtained in S2, adding them into a ball mill for ball milling, and adding 1-2 wt% of the total mass of the cemented carbide of anhydrous ethanol as a process control agent;

[0013] S4, drying the mixed powder obtained in S3 in a drying oven;

[0014] S5, pressing the dried mixed powder into a shape, and sintering it in a pressure sintering furnace at a sintering temperature of 1400~1600℃ and a sintering time of 1~3h. Ti3SiC2 is synthesized inside the YT15 cemented carbide through an in-situ reaction occurring during the sintering process, thereby obtaining an in-situ generated Ti3SiC2 reinforced YT15 cemented carbide.

[0015] Preferably, the particle size of the TiC powder in S1 is 3 μm to 44 μm, and the particle size of the Si powder is 50 nm to 44 μm.

[0016] Preferably, the Fisher grain size of WC in the S2 is 0.7-0.8 μm, the grain size of Co is 0.7-2 μm, and the grain size of TiC is 3-44 μm.

[0017] Preferably, in S1, S2 and S3, the ball milling parameters are: carried out in a vacuum environment, the ball milling speed is 200-400 rpm, and the ball milling time is 3-12 h.

[0018] Preferably, the drying process in S4 is carried out in a vacuum environment, with a drying temperature of 50-100° C. and a drying time of 3-12 hours.

[0019] Another object of the present invention is to provide an in-situ generated Ti3SiC2 reinforced YT15 cemented carbide, which is prepared using the above-mentioned in-situ generated Ti3SiC2 reinforced YT15 cemented carbide preparation method.

[0020] The interaction between the elements and the in-situ generation mechanism of Ti3SiC2 in the present invention are as follows:

[0021] 1. Element interactions and reaction pathways

[0022] During the sintering process, TiC and Si in the raw materials undergo solid-phase reaction at high temperature. The specific reaction path is:

[0023] TiC (providing Ti and C) reacts directly with Si at high temperature (1400~1600℃) to generate Ti3SiC2:

[0024] 3TiC+Si→Ti3SiC2

[0025] When Si is excessive, part of it combines with C to form SiC impurity phase:

[0026] Si+C→SiC

[0027] The SiC content increases with the increase of Si addition, verifying the existence of this side reaction.

[0028] 2. Microscopic strengthening mechanism of in-situ generation

[0029] (1) The layered structure of Ti3SiC2 alleviates stress concentration

[0030] Ti3SiC2 is a layered MAX phase material. Its weakly bonded interlayer interface can absorb crack propagation energy through interlayer slip, thereby dispersing local stress and significantly improving the fracture toughness of the material.

[0031] (2) SiC particles inhibit crack growth

[0032] The by-product SiC is a high-hardness ceramic phase. Its high modulus characteristics can pin the crack tip, hindering further crack expansion and forming a synergistic reinforcement effect with Ti3SiC2.

[0033] (3) Promoting effect of Co binder phase

[0034] Co, as a metallic binder, forms a liquid phase during the sintering process, promoting the diffusion of Ti, Si, and C atoms and ensuring a uniform reaction. At the same time, Co fills the pores at the grain boundaries, improving the density and thermal stability of the alloy.

[0035] 3. Element ratio and performance regulation rules

[0036] The Si content (0.32~1.28wt%) directly controls the amount of Ti3SiC2 produced (0.83%~3.31%). Excessive Si will lead to an increase in the SiC ratio, and the ratio of the two needs to be balanced to achieve optimal performance.

[0037] The ratio of TiC to WC (15.53~17.12wt%TiC, 75.84~78.21wt%WC) ensures sufficient Ti and C sources while maintaining high hardness of the cemented carbide substrate.

[0038] The Co content (5.76~5.94wt%) optimizes the liquid phase sintering process and ensures material densification.

[0039] (3) Beneficial effects

[0040] 1. The preparation method of the present invention uniformly generates Ti3SiC2 inside YT15 cemented carbide through in-situ reaction, avoiding the problem of excessive impurity phases in traditional methods.

[0041] 2. During the in-situ reaction, the impurity phase generated is SiC, with a content of about 0.1~0.9wt%. Ti3SiC2 and a small amount of SiC are introduced into the YT15 cemented carbide system as a composite reinforcement phase to play the role of interface strengthening. The layered structure of Ti3SiC2 can relieve stress concentration, while the high modulus particles of SiC can inhibit crack propagation. The two synergistically improve the fracture toughness of the cemented carbide.

[0042] 3. The catalytic effect of Co optimizes the atomic diffusion path and ensures uniform distribution of the reinforcement phase.

[0043] 4. The hardness, fracture toughness, density, thermal stability and processing performance of the YT15 cemented carbide prepared by the method of the present invention are significantly improved, thereby optimizing its comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the microscopic morphology of the YT15 cemented carbide prepared in Example 2 of the present invention.

[0045] The black structure indicated by the arrow in the figure is the in-situ generated Ti3SiC2.

[0046] Figure 2 This is the element spectrum of YT15 cemented carbide prepared in Example 2 of the present invention.

[0047] This figure can intuitively show the mass fraction of each element in YT15 cemented carbide. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] Example 1

[0050] In situ generation of 1wt% Ti3SiC2 reinforced YT15 cemented carbide, the preparation steps are as follows:

[0051] S1, in terms of molar ratio, cemented carbide TiC powder and Si powder were taken in a ratio of 3:1, and mixed and ball-milled in a vacuum environment at a ball-milling speed of 400 rpm and a ball-milling time of 12 h; the particle size of the TiC powder was 25 μm, and the particle size of the Si powder was 22 μm.

[0052] S2, in terms of mass percentage, WC powder, Co powder, and TiC powder were weighed in a ratio of 79:6:15 and added to a ball mill for ball milling at a speed of 400 rpm for 12 h. The Fisher particle size of WC was 0.75 μm, the particle size of Co was 1.3 μm, and the particle size of TiC was 25 μm.

[0053] S3, taking 1 wt% of the total mass of the cemented carbide from the mixed powder obtained in S1 and 99 wt% of the mixed powder obtained in S2, adding them into a ball mill and mixing them at a ball milling speed of 400 rpm for 12 h, and adding anhydrous ethanol as a process control agent at a concentration of 2 wt% of the total mass of the cemented carbide;

[0054] S4, drying the mixed powder obtained in S3 in a drying oven at 100°C for 7.5h;

[0055] S5, pressing the dried mixed powder into a mold, and sintering it in a pressure sintering furnace at a sintering temperature of 1430° C. and a sintering time of 1.5 h to obtain an in-situ generated Ti3SiC2 reinforced YT15 cemented carbide.

[0056] Example 2

[0057] In-situ generation of 2wt% Ti3SiC2 reinforced YT15 cemented carbide

[0058] The difference between Example 2 and Example 1 is that in step S3, 2 wt% of the mixed powder obtained in S1 and 98 wt% of the mixed powder obtained in S2 are added to a ball mill for ball milling and mixing.

[0059] Example 3

[0060] In-situ generation of 3wt%Ti3SiC2 reinforced YT15 cemented carbide

[0061] The difference between Example 2 and Example 1 is that in step S3, 3 wt% of the mixed powder obtained in S1 and 97 wt% of the mixed powder obtained in S2 are added to a ball mill for ball milling and mixing.

[0062] Example 4

[0063] In-situ generation of 4wt%Ti3SiC2 reinforced YT15 cemented carbide

[0064] The difference between Example 2 and Example 1 is that in step S3, 4 wt% of the mixed powder obtained in S1 and 96 wt% of the mixed powder obtained in S2 are added to a ball mill for ball milling and mixing.

[0065] Comparative Example 1

[0066] Preparation of YT15 cemented carbide

[0067] In terms of mass percentage, 15wt% TiC powder (20μm particle size), 79wt% WC powder, and 6wt% Co powder were added to a ball mill and vacuum milled. 2wt% anhydrous ethanol was added as a process control agent. The milling speed was 400rpm and the milling time was 12h. After ball milling, the mixture was dried in a vacuum drying oven at 50°C for 12h. The mixture was then pressed into a mold and sintered in a pressure sintering furnace at 1430°C for 1.5h to obtain YT15 cemented carbide.

[0068] The cemented carbides obtained in the above five embodiments were subjected to XRD detection and composition analysis using a fixed target X-ray diffractometer (PANalyticalXPert PRO MPD). The cemented carbide composition analysis results and raw material ratios are shown in Table 1, and the properties are shown in Table 2:

[0069] Table 1 Cemented carbide composition analysis results and raw material ratios

[0070]

[0071] Table 2 Cemented carbide properties

[0072]

[0073] The data in Tables 1 and 2 show that as Si content increases, the Ti3SiC2 content rises from 0.83% to 3.31%, while the alloy's fracture toughness (KIC ≥ 12 MPa·m¹ / ²) significantly improves, with minimal change in hardness. Meanwhile, the alloy's flexural strength remains at or above 1759, confirming Si's dominant role in the reaction process. In Comparative Example 1 (no Si addition), no Ti3SiC2 is formed, and its fracture toughness and flexural strength significantly deteriorate.

[0074] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0075] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing in-situ generated Ti3SiC2-reinforced YT15 cemented carbide, characterized in that: The specific steps are as follows: S1, cemented carbide TiC powder and Si powder were mixed and ball-milled in a vacuum environment at a molar ratio of 3:1; S2, weighing WC powder, Co powder and TiC powder in a ratio of 79:6:15 by mass, adding them to a ball mill and mixing them; by adding nano-silicon, the mass percentages of the raw materials and components are changed; S3, taking 1-4 wt% of the total mass of the cemented carbide of the mixed powder obtained in S1 and 96-99 wt% of the mixed powder obtained in S2, adding them into a ball mill for ball milling, and adding 1-2 wt% of the total mass of the cemented carbide of anhydrous ethanol as a process control agent; S4, drying the mixed powder obtained in S3 in a drying oven; S5, pressing the dried mixed powder into a shape, and sintering it in a pressure sintering furnace at a sintering temperature of 1400~1600℃, and a sintering time of 1~3h. Ti3SiC2 is synthesized inside the YT15 cemented carbide through an in-situ reaction occurring during the sintering process, thereby obtaining an in-situ generated Ti3SiC2 reinforced YT15 cemented carbide. During the in-situ reaction, the impurity phase generated is SiC, and its content is 0.1~0.9wt%.

2. The method for preparing in-situ generated Ti3SiC2-reinforced YT15 cemented carbide according to claim 1, characterized in that: The particle size of the TiC powder in the S1 is 3 μm to 44 μm, and the particle size of the Si powder is 50 nm to 44 μm.

3. The method for preparing in-situ generated Ti3SiC2-reinforced YT15 cemented carbide according to claim 1, characterized in that: The Fisher grain size of WC in the S2 is 0.7-0.8 μm, the grain size of Co is 0.7-2 μm, and the grain size of TiC is 3-44 μm.

4. The method for preparing in-situ generated Ti3SiC2-reinforced YT15 cemented carbide according to claim 1, characterized in that: In S1, S2 and S3, the ball milling parameters are: carried out in a vacuum environment, the ball milling speed is 200-400 rpm, and the ball milling time is 3-12 hours.

5. The method for preparing in-situ generated Ti3SiC2-reinforced YT15 cemented carbide according to claim 1, characterized in that: The drying process in S4 is carried out in a vacuum environment, with a drying temperature of 50-100° C. and a drying time of 3-12 hours.

6. An in-situ generated Ti3SiC2 reinforced YT15 cemented carbide, characterized in that: The YT15 cemented carbide is prepared by the in-situ generated Ti3SiC2 reinforced preparation method described in any one of claims 1 to 5.

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