In-situ generated Ti3SiC2 reinforced YT15 hard alloy and preparation method thereof

Abstract

The invention discloses an in-situ generated Ti3SiC2 reinforced YT15 hard alloy and a preparation method thereof, and relates to the technical field of hard alloy preparation, the method comprises the following steps: taking WC powder, Co powder, TiC powder and Si powder as raw materials, carrying out ball-milling mixing, adding absolute ethyl alcohol as a process control agent, drying, carrying out compression molding, sintering in a pressure sintering furnace, and carrying out vacuum sintering to obtain the Ti3SiC2 reinforced YT15 hard alloy. Ti3SiC2 is synthesized in the YT15 hard alloy through an in-situ reaction generated in the sintering process, and the in-situ generated Ti3SiC2 reinforced YT15 hard alloy is obtained. In the sintering process, Ti3SiC2 is generated through in-situ reaction in the YT15 hard alloy, the hardness, the fracture toughness, the density, the thermal stability and the machining performance of the YT15 hard alloy can be improved, and therefore the comprehensive performance of the YT15 hard alloy is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy, and particularly to an in-situ generated Ti 3 SiC 2 reinforced YT15 cemented carbide and its preparation method. Background Technique

[0002] As a tungsten-titanium-cobalt cemented carbide (WC-TiC-Co), YT15 has a titanium carbide content of 15%, high hardness (≥91HRA) and excellent wear resistance, and is suitable for semi-finishing and finishing of carbon steel and alloy steel, especially outstanding in continuous cutting scenarios. Compared with YG cemented carbide, the addition of titanium carbide in YT15 reduces the affinity with steel during high-speed cutting, reduces the formation of built-up edge, and thus improves the machining surface quality. However, YT15 is relatively brittle and has poor impact resistance, making it difficult to adapt to interrupted cutting or high-impact load working 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] Ti 3 SiC 2 Combines the characteristics of metals and ceramics, such as high electrical conductivity (1 / 3 of copper), high thermal conductivity (37 - 43 W / cm·K), excellent thermal shock resistance (ΔT>1000℃) and high-temperature stability (oxidation resistance at 1200℃), and at the same time has self-lubricating properties and medium strength (326 - 350 MPa), and is suitable for fields such as high-temperature protective coatings and nuclear seals. However, currently in the synthesis process of Ti 3 SiC 2 due to the limitations of existing preparation technologies, impurities (such as TiC, SiC) are easily generated during the preparation process, and the layered structure results in low interlayer shear strength and significant macroscopic brittleness; moreover, the obtained Ti 3 SiC 2 alloy has lower wear resistance than traditional cemented carbide, and its performance needs to be improved through compounding.

[0004] Due to the contradiction between the high wear resistance of YT15 cemented carbide and its insufficient brittleness and temperature resistance, therefore, the above problems can be partially solved by introducing Ti 3 SiC 2 reinforcement phase. Summary of the Invention

[0005] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides an in-situ generated Ti 3 SiC 2 reinforced YT15 cemented carbide and its preparation method. By in-situ reaction, Ti 3 SiC2 During the in-situ reaction process, the impurity phase generated is SiC, with a content of about 0.1 - 0.9 wt%, and Ti 3 SiC 2 and a small amount of SiC are introduced as composite reinforcement phases into the YT15 cemented carbide system to play the role of interface strengthening. The layered structure of Ti 3 SiC 2 can relieve stress concentration, while the high-modulus particles of SiC can inhibit crack propagation. The two work together to improve the fracture toughness of the cemented carbide.

[0006] (II) Technical Solution To achieve the above objectives, the present invention is realized through the following technical solutions: A preparation method of in-situ generated Ti 3 SiC 2 reinforced YT15 cemented carbide, and the method is completed according to the following steps: S1. Taking cemented carbide TiC powder and Si powder in a molar ratio of 3:1, and performing ball milling in a vacuum environment; S2. Weighing WC powder, Co powder, and TiC powder in a mass percentage ratio of 79:6:15 and adding them to a ball milling tank for ball milling and mixing; it should be emphasized that the ratio of WC, Co, and TiC in the raw material powder is always 79:6:15, and by adding nano-silicon additionally, the mass percentages in the raw materials and components are changed; S3. Taking the mixed powder obtained in S1 accounting for 1 - 4 wt% of the total mass of the cemented carbide, and the mixed powder obtained in S2 accounting for 96 - 99 wt% of the total mass of the cemented carbide, adding them to a ball milling tank for ball milling and mixing, and adding 1 - 2 wt% of the total mass of the cemented carbide of absolute ethanol as a process control agent; S4. Drying the mixed powder obtained in S3 in a drying oven; S5. Compacting and molding the dried mixed powder, and sintering it in a pressure sintering furnace at a sintering temperature of 1400 - 1600 °C and a sintering time of 1 - 3 h. Through the in-situ reaction occurring during the sintering process, Ti 3 SiC 2 is synthesized inside the YT15 cemented carbide, 3 SiC 2 to obtain in-situ generated Ti

[0007] Preferably, the particle size of the TiC powder in S1 is 3 μm - 44 μm, and the particle size of the Si powder is 50 nm - 44 μm.

[0008] Preferably, in S2, the Fisher grain size of WC is 0.7 - 0.8 μm, the grain size of Co is 0.7 μm - 2 μm, and the grain size of TiC is 3 μm - 44 μm.

[0009] Preferably, in S1, S2 and S3, the ball milling parameters are as follows: carried out in a vacuum environment, the ball milling speed is 200 - 400 rpm, and the ball milling time is 3 - 12 h.

[0010] Preferably, in S4, the drying process is carried out in a vacuum environment, the drying temperature is 50 - 100 °C, and the drying time is 3 - 12 h.

[0011] Another object of the present invention is to provide an in-situ generated Ti3SiC2 reinforced YT15 cemented carbide, which is prepared by using the above-mentioned method for preparing an in-situ generated Ti 3 SiC 2 reinforced YT15 cemented carbide.

[0012] The interaction between elements and the in-situ generation mechanism of Ti 3 SiC 2 are as follows: 1. Element interaction and reaction path During the sintering process, TiC and Si in the raw materials undergo a solid-phase reaction at high temperature. The specific reaction path is as follows: TiC (providing Ti and C) directly reacts with Si at high temperature (1400 - 1600 °C) to generate Ti 3 SiC 2 : 3TiC + Si → Ti 3 SiC 2 When Si is in excess, part of it combines with C to form SiC impurity phase: Si + C → SiC The content of SiC increases with the increase of Si addition amount, verifying the existence of this side reaction.

[0013] 2. Microscopic strengthening mechanism of in-situ generation (1) The layered structure of Ti 3 SiC 2 relieves stress concentration Ti 3 SiC 2 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.

[0014] (2) SiC particles inhibit crack propagation The by-product SiC is a high-hardness ceramic phase. Its high modulus characteristic can pin the crack tip and hinder the further propagation of cracks, together with Ti 3 SiC 2 to form a synergistic strengthening effect.

[0015] (3)Promotion of Co binder phase As a metal binder phase, Co forms a liquid phase during sintering, promotes the diffusion of Ti, Si, and C atoms, and ensures uniform reaction. At the same time, Co fills the grain boundary pores, improving the density and thermal stability of the alloy.

[0016] 3. Element ratio and performance regulation law The Si content (0.32~1.28 wt%) directly controls the generation amount of Ti 3 SiC 2 (0.83%~3.31%). Excessive Si will lead to an increase in the proportion of SiC, and the ratio of the two needs to be balanced to achieve the best performance.

[0017] The ratio of TiC to WC (15.53~17.12 wt% TiC, 75.84~78.21 wt% WC) ensures sufficient Ti source and C source, while maintaining the high hardness of the cemented carbide matrix.

[0018] The Co content (5.76~5.94 wt%) optimizes the liquid phase sintering process and ensures material densification.

[0019] (III)Beneficial effects 1. In the preparation method of the present invention, Ti 3 SiC 2 is uniformly generated inside the YT15 cemented carbide through in-situ reaction, avoiding the problem of excessive impurity phases in the traditional method.

[0020] 2. During the in-situ reaction process, the generated impurity phase is SiC, with a content of about 0.1~0.9 wt%. Ti 3 SiC 2 and a small amount of SiC are introduced into the YT15 cemented carbide system as composite reinforcement phases to play an interface strengthening role. The layered structure of Ti 3 SiC 2 can relieve stress concentration, while the high modulus particles of SiC can inhibit crack propagation. The two work together to improve the fracture toughness of the cemented carbide.

[0021] 3. The catalytic effect of Co optimizes the atomic diffusion path and ensures uniform distribution of the reinforcement phase.

[0022] 4. The YT15 cemented carbide prepared by the method of the present invention has significantly improved hardness, fracture toughness, density, thermal stability, and machining performance, thus optimizing its comprehensive performance. Brief Description of the Drawings

[0023] Figure 1 is the microtopography of the YT15 cemented carbide prepared in Example 2 of the present invention.

[0024] The black tissue indicated by the arrow in the figure is in-situ generated Ti 3 SiC 2 .

[0025] Figure 2 is the elemental spectrogram of the YT15 cemented carbide prepared in Example 2 of the present invention.

[0026] Through this figure, the mass fractions of various elements in the YT15 cemented carbide can be visually seen. Detailed Description of the Invention

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of 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 of 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.

[0028] Example 1 In-situ generated 1wt% Ti 3 SiC 2 reinforced YT15 cemented carbide, the preparation steps are as follows: S1, in terms of molar ratio, take cemented carbide TiC powder and Si powder in a ratio of 3:1, and carry out ball milling in a vacuum environment, with a ball milling speed of 400 rpm and a ball milling time of 12 h; the particle size of the TiC powder is 25 μm, and the particle size of the Si powder is 22 μm.

[0029] S2, in terms of mass percentage, weigh WC powder, Co powder and TiC powder in a ratio of 79:6:15 and add them to the ball milling tank for ball milling and mixing, with a ball milling speed of 400 rpm and a ball milling time of 12 h; the Fisher particle size of WC is 0.75 μm, the particle size of Co is 1.3 μm, and the particle size of TiC is 25 μm; S3, in terms of mass percentage, take 1wt% of the mixed powder obtained in S1 and 99wt% of the mixed powder obtained in S2 based on the total mass of the cemented carbide, add them to the ball milling tank for ball milling and mixing, with a ball milling speed of 400 rpm and a ball milling time of 12 h, and add 2wt% of the total mass of the cemented carbide of absolute ethanol as a process control agent; S4, dry the mixed powder obtained in S3 in a drying oven at 100 °C for 7.5 h; S5. Compact the dried mixed powder and sinter it in a pressure sintering furnace at a sintering temperature of 1430 °C for 1.5 h to obtain in-situ generated Ti 3 SiC 2 reinforced YT15 cemented carbide.

[0030] Example 2 In-situ generated 2 wt% Ti 3 SiC 2 reinforced YT15 cemented carbide The distinguishing feature of this Example 2 from Example 1 is that in step S3, take the mixed powder obtained in S1 accounting for 2 wt% of the total mass of the cemented carbide and the mixed powder obtained in S2 accounting for 98 wt%, add them to a ball milling tank for ball milling and mixing.

[0031] Example 3 In-situ generated 3 wt% Ti 3 SiC 2 reinforced YT15 cemented carbide The distinguishing feature of this Example 2 from Example 1 is that in step S3, take the mixed powder obtained in S1 accounting for 3 wt% of the total mass of the cemented carbide and the mixed powder obtained in S2 accounting for 97 wt%, add them to a ball milling tank for ball milling and mixing.

[0032] Example 4 In-situ generated 4 wt% Ti 3 SiC 2 reinforced YT15 cemented carbide The distinguishing feature of this Example 2 from Example 1 is that in step S3, take the mixed powder obtained in S1 accounting for 4 wt% of the total mass of the cemented carbide and the mixed powder obtained in S2 accounting for 96 wt%, add them to a ball milling tank for ball milling and mixing.

[0033] Comparative Example 1 Prepare YT15 cemented carbide By mass percentage, take 15 wt% TiC powder with a powder particle size of 20 μm, 79 wt% WC powder, and 6 wt% Co powder, add them to a ball milling tank for vacuum ball milling, add 2 wt% absolute ethanol as a process control agent, with a ball milling speed of 400 rpm and a ball milling time of 12 h; after ball milling, take the mixed material and dry it in a vacuum drying oven at a drying temperature of 50 °C for 12 h. Compact the mixed material and then place it in a pressure sintering furnace for sintering at a sintering temperature of 1430 °C for 1.5 h to obtain YT15 cemented carbide.

[0034] The cemented carbides obtained in the above 5 examples were subjected to XRD detection on a fixed target X-ray diffractometer (PANalytical XPert PRO MPD) and their compositions were analyzed. The results of the cemented carbide composition analysis and the raw material ratios are shown in Table 1, and the properties are shown in Table 2: Table 1 Results of the Cemented Carbide Composition Analysis and the Raw Material Ratios

[0035] Table 2 Properties of the Cemented Carbide

[0036] It can be seen from the data in Table 1 and Table 2 that as the Si content increases, the Ti 3 SiC 2 content increases from 0.83% to 3.31%. At the same time, the fracture toughness of the alloy (KIC≥12 MPa·m¹ / ²) is significantly improved, the hardness of the alloy changes little, and the flexural strength of the alloy also remains at 1759 or above, confirming the dominant role of Si in the reaction process. In Comparative Example 1 (without Si addition), no Ti 3 SiC 2 is formed, and its fracture toughness and flexural strength properties deteriorate significantly.

[0037] The description of the above examples is only used to help understand the method and core idea of the present invention. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0038] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these 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 will be accorded 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, taking cemented carbide TiC powder and Si powder in a ratio of 3:1 in terms of molar ratio, and mixing and ball milling them in a vacuum environment; S2, weigh WC powder, Co powder and TiC powder in a ratio of 79:6:15 by mass percentage, add them into a ball mill and mix them; S3, taking 1-4wt% of the total mass of the cemented carbide mixed powder obtained in S1 and 96-99wt% of the mixed powder obtained in S2, adding them into a ball mill for ball milling, and adding 1-2wt% of the total mass of the cemented carbide 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, sintering it in a pressure sintering furnace, the sintering temperature is 1400~1600℃, the sintering time is 1~3h, and Ti3SiC2 is synthesized inside the YT15 cemented carbide through the in-situ reaction occurring during the sintering process, thereby obtaining the YT15 cemented carbide reinforced with in-situ generated Ti3SiC2.

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 under vacuum environment, ball milling speed is 200-400 rpm, and ball milling time is 3-12 h.

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.

Images