CN111485155A - (Ti,W)C-based cermet tool material with alumina-coated cubic boron nitride composite powder and preparation method thereof - Google Patents

Abstract

The invention relates to a (Ti, W) C-based metal ceramic cutting tool material added with alumina coated cubic boron nitride composite powder and a preparation method thereof, wherein the cutting tool material is prepared by hot-pressing and sintering the following main raw materials in percentage by mass: 2-8% of cobalt, 1-5% of nickel, 5-10% of molybdenum, 1-20% of alumina-coated cubic boron nitride composite powder and the balance of (Ti, W) C; the sum of the mass percentages of the components is 100 percent. The cutting tool material of the invention forms Al with (Ti, W) C as a ceramic matrix, C-BN as a core₂O₃A multi-layer core-shell microstructure with an intermediate layer and a metal phase as a shell; effectively improves the compactness of the cutter material, relieves the stress concentration and gold of the internal interface of the cutterThe method belongs to the problem of abnormal growth of ceramic grains, solves the problem of reduced mechanical property caused by the transformation of c-BN to h-BN at high temperature, and the obtained cutter material has better mechanical property, particularly greatly improved bending strength and fracture toughness.

Description

(Ti,W)C-based cermet with alumina-coated cubic boron nitride composite powder Tool material and preparation method thereof

Background technique

(Ti,W)C-based cermet material is a new type of solid solution-based cermet developed on the basis of WC-Co series cemented carbide and TiC-Ni series cermet; it is based on (Ti,W)C The hard phase is a kind of composite material in which refractory metal carbides or nitrides such as WC and TaC are added at the same time, and cobalt, nickel, etc. are used as binders. Compared with the traditional WC-Co-based cemented carbide, the (Ti,W)C-based cermet tool has good high temperature red hardness, wear resistance, thermal stability, oxidation resistance and adhesion resistance at 700 ~ 1100 ℃ , high cutting temperature, its cutting speed and service life are increased by 3 to 10 times and 2 to 5 times respectively, and the main raw material resources are abundant and the cost is low. Compared with TiC-Ni-based cermet materials, the presence of WC in (Ti,W)C solid solution makes the wettability of hard particles and binder phase better (the wetting angle of TiC and Ni at 1450 °C under vacuum conditions). is 30°, while the wetting angle of WC and Ni under the same conditions is 0°). Compared with Ti(C,N)-based cermet materials, (Ti,W)C does not contain N element, so there is no problem of denitrification during high-temperature sintering of Ti(C,N)-based cermets, resulting in increased porosity and decreased strength . Therefore, (Ti,W)C-based cermets are regarded as hard composite materials with great development potential.

Chinese patent document CN106316398A discloses a tungsten carbide-titanium-based ceramic tool material added with cubic boron nitride and a preparation method thereof. The mass percentage of the raw material components of the tool material is: micron tungsten carbide titanium 80-84%, nano-cubic boron nitride 1-5%, nano-cobalt 15%; the invention uses cubic boron nitride as a reinforcing phase to achieve particle dispersion enhancement Effect. However, at high temperature, cubic boron nitride is prone to phase transition to hexagonal boron nitride, which will cause the problem of reduced mechanical properties; due to thermal expansion mismatch, the direct addition of cubic boron nitride will easily lead to large internal stress in the tool material and poor mechanical properties. high. Chinese patent document CN106904947A discloses a self-lubricating ceramic tool material with h-BN@Ni core-shell structure composite powder added and a preparation method thereof; the mass percentage of each raw material component is: α-Al ₂ O ₃ 25-45 %, (W,Ti)C 50-70%, nickel-coated hexagonal boron nitride composite powder 2-10% by mass of h-BN, MgO 0.4-1.5%. The invention can greatly improve the fracture toughness of self-lubricating ceramic tool materials and reduce the sintering temperature of ceramic tool materials; however, the mechanical properties of hexagonal boron nitride are poor, and the hardness of the metal phase is low. The good fracture toughness of metal improves the overall fracture toughness of the tool material, but does not solve the problem of low flexural strength and hardness, and has poor performance as a tool.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the present invention provides a (Ti,W)C-based cermet tool material with alumina-coated cubic boron nitride composite powder and a preparation method thereof. The present invention forms a ceramic matrix with (Ti, W)C as the ceramic matrix, c-BN as the core, and Al ₂ O ₃ as the intermediate layer by adding alumina to coat the cubic boron nitride composite powder and the metal binder phases of molybdenum, nickel and cobalt. , The multilayer core-shell microstructure with the metal binder phase as the shell; the obtained multilayer core-shell microstructure improves the compactness of the tool material and alleviates the problem of interfacial stress concentration inside the (Ti,W)C-based cermet tool and the cermet. The problem of abnormal growth of grains was successfully solved, and the problem of the phase transition of c-BN to h-BN at higher temperature resulted in the reduction of mechanical properties. Compared with no coating (that is, directly adding c-BN, Al ₂ O ₃ and metal binder phase), the mechanical properties of the obtained tool materials are improved, especially the flexural strength and fracture toughness are greatly improved.

Terminology Description:

c-BN@Al(OH) ₃ : short for aluminum hydroxide-coated cubic boron nitride composite powder;

c-BN@Al ₂ O ₃ : Abbreviation for alumina-coated cubic boron nitride composite powder.

The technical scheme of the present invention is as follows:

A (Ti,W)C-based cermet tool material added with alumina-coated cubic boron nitride composite powder is formed by hot pressing and sintering the following main raw materials by mass percentage:

Cobalt 2-8%, nickel 1-5%, molybdenum 5-10%, alumina-coated cubic boron nitride composite powder 1-20%, the rest is (Ti, W)C; the sum of the mass percentages of each component is 100%;

Wherein, the alumina-coated cubic boron nitride composite powder is prepared by the following method:

Disperse c-BN in absolute ethanol solution to obtain mixed solution 1; disperse sodium lauryl sulfate and polyethylene glycol in absolute ethanol to obtain mixed solution 2; fully mix mixed solution 1 and mixed solution 2 , react at 70～80℃ for 50～60min, and obtain modified c-BN powder after cooling, centrifugation, washing and drying;

Disperse modified c-BN powder in absolute ethanol to obtain c-BN dispersion; disperse Al(NO ₃ ) ₃ and polyethylene glycol in a mixed solution containing water, xylene and absolute ethanol to obtain Al (NO ₃ ) ₃ solution; add the Al(NO ₃ ) ₃ solution to the c-BN dispersion, mix well, add ammonia water dropwise to adjust the pH value to 7, react at 70～80℃ for 20～40min, and separate by centrifugation , washing and drying to obtain c-BN@Al(OH) ₃ ; and then calcined at 900-1200° C. under the protection of inert gas to obtain alumina-coated cubic boron nitride composite powder.

Preferably according to the present invention, the (Ti,W)C-based cermet tool material is formed by hot pressing and sintering the main raw materials in the following weight percentages: cobalt 3-6%, nickel 2-4%, molybdenum 5-8% %, the alumina-coated cubic boron nitride composite powder is 5-15%, and the rest is (Ti, W)C; the sum of the weight percentages of each component is 100%.

Preferably according to the present invention, the average particle size of the alumina-coated cubic boron nitride composite powder is 0.3-1.5 μm, the average particle size of (Ti, W)C is 2-5 μm, and the average particle size of molybdenum, cobalt, and nickel is 0.3-1.5 μm. The average particle size is 1-3 μm.

The above-mentioned preparation method of (Ti,W)C-based cermet tool material with alumina-coated cubic boron nitride composite powder added, comprising the steps of:

(1) Polyethylene glycol is dispersed in absolute ethanol to form polyethylene glycol-absolute ethanol dispersion; (Ti, W)C, molybdenum, cobalt, nickel are dispersed in polyethylene glycol-anhydrous successively ethanol dispersion, and then ball-milled for 40-80h under the protection of inert gas to prepare composite powder dispersion;

(2) disperse c-BN in absolute ethanol solution to obtain mixed solution 1; disperse sodium lauryl sulfate and polyethylene glycol in absolute ethanol to obtain mixed solution 2; mix mixed solution 1 and mixed solution 2 Mix thoroughly, react at 70～80℃ for 50～60min, and obtain modified c-BN powder after cooling, centrifugation, washing and drying;

(3) Disperse modified c-BN powder in absolute ethanol to obtain c-BN dispersion; Disperse Al(NO ₃ ) ₃ and polyethylene glycol in a mixed solution containing water, xylene and absolute ethanol Al(NO ₃ ) ₃ solution was obtained in the solution; the Al(NO ₃ ) ₃ solution was added to the c-BN dispersion, mixed evenly, and the pH value was adjusted to 7 by adding ammonia water dropwise, and the reaction was carried out at 70-80 ℃ for 20-40 min, After centrifugation, washing and drying, c-BN@Al(OH) ₃ was obtained; then, under the protection of inert gas, it was calcined at 900-1200 ℃ for 1-3 hours to obtain alumina-coated cubic boron nitride composite powder;

(4) Dispersing the alumina-coated cubic boron nitride composite powder in a polyethylene glycol-absolute ethanol solution to obtain a mixed solution; adding the mixed solution to the composite powder dispersion obtained in step (1), in Continue ball milling for 1-3 hours under the protection of inert gas; obtain mixed powder after drying and sieving;

(5) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti,W)C-based cermet tool material.

Preferably according to the present invention, in steps (1)-(4), the weight average molecular weights of the polyethylene glycols are all 2000-8000; preferably, the weight average molecular weights of the polyethylene glycols are all 4000-6000 .

Preferably according to the present invention, in the polyethylene glycol-absolute ethanol dispersion in step (1), the concentration of polyethylene glycol is 1-5 g/L, preferably 2-4 g/L.

Preferably according to the present invention, in step (1), the mass content of (Ti, W)C in the composite powder dispersion liquid is 0.2-1 g/mL.

Preferably according to the present invention, in step (1), the ball milling time is 48-60h, the ball milling is made of hard alloy balls, and the mass ratio of the balls to the material is 5-15:1.

Preferably according to the present invention, in step (2) mixed solution 1, the mass concentration of c-BN is 0.006-0.009g/mL; the mass ratio of c-BN, sodium dodecyl sulfate and polyethylene glycol is 2- 4:1-2:1; in mixed solution 2, the mass concentration of polyethylene glycol is 0.006-0.008g/ml.

Preferably according to the present invention, in step (2), the average particle size of the c-BN is 0.1-0.3 μm.

Preferably according to the present invention, in step (3) the c-BN dispersion liquid, the mass concentration of the modified c-BN powder is 0.01-0.04 g/mL.

Preferably according to the present invention, in step (3), the volume ratio of water, xylene and absolute ethanol in the mixed solution containing water, xylene and absolute ethanol is 1:2:7; the Al(NO) ₃ The mass ratio of the mixed solution containing water, xylene and absolute ethanol is 0.01-0.03 g/mL; the mass of polyethylene glycol is 3-8% of the mass of Al(NO) ₃ .

Preferably according to the present invention, in step (3), the mass ratio of the c-BN and Al(NO) ₃ is 1:1.1-1:1.5.

Preferably according to the present invention, in step (3), the concentration of the ammonia water is 0.2-0.4 mol/L.

Preferably according to the present invention, the mass ratio of the alumina-coated cubic boron nitride composite powder and polyethylene glycol in step (4) is 15:1-20:1; the alumina-coated cubic nitrogen in the mixed solution The mass concentration of the boron compound powder is 0.05-0.20 g/mL.

According to a preferred embodiment of the present invention, in step (4), the ball milling is made of hard alloy balls, and the mass ratio of the balls to the material is 10-20:1.

Preferably according to the present invention, in step (4), the sieving mesh is 200-300 meshes.

Preferably according to the present invention, in step (4), the drying is vacuum drying at 100-110° C. for 24-36 hours.

Preferably according to the present invention, in step (5), the hot-pressing sintering conditions are: the sintering temperature is 1450-1550°C, the hot-pressing pressure is 25-35MPa, the holding time is 20-40min, and the heating rate is 10-25°C/ min, the vacuum degree range is 5～7×10 ^-2 Pa.

Technical characteristics and beneficial effects of the present invention:

1. The present invention provides a novel (Ti,W)C-based cermet tool material with a multi-layer core-shell microstructure with excellent mechanical properties. The present invention uses alumina-coated cubic boron nitride composite powder as an additive phase. The composite cermet tool material was prepared by adding it into (Ti,W)C-based cermet tool material, using Mo-Co-Ni as the bonding phase, and vacuum hot pressing sintering. The tool material of the invention forms a multi-layer core-shell microstructure with c-BN as the core, Al ₂ O ₃ as the intermediate layer, and the metal bonding phase as the shell, which improves the compactness of the tool material. Taking advantage of the low thermal expansion coefficient and high elastic modulus of the c-BN core, residual compressive stress is formed inside the c-BN particles, which relieves the stress concentration at the interface; the c-BN particles are coated with an Al ₂ O ₃ interlayer. It can not only inhibit the phase transition of c-BN to h-BN at higher temperature and ensure the high mechanical properties of cubic boron nitride; it can also improve the sintering performance of c-BN by virtue of the excellent sintering performance of Al ₂ O ₃ . In addition to serving as the bonding phase of the tool, the shell metal phase can also inhibit the abnormal growth of nano-Al ₂ O ₃ ceramic particles through the heterogeneous coating effect; it forms a shell with a multi-layer core-shell microstructure under the action of high-temperature liquid phase diffusion. , preventing the merging and growing of grains, and solving the problem of abnormal growth of cermet grains. In addition, the Al ₂ O ₃ intermediate layer and the metal binder phase serve as the outer shell, and at the same time alleviate the problems of thermal expansion mismatch and stress concentration in the internal interface of the tool caused by the direct addition of cubic boron nitride, thereby improving the mechanical properties.

2. The tool material obtained by the invention has excellent mechanical properties, the hardness can reach 21.68GPa, the fracture toughness can reach 13.25MPa·m ^1/2 , and the bending strength can reach 1021MPa; BN, Al ₂ O ₃ and metal binder phase), the mechanical properties of the obtained tool material are improved, especially the flexural strength and fracture toughness are greatly improved by about 41% and 81% respectively. The tool material of the invention is used for cutting, has good tool life, and has low surface roughness of the processed workpiece.

Description of drawings

Fig. 1 is the scanning electron microscope photograph of the alumina-coated cubic boron nitride composite powder prepared in Example 1;

Fig. 2 is a photo of energy spectrum analysis of alumina-coated cubic boron nitride composite powder prepared in Example 1;

FIG. 3 is a SEM photograph of the fracture surface of the (Ti,W)C-based cermet tool material prepared in Example 1. FIG.

Detailed ways

The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

The methods are conventional methods unless otherwise specified, and the reagents can be obtained commercially unless otherwise specified.

Example 1

A (Ti,W)C-based cermet tool material added with alumina-coated cubic boron nitride composite powder is formed by hot pressing and sintering the following main raw materials by mass percentage:

Alumina-coated cubic boron nitride composite powder 10%, nickel 3.5%, molybdenum 6.5%, cobalt 5%, and the rest is (Ti,W)C; the sum of the mass percentages of each component is 100%;

The preparation steps are as follows:

(1) Disperse 0.4g polyethylene glycol (weight-average molecular weight of 4000) in 200mL of absolute ethanol for mechanical stirring and ultrasonic dispersion for 30min, and configure a polyethylene glycol-absolute ethanol dispersion with a concentration of 2g/L ; Then weigh tungsten carbide titanium, nickel, molybdenum and cobalt in turn according to the proportion and add in polyethylene glycol-absolute ethanol dispersion, mechanically stir and ultrasonically disperse for 30min, then ball mill at room temperature for 60h under nitrogen protection (ball milling adopts hard The ball milling ball of alloy material, the mass ratio of ball milling ball and material is 15:1), the composite powder dispersion liquid is prepared, and the mass content of (Ti, W)C in the composite powder dispersion liquid is 0.3g/mL; The composite powder dispersion is stored in a ball mill tank for later use.

(2) Under the conditions of mechanical stirring and ultrasonic dispersion, weigh 4 g of cubic boron nitride c-BN (average particle size is 0.2 μm) and disperse it in 500 mL of anhydrous ethanol solution to obtain mixed solution 1. According to c-BN , The mass ratio of sodium lauryl sulfate and polyethylene glycol (weight average molecular weight is 4000) is 3: 1.5: 1. Sodium lauryl sulfate and polyethylene glycol are dispersed in 200mL of absolute ethanol successively. The mixed solution 2 is obtained in the middle, the mixed solution 1 and the mixed solution 2 are fully mixed, and the reaction is carried out at 75 ° C for 60 min, and the modified c-BN powder is obtained by cooling, centrifugation, washing and drying;

(3) Under the condition of mechanical stirring and ultrasonic dispersion, disperse 4g of modified c-BN powder in 200mL of absolute ethanol to obtain c-BN dispersion; according to the mass ratio of c-BN and Al(NO ₃ ) ₃ : 1:1.5 Weigh Al(NO ₃ ) ₃ and disperse it with polyethylene glycol in 300 mL of a mixed solution containing water, xylene and absolute ethanol (the volume ratio of water, xylene and absolute ethanol is 1:2: 7) to obtain an Al(NO ₃ ) ₃ solution, the weight-average molecular weight of the polyethylene glycol used is 4000, and its mass is 5% of the Al(NO ₃ ) ₃ mass; and the Al(NO ₃ ) ₃ solution is slowly added to the solution. In the c-BN dispersion, mix evenly, add 0.3 mol/L ammonia water dropwise to adjust the pH value to 7, react at 75 °C for 30 min, centrifuge, wash and dry to obtain c-BN@Al(OH) ₃ ; and then calcined at 1100 °C for 2 h under nitrogen protection to obtain alumina-coated cubic boron nitride composite powder;

(4) Weigh the alumina-coated cubic boron nitride composite powder according to the proportion and disperse it in 100 mL of polyethylene glycol (weight average molecular weight is 4000)-absolute ethanol to obtain a mixed solution, and alumina-coated cubic boron nitride The mass ratio of the composite powder and polyethylene glycol is 15:1, and the mass concentration of the alumina-coated cubic boron nitride composite powder in the mixed solution is 0.08 g/mL; the above-mentioned mixed solution is added to the ball milling of step (1). In the tank, continue ball milling at room temperature for 2 hours under nitrogen protection. The ball milling adopts the ball milling ball made of cemented carbide, and the mass ratio of the ball milling ball to the material is 15:1; finally, it is vacuum dried at 110 °C for 24 hours, and sieved with a 200-mesh sieve. to obtain mixed powder;

(5) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti, W)C-based cermet tool material. The hot-pressed sintering conditions are: the sintering temperature is 1500° C., the hot-pressing pressure is 30MPa, and the holding time is 30min, the heating rate was 20°C/min, and the vacuum degree was 6×10 ^-2 Pa.

The (Ti,W)C-based cermet tool material blank obtained in this example is prepared into a 3mm×4mm×30mm ceramic spline through the steps of cutting-rough grinding-fine grinding-grinding-polishing, and its mechanical properties are measured as follows: hardness 21.68GPa, fracture toughness 13.25MPa·m ^1/2 , flexural strength 1021MPa.

The scanning electron microscope photo of the alumina-coated cubic boron nitride composite powder prepared in this example is shown in Figure 1. It can be seen from the figure that a uniform nanoparticle coating layer is formed on the surface of the cubic boron nitride powder;

The energy spectrum analysis photo of the alumina-coated cubic boron nitride composite powder prepared in this example is shown in Figure 2. It can be seen from the figure that the composite powder only contains the elements of alumina and cubic boron nitride, and no other impurities. element introduction;

The SEM photo of the fracture surface of the (Ti,W)C-based cermet tool material prepared in this example is shown in Figure 3. It can be seen from the figure that the alumina-coated cubic boron nitride composite powder with the core-shell structure still remains after sintering. With a core-shell structure, cubic boron nitride is located inside the alumina grains.

Example 2

A (Ti,W)C-based cermet tool material added with alumina-coated cubic boron nitride composite powder is formed by hot pressing and sintering the following main raw materials by mass percentage:

Alumina-coated cubic boron nitride composite powder 5%, nickel 4%, molybdenum 6%, cobalt 5%, and the rest is (Ti, W)C; the sum of the mass percentages of each component is 100%;

The preparation steps are as follows:

(1) Disperse 0.4g polyethylene glycol (weight-average molecular weight of 4000) in 200mL of absolute ethanol for mechanical stirring and ultrasonic dispersion for 30min, and configure a polyethylene glycol-absolute ethanol dispersion with a concentration of 2g/L ; Then weigh tungsten carbide titanium, nickel, molybdenum and cobalt in turn according to the proportion and add in polyethylene glycol-absolute ethanol dispersion, mechanically stir and ultrasonically disperse for 40min, then ball mill at room temperature for 50h under nitrogen protection (ball milling adopts hard The ball milling ball of alloy material, the mass ratio of ball milling ball and material is 15:1), the composite powder dispersion liquid is prepared, and the mass content of (Ti, W)C in the composite powder dispersion liquid is 0.48g/mL; The composite powder dispersion is stored in a ball mill tank for later use.

(2) Under the conditions of mechanical stirring and ultrasonic dispersion, weigh 3 g of cubic boron nitride c-BN (average particle size is 0.2 μm) and disperse it in 500 mL of anhydrous ethanol solution to obtain mixed solution 1. According to c-BN , The mass ratio of sodium lauryl sulfate and polyethylene glycol (weight average molecular weight is 4000) is the ratio of 3:2:1, and sodium lauryl sulfate and polyethylene glycol are dispersed in 200mL absolute ethanol successively The mixed solution 2 is obtained in the middle, the mixed solution 1 and the mixed solution 2 are fully mixed, and the reaction is carried out at 80 ° C for 50 min, and the modified c-BN powder is obtained by cooling, centrifugation, washing and drying;

(3) Under the conditions of mechanical stirring and ultrasonic dispersion, 3 g of modified c-BN powder was dispersed in 200 mL of absolute ethanol to obtain a c-BN dispersion; according to the mass ratio of c-BN and Al(NO ₃ ) ₃ , 1:1.2 Weigh Al(NO ₃ ) ₃ and disperse it with polyethylene glycol in 300 mL of a mixed solution containing water, xylene and absolute ethanol (the volume ratio of water, xylene and absolute ethanol is 1:2: 7) to obtain an Al(NO ₃ ) ₃ solution, the weight-average molecular weight of the polyethylene glycol used is 4000, and its mass is 6% of the Al(NO ₃ ) ₃ mass; and the Al(NO ₃ ) ₃ solution is slowly added to the In the c-BN dispersion, mix evenly, add dropwise ammonia water with a mass concentration of 0.3 mol/L to adjust the pH to 7, react at 80 °C for 20 min, and obtain c-BN@Al(OH) ₃ by centrifugation, washing and drying. ; and then calcined at 1100 °C for 2 h under nitrogen protection to obtain alumina-coated cubic boron nitride composite powder;

(4) Weigh the alumina-coated cubic boron nitride composite powder according to the proportion and disperse it in 100 mL of polyethylene glycol (weight average molecular weight is 4000)-absolute ethanol to obtain a mixed solution, and alumina-coated cubic boron nitride The mass ratio of the composite powder and polyethylene glycol is 15:1, and the mass concentration of the alumina-coated cubic boron nitride composite powder in the mixed solution is 0.08 g/mL; the above-mentioned mixed solution is added to the ball milling of step (1). In the tank, continue ball milling at room temperature for 3 hours under nitrogen protection. The ball milling adopts the ball milling ball made of cemented carbide, and the mass ratio of the ball milling ball to the material is 15:1; finally, it is vacuum-dried at 110 °C for 24 hours and sieved with a 200-mesh sieve. to obtain mixed powder;

(5) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti, W)C-based cermet tool material. The hot-pressed sintering conditions are: the sintering temperature is 1450° C., the hot-pressing pressure is 35MPa, and the holding time is 30min, the heating rate was 15°C/min, and the vacuum degree was 6×10 ^-2 Pa.

The (Ti,W)C-based cermet tool material blank obtained in this example is prepared into a 3mm×4mm×30mm ceramic spline through the steps of cutting-rough grinding-fine grinding-grinding-polishing, and its mechanical properties are measured as follows: hardness 20.31GPa, fracture toughness 12.46MPa·m ^1/2 , flexural strength 977MPa.

Example 3

A (Ti,W)C-based cermet tool material added with alumina-coated cubic boron nitride composite powder is formed by hot pressing and sintering the following main raw materials by mass percentage:

The alumina-coated cubic boron nitride composite powder is 15%, nickel 3%, molybdenum 6%, cobalt 6%, and the rest is (Ti, W)C; the sum of the mass percentages of each component is 100%;

The preparation steps are as follows:

(1) Disperse 0.8g polyethylene glycol (weight-average molecular weight is 4000) in 200mL of absolute ethanol, mechanically stir and ultrasonically disperse for 30min, and configure a polyethylene glycol-absolute ethanol dispersion with a concentration of 2g/L ; Then weigh tungsten carbide titanium, nickel, molybdenum and cobalt in turn according to the proportion and add in polyethylene glycol-absolute ethanol dispersion, mechanically stir and ultrasonically disperse for 30min, then ball mill at room temperature for 70h under nitrogen protection (ball milling adopts hard The ball milling ball of alloy material, the mass ratio of ball milling ball and material is 15:1), the composite powder dispersion liquid is prepared, and the mass content of (Ti, W)C in the composite powder dispersion liquid is 0.35g/mL; The composite powder dispersion is stored in a ball mill tank for later use.

(2) Under the condition of mechanical stirring and ultrasonic dispersion, weigh 4.5g cubic boron nitride c-BN (average particle size is 0.2μm) and disperse it in 500mL absolute ethanol solution to obtain mixed solution 1, according to c- The mass ratio of BN, sodium lauryl sulfate and polyethylene glycol (weight average molecular weight is 4000) is 2.5:1.5:1. Sodium lauryl sulfate and polyethylene glycol are dispersed in 200mL anhydrous in turn. Mixing liquid 2 is obtained from ethanol, fully mixing mixed liquid 1 and mixed liquid 2, reacting at 70 ° C for 60 min, and obtaining modified c-BN powder after cooling, centrifugation, washing and drying;

(3) Under the conditions of mechanical stirring and ultrasonic dispersion, 4.5g of modified c-BN powder was dispersed in 200mL of absolute ethanol to obtain c-BN dispersion; according to the mass ratio of c-BN and Al(NO ₃ ) ₃ Weigh Al(NO ₃ ) ₃ for 1:1.1, and disperse it with polyethylene glycol in 250 mL of mixed solution containing water, xylene and absolute ethanol (the volume ratio of water, xylene and absolute ethanol is 1:2 Al(NO ₃ ) ₃ solution was obtained in 7), the weight-average molecular weight of the polyethylene glycol used was 4000, and its mass was 5% of the Al(NO ₃ ) ₃ mass; and the Al(NO 3 ) ₃ solution was slowly added to the In the c-BN dispersion, mix evenly, add dropwise ammonia water with a mass concentration of 0.3 mol/L to adjust the pH value to 7, react at 70 °C for 30 min, and obtain c-BN@Al(OH) ₃ by centrifugation, washing and drying. ; and then calcined at 1100 °C for 2 h under nitrogen protection to obtain alumina-coated cubic boron nitride composite powder;

(4) Weigh the alumina-coated cubic boron nitride composite powder according to the proportion and disperse it in 100 mL of polyethylene glycol (weight average molecular weight is 4000)-absolute ethanol to obtain a mixed solution, and alumina-coated cubic boron nitride The mass ratio of the composite powder and polyethylene glycol is 15:1, and the mass concentration of the alumina-coated cubic boron nitride composite powder in the mixed solution is 0.15 g/mL; the above-mentioned mixed solution is added to the ball milling of step (1). In the tank, continue ball milling at room temperature for 1.5 hours under nitrogen protection. The ball milling adopts the ball milling ball made of cemented carbide, and the mass ratio of the ball milling ball to the material is 10:1; finally, it is vacuum-dried at 110 °C for 24 hours and passed through a 200-mesh sieve. Sieve to obtain mixed powder;

(5) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti, W)C-based cermet tool material. The hot-pressed sintering conditions are: the sintering temperature is 1500° C., the hot-pressing pressure is 35MPa, and the holding time is 25min, the heating rate was 20°C/min, and the vacuum degree was 6×10 ^-2 Pa.

The (Ti,W)C-based cermet tool material blank obtained in this example is prepared into a 3mm×4mm×30mm ceramic spline through the steps of cutting-rough grinding-fine grinding-grinding-polishing, and its mechanical properties are measured as follows: hardness 20.93GPa, fracture toughness 11.72MPa·m ^1/2 , flexural strength 993MPa.

Comparative Example 1

A (Ti,W)C-based metal ceramic tool material is formed by hot pressing and sintering the following main raw materials by mass percentage:

Cubic boron nitride 10%, nickel 3.5%, molybdenum 6.5%, cobalt 5%, the rest is (Ti, W)C; the sum of the mass percentages of each component is 100%;

The preparation steps are as follows:

(1) Disperse 0.6 g polyethylene glycol (weight average molecular weight of 4000) in 300 mL of absolute ethanol for mechanical stirring and ultrasonic dispersion for 30 min, and configure a polyethylene glycol-absolute ethanol dispersion with a concentration of 2 g/L ; Then weigh tungsten carbide titanium, nickel, molybdenum, cobalt and cubic boron nitride in sequence according to the proportions and add them to the polyethylene glycol-absolute ethanol dispersion, mechanically stir and ultrasonically disperse for 30 minutes, and then ball-mill at room temperature for 60 hours under nitrogen protection (The ball milling adopts the ball milling ball made of cemented carbide, and the mass ratio of the ball milling ball and the material is 15:1), and finally the mixed powder is obtained by vacuum drying at 110 ° C for 24 hours and sieving through a 200-mesh sieve;

(2) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti, W)C-based cermet tool material. The hot-pressed sintering conditions are: the sintering temperature is 1500° C., the hot-pressing pressure is 30MPa, and the holding time is 30min, the heating rate was 20°C/min, and the vacuum degree was 6×10 ^-2 Pa.

The (Ti,W)C-based cermet tool material blank obtained in this comparative example was prepared into a 3mm×4mm×30mm ceramic spline through the steps of cutting-rough grinding-fine grinding-grinding-polishing, and its mechanical properties were measured as: 19.14 GPa, fracture toughness 8.83MPa·m ^1/2 , flexural strength 874MPa. It can be seen from the above that the alumina-coated cubic boron nitride composite powder of the present invention has an important influence on the mechanical properties of the tool material.

Comparative Example 2

A (Ti,W)C-based metal ceramic tool material is formed by hot pressing and sintering the following main raw materials by mass percentage:

Cubic boron nitride 5%, nano-alumina 5% (particle size is 20nm), nickel 3.5%, molybdenum 6.5%, cobalt 5%, the rest is (Ti, W)C; the sum of the mass percentages of each component is 100% ;

The preparation steps are as follows:

(1) Disperse 0.6 g polyethylene glycol (weight average molecular weight of 4000) in 300 mL of absolute ethanol for mechanical stirring and ultrasonic dispersion for 30 min, and configure a polyethylene glycol-absolute ethanol dispersion with a concentration of 2 g/L ; Then weigh alumina, tungsten carbide titanium, nickel, molybdenum, cobalt and cubic boron nitride according to the proportions and add them into the polyethylene glycol-absolute ethanol dispersion, mechanically stir and ultrasonically disperse for 30min, then under nitrogen protection Ball milling at room temperature for 60h (the ball mill adopts the ball milling ball made of cemented carbide, the mass ratio of the ball milling ball and the material is 15:1), and finally the mixed powder is obtained by vacuum drying at 110°C for 24h and sieving through a 200-mesh sieve;

(2) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti, W)C-based cermet tool material. The hot-pressed sintering conditions are: the sintering temperature is 1500° C., the hot-pressing pressure is 30MPa, and the holding time is 30min, the heating rate was 20°C/min, and the vacuum degree was 6×10 ^-2 Pa.

The (Ti,W)C-based cermet tool material blank obtained in this comparative example was prepared into a 3mm×4mm×30mm ceramic spline through the steps of cutting-rough grinding-fine grinding-grinding-polishing, and its mechanical properties were measured as: 18.55 GPa, fracture toughness 7.32MPa·m ^1/2 , flexural strength 722MPa. It can be seen from the above that the alumina-coated cubic boron nitride composite powder of the present invention has an important influence on the mechanical properties of the tool material.

Comparative Example 3

A method for preparing (Ti,W)C-based cermet tool material is formed by hot pressing and sintering the following main raw materials by mass percentage:

Cubic boron nitride 2.5%, nano-alumina 2.5% (particle size is 20nm), nickel 3.5%, molybdenum 6.5%, cobalt 5%, the rest is (Ti, W)C; the sum of the mass percentages of each component is 100% ;

The preparation steps are as follows:

(1) Disperse 0.6 g polyethylene glycol (weight average molecular weight of 4000) in 300 mL of absolute ethanol for mechanical stirring and ultrasonic dispersion for 30 min, and configure a polyethylene glycol-absolute ethanol dispersion with a concentration of 2 g/L Then take by weighing nano-alumina and cubic boron nitride and add in polyethylene glycol-absolute ethanol dispersion liquid, mechanically stir and ultrasonically disperse 30min; then take by weighing tungsten carbide titanium, nickel, molybdenum and cobalt successively and add In the above dispersion liquid, mechanically stirred and ultrasonically dispersed for 30min, and then ball-milled at room temperature for 60h under nitrogen protection (the ball mill was made of cemented carbide, and the mass ratio of ball-milling ball and material was 10:1), and finally it was subjected to 110 ℃ of conditions. Vacuum drying for 24h and sieving through a 200-mesh sieve to obtain mixed powder;

(2) The obtained mixed powder is hot-pressed and sintered in a graphite mold to obtain a (Ti, W)C-based cermet tool material. The hot-pressed sintering conditions are: the sintering temperature is 1500° C., the hot-pressing pressure is 30MPa, and the holding time is 30min, the heating rate was 20°C/min, and the vacuum degree was 6×10 ^-2 Pa.

The (Ti,W)C-based cermet tool material blank obtained in this comparative example was prepared into a 3mm×4mm×30mm ceramic spline through the steps of cutting-rough grinding-fine grinding-grinding-polishing, and its mechanical properties were measured as: 19.06 GPa, fracture toughness 9.86MPa·m ^1/2 , flexural strength 738MPa. It can be seen from the above that the alumina-coated cubic boron nitride composite powder of the present invention has an important influence on the mechanical properties of the tool material.

Claims (10)

1. A (Ti, W) C-based metal ceramic cutting tool material added with alumina coated cubic boron nitride composite powder is characterized by being prepared by hot-pressing and sintering the following main raw materials in percentage by mass:

2-8% of cobalt, 1-5% of nickel, 5-10% of molybdenum, 1-20% of alumina-coated cubic boron nitride composite powder and the balance of (Ti, W) C; the sum of the mass percentages of the components is 100 percent;

the alumina-coated cubic boron nitride composite powder is prepared by the following method:

dispersing the c-BN in an absolute ethyl alcohol solution to obtain a mixed solution 1; dispersing sodium dodecyl sulfate and polyethylene glycol in absolute ethyl alcohol to obtain a mixed solution 2; fully and uniformly mixing the mixed solution 1 and the mixed solution 2, reacting for 50-60 min at 70-80 ℃, and cooling, centrifugally separating, washing and drying to obtain modified c-BN powder;

dispersing the modified c-BN powder in absolute ethyl alcohol to obtain c-BN dispersion liquid; mixing Al (NO)₃)₃And polyethylene glycol dispersed in a mixed solution containing water, xylene and anhydrous ethanol to obtain Al (NO)₃)₃A solution; mixing Al (NO)₃)₃Adding the solution into the c-BN dispersion liquid, uniformly mixing, dropwise adding ammonia water to adjust the pH value to 7, reacting for 20-40 min at 70-80 ℃, and obtaining c-BN @ Al (OH) through centrifugal separation, washing and drying₃(ii) a Then calcining at the temperature of 900-1200 ℃ under the protection of inert gas to obtain the alumina-coated cubic boron nitride composite powder.

2. The (Ti, W) -based cermet cutting tool material with an added alumina-coated cubic boron nitride composite powder of claim 1, wherein the (Ti, W) -based cermet cutting tool material is prepared by hot-pressing and sintering the following main raw materials in percentage by weight: 3-6% of cobalt, 2-4% of nickel, 5-8% of molybdenum, 5-15% of alumina-coated cubic boron nitride composite powder and the balance of (Ti, W) C; the sum of the weight percentages of the components is 100 percent.

3. The (Ti, W) -based cermet cutting tool material with the addition of the alumina-coated cubic boron nitride composite powder according to claim 1, wherein the average particle size of the alumina-coated cubic boron nitride composite powder is 0.3 to 1.5 μm, the average particle size of (Ti, W) C is 2 to 5 μm, and the average particle sizes of mo, co and ni are all 1 to 3 μm.

4. The method for producing a (Ti, W) -based cermet cutting tool material with addition of alumina-coated cubic boron nitride composite powder as set forth in any one of claims 1 to 3, comprising the steps of:

(1) dispersing polyethylene glycol in absolute ethyl alcohol to form polyethylene glycol-absolute ethyl alcohol dispersion liquid; sequentially dispersing (Ti, W) C, molybdenum, cobalt and nickel in polyethylene glycol-absolute ethyl alcohol dispersion liquid, and then carrying out ball milling for 40-80h under the protection of inert gas to prepare composite powder dispersion liquid;

(2) dispersing the c-BN in an absolute ethyl alcohol solution to obtain a mixed solution 1; dispersing sodium dodecyl sulfate and polyethylene glycol in absolute ethyl alcohol to obtain a mixed solution 2; fully and uniformly mixing the mixed solution 1 and the mixed solution 2, reacting for 50-60 min at 70-80 ℃, and cooling, centrifugally separating, washing and drying to obtain modified c-BN powder;

(3) dispersing the modified c-BN powder in absolute ethyl alcohol to obtain c-BN dispersion liquid; mixing Al (NO)₃)₃And polyethylene glycol dispersed in a mixed solution containing water, xylene and anhydrous ethanol to obtain Al (NO)₃)₃A solution; mixing Al (NO)₃)₃Adding the solution into the c-BN dispersion liquid, uniformly mixing, dropwise adding ammonia water to adjust the pH value to 7, reacting for 20-40 min at 70-80 ℃, and obtaining c-BN @ Al (OH) through centrifugal separation, washing and drying₃(ii) a Then calcining for 1-3h at the temperature of 900-;

(4) dispersing the alumina coated cubic boron nitride composite powder in a polyethylene glycol-absolute ethyl alcohol solution to obtain a mixed solution; adding the mixed solution into the composite powder dispersion liquid obtained in the step (1), and continuing ball milling for 1-3 hours under the protection of inert gas; drying and sieving to obtain mixed powder;

(5) and carrying out hot-pressing sintering on the obtained mixed powder in a graphite mold to obtain the (Ti, W) C-based metal ceramic cutter material.

5. The method for preparing a (Ti, W) C-based cermet cutting tool material with alumina-coated cubic boron nitride composite powder added as recited in claim 4 wherein in steps (1) - (4), the weight average molecular weight of the polyethylene glycol is all 2000-8000; preferably, the weight average molecular weight of the polyethylene glycol is 4000-6000.

6. The method for preparing the (Ti, W) C-based cermet cutting tool material with the addition of the alumina-coated cubic boron nitride composite powder according to claim 4, wherein the step (1) comprises one or more of the following conditions:

a. in the polyethylene glycol-absolute ethyl alcohol dispersion liquid, the concentration of polyethylene glycol is 1-5 g/L, preferably 2-4 g/L;

b. the mass content of (Ti, W) C in the composite powder dispersion liquid is 0.2-1g/m L;

c. the ball milling time is 48-60h, the ball milling is performed by adopting hard alloy ball milling balls, and the mass ratio of the ball milling balls to the materials is 5-15: 1.

7. The method for preparing the (Ti, W) C-based cermet cutting tool material with the addition of the alumina-coated cubic boron nitride composite powder according to claim 4, wherein the step (2) comprises one or more of the following conditions:

a. in the mixed solution 1, the mass concentration of c-BN is 0.006-0.009g/m L, the mass ratio of c-BN, sodium dodecyl sulfate and polyethylene glycol is 2-4:1-2:1, and in the mixed solution 2, the mass concentration of polyethylene glycol is 0.006-0.008 g/ml;

b. the c-BN average particle size is 0.1 to 0.3 mu m.

8. The method for preparing a (Ti, W) C-based cermet cutting tool material with the addition of alumina-coated cubic boron nitride composite powder according to claim 4, wherein the step (3) comprises one or more of the following conditions:

a. in the c-BN dispersion liquid, the mass concentration of the modified c-BN powder is 0.01-0.04g/m L;

b. the volume ratio of water, xylene and absolute ethyl alcohol in the mixed solution containing water, xylene and absolute ethyl alcohol is 1:2: 7; the Al (NO)₃The volume ratio of the mass of the mixed solution to the mixed solution containing water, xylene and absolute ethyl alcohol is 0.01-0.03g/m L, and the mass of polyethylene glycolIn an amount of Al (NO)₃3-8% of the mass;

c. the c-BN and Al (NO)₃The mass ratio of (1: 1.1) - (1: 1.5);

d. the concentration of the ammonia water is 0.2-0.4 mol/L.

9. The method for preparing the (Ti, W) C-based cermet cutting tool material with the addition of the alumina-coated cubic boron nitride composite powder according to claim 4, wherein the step (4) comprises one or more of the following conditions:

a. the mass ratio of the alumina-coated cubic boron nitride composite powder to the polyethylene glycol is 15:1-20:1, and the mass concentration of the alumina-coated cubic boron nitride composite powder in the mixed solution is 0.05-0.20g/m L;

b. the ball milling is performed by using ball milling balls made of hard alloy materials, and the mass ratio of the ball milling balls to the materials is 10-20: 1;

c. the sieving screen is 200-300 meshes.

10. The method for preparing a (Ti, W) C-based cermet cutting tool material with an alumina-coated cubic boron nitride composite powder added according to claim 4, wherein in the step (5), the hot-pressing sintering conditions include a sintering temperature of 1450-1550 ℃, a hot-pressing pressure of 25-35 MPa, a heat preservation time of 20-40 min, a temperature rise rate of 10-25 ℃/min, and a vacuum degree range of 5-7 × 10^-2Pa。

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