阅读说明：本技术 添加氧化铝包覆氟化钙复合粉体的Ti(CN)基自润滑金属陶瓷刀具材料及其制备方法 (Ti (CN) -based self-lubricating metal ceramic cutter material added with alumina-coated calcium fluoride composite powder and preparation method thereof ) 是由 衣明东 李传浩 魏高峰 许崇海 肖光春 陈照强 张静婕 于 2020-06-09 设计创作，主要内容包括：本发明涉及一种添加氧化铝包覆氟化钙复合粉体的Ti(CN)基自润滑金属陶瓷刀具材料及其制备方法。本发明刀具材料是由以下质量百分比的主要原料经热压烧结而成：氧化铝包覆氟化钙复合粉体1～20％,氧化镁0.25～5％,钼3～15％,镍8～20％,钴8～20％,其余为Ti(CN)；各组分质量百分比之和为100％。本发明刀具材料形成了以CaF<Sub>2</Sub>为核、Al<Sub>2</Sub>O<Sub>3</Sub>为中间层、金属相为壳的多层核壳微观结构；有效保护了内层CaF<Sub>2</Sub>,解决了加入固体润滑剂会降低刀具力学性能的难题,并缓和了刀具内部界面应力集中和金属陶瓷晶粒异常长大的问题。所得刀具材料兼具有较好的润滑性能和力学性能,尤其硬度和断裂韧性性能得到大幅度提高。(The invention relates to a Ti (CN) -based self-body added with alumina coated calcium fluoride composite powderA lubricating metal ceramic cutter material and a preparation method thereof. The cutter material is prepared by hot-pressing and sintering the following main raw materials in percentage by mass: 1-20% of aluminum oxide coated calcium fluoride composite powder, 0.25-5% of magnesium oxide, 3-15% of molybdenum, 8-20% of nickel, 8-20% of cobalt and the balance of Ti (CN); the sum of the mass percentages of the components is 100 percent. The cutter material of the invention is formed by CaF 2 Is a core, Al 2 O 3 A multi-layer core-shell microstructure with an intermediate layer and a metal phase as a shell; effectively protect the inner CaF 2 The problem that the mechanical property of the cutter is reduced by adding the solid lubricant is solved, and the problems of stress concentration of the internal interface of the cutter and abnormal growth of metal ceramic grains are alleviated. The obtained cutter material has good lubricating property and mechanical property, and particularly, the hardness and the fracture toughness property are greatly improved.)

1. A Ti (CN) -based self-lubricating metal ceramic cutter material added with aluminum oxide coated calcium fluoride composite powder is characterized by being prepared by hot-pressing and sintering the following main raw materials in percentage by mass:

1-20% of aluminum oxide coated calcium fluoride composite powder, 0.25-5% of magnesium oxide, 3-15% of molybdenum, 8-20% of nickel, 8-20% of cobalt and the balance of Ti (CN); the sum of the mass percentages of the components is 100 percent;

the aluminum oxide coated calcium fluoride composite powder is prepared by the following method:

mixing Ca (NO)₃)₂、NH₄Dispersing F in ethanol water solution, adding polyvinylpyrrolidone (PVP) -anhydrous ethanol mixed solution and xylene, and mixing to obtain Ca (NO)₃)₂Solution and NH₄F solution; mixing Ca (NO)₃)₂Solution addition to NH₄Performing ultrasonic reaction at 70-80 ℃ in the solution F, stirring and reacting for 20-30 min, cooling, performing centrifugal separation, and washing to obtain nano CaF₂Gelling;

mixing the nano CaF₂Dispersing the gel in absolute ethyl alcohol to obtain nano CaF₂A solution; 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 CaF nanoparticles₂Dropwise adding an ammonia water solution into the solution to adjust the pH value to 7, performing ultrasonic treatment at 70-80 ℃ and stirring for reaction for 20-40 min, and performing centrifugal separation, washing and drying to obtain CaF₂@Al(OH)₃(ii) a Then calcining at the temperature of 750-850 ℃ under the protection of inert gas to obtain the alumina-coated calcium fluoride composite powder.

2. The ti (cn) -based self-lubricating cermet tool material with the added alumina-coated calcium fluoride composite powder of claim 1, wherein the ti (cn) -based self-lubricating cermet tool material is prepared by hot-pressing and sintering the following main raw materials in percentage by mass: 2-10% of aluminum oxide coated calcium fluoride composite powder, 0.3-0.5% of magnesium oxide, 6-10% of molybdenum, 12-18% of nickel, 12-18% of cobalt and the balance of Ti (CN); the sum of the mass percentages of the components is 100 percent.

3. The Ti (CN) -based self-lubricating cermet cutting tool material with the added alumina-coated calcium fluoride composite powder as set forth in claim 1, wherein the average particle size of the alumina-coated calcium fluoride composite powder is 30nm to 60nm, the average particle size of Ti (CN) is 40 to 60 μm, the average particle size of molybdenum is 10 to 50 μm, the average particle size of cobalt is 10 to 50 μm, the average particle size of nickel is 10 to 50 μm, and the average particle size of magnesium oxide is 0.5 to 5 μm; preferably, the average particle size of the alumina-coated calcium fluoride composite powder is 50nm, the average particle size of Ti (CN) is 50 μm, the average particle size of molybdenum is 15-45 μm, the average particle size of cobalt is 15-45 μm, the average particle size of nickel is 15-45 μm, and the average particle size of magnesium oxide is 0.5-2 μm.

4. The method for preparing the Ti (CN) -based self-lubricating cermet cutting tool material added with the alumina-coated calcium fluoride composite powder as claimed in any one of claims 1 to 3, comprising the steps of:

(1) mixing polyethylene glycol, Ti (CN) and absolute ethyl alcohol, and uniformly dispersing to obtain a Ti (CN) suspension; dispersing molybdenum, cobalt and nickel in absolute ethyl alcohol to prepare metal dispersion liquid; uniformly mixing the metal dispersion liquid and the Ti (CN) suspension liquid, and drying to prepare Ti (CN) composite powder;

(2) mixing Ca (NO)₃)₂、NH₄Dispersing F in ethanol water solution, adding polyvinylpyrrolidone (PVP) -anhydrous ethanol mixed solution and xylene, and mixing to obtain Ca (NO)₃)₂Solution and NH₄F solution; mixing Ca (NO)₃)₂Solution addition to NH₄Performing ultrasonic reaction at 70-80 ℃ in the solution F, stirring and reacting for 20-30 min, cooling, performing centrifugal separation, and washing to obtain nano CaF₂Gelling;

(3) mixing the nano CaF₂Dispersing the gel in absolute ethyl alcohol to obtain nano CaF₂A solution; 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 CaF nanoparticles₂Dropwise adding an ammonia water solution into the solution to adjust the pH value to 7, performing ultrasonic treatment at 70-80 ℃ and stirring for reaction for 20-40 min, and performing centrifugal separation, washing and drying to obtain CaF₂@Al(OH)₃(ii) a Then calcining the mixture for 5 to 7 hours at the temperature of 750-Calcium composite powder;

(4) dispersing the Ti (CN) composite powder obtained in the step (1), magnesium oxide and polyethylene glycol in absolute ethyl alcohol, and performing ball milling for 30-40h under the protection of inert gas to obtain a mixture; adding an anhydrous ethanol suspension of the alumina-coated calcium fluoride composite powder, and then continuing ball milling for 4-5 h under the protection of inert gas; drying and sieving to obtain mixed powder;

(5) the obtained mixed powder is sintered in a graphite mould by hot pressing to obtain the Ti (CN) -based self-lubricating metal ceramic cutter material.

5. The method for preparing the Ti (CN) -based self-lubricating metal ceramic cutter material added with the alumina-coated calcium fluoride composite powder is characterized in that the step (1) comprises one or more of the following conditions:

a. the weight average molecular weight of the polyethylene glycol is 2000-10000; preferably, the polyethylene glycol has a weight average molecular weight of 4000;

b. the mass concentration of Ti (CN) in the Ti (CN) suspension is 14-17 g/ml; the mass of the polyethylene glycol is 0.4-0.5% of that of Ti (CN); the mass content of molybdenum in the metal dispersion liquid is 3-4%.

6. The method for preparing the Ti (CN) -based self-lubricating metal ceramic cutter material added with the alumina-coated calcium fluoride composite powder is characterized in that the step (2) comprises one or more of the following conditions:

a. the ethanol water solution is formed by mixing absolute ethanol and distilled water, and the volume ratio of the absolute ethanol to the distilled water is 1-1.5: 1-1.5; the polyvinylpyrrolidone (PVP) -absolute ethyl alcohol mixed solution is prepared by ultrasonically dispersing polyvinylpyrrolidone in absolute ethyl alcohol, wherein the volume ratio of the mass of the polyvinylpyrrolidone (PVP) to the absolute ethyl alcohol is 0.5-1g/50-100 mL;

b. the Ca (NO)₃)₂In solution, Ca (NO)₃)₂The mass concentration of the polyvinyl pyrrolidone is 0.01-0.03g/mL, the mass concentration of the polyvinylpyrrolidone is 0.001-0.01g/mL, and the mass concentration of the xylene and the polyvinyl pyridine is 0.01-0.01 g/mLThe volume ratio of the pyrrolidone-absolute ethyl alcohol mixed solution is 1: 3-5; the NH₄In solution F, NH₄The mass concentration of F is 0.005-0.008g/mL, the mass concentration of polyvinylpyrrolidone is 0.005-0.008g/mL, and the volume ratio of the mixed solution of xylene and polyvinylpyrrolidone-absolute ethyl alcohol is 1: 3-5;

c、Ca(NO₃)₂and NH₄The molar ratio of F is 1: 2-2.3;

d. nano CaF₂The average particle diameter of the gel particles is 10-50 nm; preferably, nano CaF₂The average particle diameter of the gel particles is 10 to 20 nm.

7. The method for preparing the Ti (CN) -based self-lubricating metal ceramic cutter material added with the alumina-coated calcium fluoride composite powder is characterized in that the step (3) comprises one or more of the following conditions:

a. the nano CaF₂Nano CaF in solution₂The mass concentration of the gel is 0.003-0.01 g/mL; in the mixed solution containing water, xylene and absolute ethyl alcohol, the volume ratio of the water, the xylene and the absolute ethyl alcohol is 1:2: 6-8; the Al (NO)₃)₃In solution, Al (NO)₃)₃The mass ratio of the water to the mixed solution containing water, xylene and absolute ethyl alcohol is 2-3 g/100-150 mL;

b. the weight average molecular weight of the polyethylene glycol is 2000-10000; preferably, the polyethylene glycol has a weight average molecular weight of 4000; the mass of the polyethylene glycol is Al (NO)₃)₃5-10% of the mass;

c. the Al (NO)₃)₃And CaF₂The mass ratio of (A) to (B) is 5-6: 1;

d. the ammonia water solution is prepared from an ammonia water reagent with the mass concentration of 25-28% and absolute ethyl alcohol according to the volume ratio of 1: 3;

e. the calcining temperature is 800 ℃, and the calcining time is 6 h.

8. The method for preparing the Ti (CN) -based self-lubricating metal ceramic cutter material added with the alumina-coated calcium fluoride composite powder is characterized in that the step (4) comprises one or more of the following conditions:

a. the weight average molecular weight of the polyethylene glycol is 2000-10000; preferably, the polyethylene glycol has a weight average molecular weight of 4000; the mass of the polyethylene glycol is 60-70% of that of the magnesium oxide;

b. in the mixture, the mass concentration of the magnesium oxide is 0.0007-0.0008 g/ml;

c. in an absolute ethyl alcohol suspension of the alumina-coated calcium fluoride composite powder, the volume ratio of the mass of the alumina-coated calcium fluoride composite powder to absolute ethyl alcohol is 0.02-0.05 g/ml;

d. 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;

e. the sieving screen is 200-300 meshes.

9. The method for preparing the Ti (CN) -based self-lubricating cermet cutting tool material with the added alumina-coated calcium fluoride composite powder as claimed in claim 4, wherein in the step (5), the hot-pressing sintering conditions include a sintering temperature of 1450-1500 ℃, a hot-pressing pressure of 30-35 MPa, a heat preservation time of 30-40 min, a temperature rise rate of 20-25 ℃/min, and a vacuum degree range of 5-7 × 10^-2Pa。

Technical Field

The invention relates to a Ti (CN) -based self-lubricating metal ceramic cutter material added with alumina coated calcium fluoride composite powder and a preparation method thereof, belonging to the technical field of Ti (CN) -based metal ceramic cutter materials.

Background

Ti (C, N) -based cermet is a new particle-reinforced composite material appearing in the early 70 s of the 20 th century; it is a kind of composite material which uses Ti (C, N) as hard phase, at the same time adds WC, TaC and other refractory metal carbide or nitride, and uses Ni or Co and other as adhesive. Compared with the traditional WC-based hard alloy, the Ti (C, N) -based metal ceramic cutter has better wear resistance, thermal stability, high-temperature red hardness at 700-1100 ℃, oxidation resistance and adhesion resistance, high cutting temperature, 3-10 times and 2-5 times of improvement of the cutting speed and the service life respectively, abundant main raw material resources and low cost, and is an ideal upgraded substitute product of the WC-Co-based hard alloy high-speed high-efficiency cutter.

At present, the preparation of Ti (C, N) -based cermet cutting tool materials has been reported. For example, chinese patent document CN102433482A discloses a ti (CN) cermet woodworking cutting tool material and a method for preparing the same; the formula comprises the following components: 50-65% of Ti (CN) powder, 5-10% of cobalt powder, 5-10% of nickel powder, 8-15% of molybdenum powder and carbonized powder10-20% of tungsten powder, 4-8% of tantalum carbide powder, and 0-1.0% of chromium carbide and vanadium carbide powder; the preparation method comprises the following steps: burdening → ball milling → spray drying → pressing → pressure sintering → finished product; the obtained cutter has improved durability, service life and cutting speed. For another example, chinese patent document CN105112756A discloses a titanium carbonitride composite alumina metal ceramic cutting tool material and a preparation method thereof; the material comprises the following components in percentage by weight: 50-65% Ti (C, N), 30-45% Al₂O₃0.5 to 1% of MgO and 3 to 5% of a mixture of Ni and Mo. The wear resistance and service life of the obtained cutter are improved. However, the Ti (C, N) -based cermet system has poor self-lubricating effect due to no addition of lubricant, so that the Ti (C, N) -based cermet system has relatively high friction coefficient, poor wear resistance and undesirable service life.

In view of the above problems, the lubricating effect can be improved by adding a solid lubricant to the tool material, but if the solid lubricant is directly added to the tool material system, the mechanical properties of the tool material are seriously impaired. Therefore, researchers begin to coat the solid lubricant by adopting a special process, and then add the coated powder into the base material of the cutter, so that the obtained cutter material has good mechanical property and lubricating property, and a new field is opened up for the application of the solid self-lubricating material. Chinese patent document CN107602097A discloses Al added with nano-coated solid lubricant₂O₃the/Ti (C, N) nano-based ceramic cutter material and the preparation method thereof comprise the following components: nano CaF₂@Al₂O₃1-30% of coated composite powder, 0.1-3% of MgO, 1-55% of Ti (C, N), and the balance of Al₂O₃% is volume percentage; the defect of poor mechanical property of the self-lubricating ceramic cutter is effectively overcome by adding the nano-coated solid lubricant; but CaF₂@Al₂O₃The coated composite powder is used as a single phase in the cutter material, and the physical property of the coated composite powder is mainly formed by a shell Al₂O₃Determined, but due to CaF inside the coating₂Coefficient of thermal expansion greater than Al₂O₃Then will be to Al₂O₃Generating compressive stress to thereby generate residueResidual stress reduces mechanical properties such as the strength of the cutter material.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a Ti (CN) -based self-lubricating metal ceramic cutter material added with alumina-coated calcium fluoride composite powder and a preparation method thereof. The invention adds alumina coated calcium fluoride composite powder and metal binding phase into Ti (CN) -based ceramic material to form CaF₂Is a core, Al₂O₃A multi-layer core-shell microstructure with an intermediate layer and a metal binder phase as a shell; the microstructure of the invention effectively protects the solid lubricant CaF with low mechanical property of the inner layer₂And use of Al₂O₃The high elastic modulus of the middle layer ceramic phase bears stress and the outer layer metal binding phase bears deformation, and simultaneously, based on the residual stress toughening mechanism of the nano solid lubricant, the problem that the mechanical property of the cutter is reduced by adding the solid lubricant is successfully solved, and the problems of interface stress concentration in the Ti (CN) -based metal ceramic cutter and abnormal growth of metal ceramic grains are alleviated. The obtained cutter material has good lubricating property and mechanical property, and particularly, the hardness and the fracture toughness property are greatly improved; the cutter material is used for cutting, has a good service life, and is low in surface roughness of a processed workpiece.

Description of terms:

CaF₂@Al₂O₃: is the abbreviation of the alumina coated calcium fluoride composite powder;

CaF₂@Al(OH)₃: it is a abbreviation for aluminum hydroxide coated calcium fluoride composite powder.

The technical scheme of the invention is as follows:

a Ti (CN) -based self-lubricating metal ceramic cutter material added with aluminum oxide coated calcium fluoride composite powder is prepared by hot-pressing and sintering the following main raw materials in percentage by mass:

1-20% of aluminum oxide coated calcium fluoride composite powder, 0.25-5% of magnesium oxide, 3-15% of molybdenum, 8-20% of nickel, 8-20% of cobalt and the balance of Ti (CN); the sum of the mass percentages of the components is 100 percent;

the aluminum oxide coated calcium fluoride composite powder is prepared by the following method:

mixing Ca (NO)₃)₂、NH₄Dispersing F in ethanol water solution, adding polyvinylpyrrolidone (PVP) -anhydrous ethanol mixed solution and xylene, and mixing to obtain Ca (NO)₃)₂Solution and NH₄F solution; mixing Ca (NO)₃)₂Solution addition to NH₄Performing ultrasonic reaction at 70-80 ℃ in the solution F, stirring and reacting for 20-30 min, cooling, performing centrifugal separation, and washing to obtain nano CaF₂Gelling;

mixing the nano CaF₂Dispersing the gel in absolute ethyl alcohol to obtain nano CaF₂A solution; 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 CaF nanoparticles₂Dropwise adding an ammonia water solution into the solution to adjust the pH value to 7, performing ultrasonic treatment at 70-80 ℃ and stirring for reaction for 20-40 min, and performing centrifugal separation, washing and drying to obtain CaF₂@Al(OH)₃(ii) a Then calcining at the temperature of 750-850 ℃ under the protection of inert gas to obtain the alumina-coated calcium fluoride composite powder.

According to the invention, the preferable Ti (CN) -based self-lubricating metal ceramic cutter material is prepared by hot-pressing and sintering the following main raw materials in percentage by mass: 2-10% of aluminum oxide coated calcium fluoride composite powder, 0.3-0.5% of magnesium oxide, 6-10% of molybdenum, 12-18% of nickel, 12-18% of cobalt and the balance of Ti (CN); the sum of the mass percentages of the components is 100 percent.

According to the invention, the average particle size of the alumina-coated calcium fluoride composite powder is 30nm-60nm, the average particle size of Ti (CN) is 40-60 μm, the average particle size of molybdenum is 10-50 μm, the average particle size of cobalt is 10-50 μm, the average particle size of nickel is 10-50 μm, and the average particle size of magnesium oxide is 0.5-5 μm; preferably, the average particle size of the alumina-coated calcium fluoride composite powder is 50nm, the average particle size of Ti (CN) is 50 μm, the average particle size of molybdenum is 15-45 μm, the average particle size of cobalt is 15-45 μm, the average particle size of nickel is 15-45 μm, and the average particle size of magnesium oxide is 0.5-2 μm.

The preparation method of the Ti (CN) -based self-lubricating metal ceramic cutter material added with the alumina-coated calcium fluoride composite powder comprises the following steps:

(1) mixing polyethylene glycol, Ti (CN) and absolute ethyl alcohol, and uniformly dispersing to obtain a Ti (CN) suspension; dispersing molybdenum, cobalt and nickel in absolute ethyl alcohol to prepare metal dispersion liquid; uniformly mixing the metal dispersion liquid and the Ti (CN) suspension liquid, and drying to prepare Ti (CN) composite powder;

(2) mixing Ca (NO)₃)₂、NH₄Dispersing F in ethanol water solution, adding polyvinylpyrrolidone (PVP) -anhydrous ethanol mixed solution and xylene, and mixing to obtain Ca (NO)₃)₂Solution and NH₄F solution; mixing Ca (NO)₃)₂Solution addition to NH₄Performing ultrasonic reaction at 70-80 ℃ in the solution F, stirring and reacting for 20-30 min, cooling, performing centrifugal separation, and washing to obtain nano CaF₂Gelling;

(3) mixing the nano CaF₂Dispersing the gel in absolute ethyl alcohol to obtain nano CaF₂A solution; 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 CaF nanoparticles₂Dropwise adding an ammonia water solution into the solution to adjust the pH value to 7, performing ultrasonic treatment at 70-80 ℃ and stirring for reaction for 20-40 min, and performing centrifugal separation, washing and drying to obtain CaF₂@Al(OH)₃(ii) a Then calcining for 5-7h at the temperature of 750-;

(4) dispersing the Ti (CN) composite powder obtained in the step (1), magnesium oxide and polyethylene glycol in absolute ethyl alcohol, and performing ball milling for 30-40h under the protection of inert gas to obtain a mixture; adding an anhydrous ethanol suspension of the alumina-coated calcium fluoride composite powder, and then continuing ball milling for 4-5 h under the protection of inert gas; drying and sieving to obtain mixed powder;

(5) the obtained mixed powder is sintered in a graphite mould by hot pressing to obtain the Ti (CN) -based self-lubricating metal ceramic cutter material.

Preferably, in step (1), the polyethylene glycol has a weight average molecular weight of 2000 to 10000; preferably, the polyethylene glycol has a weight average molecular weight of 4000.

Preferably, in step (1), the mass concentration of Ti (CN) in the Ti (CN) suspension is 14-17 g/ml; the mass of the polyethylene glycol is 0.4-0.5% of that of Ti (CN); the mass content of molybdenum in the metal dispersion liquid is 3-4%.

According to the invention, in the step (2), the ethanol aqueous solution is formed by mixing absolute ethanol and distilled water, and the volume ratio of the absolute ethanol to the distilled water is 1-1.5: 1-1.5; the polyvinylpyrrolidone (PVP) -absolute ethyl alcohol mixed solution is prepared by ultrasonically dispersing polyvinylpyrrolidone in absolute ethyl alcohol, and the volume ratio of the mass of the polyvinylpyrrolidone (PVP) to the absolute ethyl alcohol is 0.5-1g/50-100 mL.

Preferably, in step (2), the Ca (NO) is₃)₂In solution, Ca (NO)₃)₂The mass concentration of the mixed solution is 0.01-0.03g/mL, the mass concentration of the polyvinylpyrrolidone is 0.001-0.01g/mL, and the volume ratio of the mixed solution of the dimethylbenzene to the polyvinylpyrrolidone-absolute ethyl alcohol is 1: 3-5; the NH₄In solution F, NH₄The mass concentration of F is 0.005-0.008g/mL, the mass concentration of polyvinylpyrrolidone is 0.005-0.008g/mL, and the volume ratio of the mixed solution of xylene and polyvinylpyrrolidone-absolute ethyl alcohol is 1: 3-5.

Preferably, in the step (2), the washing is performed by washing with distilled water for 2 to 3 times.

Preferably, according to the invention, in step (2), Ca (NO)₃)₂And NH₄The molar ratio of F is 1: 2-2.3.

According to the invention, in step (2), preferably, the nano CaF₂The average particle diameter of the gel particles is 10-50 nm; preferably, nano CaF₂The average particle diameter of the gel particles is 10 to 20 nm.

Preferably, according to the present invention, in the step (3),the nano CaF₂Nano CaF in solution₂The mass concentration of the gel is 0.003-0.01 g/mL; in the mixed solution containing water, xylene and absolute ethyl alcohol, the volume ratio of the water, the xylene and the absolute ethyl alcohol is 1:2: 6-8; the Al (NO)₃)₃In solution, Al (NO)₃)₃The mass ratio of the (b) to the volume ratio of the mixed solution containing water, xylene and absolute ethyl alcohol is 2-3 g/100-150 mL.

Preferably, in the step (3), the polyethylene glycol has a weight average molecular weight of 2000 to 10000; preferably, the polyethylene glycol has a weight average molecular weight of 4000; the mass of the polyethylene glycol is Al (NO)₃)₃5-10% of the mass.

Preferably, according to the present invention, in the step (3), the Al (NO) is₃)₃And CaF₂The mass ratio of (A) to (B) is 5-6: 1.

Preferably, in the step (3), the ammonia water solution is prepared by ammonia water reagent with the mass concentration of 25-28% and absolute ethyl alcohol according to the volume ratio of 1: 3.

Preferably, in step (3), the washing is performed once by using absolute ethyl alcohol and distilled water; the inert gas is nitrogen or argon.

According to the invention, in the step (3), the calcining temperature is 800 ℃ and the calcining time is 6 h.

Preferably, in the step (4), the polyethylene glycol has a weight average molecular weight of 2000 to 10000; preferably, the polyethylene glycol has a weight average molecular weight of 4000; the mass of the polyethylene glycol is 60-70% of that of the magnesium oxide.

According to the invention, the mass concentration of the magnesium oxide in the mixture in the step (4) is preferably 0.0007-0.0008 g/ml.

According to the invention, in the anhydrous ethanol suspension of the alumina-coated calcium fluoride composite powder in the step (4), the volume ratio of the mass of the alumina-coated calcium fluoride composite powder to the anhydrous ethanol is 0.02-0.05 g/ml.

Preferably, in step (4), the inert gas is nitrogen or argon.

According to the invention, in the step (4), the ball milling is performed by using hard alloy ball milling balls, and the mass ratio of the ball milling balls to the materials is 10-20: 1.

According to the invention, in the step (4), the sieving screen is 200-300 meshes.

According to the invention, in the step (4), the drying is preferably carried out for 24-36 h under the condition of 100-110 ℃ in vacuum.

According to the invention, in the step (5), the hot-pressing sintering conditions comprise that the sintering temperature is 1450-1500 ℃, the hot-pressing pressure is 30-35 MPa, the heat preservation time is 30-40 min, the temperature rise rate is 20-25 ℃/min, and the vacuum degree range is 5-7 × 10^-2Pa。

The invention has the technical characteristics and beneficial effects that:

1. the invention provides a novel Ti (CN) -based self-lubricating metal ceramic cutter material with a multilayer core-shell microstructure and excellent mechanical properties. Firstly, adding rare metals such as molybdenum, cobalt and nickel into titanium carbonitride powder as binder phase, and uniformly mixing the binder phase and the binder phase to prepare Ti (CN) composite powder; then adding the prepared alumina-coated calcium fluoride composite powder and a sintering aid magnesium oxide into the Ti (CN) composite powder, performing ball milling to obtain mixed powder, and performing vacuum hot-pressing sintering to obtain the Ti (CN) -based self-lubricating metal ceramic cutter material with a multilayer core-shell microstructure, wherein the Ti (CN) -based self-lubricating metal ceramic cutter material is added with the alumina-coated calcium fluoride composite powder.

2. The preparation method of the invention uses polyethylene glycol which has steric hindrance effect and good dispersion effect on Ti (CN) composite powder and the like. In the preparation process of the nano calcium fluoride particles, the polyvinylpyrrolidone is used as a high molecular compound and is insensitive to the pH value, so that the polyvinylpyrrolidone used as a dispersing agent has a good dispersing effect. In addition, if the preparation of the nano calcium fluoride is carried out in pure water, the particle size of the calcium fluoride is large and different, if the nano calcium fluoride prepared in a water-alcohol mixed solution is small and serious in agglomeration, and if an organic solvent xylene is adopted to properly dissolve ethanol, the particle size of the prepared nano calcium fluoride is moderate; namely, the specific polyvinylpyrrolidone (PVP) -absolute ethyl alcohol mixed solution and the xylene are added, so that the preparation of the nano calcium fluoride with moderate particle size, uniform particle size and better dispersion is facilitated. The preparation method of the invention uses the sintering aid MgO, because Ti (CN) is easily dissolved in the liquid phase containing Mg at a higher sintering temperature, a solid solution is formed when the Ti (CN) is cooled and separated out, which is beneficial to strengthening the crystal grain interface, and the MgO can effectively reduce the sintering temperature, reduce air holes and improve the compactness of the cutter material.

3. The mixed powder obtained in the step (4) of the preparation method is fully mixed, and the molybdenum, cobalt, nickel and alumina coated calcium fluoride composite powder can be uniformly distributed in the titanium carbonitride, so that a multilayer core-shell microstructure with calcium fluoride as a core, alumina as an intermediate layer and molybdenum, cobalt and nickel as a shell is realized under the condition of hot-pressing sintering. The coating of the calcium fluoride by the alumina is realized by preparing the alumina-coated calcium fluoride composite powder, wherein the outer layer of the alumina is a ceramic phase. Rare metals such as molybdenum, cobalt and nickel are used as metal phases, and in the hot-pressing sintering process, liquid-phase metal can be solidified and grown in a non-uniform nucleation mode by taking an alumina ceramic phase as a substrate interface, so that the alumina ceramic phase is coated, a multilayer core-shell microstructure with calcium fluoride as a core, alumina as an intermediate layer and molybdenum, cobalt and nickel as a shell is formed; and the molybdenum, cobalt and nickel are used as binding phases to effectively bind the alumina-coated calcium fluoride composite powder with the matrix Ti (CN). The rare metal molybdenum adopted by the invention not only can effectively improve the wettability of cobalt and nickel so as to stabilize the carbonitride, but also can inhibit the growth of carbide grains during sintering, thereby playing the role of refining the grains.

4. The invention takes Mo-Co-Ni as a binder phase and alumina coated calcium fluoride as an additive phase to form CaF₂Is a core, Al₂O₃Is a multilayer core-shell microstructure with an intermediate layer and a metal bonding phase Mo-Co-Ni as a shell. The microstructure realizes CaF₂Solid lubricant CaF as lubricant with lubricating effect and low mechanical property of inner layer protected₂；CaF₂Coefficient of thermal expansion greater than Al₂O₃Will be directed to Al₂O₃Generating compressive stress, while the present invention utilizes an intermediate layer of Al₂O₃The high elastic modulus of the ceramic phase bears the stress, and the outer metal binding phase bears the deformation; based on the residual stress toughening mechanism of the intragranular nano solid lubricant, in the intragranular nano composite ceramic material, the difference between the thermal expansion coefficient and the elastic modulus of the matrix and the intragranular nano solid lubricant causes the formation of residual stress between the two phases, and when cracks are expanded to the nano solid lubricant, the outer metal binding phase can effectively reduce Al₂O₃The radial compressive stress enables the cracks to deflect and expand along the interface of the particles and the matrix, thereby effectively reducing the expansion of the cracks and successfully solving the problem that the mechanical property of the cutter is reduced by adding the solid lubricant; and the multilayer core-shell microstructure alleviates the problem of interface stress concentration inside the Ti (CN) -based cermet cutter and the problem of abnormal growth of cermet grains.

5. The cutter material obtained by the invention has good self-lubricating property and mechanical property, and particularly, the hardness and the fracture toughness of the cutter material are greatly improved. The hardness of the obtained cutter material can reach 23.93GPa, and the fracture toughness can reach 9.94 MPa.m^1/2(ii) a The cutter material is used for cutting, has a good service life, and is low in surface roughness of a processed workpiece.

Drawings

FIG. 1 is an SEM image of a cross section of a Ti (CN) -based self-lubricating cermet cutting tool material prepared in example 2.

FIG. 2 is a SEM image of the crack propagation of the Ti (CN) -based self-lubricating cermet cutting tool material prepared in example 2.

Detailed Description

The present invention will be further described with reference to specific examples, but the present invention is not limited to the following examples.

The method is a conventional method unless otherwise specified, and the reagent is commercially available without further specified.