Silicon nitride and titanium nitride reinforced copper-based composite material and preparation method thereof

Abstract

The invention belongs to the technical field of copper-based composite materials, and particularly relates to a silicon nitride and titanium nitride reinforced copper-based composite material and a preparation method thereof. The copper-based composite material provided by the invention comprises 7-20 wt% of silicon nitride particles, 4-20 wt% of titanium nitride particles and 68-84 wt% of a copper matrix, the silicon nitride particles comprise one or more of an alpha-Si3N4 particle, a beta-Si3N4 particle and a beta-Si3N4 crystal whisker; the silicon nitride particles and the titanium nitride particles are dispersed in the copper matrix, and more than 70 wt% of titanium nitride particles in the titanium nitride particles are located on the surfaces of the silicon nitride particles. The copper-based composite material provided by the invention has relatively high density and good thermal conductivity, electrical conductivity, hardness and wear resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of copper-based composite materials, and in particular relates to a silicon nitride and titanium nitride reinforced copper-based composite material and a preparation method thereof. Background Art

[0002] Copper is one of the most widely used metal materials, with high thermal conductivity, high electrical conductivity, high ductility and other characteristics, but its hardness is low, which affects its wear resistance and load-bearing capacity. Silicon nitride ceramics have high thermal conductivity, high hardness and other characteristics, but their toughness is low and they are not conductive. Combining silicon nitride with copper to prepare copper-based composites has always attracted widespread attention. However, due to the very poor wettability between copper and silicon nitride ceramics, the densification degree of the composite material decreases seriously with the increase of silicon nitride content. For example, the document Improved mechanical properties of Cu matrix composites reinforced with β-Si3N4 whiskers (Jinwei Yin, Dongxu Yao, Hailong Hu, Yongfeng Xia, Kaihui Zuo, Yu-Ping Zeng. Materials Science & Engineering A 607 (2014) 287-293) and Chinese patent CN201210364842.6 disclose enhanced copper-based composites; however, as the silicon nitride content in the copper-based composite increases, its porosity increases, causing the hardness of the composite to drop sharply, even lower than that of pure copper. In addition to affecting the hardness, the increase in porosity in the composite material will also have a significant impact on the compressive strength, thermal conductivity, electrical conductivity, wear resistance, etc. of the composite material.

[0003] In order to reduce the porosity of composite materials, researchers have conducted a lot of research. Among them, alloying is an important method to improve wettability. Studies have shown that the density of composite materials can be improved by introducing metals such as silver and tin to regulate the wettability of copper and silicon nitride. However, compared with copper alone, the electrical conductivity and thermal conductivity of the alloy will decrease, which leads to different degrees of decrease in the thermal conductivity and electrical conductivity of the composite material. The formation of the alloy causes the melting point of the material to decrease, which also affects the temperature resistance of the material. Summary of the invention

[0004] The object of the present invention is to provide a silicon nitride and titanium nitride reinforced copper-based composite material and a preparation method thereof. The copper-based composite material provided by the present invention has high density and good thermal conductivity, electrical conductivity, hardness and wear resistance.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a silicon nitride and titanium nitride reinforced copper-based composite material, comprising the following components in percentage by weight: 7-20wt% of silicon nitride particles, 4-20wt% of titanium nitride particles, and 68-84wt% of a copper matrix;

[0007] The silicon nitride particles include one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers;

[0008] The silicon nitride particles and the titanium nitride particles are dispersed in the copper matrix, and more than 70 wt % of the titanium nitride particles in the titanium nitride particles are located on the surface of the silicon nitride particles.

[0009] Preferably, the average particle size of the α-Si3N4 particles and the β-Si3N4 particles is independently 3 to 50 microns;

[0010] The average diameter of the β-Si3N4 whisker is 0.3 to 5 microns, and the average length is 3 to 100 microns.

[0011] Preferably, the average particle size of the titanium nitride particles is 0.1 to 5 microns.

[0012] Preferably, the relative density of the copper-based composite material is 89.5-99.5%.

[0013] The present invention provides a method for preparing the silicon nitride and titanium nitride reinforced copper-based composite material described in the above technical solution, comprising the following steps:

[0014] Mixing copper powder, silicon nitride powder and metal titanium powder to obtain a mixed material, wherein the silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers;

[0015] The mixed material is sintered in a protective gas atmosphere to obtain the copper-based composite material.

[0016] Preferably, the mixing comprises the following steps:

[0017] Copper powder, silicon nitride powder, metal titanium powder and solvent are wet mixed to obtain slurry, wherein the average particle size of the copper powder is 1 to 200 microns, and the average particle size of the metal titanium powder is 0.5 to 50 microns;

[0018] The slurry is dried to obtain the mixed material.

[0019] Preferably, the wet mixing method includes one or more of planetary mixing, drum mixing and stirring mixing;

[0020] The drying method includes one or more of air-blast drying, vacuum drying and spray granulation.

[0021] Preferably, the solvent includes ethanol and / or water; the wet mixed raw materials also include grinding balls, and the grinding balls include one or more of silicon nitride balls, aluminum oxide balls, agate balls and silicon carbide balls.

[0022] Preferably, the sintering method includes pressureless sintering after pressure forming, or directly placing in a pressure mold and using hot pressing sintering, or directly placing in a pressure mold and using SPS sintering.

[0023] Preferably, the sintering temperature is 900-1100° C., and the holding time is 5-120 min.

[0024] The present invention provides a silicon nitride and titanium nitride reinforced copper-based composite material, comprising the following components in percentage by mass: 7-20wt% silicon nitride particles, 4-20wt% titanium nitride particles, and 68-84wt% copper matrix; the silicon nitride particles include one or more of α-Si3N4 particles, β-Si3N4 particles, and β-Si3N4 whiskers; the silicon nitride particles and the titanium nitride particles are dispersed in the copper matrix, and more than 70wt% of the titanium nitride particles in the titanium nitride particles are located on the surface of the silicon nitride particles. In the present invention, more than 70wt% of the titanium nitride particles in the titanium nitride particles are located on the surface of the silicon nitride particles, so that the titanium nitride particles are enriched and distributed at the interface between the copper matrix and the silicon nitride particles. Since the wettability between titanium nitride and copper is good, titanium nitride improves the interface wettability between the copper matrix and the silicon nitride particles. Therefore, the silicon nitride and titanium nitride reinforced copper-based composite material provided by the present invention has a higher degree of densification under the condition of a higher silicon nitride content. At the same time, copper exists in a single substance form, and the composite material can maintain higher thermal conductivity and electrical conductivity than the alloy. In addition, compared with silicon nitride particles, titanium nitride has good electrical conductivity and high hardness. Therefore, the copper-based composite material provided by the present invention has a higher density and good thermal conductivity, electrical conductivity, hardness and wear resistance.

[0025] The present invention provides a method for preparing a silicon nitride and titanium nitride reinforced copper-based composite material described in the above technical solution, comprising the following steps: mixing copper powder, silicon nitride powder and metal titanium powder to obtain a mixed material, wherein the silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers; sintering the mixed material in a protective gas atmosphere to obtain the copper-based composite material. In the sintering and heating process of the present invention, on the one hand, metal titanium first partially reacts with silicon nitride to form a titanium silicon nitrogen compound on the surface of silicon nitride, and then nitridates on the surface of silicon nitride to form titanium nitride particles after further heating; on the other hand, silicon nitride provides a nucleation point for the nitridation of titanium, thereby promoting the nitridation reaction. These two aspects jointly promote the in-situ formation of more titanium nitride particles on the surface of silicon nitride ceramics. Finally, these particles improve the wettability between silicon nitride and copper, improve the sintering activity of the material, and realize the densification preparation of the material with a high silicon nitride content. The present invention uses metal titanium powder as raw material. Compared with directly introducing titanium nitride particles, due to the good wettability between titanium nitride and copper, more titanium nitride particles will be completely wrapped by copper, and the effect on the interface regulation between silicon nitride and copper is small. The method of forming titanium nitride in situ using metal titanium can make more titanium nitride form on the surface of silicon nitride particles, thereby more effectively improving the interface wettability between the copper matrix and the silicon nitride particles. Thus, the copper-based composite material obtained by the preparation method provided by the present invention can have a higher degree of densification under the condition of a high silicon nitride content. At the same time, copper exists in a single substance form, and the composite material can maintain a higher thermal conductivity and electrical conductivity relative to the alloy. In addition, relative to silicon nitride particles, titanium nitride has good electrical conductivity and high hardness. Therefore, the copper-based composite material provided by the present invention has a higher density and good thermal conductivity, electrical conductivity, hardness and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the structure of the copper-based composite material provided by the present invention;

[0027] Figure 2 This is the XRD structure diagram of the sample in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The present invention provides a silicon nitride and titanium nitride reinforced copper-based composite material, comprising the following components in percentage by weight: 7-20wt% of silicon nitride particles, 4-20wt% of titanium nitride particles, and 68-84wt% of a copper matrix;

[0029] The silicon nitride particles include one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers;

[0030] The silicon nitride particles and the titanium nitride particles are dispersed in the copper matrix, and more than 70 wt % of the titanium nitride particles in the titanium nitride particles are located on the surface of the silicon nitride particles.

[0031] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0032] In terms of mass percentage, the silicon nitride and titanium nitride reinforced copper-based composite material provided by the present invention includes 7 to 20wt% of silicon nitride particles, which can be 12wt%, 15wt%, 19wt%, 7wt%, 8wt% or 11wt% in the embodiment. In the present invention, the silicon nitride particles include one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers, and are specifically α-Si3N4 particles, β-Si3N4 particles or β-Si3N4 whiskers in the embodiment, and are more preferably β-Si3N4 whiskers. The average particle size of the α-Si3N4 particles is preferably 3 to 50 microns, and is specifically 2 microns, 10 microns or 1 micron in the embodiment. The average particle size of the β-Si3N4 particles is preferably 3 to 50 microns, and is specifically 50 microns or 5 microns in the embodiment. The average diameter of the β-Si3N4 whiskers is preferably 0.3 to 5 microns, specifically 0.5 microns or 2 microns in the embodiment; the average length of the β-Si3N4 whiskers is preferably 3 to 100 microns, specifically 20 microns or 100 microns in the embodiment.

[0033] In terms of mass percentage, the silicon nitride and titanium nitride reinforced copper-based composite material provided by the present invention includes 4-20wt% of titanium nitride particles, which may be 10wt%, 13wt%, 19wt%, 4wt% or 8wt% in the embodiments. In the present invention, the average particle size of the titanium nitride particles is preferably 0.1-5 microns.

[0034] In terms of mass percentage, the silicon nitride and titanium nitride reinforced copper-based composite material provided by the present invention includes 68-84wt% of the copper matrix, and in the embodiments it can be 78wt%, 75wt%, 68wt%, 83wt%, 73wt%, 84wt% or 81wt%.

[0035] In the present invention, the relative density of the silicon nitride and titanium nitride reinforced copper-based composite material is preferably 89.5-99.5%.

[0036] In the present invention, the silicon nitride and titanium nitride reinforced copper-based composite material is a sintered material.

[0037] In the present invention, the raw materials for preparing the silicon nitride and titanium nitride reinforced copper-based composite material include copper powder, silicon nitride powder and metal titanium powder. The silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers. The copper-based composite material is obtained by sintering the raw materials for preparing the copper powder, silicon nitride powder and metal titanium powder.

[0038] In the present invention, the raw materials for preparing the copper-based composite material include the following raw materials in percentage by weight: 8-20wt% silicon nitride powder, 70-86wt% copper powder, and 3-15wt% titanium powder. The silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles, and β-Si3N4 whiskers.

[0039] The present invention provides a method for preparing the silicon nitride and titanium nitride reinforced copper-based composite material described in the above technical solution, comprising the following steps:

[0040] Copper powder, silicon nitride powder and metallic titanium powder are mixed to obtain a mixed material, wherein the silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers, and the mixed material includes the following components in percentage by mass: 8-20wt% of silicon nitride powder, which may be 12wt%, 15wt%, 20wt% or 8wt% in the embodiment, 70-86wt% of copper powder, which may be 80wt%, 77wt%, 70wt%, 86wt%, 85wt% or 83wt% in the embodiment, and 3-15wt% of metallic titanium powder, which may be 8wt%, 10wt%, 6wt%, 15wt%, 3wt% or 9wt% in the embodiment.

[0041] The mixed material is sintered in a protective gas atmosphere to obtain the copper-based composite material.

[0042] The present invention mixes copper powder, silicon nitride powder and metal titanium powder to obtain a mixed material, wherein the silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers, and the mixed material includes the following components in percentage by weight: 8-20wt% silicon nitride powder, 70-86wt% copper powder and 3-15wt% metal titanium powder. In the present invention, the average particle size of the α-Si3N4 particles is preferably 3-50 microns, and specifically 2 microns, 10 microns or 1 micron in the embodiment. The average particle size of the β-Si3N4 particles is preferably 3-50 microns, and specifically 50 microns or 5 microns in the embodiment. The average diameter of the β-Si3N4 whiskers is preferably 0.3-5 microns, and specifically 0.5 microns or 2 microns in the embodiment; the average length of the β-Si3N4 whiskers is preferably 3-100 microns, and specifically 20 microns or 100 microns in the embodiment. The average particle size of the copper powder is preferably 1 to 200 microns, and is specifically 100 microns, 200 microns, 50 microns or 1 micron in the embodiment. The average particle size of the metal titanium powder is preferably 0.5 to 50 microns, and is specifically 1 micron, 50 microns or 0.5 microns in the embodiment. In terms of mass percentage, the mixed material includes 8 to 20 wt% of silicon nitride powder, and is specifically 12 wt%, 15 wt%, 20 wt% or 8 wt% in the embodiment. In terms of mass percentage, the mixed material includes 70 to 86 wt% of copper powder, and is specifically 80 wt%, 77 wt%, 70 wt%, 86%, 85 wt% or 83 wt% in the embodiment. In terms of mass percentage, the mixed material includes 3 to 15 wt% of metal titanium powder, and is specifically 8 wt%, 10 wt%, 6 wt%, 15 wt%, 3 wt% or 9 wt% in the embodiment.

[0043] In the present invention, the mixing preferably comprises the following steps:

[0044] Wet mixing copper powder, silicon nitride powder, metal titanium powder and solvent to obtain slurry;

[0045] The slurry is dried to obtain the mixed material.

[0046] The present invention wet mixes copper powder, silicon nitride powder, metal titanium powder and solvent to obtain a slurry. In the present invention, the wet mixing method preferably includes one or more of planetary mixing, drum mixing and stirring mixing, and in the embodiment, it is specifically planetary mixing, drum mixing or stirring mixing. The solvent preferably includes ethanol and / or water. The raw materials for the wet mixing preferably also include grinding balls, and the grinding balls preferably include one or more of silicon nitride balls, aluminum oxide balls, agate balls and silicon carbide balls. The present invention has no special requirements for the amount of solvent used during the mixing, and it is sufficient to ensure that the wet mixing proceeds smoothly. The present invention has no special requirements for the average particle size and amount of the grinding balls, and they can be added according to the average particle size and ball-to-material ratio of the grinding balls well known to those skilled in the art. The time of the wet mixing is preferably 2 to 24 hours, and in the embodiment, it is specifically 4 hours, 20 hours or 2 hours.

[0047] After obtaining the slurry, the present invention dries the slurry to obtain the mixed material. In the present invention, the drying method preferably includes one or more of air drying, vacuum drying and spray granulation. The air drying temperature is preferably 40 to 45° C., and the air drying time is preferably 6 to 8 hours. The vacuum drying temperature is preferably 45 to 50° C., and the vacuum drying time is preferably 2 to 3 hours.

[0048] After obtaining the mixed material, the present invention sintered the mixed material in a protective gas atmosphere to obtain the copper-based composite material. In the present invention, the sintering method preferably includes pressureless sintering after pressure forming, or directly placing it in a pressure mold and using hot pressing sintering, or directly placing it in a pressure mold and using SPS sintering. The protective gas is preferably nitrogen. The sintering temperature is preferably 900-1100°C, and in the embodiments, it is specifically 980°C, 1050°C, 1000°C, 900°C or 1100°C; the sintering holding time is preferably 5-120min, and in the embodiments, it is specifically 5min, 60min, 120min, 30min or 10min.

[0049] In the present invention, the sintering method is preferably pressure-forming followed by pressureless sintering, and the pressure-forming followed by pressureless sintering preferably includes sequentially performing dry pressing, cold isostatic pressing and pressureless sintering, the pressure of the dry pressing is preferably 40 MPa, and the pressure of the cold isostatic pressing is preferably 200 MPa.

[0050] In the present invention, the sintering method is preferably to directly place the sintering in a pressure mold and use hot pressing sintering. The pressure of the sintering is preferably 30-45 MPa, and specifically 40 MPa, 45 MPa or 30 MPa in the embodiments.

[0051] In the present invention, the sintering method is preferably to directly place the sintering in a pressure mold using SPS, and the pressure of the sintering directly placed in a pressure mold using SPS is preferably 30-45 MPa, specifically 40 MPa, 45 MPa or 30 MPa in the embodiments.

[0052] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] The schematic diagram of the structure of the copper-based composite material (i.e., sintered body) prepared in the following examples is as follows: Figure 1 Shown

[0054] Example 1

[0055] According to the mass fraction, 80wt% of copper powder with an average particle size of 100 microns, 12wt% of α-Si3N4 powder with an average particle size of 2 microns, and 8wt% of metal titanium powder with an average particle size of 1 micron were weighed and placed in a ball mill. An appropriate amount of anhydrous ethanol was added as a solvent. Silicon nitride balls were added and planetary ball milling was performed for 4 hours. The mixture was dried at 40°C for 8 hours to obtain a mixed powder.

[0056] The obtained mixed powder is directly placed in a pressure mold and sintered for 5 minutes at 980°C and nitrogen atmosphere protection at a pressure of 40MPa using an SPS sintering process. The copper-based composite material is obtained by cooling the furnace. The obtained copper-based composite material contains: 12wt% of α-Si3N4 particles, 10wt% of titanium nitride particles, and 78wt% of a copper matrix, wherein 80-85wt% of the titanium nitride particles are located on the surface of the α-Si3N4 particles.

[0057] Example 2

[0058] According to the mass fraction, 77wt% of copper powder with an average particle size of 100 microns, 15wt% of β-Si3N4 whiskers with an average diameter of 0.5 microns and an average length of 20 microns, and 8wt% of metal titanium powder with an average particle size of 50 microns were weighed and placed in a ball mill. An appropriate amount of anhydrous ethanol was added as a solvent, and silicon nitride balls were added for planetary ball milling for 20 hours. The mixture was dried at 45°C for 8 hours to obtain a mixed powder.

[0059] The obtained mixed powder is directly placed in a pressure mold and sintered for 60 minutes at a pressure of 45MPa, 1050°C and under the protection of a nitrogen atmosphere using a hot pressing sintering process. The copper-based composite material is obtained by cooling the furnace. The obtained copper-based composite material contains: 15wt% of β-Si3N4 whiskers, 10wt% of titanium nitride particles, and 75wt% of a copper matrix, wherein 75-80wt% of the titanium nitride particles are located on the surface of the β-Si3N4 whiskers.

[0060] Example 3

[0061] According to the mass fraction, 70wt% of copper powder with an average particle size of 200 microns, 20wt% of β-Si3N4 powder with an average particle size of 50 microns, and 10wt% of metal titanium powder with an average particle size of 50 microns were weighed and placed in a ball mill. An appropriate amount of anhydrous ethanol was added as a solvent. Silicon nitride balls were added and planetary ball milling was performed for 20 hours. The mixture was dried at 45°C for 8 hours to obtain a mixed powder.

[0062] The obtained mixed powder is directly placed in a pressure mold and sintered for 60 minutes at 45MPa pressure, 1050°C and nitrogen atmosphere protection using a hot pressing sintering process, and the copper-based composite material is obtained by cooling the furnace. The obtained copper-based composite material contains: 19wt% of β-Si3N4 particles, 13wt% of titanium nitride particles, and 68wt% of a copper matrix, wherein more than 70wt% of the titanium nitride particles are located on the surface of the β-Si3N4 particles.

[0063] Example 4

[0064] According to the mass fraction, 86wt% of copper powder with an average particle size of 50 microns, 8wt% of α-Si3N4 particles with an average particle size of 10 microns, and 6wt% of metal titanium powder with an average particle size of 0.5 microns were weighed and placed in a ball mill, and an appropriate amount of anhydrous ethanol was added as a solvent. Silicon nitride balls were added for planetary ball milling for 2 hours, and vacuum dried at 50°C for 2 hours to obtain a mixed powder, in which more than 70wt% of the titanium nitride particles were located on the surface of the α-Si3N4 particles.

[0065] The obtained mixed powder is formed by 40MPa dry pressing combined with 200MPa cold isostatic pressing. The formed block is kept at 1000°C for 120min in a nitrogen protective atmosphere, and the temperature is reduced along with the furnace to obtain a copper-based composite material. The obtained copper-based composite material contains: 7wt% of α-Si3N4 particles, 10wt% of titanium nitride particles, and 83wt% of a copper matrix, wherein 85-90wt% of the titanium nitride particles are located on the surface of the α-Si3N4 particles.

[0066] Example 5

[0067] According to the mass fraction, 77wt% of copper powder with an average particle size of 1 micron, 8wt% of α-Si3N4 powder with an average particle size of 1 micron, and 15wt% of metal titanium powder with an average particle size of 1 micron were weighed and placed in a ball mill, an appropriate amount of deionized water was added as a solvent, alumina balls were added and roller milled for 4 hours, and spray granulation was performed directly to obtain a mixed powder.

[0068] The obtained mixed powder is directly placed in a pressure mold and sintered for 30 minutes at 900°C and nitrogen atmosphere protection at a pressure of 30MPa using a hot pressing sintering process. The copper-based composite material is obtained by cooling the furnace. The obtained copper-based composite material contains: 8wt% of α-Si3N4 particles, 19wt% of titanium nitride particles, and 73wt% of a copper matrix, wherein 82-86wt% of the titanium nitride particles are located on the surface of the α-Si3N4 particles.

[0069] Example 6

[0070] According to the mass fraction, 85wt% of copper powder with an average particle size of 100 microns, 12wt% of β-Si3N4 powder with an average particle size of 5 microns, and 3wt% of metal titanium powder with an average particle size of 1 micron were weighed and placed in a stirred mill. An appropriate amount of anhydrous ethanol was added as a solvent. Agate balls were added for stirring and abrasion for 4 hours, and the mixture was dried at 40°C for 8 hours to obtain a mixed powder.

[0071] The obtained mixed powder is directly placed in a pressure mold and sintered for 5 minutes at a pressure of 30MPa, 1100°C and under nitrogen atmosphere protection using an SPS sintering process. The copper-based composite material is obtained as the furnace is cooled. The obtained copper-based composite material contains: 12wt% of β-Si3N4 particles, 4wt% of titanium nitride particles, and 84wt% of a copper matrix, wherein 83-88wt% of the titanium nitride particles are located on the surface of the β-Si3N4 particles.

[0072] Example 7

[0073] According to the mass fraction, 83wt% of copper powder with an average particle size of 50 microns, 8wt% of β-Si3N4 whiskers with an average diameter of 2 microns and an average length of 100 microns, and 9wt% of metal titanium powder with an average particle size of 0.5 microns were weighed and placed in a ball mill. An appropriate amount of deionized water was added as a solvent. Silicon carbide balls were added and roller milled for 4 hours. The mixture was vacuum dried at 50°C for 2 hours to obtain a mixed powder.

[0074] The obtained mixed powder is directly placed in a pressure mold and sintered for 10 minutes at 40MPa pressure, 1000°C and nitrogen atmosphere protection using an SPS sintering process, and the copper-based composite material is obtained as the furnace is cooled. The obtained copper-based composite material contains: 11wt% of β-Si3N4 whiskers, 8wt% of titanium nitride particles, and 81wt% of a copper matrix, wherein 86-91wt% of the titanium nitride particles are located on the surface of the β-Si3N4 whiskers.

[0075] Comparative Example 1

[0076] According to the mass fraction, 86% of copper powder with an average particle size of 100 μm and 14% of α-Si3N4 powder with an average particle size of 2 μm were weighed and placed in a ball mill, an appropriate amount of anhydrous ethanol was added as a solvent, silicon nitride balls were added for planetary ball milling for 4 hours, and air dried at 40°C for 8 hours to obtain a mixed powder.

[0077] The obtained mixed powder is directly placed in a pressure mold and sintered for 5 minutes at 40MPa pressure, 980°C and nitrogen atmosphere protection using an SPS sintering process. The copper-based composite material is obtained by cooling the furnace. The obtained copper-based composite material contains: 14wt% of α-Si3N4 particles and 86wt% of a copper matrix.

[0078] Comparative Example 2

[0079] According to the mass fraction, 80% of copper powder with an average particle size of 100 μm, 12% of α-Si3N4 powder with an average particle size of 2 μm, and 8% of titanium nitride powder with an average particle size of 1 μm were weighed and placed in a ball mill. An appropriate amount of anhydrous ethanol was added as a solvent. Silicon nitride balls were added and planetary ball milling was performed for 4 hours. The mixture was dried at 40°C for 8 hours to obtain a mixed powder.

[0080] The obtained mixed powder was directly placed in a pressure mold and sintered for 5 minutes at 40MPa pressure, 980℃, and nitrogen atmosphere protection by SPS sintering process, and the copper-based composite material was obtained by cooling the furnace. The obtained copper-based composite material contained: 12wt% α-Si3N4 particles, 8wt% titanium nitride particles, and 80wt% copper matrix, wherein 40-50wt% of the titanium nitride particles were located on the surface of β-Si3N4 whiskers.

[0081] Test Case

[0082] The silicon nitride reinforced copper-based composite material prepared in Example 1 was subjected to XRD detection to obtain an XRD spectrum, as shown in FIG. Figure 2 As shown. Figure 2 It can be seen from the XRD results that the main components of the material of Example 1 are copper phase, silicon nitride phase and titanium nitride, which is consistent with the expected results, and no chemical reaction occurs during the sintering process. The XRD results of Examples 2 to 7 are basically consistent with those of Example 1, and will not be repeated here.

[0083] The hardness of the composite materials prepared in Examples 1 to 7 and Comparative Examples 1 to 2 was tested using a Vickers hardness tester, and the results are listed in Table 1.

[0084] The tribological properties of the composite materials prepared in Examples 1 to 7 and Comparative Examples 1 to 2 were characterized using a UMT universal friction and wear tester (Bruker, America). The sintered composite material was used as the base sample and rubbed against a commercial silicon nitride sphere with a diameter of 6.5 mm (hardness 15.16 GPa) at room temperature. The sliding speed was 200 rpm, the applied load was 5 N, and each friction test lasted 30 min. The friction coefficient was recorded using a sensor, and the wear volume V (mm) was measured using a three-dimensional profiler (Retc instruments, San Jose, CA, USA). 3 ), and calculate the wear rate: W = V / FL, where W is the wear rate (mm 3 ·N -1 ·m -1 ), F is the applied load (N), L is the sliding distance (m), and the test results and calculation results are listed in Table 1.

[0085] Table 1 Performance parameters of the composite materials prepared in Examples 1 to 7 and Comparative Examples 1 to 2

[0086]

[0087]

[0088] It can be seen from the results in Table 1 that the composite material provided by the present invention has a higher density and good hardness and wear resistance. Compared with silicon nitride particles, the hardness and wear rate of the composite material are better improved after the addition of silicon nitride.

[0089] By comparing the data of Example 1 and Comparative Example 1, it can be found that titanium nitride is the key to achieving high densification of the material and high hardness and high wear resistance of the material. From Comparative Example 2, it can be seen that compared with Comparative Example 1 in which no titanium nitride is added, the addition of titanium nitride has a certain improvement effect on density, hardness and wear resistance. However, compared with Example 1, the effect of adding titanium nitride is much lower than that of adding metallic titanium.

[0090] From the above embodiments, it can be seen that the present invention provides a copper-based composite material, including the following components in percentage by mass: 7-20wt% silicon nitride particles, 4-20wt% titanium nitride particles, and 68-84wt% copper matrix; the silicon nitride particles include one or more of α-Si3N4 particles, β-Si3N4 particles, and β-Si3N4 whiskers; the silicon nitride particles and the titanium nitride particles are dispersed in the copper matrix, and more than 70wt% of the titanium nitride particles in the titanium nitride particles are located on the surface of the silicon nitride particles. The copper-based composite material is obtained by sintering the preparation raw materials including copper powder, silicon nitride powder, and metal titanium powder. The present invention uses metal titanium powder as a raw material. Compared with the direct introduction of titanium nitride particles, due to the better wettability between titanium nitride and copper, more titanium nitride particles will be completely wrapped by copper, and the effect on the interface adjustment between silicon nitride and copper is relatively small. The present invention adopts the method of in-situ formation of metallic titanium to make more titanium nitride form on the surface of silicon nitride particles, thereby more effectively improving the interface wettability between the copper matrix and the silicon nitride particles. Thus, the copper-based composite material obtained by the preparation method provided by the present invention can have a higher degree of densification under the condition of a high silicon nitride content. At the same time, copper exists in a single substance form, and relative to the alloy, the composite material can maintain a higher thermal conductivity and electrical conductivity. In addition, relative to silicon nitride particles, titanium nitride has good electrical conductivity and high hardness. Therefore, the copper-based composite material provided by the present invention has a higher density and good thermal conductivity, electrical conductivity, hardness and wear resistance.

[0091] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A silicon nitride and titanium nitride reinforced copper-based composite material, characterized in that: The invention comprises the following components in percentage by weight: 7-20wt% of silicon nitride particles, 4-20wt% of titanium nitride particles, and 68-84wt% of copper matrix; The silicon nitride particles include one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers; The silicon nitride particles and the titanium nitride particles are dispersed in the copper matrix, and more than 70 wt % of the titanium nitride particles in the titanium nitride particles are located on the surface of the silicon nitride particles.

2. The silicon nitride and titanium nitride reinforced copper-based composite material according to claim 1, characterized in that: The average particle sizes of the α-Si3N4 particles and the β-Si3N4 particles are independently 3 to 50 microns; The average diameter of the β-Si3N4 whisker is 0.3 to 5 microns, and the average length is 3 to 100 microns.

3. The silicon nitride and titanium nitride reinforced copper-based composite material according to claim 1, characterized in that: The average particle size of the titanium nitride particles is 0.1 to 5 microns.

4. The silicon nitride or titanium nitride reinforced copper-based composite material according to any one of claims 1 to 3, characterized in that: The relative density of the copper-based composite material is 89.5-99.5%.

5. The method for preparing the silicon nitride or titanium nitride reinforced copper-based composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing copper powder, silicon nitride powder and metal titanium powder to obtain a mixed material, wherein the silicon nitride powder includes one or more of α-Si3N4 particles, β-Si3N4 particles and β-Si3N4 whiskers; The mixed material is sintered in a protective gas atmosphere to obtain the silicon nitride and titanium nitride reinforced copper-based composite material.

6. The preparation method according to claim 5, characterized in that: The mixing comprises the following steps: Copper powder, silicon nitride powder, titanium powder and solvent are wet mixed to obtain slurry, wherein the average particle size of the copper powder is 1 to 200 microns, and the average particle size of the titanium powder is 0.5 to 50 microns; The slurry is dried to obtain the mixed material.

7. The preparation method according to claim 6, characterized in that: The wet mixing method includes one or more of planetary mixing, drum mixing and stirring mixing; The drying method includes one or more of air-blast drying, vacuum drying and spray granulation.

8. The preparation method according to claim 7, characterized in that: The solvent includes ethanol and / or water; the wet mixed raw materials also include grinding balls, and the grinding balls include one or more of silicon nitride balls, aluminum oxide balls, agate balls and silicon carbide balls.

9. The preparation method according to claim 5, characterized in that: The sintering method includes pressureless sintering after pressure forming, or directly placing in a pressure mold and using hot pressing sintering, or directly placing in a pressure mold and using SPS sintering.

10. The preparation method according to claim 5 or 9, characterized in that: The sintering temperature is 900-1100° C., and the heat preservation time is 5-120 minutes.

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