Metal / diamond composite powder, method for preparing the same, and use thereof

Abstract

The application discloses a metal / diamond composite powder, which comprises spherical metal powder and diamond micro-powder with a metal layer on the surface embedded in the outer layer of the spherical metal powder, and stable combination is formed between the spherical metal powder and the diamond micro-powder with the metal layer on the surface, wherein a carbide connection is formed between the metal layer and the diamond micro-powder, and the metal layer and the spherical metal powder are connected through metal element diffusion; a preparation method is as follows: the diamond micro-powder with the metal layer on the surface is vacuum sintered, then mechanically ball milled with the spherical metal powder, and then vacuum sintered again; the composite powder is used for additive manufacturing. In the composite powder, stable combination is formed between the spherical metal powder and the diamond micro-powder with the metal layer on the surface, the uniformity and stability of the composite powder are improved; the vacuum sintering and mechanical ball milling are adopted to ensure firm combination of the spherical metal powder and the diamond micro-powder; and the composite powder is applied to additive manufacturing, and the forming quality is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of powder materials, and particularly relates to a metal / diamond composite powder and a preparation method and application thereof. BACKGROUND

[0002] Diamond is widely used in the fields of hard material processing, electronic packaging materials and the like due to its unique characteristics such as extremely high hardness, excellent thermal conductivity and low thermal expansion coefficient. Since diamond has a high cost and poor processability and formability, diamond composite materials are usually used in actual application, wherein a metal material is used as a binder phase, and diamond is used as a reinforcing particle. The metal / diamond composite material has the characteristics of low cost, high diamond particle holding force, high thermal conductivity and the like, and has important applications in many fields.

[0003] The metal / diamond composite material is mainly prepared by using metal and diamond powder as raw materials, and is usually manufactured by a powder metallurgy method. For manufacturing special-structure parts such as special-shaped parts and ultra-thin parts, a mold needs to be manufactured or complex post-processing is needed, which greatly increases the manufacturing cycle, complexity and manufacturing cost, and is a bottleneck in the development of the metal / diamond composite material manufacturing.

[0004] Additive manufacturing technology is an advanced rapid prototyping technology. Its principle is to establish a three-dimensional model and edit model data, adopt a layering-slicing-accumulation form, and use powder and other raw materials to form a part layer by layer. The additive manufacturing process can realize the special-shaped and complex of the part, can simplify the production process, reduce the production cost, and improve the production efficiency. The formed part has high density and high precision, and can solve the problems of long process and difficulty in forming complex structures in the traditional powder metallurgy process. The requirements of the additive manufacturing process for the powder mainly include the following aspects: 1) the powder has good fluidity and spreading property to meet the spreading process of the single-layer powder; 2) the powder has good uniformity and stability to ensure the consistency of each layer of powder; and 3) the powder has stable performance after multiple uses and can be reused. Generally speaking, spherical pre-alloyed powder is the best choice for additive manufacturing technology. The conventional preparation methods mainly include gas atomization (GA) and plasma rotating electrode process (PREP). However, due to the difference between diamond and metal, it is difficult to prepare pre-alloyed powder, so mixed powder is usually used as the forming raw material. However, the diamond powder is usually not spherical, and the density of diamond is quite different from that of traditional metal powder, so the powder is prone to layering and segregation during the powder spreading process. SUMMARY

[0005] The technical problem solved by the present application is to provide a metal / diamond composite powder to solve the problems of the prior art.

[0006] To solve the above technical problems, the present application adopts the technical scheme of a metal / diamond composite powder, characterized in that it comprises spherical metal powder and diamond micro-powder with a metal layer embedded on the outer layer of the spherical metal powder, and the spherical metal powder and the diamond micro-powder with a metal layer form a stable combination, wherein the metal layer and the diamond micro-powder form a carbide connection, and the metal layer and the spherical metal powder are connected by metal element diffusion.

[0007] The metal / diamond composite powder is characterized in that the spherical metal powder is copper-based alloy powder or nickel-based alloy powder.

[0008] The metal / diamond composite powder is characterized in that the metal layer is composed of titanium or tungsten.

[0009] By limiting the type of spherical metal powder and the composition of the metal layer, the matching between the two is ensured, and good combination is achieved.

[0010] The metal / diamond composite powder is characterized in that the volume content of the spherical metal powder in the metal / diamond composite powder is 80% to 95%, and the volume content of the diamond micro-powder with a metal layer is 5% to 20%.

[0011] Meanwhile, the present application also discloses a method for preparing the metal / diamond composite powder as described above, characterized in that the method comprises the following steps:

[0012] Step one, vacuum sintering the diamond micro-powder with a metal layer to form a trace amount of carbide between the metal layer and the diamond micro-powder;

[0013] Step two, mechanically ball milling the diamond micro-powder with a metal layer after vacuum sintering in step one and the spherical metal powder to embed the diamond micro-powder with a metal layer on the surface of the spherical metal powder, forming a metal / diamond mixed powder with a core-shell structure;

[0014] Step three, vacuum sintering the metal / diamond mixed powder with core-shell structure obtained in step two, so that the metal layer and the spherical metal powder are combined by metal element diffusion to form metallurgical bonding, and a metal / diamond composite powder is obtained.

[0015] The metal / diamond composite powder has the characteristics that the particle size of the diamond powder with a metal layer on the surface in step one is 5-10 mu m, and the thickness of the metal layer is 1-3 mu m.

[0016] The method has the characteristics that the temperature of the vacuum sintering in step one is 700-850 DEG C, and the holding time is 1-2 hours. By limiting the process parameters of the vacuum sintering in this step, a small amount of carbide is formed between the metal layer and the diamond powder.

[0017] The metal / diamond composite powder has the characteristics that the particle size of the spherical metal powder in step two is 30-105 mu m. The spherical metal powder with this size matches the particle size of the diamond powder, and a better embedding effect can be achieved.

[0018] The method has the characteristics that the temperature of the vacuum sintering in step three is 700-850 DEG C, and the holding time is 1-2 hours. By limiting the process parameters of the vacuum sintering in this step, metal element diffusion occurs between the metal layer and the spherical metal powder to form metallurgical bonding, and the firmness of the combination of the two is improved.

[0019] In addition, the application also discloses an application of the metal / diamond composite powder as described above, which has the characteristics that the metal / diamond composite powder is used for electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing.

[0020] Compared with the prior art, the application has the following advantages:

[0021] 1. The metal / diamond composite powder comprises spherical metal powder and diamond powder with a metal layer on the surface embedded in the outer layer of the spherical metal powder. Through the embedding effect of the diamond powder with a metal layer on the surface in the spherical metal powder, the combination of the metal layer and the diamond powder through carbide connection and the metal element diffusion connection between the metal layer and the spherical metal powder are combined, so that the spherical metal powder and the diamond powder with a metal layer on the surface are stably combined. When the metal / diamond composite powder flows, fills and spreads, the diamond powder in the outer layer of the spherical metal powder will not fall off, delaminate or segregate, and the uniformity and stability of the metal / diamond composite powder are improved.

[0022] 2. In the preparation process of this invention, diamond micropowder with a metal layer on its surface (generally prepared by vacuum evaporation) is first vacuum sintered to promote the formation of trace carbides between the metal layer and the diamond micropowder, strengthen the interfacial bonding strength between the metal layer and the diamond, and prevent the metal layer from separating from the diamond. Then, it is mechanically ball-milled with spherical metal powder. Utilizing the difference in hardness between the diamond and the spherical metal powder matrix, the diamond micropowder with a metal layer on its surface is embedded in the surface of the spherical metal powder, forming a metal / diamond mixed powder with a core-shell structure, i.e., the "core" is the spherical metal powder and the "shell" is the diamond micropowder with a metal layer on its surface. Vacuum sintering then allows the metal layer and the spherical metal powder to form a metallurgical bond through the diffusion of metal elements, resulting in a metal / diamond composite powder. This ensures a strong bond between the spherical metal powder and the diamond micropowder and avoids the problem of diamond segregation and delamination caused by density differences between the spherical metal powder and the diamond micropowder.

[0023] 3. When the metal / diamond composite powder of the present invention is used as a raw material powder in additive manufacturing, during the continuous flow and spreading process of the metal / diamond composite powder, the spherical metal powder drives the flow of diamond micro powder, which improves the overall powder fluidity and maintains the uniformity and stability of the composite powder. This improves the uniformity and stability of the additive manufacturing process, solves the problems of diamond and metal bonding and inability to pre-alloy, as well as the layering and aggregation of diamond and metal mixed powders, and improves the recovery rate of the metal / diamond composite powder after application.

[0024] 4. When the metal / diamond composite powder of the present invention is used as a raw material powder in electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing, the components of the metal / diamond composite powder are tightly bonded together, and the spherical metal powder has a fixing effect on the diamond micro powder embedded therein, which reduces the diamond splashing phenomenon caused by high energy beam action and improves the forming quality.

[0025] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0026] Example 1

[0027] The metal / diamond composite powder of the embodiment comprises spherical Ni-Cu alloy powder and diamond micro-powder with a titanium metal layer embedded on the outer layer of the spherical Ni-Cu alloy powder, the volume content of the spherical Ni-Cu alloy powder in the metal / diamond composite powder is 95%, the volume content of the diamond micro-powder with a titanium metal layer is 5%, and a stable combination is formed between the spherical Ni-Cu alloy powder and the diamond micro-powder with a titanium metal layer, wherein a carbide connection is formed between the titanium metal layer and the diamond micro-powder, and the titanium metal layer and the spherical Ni-Cu alloy powder are connected through metal element diffusion.

[0028] The metal / diamond composite powder preparation method of the embodiment comprises the following steps:

[0029] Step one, vacuum sintering diamond micro-powder with a particle size of 5-10 μm and a titanium metal layer with a thickness of 1 μm on the surface, the vacuum sintering temperature is 700°C, and the holding time is 1 h, so that a small amount of carbide is formed between the titanium metal layer and the diamond micro-powder;

[0030] Step two, mechanical ball milling the diamond micro-powder with a titanium metal layer on the surface after vacuum sintering in step one and spherical Ni-Cu alloy powder with a particle size of 30-105 μm, so that the diamond micro-powder with a titanium metal layer is embedded on the surface of the spherical Ni-Cu alloy powder, forming metal / diamond mixed powder with core-shell structure, wherein the "core" is the spherical Ni-Cu alloy powder, and the "shell" is the diamond micro-powder with a titanium metal layer on the surface;

[0031] Step three, vacuum sintering the metal / diamond mixed powder with core-shell structure obtained in step two, the vacuum sintering temperature is 700°C, and the holding time is 1 h, so that the titanium metal layer and the spherical Ni-Cu alloy powder are connected through metal element diffusion to form metallurgical bonding, obtaining the metal / diamond composite powder.

[0032] It is detected that the diamond micro-powder on the surface of the metal / diamond composite powder prepared in the embodiment will not fall off or gather during flowing, filling and spreading, and the uniformity and stability of the composite powder can be maintained. When the metal / diamond composite powder prepared in the embodiment is applied to electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing to prepare metal / diamond composite materials, the problems such as diamond spatter, uneven distribution of diamond, and low recovery rate of composite powder during the forming process can be effectively avoided, and obvious advantages are obtained.

[0033] Embodiment 2

[0034] The metal / diamond composite powder of the embodiment comprises spherical Ni-Cu alloy powder and diamond micro-powder with a titanium metal layer embedded on the outer layer of the spherical Ni-Cu alloy powder, the volume content of the spherical Ni-Cu alloy powder in the metal / diamond composite powder is 80%, the volume content of the diamond micro-powder with a titanium metal layer is 20%, and a stable combination is formed between the spherical Ni-Cu alloy powder and the diamond micro-powder with a titanium metal layer, wherein a carbide connection is formed between the titanium metal layer and the diamond micro-powder, and the titanium metal layer and the spherical Ni-Cu alloy powder are connected through metal element diffusion.

[0035] The metal / diamond composite powder preparation method of the embodiment comprises the following steps:

[0036] Step one, vacuum sintering diamond micro-powder with a particle size less than 10 μm and a titanium metal layer with a thickness of 3 μm on the surface, the vacuum sintering temperature is 850°C, and the holding time is 2 h, so that a small amount of carbide is formed between the titanium metal layer and the diamond micro-powder;

[0037] Step two, mechanical ball milling the diamond micro-powder with a titanium metal layer obtained after vacuum sintering in step one and spherical Ni-Cu alloy powder with a particle size of 30 μm to 105 μm, so that the diamond micro-powder with a titanium metal layer is embedded on the surface of the spherical Ni-Cu alloy powder, forming metal / diamond mixed powder with core-shell structure, wherein the "core" is the spherical Ni-Cu alloy powder, and the "shell" is the diamond micro-powder with a titanium metal layer;

[0038] Step three, vacuum sintering the metal / diamond mixed powder with core-shell structure obtained in step two, the vacuum sintering temperature is 850°C, and the holding time is 2 h, so that the titanium metal layer and the spherical Ni-Cu alloy powder are connected through metal element diffusion to form metallurgical bonding, obtaining the metal / diamond composite powder.

[0039] It is detected that when the metal / diamond composite powder prepared in the embodiment flows, fills and spreads, the diamond micro-powder on the surface will not fall off or aggregate, and the uniformity and stability of the composite powder can be maintained. When the metal / diamond composite powder prepared in the embodiment is applied to electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing to prepare metal / diamond composite materials, the problems of diamond spatter, uneven distribution of diamond and low recovery rate of composite powder in the forming process can be effectively avoided, and obvious advantages are obtained.

[0040] Embodiment 3

[0041] The metal / diamond composite powder of the embodiment comprises spherical Ni-Cu alloy powder and diamond micro-powder with a tungsten metal layer embedded on the outer surface of the spherical Ni-Cu alloy powder, the volume content of the spherical Ni-Cu alloy powder in the metal / diamond composite powder is 95%, the volume content of the diamond micro-powder with a tungsten metal layer is 5%, and a stable combination is formed between the spherical Ni-Cu alloy powder and the diamond micro-powder with a tungsten metal layer, wherein a carbide connection is formed between the tungsten metal layer and the diamond micro-powder, and the tungsten metal layer and the spherical Ni-Cu alloy powder are connected by metal element diffusion.

[0042] The metal / diamond composite powder preparation method of the embodiment comprises the following steps:

[0043] Step one, vacuum sintering diamond micro-powder with a particle size less than 10 μm and a tungsten metal layer with a thickness of 1 μm on the surface, the vacuum sintering temperature is 700 ℃, and the holding time is 1 h, so that a small amount of carbide is formed between the tungsten metal layer and the diamond micro-powder;

[0044] Step two, mechanical ball milling the diamond micro-powder with a tungsten metal layer on the surface after vacuum sintering in step one and spherical Ni-Cu alloy powder with a particle size of 30 μm to 105 μm, so that the diamond micro-powder with a tungsten metal layer is embedded on the surface of the spherical Ni-Cu alloy powder to form metal / diamond mixed powder with core-shell structure, wherein the "core" is the spherical Ni-Cu alloy powder, and the "shell" is the diamond micro-powder with a tungsten metal layer;

[0045] Step three, vacuum sintering the metal / diamond mixed powder with core-shell structure obtained in step two, the vacuum sintering temperature is 700 ℃, and the holding time is 1 h, so that the tungsten metal layer and the spherical Ni-Cu alloy powder are connected by metal element diffusion to form metallurgical bonding, and the metal / diamond composite powder is obtained.

[0046] It is detected that the diamond micro-powder on the surface of the metal / diamond composite powder prepared in the embodiment will not fall off or aggregate during flowing, filling and spreading, and the uniformity and stability of the composite powder can be maintained. When the metal / diamond composite powder prepared in the embodiment is applied to electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing to prepare metal / diamond composite materials, the problems of diamond spattering, uneven distribution of diamond and low recovery rate of composite powder during the forming process can be effectively avoided, and obvious advantages are obtained.

[0047] Embodiment 4

[0048] The metal / diamond composite powder of the embodiment comprises spherical Ni-Cu alloy powder and diamond micro-powder with a tungsten metal layer embedded on the surface of the spherical Ni-Cu alloy powder, the volume content of the spherical Ni-Cu alloy powder in the metal / diamond composite powder is 80%, the volume content of the diamond micro-powder with a tungsten metal layer is 20%, and the spherical Ni-Cu alloy powder and the diamond micro-powder with a tungsten metal layer form a stable combination, wherein the tungsten metal layer and the diamond micro-powder form a carbide connection, and the tungsten metal layer and the spherical Ni-Cu alloy powder are connected by metal element diffusion.

[0049] The metal / diamond composite powder preparation method of the embodiment comprises the following steps:

[0050] Step one, vacuum sintering diamond micro-powder with a particle size less than 10 μm and a 3 μm thick tungsten metal layer on the surface, the vacuum sintering temperature is 850℃, and the holding time is 2 h, so that a trace amount of carbide is formed between the tungsten metal layer and the diamond micro-powder;

[0051] Step two, mechanical ball milling the diamond micro-powder with a tungsten metal layer on the surface obtained after vacuum sintering in step one and spherical Ni-Cu alloy powder with a particle size of 30 μm to 105 μm, so that the diamond micro-powder with a tungsten metal layer is embedded on the surface of the spherical Ni-Cu alloy powder, forming metal / diamond mixed powder with a core-shell structure, wherein the "core" is the spherical Ni-Cu alloy powder, and the "shell" is the diamond micro-powder with a tungsten metal layer;

[0052] Step three, vacuum sintering the metal / diamond mixed powder with a core-shell structure obtained in step two, the vacuum sintering temperature is 850℃, and the holding time is 2 h, so that the tungsten metal layer and the spherical Ni-Cu alloy powder are connected by metal element diffusion to form metallurgical combination, obtaining the metal / diamond composite powder.

[0053] It is detected that the diamond micro-powder on the surface of the metal / diamond composite powder prepared in the embodiment will not fall off or gather during flowing, filling and spreading, and the uniformity and stability of the composite powder can be maintained. When the metal / diamond composite powder prepared in the embodiment is applied to electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing to prepare metal / diamond composite materials, the problems such as diamond spatter, uneven distribution of diamond and low recovery rate of composite powder in the forming process can be effectively avoided, and obvious advantages are obtained.

[0054] The above is only a preferred embodiment of the present application, and does not limit the present application. Any simple modification, change and equivalent change made on the basis of the technical essence of the present application to the above embodiment are still within the protection scope of the technical solution of the present application.

Claims

1. A method of producing a metal / diamond composite powder, characterized by, The metal / diamond composite powder comprises spherical metal powder and diamond micro-powder with a metal layer embedded on the outer layer of the spherical metal powder, and the spherical metal powder and the diamond micro-powder with the metal layer are stably combined, wherein the metal layer and the diamond micro-powder are connected by carbide, and the metal layer and the spherical metal powder are connected by metal element diffusion, the spherical metal powder is copper-based alloy powder or nickel-based alloy powder, and the metal layer is composed of titanium or tungsten. The method comprises the following steps: Step one, vacuum sintering the diamond micro-powder with the metal layer to form a trace amount of carbide between the metal layer and the diamond micro-powder; the particle size of the diamond micro-powder with the metal layer is 5-10 microns, and the thickness of the metal layer is 1-3 microns; the temperature of the vacuum sintering is 700-850 degrees Celsius, and the holding time is 1-2 hours; Step two, mechanically ball milling the diamond micro-powder with the metal layer after the vacuum sintering in step one and the spherical metal powder to embed the diamond micro-powder with the metal layer on the surface of the spherical metal powder, and form a metal / diamond mixed powder with a core-shell structure; the particle size of the spherical metal powder is 30-105 microns; Step three, vacuum sintering the metal / diamond mixed powder with the core-shell structure obtained in step two to form a metallurgical bond between the metal layer and the spherical metal powder by metal element diffusion, and obtain the metal / diamond composite powder; the temperature of the vacuum sintering is 700-850 degrees Celsius, and the holding time is 1-2 hours.

2. The method of claim 1, wherein the metal / diamond composite powder is prepared by the steps of: The volume content of the spherical metal powder in the metal / diamond composite powder is 80-95%, and the volume content of the diamond micro-powder with the metal layer is 5-20%.

3. Use of a metal / diamond composite powder produced according to the method as claimed in claim 1 or 2, characterized in that, The metal / diamond composite powder is used for electron beam selective melting additive manufacturing, laser selective melting additive manufacturing or laser coaxial powder feeding additive manufacturing.