A method for additive manufacturing of polycrystalline diamond

Abstract

This invention relates to a method for additive manufacturing of polycrystalline diamond, specifically implemented according to the following steps: pre-sintering of multi-layered shell-structured diamond powder composed of multiple layers of different metals, followed by heat preservation and then allowing it to stand at room temperature; preheating a forming base plate to 500℃~800℃; layering the room-temperature-already-stationary multi-layered shell-structured diamond powder onto the preheated forming base plate, and melting each layer repeatedly with an electron beam; the multi-layered shell-structured diamond powder is a coated diamond powder, comprising, from the inside out, a first coating layer (tungsten coating layer); a second coating layer (nickel coating layer); and a third coating layer (iron or copper coating layer). This invention ensures uniform distribution of diamond and metal; avoids damage to the diamond powder caused by direct electron beam bombardment; and improves the bonding strength at the diamond-metal interface.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and more particularly to a method for additive manufacturing of polycrystalline diamond. Background Technology

[0002] Diamond, as the hardest substance in nature, possesses extremely high wear resistance, making tools made from it particularly suitable for machining hard and brittle materials. Polycrystalline diamond is a diamond polymer formed by agglomerating diamond microparticles together using a binder, creating diamond-binder-diamond bonds. It exhibits greater impact resistance than single-crystal diamond, especially polycrystalline diamond materials using metallic binders, which are widely used in diamond grinding tools, diamond sawing tools, diamond cutting tools, and diamond drilling tools. Traditional polycrystalline diamond materials are manufactured using high-temperature, high-pressure sintering, but this technology is severely limited when manufacturing diamond components with complex structures.

[0003] Additive manufacturing is an advanced manufacturing technology suitable for the direct forming of complex structures. Based on dimensionality reduction and discretization, it transforms complex three-dimensional solids into two-dimensional planes through slicing, and then stacks these layers to achieve direct and rapid manufacturing of solid parts. Among these technologies, powder bed electron beam additive manufacturing, which uses high-energy electron beams as an energy source, has been widely used in the direct forming of metallic materials due to its high energy utilization, high forming efficiency, and low stress in the formed samples. It also shows potential application in the forming of complex diamond parts.

[0004] Additive manufacturing of polycrystalline diamond materials typically uses composite powders made from a mixture of metal powder and diamond micron powder as raw materials. When the powder is irradiated by a high-energy electron beam, the metal powder melts, forming a molten metal that binds diamond particles, thus forming a polycrystalline diamond mass. However, because the electron beam is a high-energy beam, directly bombarding the diamond surface can cause diamond deformation. Simultaneously, diamond undergoes graphitization damage under high temperatures. In a diamond crystal, each carbon atom forms covalent bonds with four other carbon atoms using sp3 hybrid orbitals, creating a tetrahedron. Graphitization refers to the breaking of the original sp3 hybrid bonds in diamond, forming the sp2 hybrid bonds of graphite. Graphite and diamond have significantly different properties, and graphitization of diamond severely affects the performance of the composite material. Typically, the graphitization temperature is 800-1000℃.

[0005] Because additive manufacturing involves melting metal to bond diamond particles, the molten metal reacts with diamond at a temperature far exceeding that of conventional diamond graphitization, leading to graphitization of the diamond. Furthermore, since the diamond particles are solid while the metal melts into a liquid during forming, good wetting and spreading are required to achieve interfacial bonding and densification of the entire formed sample. However, due to the viscosity and wettability of the small molten pool, a large number of metal droplets spheroidize during electron beam additive manufacturing, creating numerous pores around these droplets. Therefore, this patent innovates and improves upon these issues from both the perspectives of powder raw materials and forming process.

[0006] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.

[0007] It should be noted that this section is intended to provide background or context for the technical solutions of the invention as set forth in the claims. The description herein does not imply acceptance as prior art simply because it is included in this section. Summary of the Invention

[0008] The purpose of this invention is to provide a method for additive manufacturing of polycrystalline diamond, thereby at least partially solving one or more problems caused by the limitations and defects of related technologies.

[0009] This invention provides a method for additive manufacturing of polycrystalline diamond, which is implemented according to the following steps:

[0010] After pre-sintering, diamond powder with a multi-layer shell structure composed of different metals is kept at a certain temperature and then allowed to stand at room temperature.

[0011] Preheat the forming base plate to 500℃~800℃;

[0012] Multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid layer by layer on the preheated forming base plate and then melted multiple times with an electron beam.

[0013] The multi-layer shell structure diamond powder is a coated diamond powder. The multi-layer shell structure diamond powder includes, from the inside to the outside, a first coating layer, which is a tungsten coating layer; a second coating layer, which is a nickel coating layer; and a third coating layer, which is either an iron coating layer or a copper coating layer.

[0014] In this invention, the thickness of the first coating layer is 1 μm to 5 μm.

[0015] In this invention, the thickness of the second coating layer is 5 μm to 50 μm.

[0016] In this invention, the thickness of the third coating layer is 5μm to 50μm.

[0017] In this invention, the pre-sintering temperature of the diamond powder with multi-layer shell structure is 500℃~800℃ and the holding time is 1h~2h.

[0018] In this invention, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid layer by layer on a preheated forming base plate. The thickness of the multi-layered shell-structured diamond powder is 50μm-100μm.

[0019] In this invention, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid layer by layer on a preheated forming base plate, and then melted layer by layer multiple times using an electron beam. The specific steps are as follows:

[0020] A layer of multi-layer shell structure diamond powder is spread on the preheated forming base plate and allowed to stand at room temperature;

[0021] The multi-layered shell structure diamond powder layer, which has been left to stand at room temperature, is melted twice using an electron beam. After the two meltings, the process is paused until the molten metal solidifies and cools, forming the first layer of polycrystalline diamond.

[0022] The above steps are repeated using the first polycrystalline diamond substrate to prepare the next polycrystalline diamond layer;

[0023] Continue until the desired polycrystalline diamond thickness is achieved.

[0024] In this invention, the electron beam current is 5mA to 8mA during the two-stage melting of a multi-layered shell structure diamond powder layer that has been left to stand at room temperature.

[0025] In this invention, during the multiple melting processes of powder on the forming substrate using an electron beam, the electron beam scanning speed is 6 m / s to 10 m / s.

[0026] In this invention, the pause time after the two melting processes is 5s to 10s.

[0027] The technical solution provided by this invention may include the following beneficial effects:

[0028] 1. In the powder bed electron beam additive manufacturing process, the distribution of diamond and metal can be kept uniform during the powder spreading and flow.

[0029] 2. It can avoid diamond damage caused by direct bombardment of diamond powder by the electron beam during electron beam powder bed additive manufacturing;

[0030] 3. During the heating process, a small amount of tungsten carbide can be generated at the interface between the tungsten coating layer and the diamond particles. At the same time, it has good wettability with Ni-Fe or Ni-Cu, which can improve the bonding strength between the diamond and the metal bonding phase interface.

[0031] In the process of polycrystalline diamond powder bed electron beam additive manufacturing, a single-layer low-energy multiple melting method is used to melt the powder layer. At the same time, a cooling process is added between the molten layers to reduce the overall temperature, shorten the life of the molten pool, and further reduce the thermal damage when the high-temperature molten pool comes into contact with diamond particles. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0033] Figure 1 This diagram illustrates a process flow diagram of a polycrystalline diamond additive manufacturing method according to an exemplary embodiment of the present invention. Detailed Implementation

[0034] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the invention will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0035] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0036] This exemplary embodiment first provides a polycrystalline diamond additive manufacturing method, referencing... Figure 1 As shown, the control method includes the following steps:

[0037] Step S101: After pre-sintering the diamond powder with a multi-layer shell structure composed of multiple metals, heat preservation is carried out and then the mixture is allowed to stand at room temperature.

[0038] During the heating process, a small amount of tungsten carbide can be generated at the interface between the tungsten coating and the diamond particles. At the same time, it has good wettability with Ni-Fe or Ni-Cu, which can improve the bonding strength between the diamond and the metal bonding phase interface.

[0039] Step S102: Preheat the forming base plate to 500℃~800℃. This is to prevent graphitization damage to the diamond under high temperature.

[0040] Step S103: Layer by layer, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid on the preheated forming base plate and melted multiple times with an electron beam. During the powder bed electron beam additive manufacturing process, the distribution of diamond and metal remains uniform throughout the powder spreading and flow.

[0041] The multi-layer shell structure diamond powder is a coated diamond powder. The multi-layer shell structure diamond powder includes, from the inside to the outside, a first coating layer, which is a tungsten coating layer; a second coating layer, which is a nickel coating layer; and a third coating layer, which is either an iron coating layer or a copper coating layer.

[0042] Tungsten carbides are formed between diamond and tungsten, while tungsten nickel iron or tungsten-based copper diffuse into each other in a solid solution.

[0043] Optionally, in some embodiments, the thickness of the first coating layer is 1 μm to 5 μm.

[0044] Optionally, in some embodiments, the thickness of the second coating layer is 5 μm to 50 μm.

[0045] Optionally, in some embodiments, the thickness of the third coating layer is 5 μm to 50 μm.

[0046] Optionally, in some embodiments, the pre-sintering temperature of the diamond powder with multi-layer shell structure after pre-sintering is 500℃~800℃, and the holding time is 1h~2h.

[0047] Optionally, in some embodiments, a multi-layer shell structure diamond powder, which has been left to stand at room temperature, is laid layer by layer on a preheated forming base plate. The thickness of the multi-layer shell structure diamond powder is 50μm-100μm.

[0048] Optionally, in some embodiments, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid layer by layer on a preheated forming base plate, and then melted layer by layer multiple times with an electron beam, specifically according to the following steps:

[0049] A layer of multi-layer shell structure diamond powder is spread on the preheated forming base plate and allowed to stand at room temperature;

[0050] The multi-layered shell structure diamond powder layer, which has been left to stand at room temperature, is melted twice using an electron beam. After the two meltings, the process is paused until the molten metal solidifies and cools, forming the first layer of polycrystalline diamond.

[0051] The above steps are repeated using the first polycrystalline diamond substrate to prepare the next polycrystalline diamond layer;

[0052] Continue until the desired polycrystalline diamond thickness is achieved.

[0053] The powder layer is melted by a single-layer low-energy multiple melting method. At the same time, a cooling process is added between the melted layers to reduce the overall temperature, shorten the life of the molten pool, and further reduce the thermal damage when the high-temperature molten pool comes into contact with the diamond particles.

[0054] Optionally, in some embodiments, during the two-stage melting of the multilayer shell-structured diamond powder layer that has been left to stand at room temperature, the electron beam current is 5mA to 8mA. This avoids damage to the diamond caused by direct bombardment of the diamond powder by the electron beam during electron beam powder bed additive manufacturing.

[0055] Optionally, in some embodiments, during the multiple melting processes of powder on the forming substrate using an electron beam, the electron beam scanning speed is 6 m / s to 10 m / s.

[0056] Optionally, in some embodiments, the pause time after the two melting processes is 5s to 10s.

[0057] After being formed by powder bed electron beam additive manufacturing, a polycrystalline diamond material is formed by bonding diamond micropowder with a small amount of Ni-Fe or Ni-Cu binder phase. The Ni-Fe or Ni-Cu solid solution can improve the overall plasticity of polycrystalline diamond.

[0058] Example 1

[0059] A method for additive manufacturing of polycrystalline diamond, the control method comprising the following steps:

[0060] (1) After pre-sintering the diamond powder with multi-layer shell structure, heat preservation is carried out and then the mixture is allowed to stand at room temperature.

[0061] The multi-layer shell structure diamond powder is a coated diamond powder, which consists of a first coating layer, a second coating layer and a third coating layer from the inside out.

[0062] The thickness of the first coating layer is 1 μm, and the first coating layer is a tungsten coating layer; the thickness of the second coating layer is 5 μm, and the second coating layer is a nickel coating layer.

[0063] The thickness of the third coating layer is 5 μm, and the third coating layer is an iron coating layer.

[0064] After pre-sintering the diamond powder with a multi-layer shell structure, the pre-sintering temperature was 500℃ and the holding time was 1h.

[0065] (2) Preheat the forming base plate to 500℃.

[0066] (3) Layer by layer diamond powder with multi-layer shell structure that has been left to stand at room temperature is laid on the preheated forming base plate and melted multiple times with an electron beam.

[0067] The thickness of the multi-layer shell structure diamond powder is 50 μm, which is laid layer by layer on the preheated forming base plate and left to stand at room temperature.

[0068] Layer by layer, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid on the preheated forming base plate and melted multiple times using an electron beam. The specific steps are as follows:

[0069] A layer of multi-layer shell structure diamond powder is spread on the preheated forming base plate and allowed to stand at room temperature;

[0070] The multi-layered shell structure diamond powder layer, which has been left to stand at room temperature, is melted twice using an electron beam. After the two meltings, the process is paused until the molten metal solidifies and cools, forming the first layer of polycrystalline diamond.

[0071] The above steps are repeated using the first polycrystalline diamond substrate to prepare the next polycrystalline diamond layer;

[0072] Continue until the desired polycrystalline diamond thickness is achieved.

[0073] In the process of using an electron beam to melt a multi-layered shell structure diamond powder layer that has been left to stand at room temperature twice, the electron beam current is 5mA.

[0074] During the process of repeatedly melting the powder on the forming base plate using an electron beam, the electron beam scanning speed is 6 m / s.

[0075] The pause time after two meltings is 5 seconds.

[0076] Example 2

[0077] A method for additive manufacturing of polycrystalline diamond, the control method comprising the following steps:

[0078] (1) After pre-sintering the diamond powder with multi-layer shell structure, heat preservation is carried out and then the mixture is allowed to stand at room temperature.

[0079] The multi-layer shell structure diamond powder is a coated diamond powder, which consists of a first coating layer, a second coating layer and a third coating layer from the inside out.

[0080] The thickness of the first coating layer is 5 μm, and the first coating layer is a tungsten coating layer; the thickness of the second coating layer is 50 μm, and the second coating layer is a nickel coating layer.

[0081] The thickness of the third coating layer is 50 μm, and the third coating layer is an iron coating layer.

[0082] After pre-sintering the diamond powder with a multi-layer shell structure, the pre-sintering temperature was 800℃ and the holding time was 2h.

[0083] (2) Preheat the forming base plate to 800℃.

[0084] (3) Layer by layer diamond powder with multi-layer shell structure that has been left to stand at room temperature is laid on the preheated forming base plate and melted multiple times with an electron beam.

[0085] The thickness of the multi-layer shell structure diamond powder is 100μm. The powder is laid layer by layer on the preheated forming base plate and left to stand at room temperature.

[0086] Layer by layer, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid on the preheated forming base plate and melted multiple times using an electron beam. The specific steps are as follows:

[0087] A layer of multi-layer shell structure diamond powder is spread on the preheated forming base plate and allowed to stand at room temperature;

[0088] The multi-layered shell structure diamond powder layer, which has been left to stand at room temperature, is melted twice using an electron beam. After the two meltings, the process is paused until the molten metal solidifies and cools, forming the first layer of polycrystalline diamond.

[0089] Repeat the above steps using the first polycrystalline diamond substrate to prepare the next polycrystalline diamond layer; until the desired polycrystalline diamond thickness is achieved.

[0090] In the process of using an electron beam to melt a multi-layered shell structure diamond powder layer that has been left to stand at room temperature twice, the electron beam current is 8mA.

[0091] During the process of repeatedly melting the powder on the forming base plate using an electron beam, the electron beam scanning speed is 10 m / s.

[0092] The pause time after two meltings is 10 seconds.

[0093] Example 3

[0094] A method for additive manufacturing of polycrystalline diamond, the control method comprising the following steps:

[0095] (1) After pre-sintering the diamond powder with multi-layer shell structure, heat preservation is carried out and then the mixture is allowed to stand at room temperature.

[0096] The multi-layer shell structure diamond powder is a coated diamond powder, which consists of a first coating layer, a second coating layer and a third coating layer from the inside out.

[0097] The thickness of the first coating layer is 3 μm, and the first coating layer is a tungsten coating layer; the thickness of the second coating layer is 25 μm, and the second coating layer is a nickel coating layer.

[0098] The thickness of the third coating layer is 30 μm, and the third coating layer is an iron coating layer.

[0099] The diamond powder with a multi-layer shell structure was pre-sintered and then kept at a temperature of 650℃ for 1.5h.

[0100] (2) Preheat the forming base plate to 700℃.

[0101] (3) Layer by layer diamond powder with multi-layer shell structure that has been left to stand at room temperature is laid on the preheated forming base plate and melted multiple times with an electron beam.

[0102] The thickness of the multi-layer shell structure diamond powder is 75 μm, which is laid layer by layer on the preheated forming base plate and left to stand at room temperature.

[0103] Layer by layer, multi-layered shell-structured diamond powder, which has been left to stand at room temperature, is laid on the preheated forming base plate and melted multiple times using an electron beam. The specific steps are as follows:

[0104] A layer of multi-layer shell structure diamond powder is spread on the preheated forming base plate and allowed to stand at room temperature;

[0105] The multi-layered shell structure diamond powder layer, which has been left to stand at room temperature, is melted twice using an electron beam. After the two meltings, the process is paused until the molten metal solidifies and cools, forming the first layer of polycrystalline diamond.

[0106] Repeat the above steps using the first polycrystalline diamond substrate to prepare the next polycrystalline diamond layer; until the desired polycrystalline diamond thickness is achieved.

[0107] In the process of using an electron beam to melt a multi-layered shell structure diamond powder layer that has been left to stand at room temperature twice, the electron beam current is 6mA.

[0108] During the process of repeatedly melting the powder on the forming base plate using an electron beam, the electron beam scanning speed is 8 m / s.

[0109] The pause time after two meltings is 7 seconds.

[0110] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" that may appear in the above description indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0111] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0112] In the embodiments of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0113] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature include the first feature being directly below or diagonally below the second feature, or simply indicating that the first feature is at a lower horizontal level than the second feature.

[0114] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0115] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the appended claims.

Claims

1. A method for manufacturing polycrystalline diamond, characterized in that, The specific steps are as follows: After pre-sintering, diamond powder with a multi-layer shell structure composed of different metals is kept at a certain temperature and then allowed to stand at room temperature. Preheat the forming base plate to 500℃~800℃; Multi-layered shell structure diamond powder, which has been left to stand at room temperature, is laid layer by layer on the preheated forming base plate and melted layer by layer with an electron beam multiple times. The multi-layer shell structure diamond powder is a coated diamond powder, which includes, from the inside out, a first coating layer, which is a tungsten coating layer with a thickness of 1μm to 5μm; a second coating layer, which is a nickel coating layer with a thickness of 5μm to 50μm; and a third coating layer, which is either an iron coating layer or a copper coating layer. The process involves layering multi-layered diamond powder with a shell structure, which has been left to stand at room temperature, onto a preheated forming base plate and melting it layer by layer using an electron beam multiple times. A layer of multi-layer shell-structured diamond powder with a thickness of 75μm~100μm is spread on the preheated forming base plate and left to stand at room temperature. The multi-layered shell structure diamond powder layer, which has been left to stand at room temperature, is melted twice using an electron beam. After the two meltings, the melting is paused to allow the molten metal to solidify and cool. The pause time after the two meltings is 5s to 10s, forming the first layer of polycrystalline diamond. Repeat the above steps on the first layer of polycrystalline diamond to prepare the next layer of polycrystalline diamond; Continue until the desired polycrystalline diamond thickness is achieved.

2. The method for manufacturing polycrystalline diamond according to claim 1, characterized in that, The thickness of the third coating layer is 5μm to 50μm.

3. The method for manufacturing polycrystalline diamond according to any one of claims 1-2, characterized in that, The pre-sintering temperature of the diamond powder with multi-layer shell structure after pre-sintering is 500℃~800℃, and the holding time is 1h~2h.

4. The method for manufacturing polycrystalline diamond according to claim 3, characterized in that, In the process of using an electron beam to melt the diamond powder layer of the multi-layer shell structure that has been left to stand at room temperature twice, the electron beam current is 5mA~8mA.

5. The method for manufacturing polycrystalline diamond according to claim 4, characterized in that, In the process of using an electron beam to melt the diamond powder layer of the multi-layer shell structure that has been left to stand at room temperature twice, the electron beam scanning speed is 6m / s to 10m / s.

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