A method for manufacturing a metal-based diamond composite material

Abstract

The present invention relates to a method for manufacturing a metal-based diamond composite material, comprising: introducing a printed model of a metal-based diamond composite material into an additive manufacturing device, turning on an electron beam after spreading the powder to perform heat treatment on the powder laid on a substrate according to a heat treatment process, wherein the heat treatment process includes preheating the powder bed before printing, scanning printing, and cooling after printing; scanning printing is performed after the preheating of the powder bed before printing is completed, wherein the energy density E during the scanning printing process is v The value range is 20J / mm 3 ≤E v ≤35J / mm 3 The present invention performs heat treatment on the powder laid on the substrate before and after printing, and controls the average heat input, energy density and the proportional relationship between the two in the entire printing process, so as to achieve the synergistic effect between the parameters and achieve the purpose of optimizing the printing process, so that the metal-based diamond composite material will not peel during the processing, the burning loss is effectively reduced, the printed part has a high density, and the processing efficiency and product qualification rate are improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of additive manufacturing technology, and in particular to a method for manufacturing a metal-based diamond composite material. Background Art

[0002] Additive manufacturing is an advanced manufacturing method that can realize the transformation from materials to parts in an integrated manner through 3D model design, slicing and printing. It is very suitable for the preparation of hard and brittle metal-based diamond composite parts. However, there are also many problems in the additive manufacturing process. For example, in the additive manufacturing of metal-based diamond composites, when the heat input is too high, the powder bed temperature is high, it is easy to peel and be scraped away, resulting in uneven powder spreading and affecting the printing quality; when the heat input is low, the metal powder may not be fully melted or the metal liquid is not fully spread in the molten pool, so that the diamond particles are not tightly combined with the metal matrix, pores are formed inside, and the density of the printed parts is reduced; if the melting process is not set properly, it will cause carbonization and burning of diamonds, reducing the wear resistance of the printed parts. Control of heat input, printing layer temperature and printing process, as well as studying the mutual influence of various parameters, are crucial in the process of electron beam additive manufacturing of metal-based diamond composites.

[0003] Therefore, the following difficulties still exist in the processing and manufacturing of metal-based diamond composites: 1. Diamond is a metastable phase, which is very easy to undergo graphitization stable phase transformation under the action of high-temperature heat source or catalytic metal, and is prone to oxidation damage under high temperature or oxygen-containing conditions; 2. Diamond has a high refractive index and reflectivity for light, which will reduce the energy absorption rate during laser processing, reduce processing efficiency and melting quality.

[0004] Therefore, it is necessary to improve one or more problems existing in the above-mentioned related technical solutions.

[0005] It should be noted that this section is intended to provide background or context for the technical solutions of the present invention stated in the claims. The description herein is not admitted to be prior art by inclusion in this section. Summary of the invention

[0006] The object of the present invention is to provide a method for manufacturing a metal-based diamond composite material, thereby solving one or more problems caused by limitations and defects of the related art at least to a certain extent.

[0007] The present invention provides a method for manufacturing a metal-based diamond composite material, comprising:

[0008] The printed model of the metal-based diamond composite material is imported into the additive manufacturing equipment. After the powder is spread, the electron beam is turned on to heat treat the powder laid on the substrate according to the heat treatment process. The heat treatment process includes preheating the powder bed before printing, scanning printing and cooling after printing;

[0009] The preset value range of the average heat input P of the heat treatment process is: 300 J / s≤P≤360 J / s, and the average heat input P is determined according to the following formula:

[0010]

[0011] Where U is the electron beam voltage, I1 is the current for preheating the powder bed before printing the current layer, I2 is the melting current for scanning printing of the current layer, t1 is the time for preheating the powder bed before printing the current layer, t2 is the time for scanning printing of the current layer, and t 总 is the total printing time of the current layer, t 总 =t1+t2+t3+t 铺粉 , where t 铺粉 is the time for spreading powder of the current layer, and t3 is the time for cooling down the current layer after printing;

[0012] After the preheating of the powder bed before printing is completed, the scanning printing is performed, wherein the energy density E during the scanning printing process is v The value range is 20J / mm 3 ≤E v ≤35J / mm 3 , E v Determined according to the following formula:

[0013]

[0014] Where, v is the scanning speed of the current layer, h is the powder layer thickness of the current layer, and d is the scanning spacing of the current layer; The value range is 10~16.

[0015] In the present invention, a defocused lower beam is used for the electron beam when the powder bed is preheated before printing, and a focused lower beam is used for the electron beam during scanning printing.

[0016] In the present invention, the electron beam current for preheating the powder bed before printing is 15-25 mA, and the electron beam current during scanning printing is 1-5 mA.

[0017] In the present invention, during the cooling process after printing, the electron beam is not turned on and the cooling time is 0 to 10 seconds.

[0018] In the present invention, in the powder used for printing the metal-based diamond composite material, the volume percentage of diamond powder is 1% to 40%, and the rest is matrix powder, and the matrix powder is at least one of nickel alloy or copper alloy.

[0019] In the present invention, the process of preheating the substrate before powdering is as follows:

[0020] Preheating for a first time period using a first preheating current;

[0021] A second preheating current is used for preheating for a second time period, wherein the first preheating current is smaller than the second preheating current.

[0022] In the present invention, during the scanning and printing process, the scanning line is rotated layer by layer by a preset angle, and the preset angle is 45 to 90 degrees.

[0023] In the present invention, during the scanning and printing, the scanning path is S-shaped.

[0024] In the present invention, the electron beam voltage U is 50-70 kV.

[0025] In the present invention, after the substrate is preheated, the temperature of the substrate is 500-600°C.

[0026] The technical solution provided by the present invention may include the following beneficial effects:

[0027] In the present invention, the powder laid on the substrate is heat treated before and after printing, that is, the powder bed is preheated before printing, scanning printing and cooling after printing, and multiple parameters in the heat treatment and melting process and their relationship are limited. Specifically, the average heat input, energy density and the proportional relationship between the two in the entire printing and forming process are controlled to achieve synergy between the parameters and achieve the purpose of optimizing the printing process, so that the metal-based diamond composite material will not peel during the powder preheating process, and the burn loss during the printing process is effectively reduced. At the same time, the obtained printed parts have high density, which improves the processing efficiency and product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0029] Figure 1 A schematic flow chart showing a method for manufacturing a metal-based diamond composite material in an exemplary embodiment of the present invention;

[0030] Figure 2 The macroscopic morphology photos of the parts printed by the control group 1, the control group 2 and the experimental group of the present invention are shown;

[0031] Figure 3 The scanning electron microscope images of the parts printed by the control group 1, the control group 2 and the experimental group of the present invention are shown. DETAILED DESCRIPTION

[0032] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present invention will be more comprehensive and complete and fully convey the concepts of the example 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.

[0033] In addition, the accompanying drawings are only schematic illustrations of embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and their repeated descriptions will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0034] This example embodiment provides a method for manufacturing a metal-based diamond composite material. Figure 1 As shown, the manufacturing method comprises the following steps:

[0035] Step S101: import the printed model of the metal-based diamond composite material into the additive manufacturing equipment, turn on the electron beam after spreading the powder, and heat-treat the powder laid on the substrate according to the heat treatment process. The heat treatment process includes preheating the powder bed before printing, scanning printing and cooling after printing.

[0036] The preset value range of the average heat input P of the heat treatment process is: 300 J / s≤P≤360 J / s, for example, it can be 320 J / s, 340 J / s, 350 J / s, etc., but it is not limited thereto. The average heat input P is determined according to the following formula:

[0037]

[0038] Where U is the electron beam voltage, I1 is the powder bed preheating current before printing the current layer, I2 is the melting current of the scanning printing of the current layer, t1 is the powder bed preheating time before printing the current layer, t2 is the scanning printing time of the current layer, t 总 is the total printing time of the current layer, where t 总 =t1+t2+t3+t 铺粉 , t 铺粉 is the time for spreading powder of the current layer, and t3 is the time for cooling down the current layer after printing;

[0039] Step S102: Scanning and printing are performed after the powder bed is preheated before printing. The energy density E during the scanning and printing process is v The value range is 20J / mm 3 ≤E v ≤35J / mm 3 , Ev Determined according to the following formula:

[0040]

[0041] In the formula, v is the current layer scanning speed, h is the current layer powder thickness, and d is the current layer scanning spacing; The value range of is 10~16, for example, the value range can be 11, 12, 13, 14, 15, etc., but it is not limited thereto.

[0042] Through the above method, the powder laid on the substrate is heat treated before and after printing. The heat treatment includes preheating of the powder bed before printing, scanning printing and cooling after printing, and multiple parameters in the heat treatment and scanning printing process and their relationship with each other are limited. Specifically, the average heat input, energy density and the proportional relationship between the two in the entire printing and forming process are controlled to achieve synergy between the parameters and achieve the purpose of optimizing the printing process, so that the metal-based diamond composite material will not peel during the powder preheating process, and the burn loss during the printing process is effectively reduced. At the same time, the obtained printed parts have high density, which improves the processing efficiency and product qualification rate.

[0043] It should be noted that this application requires the energy density to meet 20J / mm 3 ≤E v ≤35J / mm 3 , when the energy density is lower than 20J / mm 3 When the energy density is higher than 35J / mm, the molten pool may not be fully melted due to insufficient heat input, resulting in the formation of many tiny holes inside the part. 3 When the energy density is too high, printed parts such as diamond will be severely burned.

[0044] It should be noted that, in some embodiments, the electron beam uses a defocused lower beam when preheating the powder bed before printing, and uses a focused lower beam when scanning and printing. Specifically, the electron beam current for preheating the powder bed before printing can use a defocused current of 15 to 25 mA, such as 18 mA, 20 mA, 22 mA, etc., and the defocused current lower beam is used to preheat all the powders on the entire substrate as a whole; the electron beam current during scanning and printing can use a focused current of 1 to 5 mA, such as 2 mA, 3 mA, 4 mA, etc., and the focused current lower beam is used to accurately melt and scan the part to be printed.

[0045] It is understandable that during the cooling process after printing, the electron beam is not turned on, and the cooling time is 0~10s, which is adjusted according to the range of average heat input to ensure that the average heat input P reaches the preset value range. Cooling the powder bed after printing can effectively reduce the average heat input, avoid serious burning of parts during the printing process, improve the quality of part forming, and obtain a print with higher density.

[0046] Optionally, in some embodiments, in the powder used for printing the metal-based diamond composite material, the volume percentage of diamond powder is 1%~40%, and the rest is matrix powder, and the matrix powder is at least one of nickel alloy or copper alloy, but the matrix powder is not limited thereto.

[0047] In addition, the process of preheating the substrate before powdering is as follows:

[0048] First, preheating for a first time period using a first preheating current;

[0049] Then, a second preheating current is used for preheating for a second time period, wherein the first preheating current is smaller than the second preheating current.

[0050] In this embodiment, the substrate is preheated with a smaller current first, for example, to 300° C., and then preheated with a larger current to 500-600° C., thus completing the preheating of the substrate in sequence.

[0051] A specific embodiment is listed below to illustrate the manufacturing method of the present application.

[0052] This embodiment uses NiCu+10wt% diamond powder for printing, and three groups, namely control group 1, control group 2 and experimental group, are used for experiments.

[0053] 1. Load NiCu+10wt% diamond powder into the additive manufacturing equipment and wait until the vacuum degree of the forming chamber drops to 1.9×10 -2 When the vacuum degree of the molding chamber is below 1×10 -1 Pa.

[0054] 2. Substrate preheating

[0055] Turn on the electron beam high voltage power supply, first use 10mA, 13.6m / s electron beam to preheat for 10min, heat the substrate to 300℃, then use 15mA, 13.6m / s electron beam to preheat for 8min, heat the substrate to 550℃.

[0056] 3. Heat treatment

[0057] First, the average heat input P during the printing process was calculated and adjusted. The electron beam current for the powder bed preheating treatment before printing in the three groups was 22mA, and the preheating time was 5s; the melting current, scanning speed and melting time of the three groups were 2mA, 1.5m / s, 30s, 4mA, 1m / s, 33s, and 4mA, 2m / s, 32s. The thickness of the printed layer in the three groups was 0.05mm. Control group 1 and control group 2 did not cool down after printing, and the experimental group set a cooling time of 5s.

[0058] According to the above parameters, the average heat inputs of the three groups were calculated to be 291.4 J / s, 382.1 J / s, and 340 J / s, respectively.

[0059] Then, the energy density of the three groups was calculated. The energy density of the three groups was: 16J / mm 3 ,48 / mm 3 , 24J / mm 3 .

[0060] Finally, calculate the P / E of the three groups of processes v The ratios of the three groups were 18.2, 8.0, and 14.2, respectively.

[0061] The above parameters are used for scanning melting, and an S-shaped scanning strategy is adopted. The scanning line rotates 90° layer by layer. After each layer is melted, the base plate drops 0.05mm and continues to print the next layer, finally completing the printing of the part.

[0062] 4. Evaluate the printed workpiece

[0063] like Figure 2 As shown, the surface of the printed part of the control group 1 is gray, the surface of the control group 2 is partially black, and obvious diamond carbide appears, and the surface of the parts of the experimental group has a good metallic luster.

[0064] like Figure 3 As shown, the diamond in the control group 1 did not burn, the diamond in the control group 2 was severely burned, and the diamond in the experimental group was only slightly burned and well bonded to the NiCu matrix.

[0065] The density of the three groups was measured. The density of the control group 1, the control group 2 and the experimental group was 5.95 g / mm 3 、7.10g / mm 3 、7.26g / mm 3 .

[0066] It can be seen that the energy density of control group 1 is too low, forming many tiny holes, which significantly reduces the density. The energy density of control group 2 is too high, and the P / E vWhen the ratio is lower than 15, the synergistic effect of average heat input and energy density is lost, the surface temperature of the part is too high, over-melting occurs, and the diamond is severely burned. v The ratios are all within the set range, the surface of the parts has good metallic luster and high density.

[0067] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like that may appear in the above description indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0069] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the embodiments of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0071] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0072] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. A method for manufacturing a metal-based diamond composite material, characterized in that: include: The printed model of the metal-based diamond composite material is imported into the additive manufacturing equipment. After the powder is spread, the electron beam is turned on to heat treat the powder laid on the substrate according to the heat treatment process. The heat treatment process includes preheating the powder bed before printing, scanning printing and cooling after printing; The preset value range of the average heat input P of the heat treatment process is: 300 J / s≤P≤360 J / s, and the average heat input P is determined according to the following formula: ； Where U is the electron beam voltage, I1 is the current for preheating the powder bed before printing the current layer, I2 is the melting current for scanning printing of the current layer, t1 is the time for preheating the powder bed before printing the current layer, t2 is the time for scanning printing of the current layer, and t 总 is the total printing time of the current layer, t 总 =t1+t2+t3+t 铺粉 , where t 铺粉 is the time for spreading powder of the current layer, and t3 is the time for cooling down the current layer after printing; After the preheating of the powder bed before printing is completed, the scanning printing is performed, wherein the energy density E during the scanning printing process is v The value range is 20J / mm 3 ≤E v ≤35J / mm 3 , E v Determined according to the following formula: ； Where, v is the scanning speed of the current layer, h is the powder layer thickness of the current layer, and d is the scanning spacing of the current layer; The value range is 10~16.

2. The method for manufacturing a metal-based diamond composite material according to claim 1, characterized in that: When the powder bed is preheated before printing, the electron beam uses a defocused lower beam, and when the scanning printing is performed, the electron beam uses a focused lower beam.

3. The method for manufacturing a metal-based diamond composite material according to claim 2, characterized in that: The electron beam current for preheating the powder bed before printing is 15-25 mA, and the electron beam current for scanning printing is 1-5 mA.

4. The method for manufacturing a metal-based diamond composite material according to claim 1, characterized in that: During the post-printing cooling process, the electron beam is not turned on and the cooling time is 0 to 10 seconds.

5. The method for manufacturing a metal-based diamond composite material according to claim 1, characterized in that: In the powder used for printing the metal-based diamond composite material, the volume percentage of diamond powder is 1% to 40%, and the rest is matrix powder, and the matrix powder is at least one of nickel alloy or copper alloy.

6. The method for manufacturing a metal-based diamond composite material according to claim 1, characterized in that: The process of preheating the substrate before powdering is as follows: Preheating for a first time period using a first preheating current; A second preheating current is used for preheating for a second time period, wherein the first preheating current is smaller than the second preheating current.

7. The method for manufacturing a metal-based diamond composite material according to claim 1, characterized in that: During the scanning and printing process, the scanning line is rotated layer by layer by a preset angle, and the preset angle is 45-90 degrees.

8. The method for manufacturing a metal-based diamond composite material according to claim 7, characterized in that: During the scanning and printing, the scanning path is S-shaped.

9. The method for manufacturing a metal-based diamond composite material according to any one of claims 1 to 8, characterized in that: The electron beam voltage U is 50-70 kV.

10. The method for manufacturing a metal-based diamond composite material according to claim 6, characterized in that: After preheating the substrate, the temperature of the substrate is 500-600°C.

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