CN-117733171-B - Bimetal additive and preparation method thereof

CN117733171BCN 117733171 BCN117733171 BCN 117733171BCN-117733171-B

Abstract

The application relates to a bimetal additive and a preparation method thereof, belonging to the technical field of additive manufacturing, wherein the method comprises the steps of obtaining a first metal, a gradient material and a second metal, wherein the melting point of the second metal is higher than that of the first metal, the melting point of the gradient material is between the first metal and the second metal, respectively mixing the first metal, the gradient material and the second metal with a binder to prepare a first slurry, a gradient slurry and a second slurry, printing the first slurry, the gradient slurry and the second slurry layer by layer to obtain a green body part containing a first metal layer, a gradient material layer and a second metal layer, degreasing and gradient sintering the green body part to obtain the bimetal additive, and realizing densification of the bimetal material by arranging the gradient material.

Inventors

LI XIANGYOU
LI JIANGTAO
WANG ZEMIN
HE BING
LI SHUHAN
HUANG ZHIJIE
ZHAO YUTING

Assignees

华中科技大学鄂州工业技术研究院
华中科技大学

Dates

Publication Date: 20260512
Application Date: 20231215

Claims (8)

1. A method of preparing a bimetallic additive, the method comprising: obtaining a first metal, a gradient material and a second metal, wherein the melting point of the second metal is higher than that of the first metal, and the melting point of the gradient material is between the first metal and the second metal; Mixing a first metal, a gradient material and a second metal with a binder respectively to prepare a first slurry, a gradient slurry and a second slurry; Printing the first slurry, the gradient slurry and the second slurry layer by layer to obtain a green part containing a first metal layer, a gradient material layer and a second metal layer, wherein the gradient material layer is arranged between the first metal layer and the second metal layer; Degreasing and gradient sintering are carried out on the green body piece, and a bimetal additive is obtained; The gradient material layer comprises at least one gradient sub-layer, wherein the melting point of the gradient material in the gradient sub-layer is gradually increased along the direction from the first metal layer to the second metal layer, and the thickness of the gradient sub-layer is 0.1-2 mm; The method comprises the steps of sintering a green part, gradually heating the green part, gradually generating a sintering neck at a joint by low-melting-point metal powder, reducing and densifying pores, starting diffusion fusion of peripheral gradient material powder to form the sintering neck when the green part is sintered and densified, starting to melt the low-melting-point metal when the temperature is continuously increased to be higher than the melting point of the low-melting-point metal, and basically sintering and densifying the peripheral gradient material when the temperature is continuously increased to be higher than the melting point of the low-melting-point metal, so that the melted low-melting-point metal cannot exude, densifying the gradient material according to the sintering temperature gradient until the last layer of gradient material is sintered and densified, and further increasing the temperature to the sintering temperature of the high-melting-point metal, wherein the last layer of gradient material is melted, but does not infiltrate the basically densified high-melting-point metal, and continuously sintering until the high-melting-point metal is densified, thereby completing the whole sintering.
2. The method for preparing the bimetal additive according to claim 1, wherein the number of the gradient sublayers is 1-5.
3. The method of preparing a bimetal additive according to claim 1, wherein the gradient material has a particle size of 10-150 μm, and/or In the gradient slurry, the volume ratio of the gradient material is 20% -40%, and/or The gradient material includes at least one of an alloy and a composite material.
4. The method of producing a bimetal additive material of claim 1, wherein the first metal has a particle size of 10 to 80 μm, and/or The volume ratio of the first metal in the first slurry is 40% -60%, and/or The particle size of the second metal is 10-80 mu m, and/or In the second slurry, the volume ratio of the second metal is 40% -60%.
5. The method for preparing a bimetal additive according to claim 1, wherein the thickness of the second metal layer is 0.1-2 mm.
6. The method of claim 1, wherein the degreasing peak temperature is 120-600 ℃, and/or The peak temperature of the gradient sintering is 700-1800 ℃.
7. The method of preparing a bimetallic additive of claim 1, wherein the printing comprises photo-curing printing and extrusion printing.
8. A bimetallic additive, characterized in that it is produced by the method of any one of claims 1 to 7.

Description

Bimetal additive and preparation method thereof Technical Field The application relates to the technical field of additive manufacturing, in particular to a bimetal additive and a preparation method thereof. Background The bimetal additive manufacturing is to add a second metal on the basis of single metal additive manufacturing to realize the distribution of different properties, the material characteristics can be combined as required, the wider properties are provided, and the economic efficiency is higher. The current manufacturing method of bimetal additive can be divided into direct and indirect two types, wherein the direct additive manufacturing refers to the process that a heat source such as laser, electron beam, electric arc and the like is used for melting metal and then depositing the metal on the upper layer during the additive manufacturing, and the common processes include laser near net forming, powder bed melting and the like, and the indirect additive manufacturing refers to the process that a green body part containing metal powder and a binder is manufactured firstly, then the binder is removed through degreasing, finally the metal part is sintered, and the common processes include binder spraying, extrusion printing and the like. Most of the existing bimetal additive manufacturing is direct molding, for example, chinese patent application CN114871452a proposes a method for forming bimetal by laser selective melting, however, the manufacturing equipment is expensive, so that the manufacturing threshold of bimetal is higher. The Chinese patent application CN116372315A proposes a copper/steel bimetallic material and a CMT electric arc additive manufacturing method thereof, wherein the addition of a high-energy heat source similar to laser leads to high equipment cost, and simultaneously has additional requirements on working environment. The direct forming method has the advantages of higher cost, higher requirement on working environment, higher temperature in the material adding process, larger stress after cooling, easy cracking and warping of the bimetal interface due to different thermal expansion coefficients, complicated switching of different metal powder and certain potential safety hazard during processing of the metal powder. The indirect forming equipment has the advantages of low cost, low environmental requirement, high safety coefficient of slurry used in the material adding process, simple and convenient switching of different materials, and more advantages in the bimetal material adding manufacturing. For example, chinese patent application CN113500205B proposes a 3D printing method of a bimetal material, which adopts an indirect forming method, wherein copper paste and iron paste are extruded and formed by an injector, and the high-temperature sintering and forming under the same sintering parameters are realized by adjusting the proportion of binder in the paste, and the same shrinkage rate is achieved. However, the conditioning of the slurry necessarily causes a change in the solids content, and for a combination of metals, conditioning the formulation is obviously a very time-consuming task. In addition, it can be seen in the printed sintered pictures that the print is not dense, has many macroscopic gaps, which has a very detrimental effect on the performance of the bimetallic part. Disclosure of Invention The inventors found that the method provided by CN113500205B had less melting of iron particles and higher melting of copper particles at the stage of densification, which is expected to be low sintering temperature of copper, iron particles did not start yet at the time of onset of diffusion fusion of the particles, and iron particles may just start to fuse at the higher degree of fusion of the copper particles, so that the final sintered part was not dense, especially for iron, and there were many voids inside. The application provides a bimetal additive and a preparation method thereof, which are used for improving the compactness of the bimetal additive. In a first aspect, the present application provides a method for preparing a bimetallic additive, the method comprising: obtaining a first metal, a gradient material and a second metal, wherein the melting point of the second metal is higher than that of the first metal, and the melting point of the gradient material is between the first metal and the second metal; Mixing a first metal, a gradient material and a second metal with a binder respectively to prepare a first slurry, a gradient slurry and a second slurry; Printing the first slurry, the gradient slurry and the second slurry layer by layer to obtain a green part containing a first metal layer, a gradient material layer and a second metal layer, wherein the gradient material layer is arranged between the first metal layer and the second metal layer; degreasing and gradient sintering are carried out on the green body piece, and the bimetal additive is ob