CN108930054B - A metal micro-3D printing method based on self-assembled molecular film control technology - Google Patents

Abstract

The invention relates to a novel 3D metal printing method based on a self-assembly molecular membrane control technology, and belongs to the field of 3D metal printing and micro-nano manufacturing. The novel 3D metal printing method needs to add a special organic molecule into the electroplating solution, and the organic molecule can form a layer of compact self-assembled molecular film with good insulation on the whole surface of the printed metal. The molecular film can effectively isolate the printed piece from the electrolyte and can block all electrochemical reactions on the surface of the printed piece. During printing, a certain range of reduction potential is applied to the printed object to enable metal ions in the electroplating solution to perform reduction reaction. The laser is used for removing the self-assembled molecular film adsorbed on the surface of the metal, so that the metal is directly contacted with the electrolyte, and the electrodeposition is only carried out in a laser irradiation area, thereby realizing the metal additive manufacturing at a specified position.

Description

A metal micro-3D printing method based on self-assembled molecular film control technology

technical field

The invention belongs to the fields of additive manufacturing and micro-nano manufacturing, and relates to a new metal additive manufacturing method based on self-assembled molecular film control technology, laser technology and electrochemical technology.

technical background

Additive manufacturing technology is a forming technology based on the idea of discrete accumulation forming. This technology uses computer, CAD and other workpieces to slice and layer three-dimensional entities, and build three-dimensional shapes layer by layer with sections that change layer by layer. The technology eliminates the need for molds and fixtures and has the ability to build complex shapes. At present, 3D printing of non-metallic materials such as plastics has basically reached the level of commercial application. But for metal 3D printing, it is still in the laboratory stage.

The current principle of metal 3D printing technology is mainly metal powder sintering technology, in addition to droplet printing technology, ultrasonic 3D metal printing technology, etc. For metal powder sintering technology, according to the different heat sources used, it can be divided into electron beam melting technology, electron beam welding technology and selective laser melting technology. The principles of the above technologies are very similar and can be classified as 3D metal printing based on thermophysical methods; they all need to melt metal powder at a specified location at high temperature, and then solidify to form a 3D metal entity. The melting and solidification process usually leads to problems such as surface roughness, stress concentration, coarse grains, uneven structure, pores, and low mechanical strength of the printed metal parts. The above problems are difficult to overcome by 3D metal printing technology using thermophysical methods. In addition, the above techniques are limited by the size of the heat source and the size of the metal powder, and generally cannot print metal components with feature sizes smaller than one millimeter.

Electroplating technology and electroforming technology are metal additive manufacturing processes based on electrochemical technology, which have been widely used in the industry. Current electroplating techniques are commonly used for the surface treatment of metal parts, and the thickness of the coating is usually in the micrometer level. The reason why electroplating technology cannot be used for 3D metal printing is that metal deposition cannot be achieved in specified locations. Similar to electroplating technology, electroforming technology is another metal additive manufacturing technology based on electrochemical principles. Electroforming technology requires the use of a mandrel, using electrochemical principles to electrodeposit metal on the mandrel, and then separate from the mandrel to achieve the manufacture or replication of metal products.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an additive manufacturing technology suitable for tiny metal parts.

The principle of the present invention is: by adding organic molecules that can form an insulating and dense self-assembled molecular film on the metal surface into the electroplating solution, the surface of the printed metal parts immersed in the electroplating solution is completely covered by the self-assembled molecular film. When a potential that can reduce the metal ions in the electroplating solution is applied to the metal part, the insulating self-assembled molecular film can prevent the electrochemical reaction of the metal ions on the surface of the metal part, so that the entire surface of the metal part will not be electrocuted. deposition. This technology uses a laser beam with a specific energy or a two-dimensional laser pattern to illuminate the surface of a metal part to remove the self-assembled molecular film adsorbed on its surface. After the self-assembled molecular film is removed, electrochemical deposition can take place in the laser-irradiated area. Three-dimensional metal structures can be printed by controlling the trajectory of the laser beam or the shape of the two-dimensional laser pattern.

The characteristics of the present invention are as follows:

1. The metal additive manufacturing of the present invention is based on the principle of electrochemistry, and the growth rate of metal per minute in the direction of the laser is in the order of microns, which makes it very suitable for the production of tiny metal parts.

2. Since the principle of the metal additive material of the present invention is consistent with that of electroplating, the metal parts produced by printing have no thermal stress, the mechanical strength of the workpiece is high, and the surface is smooth.

3. By controlling the change of the laser pattern, tiny metal parts with complex structures can be printed.

Description of drawings

Figure 1 is a schematic diagram of the principle of 3D metal printing based on the control technology of self-assembled molecular films

Detailed ways

See Figure 1. The invention is a new method of 3D metal printing based on the control technology of self-assembled molecular film, specifically adding a special organic molecule into the electroplating solution, the organic molecule can form a dense layer on the surface of the metal to be printed with good insulation self-assembled molecular membranes. The molecular film can effectively separate the printed part and the electrolyte, and can block the electrochemical reaction on the surface of the printed part. During the printing process, it is necessary to apply a certain range of reduction potential to the printed part, which can make the metal ions in the electroplating solution undergo a reduction reaction. The role of the laser is to remove the self-assembled molecular film adsorbed on the metal surface, so that the metal is directly in contact with the electrolyte, so that electrodeposition only occurs in the laser-irradiated area, and metal additive manufacturing at a specified location is realized. During the printing process, the energy density of the laser used is suitable to just remove the self-assembled molecular film. Too much laser energy density will cause thermal melting of the workpiece and damage the workpiece.

When a laser beam with a smaller diameter is used, the laser beam needs to be scanned two-dimensionally point by point and line by line during the printing process to achieve larger area metal deposition.

A two-dimensional laser pattern with an editable pattern shape can also be used to directly project the surface of the workpiece to be printed. During the printing process, three-dimensional metal components can be printed by adjusting the geometry of the two-dimensional patterns.

Claims (3)

1. A metal micro 3D printing method based on a self-assembly molecular membrane control technology is characterized in that: the electroplating solution contains an organic molecule, the organic molecule can be spontaneously adsorbed on the surface of the printed metal to form a compact and insulated self-assembled molecular film, and the molecular film can effectively realize the physical isolation of the workpiece from the electroplating solution and block all electrochemical reactions generated on the surface of the metal; in the printing process, a potential capable of enabling metal ions in electroplating solution to generate reduction reaction on the surface of the workpiece is applied, and meanwhile, laser with proper energy density is adopted to remove the self-assembled molecular film adsorbed on the metal surface, so that the metal surface is directly contacted with the electroplating solution, and the electrochemical deposition is controlled to be only generated in a laser irradiation area.

2. The metallic micro 3D printing method according to claim 1, wherein: the laser may be a laser beam with a small diameter or a laser pattern with an editable two-dimensional shape.

3. The metallic micro 3D printing method according to claim 1, wherein: the energy density of the laser is preferably just enough to remove the self-assembled molecular film.

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