阅读说明：本技术 一种多材料增材制造成型系统及方法 (Multi-material additive manufacturing and forming system and method ) 是由 鲁中良 周航 王成玉 苗恺 李涤尘 于 2020-12-22 设计创作，主要内容包括：本发明公开了一种多材料增材制造成型系统及方法,所述系统包括：激光系统；腔体,所述腔体内设置有吸粉系统、送粉系统、铺粉系统、工作缸和多个储粉缸；其中,所述吸粉系统用于吸收多余的原料粉末；所述铺粉系统可移动的设置于所述腔体内,用于将部分储粉缸中的原料粉末送入工作缸；所述送粉系统可移动的安装于所述铺粉系统,用于将其余储粉缸提供的原料粉末送入工作缸；基板及加热系统,所述基板及加热系统设置于所述工作缸内；换气系统,用于将腔体抽真空并充入保护气。本发明可利用增材制造的方法实现金属/陶瓷多材料一体化成形,能够解决因不同粉末性质差异大而导致的打印工艺兼容性问题。(The invention discloses a multi-material additive manufacturing and molding system and a method, wherein the system comprises: a laser system; the powder spraying device comprises a cavity, wherein a powder sucking system, a powder feeding system, a powder paving system, a working cylinder and a plurality of powder storage cylinders are arranged in the cavity; wherein the powder absorbing system is used for absorbing redundant raw material powder; the powder paving system is movably arranged in the cavity and is used for conveying part of raw material powder in the powder storage cylinder into the working cylinder; the powder feeding system is movably arranged on the powder paving system and is used for feeding the raw material powder provided by the rest powder storage cylinders into the working cylinder; the substrate and the heating system are arranged in the working cylinder; and the ventilation system is used for vacuumizing the cavity and filling protective gas. The invention can realize the integrated forming of metal/ceramic multi-material by using an additive manufacturing method, and can solve the problem of printing process compatibility caused by large difference of properties of different powders.)

1. A multi-material additive manufacturing molding system, comprising:

a laser system for providing a source of fine laser heat for melting the feedstock powder;

the powder feeding device comprises a cavity (3), wherein a powder sucking system, a powder feeding system (9), a powder laying system (10), a working cylinder (7) and a plurality of powder storage cylinders (8) are arranged in the cavity (3); the powder absorbing system is used for absorbing redundant raw material powder and preventing mutual pollution among the raw material powder; the powder spreading system (10) is movably arranged in the cavity (3) and is used for feeding part of raw material powder in the powder storage cylinder (8) into the working cylinder (7); the other powder storage cylinders (8) are arranged on the powder laying system (10) and used for providing raw material powder for the powder feeding system (9); the powder feeding system (9) is movably arranged on the powder paving system (10) and is used for feeding the raw material powder provided by the rest powder storage cylinders (8) into the working cylinder (7);

the substrate and heating system (6), the substrate and heating system (6) is arranged in the working cylinder (7) and is used for preheating raw material powder;

and the ventilation system (5) is used for vacuumizing the cavity (3) and filling protective gas.

2. A multi-material additive manufacturing and moulding system according to claim 1, wherein the working cylinder (7) and part of the powder storage cylinder (8) are fixedly arranged in the cavity (3);

the cavity (3) is opened in a front-back door mode; wherein, one end of the working cylinder (7) is the front end, and one end of the powder storage cylinder (8) is the rear end;

the powder spreading system (10) performs front and back powder spreading movement;

the movement direction of the powder feeding system (9) is perpendicular to the movement direction of the powder paving system (10).

3. A multi-material additive manufacturing and molding system according to claim 1, wherein the substrate and the heating system (6) are capable of preheating at a temperature in a range of 0-1000 ℃.

4. A multi-material additive manufacturing molding system according to claim 1,

a first sliding rail is fixedly arranged in the cavity (3);

a plunger is arranged in the partial powder storage cylinder (8) and used for pushing out raw material powder;

the powder paving system (10) comprises: a beam and a scraper; the cross beam is movably arranged on the first sliding rail, and the scraper is fixedly arranged on the cross beam and used for scraping the raw material powder pushed out by the plunger into the working cylinder (7); a second sliding rail is fixedly arranged on the cross beam;

the powder feeding system (9) is movably arranged on the second slide rail;

the powder feeding system (9) comprises:

one or more screw extrusion type powder feeding heads are movably arranged on the second slide rail and are communicated with the other powder storage cylinders (8) through connecting pipes;

the laser range finder is arranged on the cross beam and used for ensuring the moving precision of the powder feeding head;

the motor is arranged at the rear end of the screw extrusion type powder feeding head and used for controlling the powder feeding speed;

and the shaping plate can be vertically moved and is arranged on the cross beam and used for flattening the powder bed after powder feeding.

5. A multi-material additive manufacturing method based on the multi-material additive manufacturing molding system of claim 1, comprising the steps of:

respectively putting the various raw material powders which are dried and sieved in vacuum into the plurality of powder storage tanks;

setting forming parameters and importing the forming parameters into a model;

introducing protective gas, preheating, and printing according to a preset forming process.

6. The multi-material additive manufacturing method according to claim 5, wherein when the raw material powder is ceramic powder, the ceramic powder after vacuum drying and sieving is subjected to surface treatment and metallization or is uniformly mixed with metal powder to obtain treated ceramic powder; and putting the treated ceramic powder into a powder storage cylinder.

7. The multi-material additive manufacturing method according to claim 6, wherein a thin film method, a thick film method or an electroless plating method is adopted when the ceramic powder after vacuum drying and sieving is subjected to surface treatment metallization;

wherein the metal melting point of the coating is lower than that of the ceramic powder, and the thickness of the coating ranges from 1 to 15 mu m.

8. The multi-material additive manufacturing method according to claim 6, wherein when the ceramic powder after vacuum drying and sieving is uniformly mixed with the metal powder, the difference between the median particle size of the metal powder and the median particle size of the ceramic powder is less than or equal to 5 μm, and the metal powder accounts for 5-50% of the mass of the ceramic powder.

9. The multi-material additive manufacturing method of claim 6, wherein the raw material powder comprises a ceramic powder and a metal powder; wherein, when the ceramic powder is subjected to surface treatment and metallization or is mixed with metal powder, the adopted metal is aluminum, titanium, nickel or iron; the metal powder is aluminum alloy, titanium alloy, nickel alloy or stainless steel powder.

10. The multi-material additive manufacturing method of claim 5, wherein the plurality of raw material powders include a metal powder and a ceramic powder;

the particle size range of the metal powder and the ceramic powder is 15-75 mu m, the median particle size of the ceramic powder is 0-15 mu m smaller than that of the metal powder, and the difference between the median particle sizes of the metal powder and the metal powder or between the ceramic powder and the ceramic powder is less than or equal to 5 mu m;

the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power range is 100-500W, the scanning speed range is 400-1500 mm/s, the scanning interval range is 20-100 μm, and the printing layer thickness range is 30-60 μm; the laser scanning strategy is checkerboard scanning;

introducing argon as protective gas, and controlling the water oxygen content to be less than or equal to 100 ppm;

the preheating temperature of the substrate is 200-500 ℃;

the preset forming process comprises the following steps: laying a raw material powder, sintering by laser, and sucking off the redundant raw material powder; and feeding another raw material powder, carrying out surface leveling treatment, carrying out laser sintering, and repeating layer by layer.

Technical Field

The invention belongs to the technical field of additive manufacturing, and particularly relates to a multi-material additive manufacturing and forming system and method.

Background

The laser additive manufacturing technology is additive manufacturing technology using laser as an energy source, has the advantages of no limitation of part structures, wide application range and the like, and can be used for machining and manufacturing thin-wall parts with complex structures and difficult machining. The laser additive manufacturing technology can be divided into a selective laser melting technology taking powder bed powder laying as a technical characteristic and a direct laser metal forming technology taking synchronous powder feeding as a technical characteristic according to the forming principle.

At present, the laser additive manufacturing technology can form titanium alloy, high-temperature alloy, iron-based alloy, aluminum alloy, refractory alloy, amorphous alloy, ceramic material, gradient material and the like; however, because of the difference in properties of different powders, the first difficulty of the integrated molding technology is to solve the compatibility problem of the printing processes of different materials, and particularly, for metal and ceramic materials with extremely different properties, it is very difficult to realize integrated molding by using laser additive manufacturing.

In recent years, ceramic metallization technology is gradually developed, a layer of metal is coated on the surface of ceramic particles, and the metal is used as an adhesive to provide great convenience for the molding of ceramic materials, so that the problems of cracks and molding quality in ceramic laser molding are solved. Cermets are also the hot spot of recent research, and have the toughness, high thermal conductivity and good thermal stability of metals, as well as the high temperature resistance, corrosion resistance and wear resistance of ceramics. The metal ceramic is widely applied to shells of rockets, missiles and supersonic airplanes, flame nozzles of combustion chambers and the like.

The multi-material forming process has wide application prospect, and has wide application prospect in a plurality of key fields such as aerospace, nuclear energy, automobiles, electronics and the like. In the field of aerospace, the multi-material forming technology based on additive manufacturing can manufacture elements with complex shapes and gradient structures, and the elements are used for key parts such as engine blades, nose cones and the like. In the nuclear energy field, the metal/ceramic multi-material integrated molding technology of the rod-shaped fuel element based on the additive manufacturing technology can solve the defects of complex preparation process, long period and high cost in the traditional preparation technology, and is an important technical change exploration for the manufacturing mode of the fuel element.

In view of the above, a need exists for a new multi-material additive manufacturing molding system and method.

Disclosure of Invention

The present invention is directed to a multi-material additive manufacturing and molding system and method, which solve one or more of the above problems. The invention can realize the integrated forming of metal/ceramic multi-material by using an additive manufacturing method, and can solve the problem of printing process compatibility caused by large difference of properties of different powders.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention relates to a multi-material additive manufacturing and molding system, which comprises:

a laser system for providing a source of fine laser heat for melting the feedstock powder;

the powder spraying device comprises a cavity, wherein a powder sucking system, a powder feeding system, a powder paving system, a working cylinder and a plurality of powder storage cylinders are arranged in the cavity; the powder absorbing system is used for absorbing redundant raw material powder and preventing mutual pollution among the raw material powder; the powder paving system is movably arranged in the cavity and is used for conveying part of raw material powder in the powder storage cylinder into the working cylinder; the other powder storage cylinders are arranged on the powder paving system and used for providing raw material powder for the powder feeding system; the powder feeding system is movably arranged on the powder paving system and is used for feeding the raw material powder provided by the rest powder storage cylinders into the working cylinder;

the base plate and the heating system are arranged in the working cylinder and are used for preheating the raw material powder;

and the ventilation system is used for vacuumizing the cavity and filling protective gas.

The invention has the further improvement that the working cylinder and part of the powder storage cylinder are fixedly arranged in the cavity;

the cavity is in a front-back door opening mode; wherein, one end of the working cylinder is the front end, and one end of the powder storage cylinder is the rear end;

the powder spreading system performs front and back powder spreading movement;

the movement direction of the powder feeding system is perpendicular to the movement direction of the powder paving system.

The invention is further improved in that the preheating temperature range of the substrate and the heating system is 0-1000 ℃.

The invention has the further improvement that a first slide rail is fixedly arranged in the cavity; a plunger is arranged in the partial powder storage cylinder and used for pushing out raw material powder; the powder paving system comprises: a beam and a scraper; the cross beam is movably arranged on the first sliding rail, and the scraper is fixedly arranged on the cross beam and used for scraping the raw material powder pushed out by the plunger into the working cylinder; a second sliding rail is fixedly arranged on the cross beam; the powder feeding system is movably arranged on the second sliding rail; the powder feeding system comprises: one or more screw extrusion type powder feeding heads are movably arranged on the second sliding rail and are communicated with the other powder storage cylinders through connecting pipes; the laser range finder is arranged on the cross beam and used for ensuring the moving precision of the powder feeding head; the motor is arranged at the rear end of the screw extrusion type powder feeding head and used for controlling the powder feeding speed; and the shaping plate can be vertically moved and is arranged on the cross beam and used for flattening the powder bed after powder feeding.

The invention discloses a multi-material additive manufacturing method, which is based on the multi-material additive manufacturing and molding system and comprises the following steps:

respectively putting the various raw material powders which are dried and sieved in vacuum into the plurality of powder storage tanks;

setting forming parameters and importing the forming parameters into a model;

introducing protective gas, preheating, and printing according to a preset forming process.

The invention has the further improvement that when the raw material powder is ceramic powder, the ceramic powder after vacuum drying and sieving is subjected to surface treatment and metallization or is uniformly mixed with metal powder to obtain treated ceramic powder; and putting the treated ceramic powder into a powder storage cylinder.

The further improvement of the invention is that a film method, a thick film method or a chemical plating method is adopted when the ceramic powder after vacuum drying and sieving is subjected to surface treatment and metallization; wherein the metal melting point of the coating is lower than that of the ceramic powder, and the thickness of the coating ranges from 1 to 15 mu m.

The invention is further improved in that when the ceramic powder after vacuum drying and sieving is uniformly mixed with the metal powder, the difference between the median particle size of the metal powder and the median particle size of the ceramic powder is less than or equal to 5 mu m, and the metal powder accounts for 5-50% of the mass of the ceramic powder.

The invention is further improved in that the raw material powder comprises a ceramic powder and a metal powder; wherein, when the ceramic powder is subjected to surface treatment and metallization or is mixed with metal powder, the adopted metal is aluminum, titanium, nickel or iron; the metal powder is aluminum alloy, titanium alloy, nickel alloy or stainless steel powder.

The invention is further improved in that the plurality of raw material powders include metal powders and ceramic powders;

the particle size range of the metal powder and the ceramic powder is 15-75 mu m, the median particle size of the ceramic powder is 0-15 mu m smaller than that of the metal powder, and the difference between the median particle sizes of the metal powder and the metal powder or between the ceramic powder and the ceramic powder is less than or equal to 5 mu m;

the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power range is 100-500W, the scanning speed range is 400-1500 mm/s, the scanning interval range is 20-100 μm, and the printing layer thickness range is 30-60 μm; the laser scanning strategy is checkerboard scanning;

introducing argon as protective gas, and controlling the water oxygen content to be less than or equal to 100 ppm;

the preheating temperature of the substrate is 200-500 ℃;

the preset forming process comprises the following steps: laying a raw material powder, sintering by laser, and sucking off the redundant raw material powder; and feeding another raw material powder, carrying out surface leveling treatment, carrying out laser sintering, and repeating layer by layer.

Compared with the prior art, the invention has the following beneficial effects:

the invention can realize the integrated forming of metal/ceramic multi-material by using an additive manufacturing method, and can solve the problem of printing process compatibility caused by large difference of properties of different powders.

Compared with the traditional selective laser melting equipment, the equipment provided by the invention can realize the printing of two kinds of powder: the first powder adopts a powder spreading mode, and laser selective melting is carried out after a scraper is used for leveling; the second powder adopts a powder feeding mode, and after the powder is fed by a screw rod, the shaping plate is flattened and then is subjected to selective laser melting.

Compared with the traditional manufacturing method of metal machining and ceramic sintering forming, the multi-material additive manufacturing method is convenient, fast and efficient, and can realize near-net forming of a complex structure; compared with the traditional single material or composite material laser powder bed melting technology, the method can realize the integrated molding of two different materials, and solves the problem of compatibility of the printing process caused by large difference of different powder properties; compared with the multi-nozzle or coaxial powder feeding laser cladding deposition technology widely researched at present, the method can ensure the compactness of the material, ensure that the organization of the metal part is fine and uniform, and the adhesion of the ceramic part is firm and reliable.

According to the invention, the ceramic particles are treated, and a layer of metal is coated on the surface of the ceramic particles or the ceramic particles are uniformly mixed with metal powder, so that on one hand, the heat conduction in the laser heating process is improved, the integral temperature gradient is reduced, and the temperature distribution is more uniform; on the one hand, the metal acts as a binder for the bonding of the ceramic particles, avoiding the high energy required for melting the ceramic.

The invention can realize the integrated manufacture of a plurality of materials such as metal, ceramics and the like by utilizing the characteristics of rapid manufacture, high forming precision and the like of laser additive manufacturing equipment, and avoids long processing time and low processing precision caused by assembly. The invention has reasonable design, high precision of the formed part and less cracks and can realize the forming of a complex structure.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a schematic flow diagram of a multi-material additive manufacturing method according to an embodiment of the invention;

FIG. 2 is a schematic diagram of a multi-material molding system according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a cylindrical sample according to an embodiment of the present invention;

in the figure, 1 is a laser, 2 is a galvanometer, 3 is a cavity, 4 is an air exchange system, 5 is a powder suction pipe, 6 is a substrate and heating system, 7 is a working cylinder, 8 is a powder storage cylinder, 9 is a powder feeding system, and 10 is a powder spreading system; 11 is a cladding; 12 is a fuel pellet; and 13 is a mesopore.

Detailed Description

In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.

Referring to fig. 1, a multi-material additive manufacturing method according to an embodiment of the present invention includes the following steps:

step 1, preparing metal powder and ceramic powder, drying in vacuum and sieving;

step 2, carrying out surface treatment metallization on the ceramic powder after vacuum drying or uniformly mixing the ceramic powder with preset metal powder;

step 3, cleaning the metallized ceramic powder or mixed powder treated in the step 2, drying in vacuum and sieving;

and 4, respectively filling the metal powder obtained in the step 1 and the powder obtained in the step 3 into corresponding powder cylinders, setting forming parameters and a scanning strategy, guiding the model into multi-material additive manufacturing equipment, introducing protective gas, preheating, and printing according to a set forming process.

Wherein, if the two powders required for molding are both metal powders, the steps 2 to 3 can be eliminated.

In step 1 of an embodiment of the present invention, the particle size ranges of the metal powder and the ceramic powder are between 15 μm and 75 μm (it can be ensured that the thickness of each layer of powder is suitable, and a sufficient and suitable melting degree is achieved during laser scanning, and at the same time, the forming precision is ensured), and the median particle size of the ceramic powder is smaller than that of the metal powder by 0 μm to 15 μm (a margin is left for the thickness of the plating layer in step 2, so that the particle size of the ceramic powder after plating is equivalent to that of the metal powder), and the difference between the median particle sizes of the metal powder and the metal powder or between the ceramic powder and the ceramic powder is smaller than 5 μm (the particle size; in the step 1, during vacuum drying, the drying temperature is set to be 50-300 ℃, and the vacuum drying is carried out for 2-10 h (fully drying the water in the raw material powder, preventing agglomeration and improving the fluidity of the raw material powder); in the step 1, a sieve mesh with 200-500 meshes is selected during sieving (larger residue foreign matters and powder particles with large particle size are sieved).

In step 2 of another embodiment of the present invention, the surface treatment metallization may be selected from a thin film method (vacuum evaporation, ion plating, sputter coating, etc.), a thick film method, a chemical plating method, and the like; wherein the metal melting point of the coating is required to be lower than that of the ceramic powder, and the thickness of the coating is 1-15 μm;

in step 2, the process of mixing the metal powder and the ceramic powder comprises the following steps: selecting proper metal powder, mixing the metal powder with ceramic powder according to a certain proportion, and carrying out ball milling; wherein the difference between the median particle size of the metal powder and the median particle size of the ceramic powder is less than 5 mu m, and the metal powder accounts for 5-50% of the mass of the ceramic powder. During ball milling: absolute ethyl alcohol is used as a solvent, the rotating speed of a ball mill is set to be 100-300 rpm, and the ball milling time is 2-10 hours; setting ball milling mode as starting 10-30min, pausing 10-30min, and circulating.

In the embodiment of the invention, in the step 2, when one raw material powder is aluminum nitride ceramic powder and the other raw material powder is aluminum alloy, aluminum metal is selected as the metal material for ceramic metallization or mixing; or, in the step 2, when one raw material powder is titanium carbide ceramic powder and the other raw material powder is titanium alloy, titanium metal is selected as the metal material for ceramic metallization or mixing; or, in the step 2, when one raw material powder is alumina ceramic powder and the other raw material powder is nickel alloy, the metal material for ceramic metallization or mixing is nickel metal.

In step 3 of another embodiment of the present invention, the metallization powder cleaning process comprises: putting the metalized powder into absolute ethyl alcohol, setting ultrasonic cleaning time to be 20-60 min, taking out, adding the absolute ethyl alcohol, washing for 10-60 s, and then flatly laying and standing for 1-10 min;

in the step 3, the mixed powder cleaning process comprises the following steps: carrying out suction filtration to remove absolute ethyl alcohol, taking out, adding absolute ethyl alcohol, washing for 5-20 s, and then laying and standing for 1-10 min;

in the step 3, during vacuum drying, the drying temperature is set to be 50-300 ℃, and the vacuum drying is carried out for 2-10 hours;

in the step 3, a sieve mesh with 200-500 meshes is selected during sieving.

In step 4 of another embodiment of the present invention, the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power range is 100-500W, the scanning speed range is 400-1500 mm/s, the scanning interval range is 20-100 μm, the printing layer thickness is 30-60 μm, and the laser scanning strategy is checkerboard scanning.

In the step 4, the introduced protective gas is argon, and the water oxygen content is controlled to be less than 100 ppm;

in the step 4, preheating a formed substrate and powder, wherein the preheating temperature of the substrate is 200-500 ℃;

in the step 4, the forming process comprises the following steps: spreading the first powder, laser sintering, sucking the redundant first powder, conveying the second powder, carrying out surface leveling treatment, laser sintering and repeating layer by layer.

Referring to fig. 2, a multi-material forming system according to an embodiment of the present invention includes: the device comprises a laser system, a cavity 3, an air exchange system 4, a powder suction system, a substrate and heating system 6, a powder feeding system 9, a powder paving system 10, other motion mechanisms and an electric control device;

the laser system comprises a laser 1 and a vibrating mirror 2, wherein the vibrating mirror 2 is arranged at the top of a cavity 3 and can be electrically controlled to lift up and down so as to adjust the focal length in real time; the cavity 3 is opened front and back, and the front working cylinder 7 and the rear powder feeding cylinder 8 are used for spreading powder front and back.

In the embodiment of the invention, in the powder suction system, the powder recovery cylinder is arranged at the lower end of the cavity and used for storing absorbed powder; the motor is arranged at the lower end of the cavity and used for providing energy required by powder absorption; one end of the powder suction pipe 5 is fixed on the top end of the cavity body, and the other end is connected with the powder recovery cylinder.

In the embodiment of the present invention, the preheating temperature of the substrate and the heating system 6 is 0-1000 ℃.

In the powder feeding system of the embodiment of the invention, the screw extrusion type powder feeding head is arranged on a beam of the powder laying mechanism and is provided with a slide rail which can move transversely; the laser range finder is arranged on a beam of the powder spreading mechanism to ensure the moving precision of the powder feeding head; the motor is connected to the rear end of the screw extrusion type powder feeding head and controls the powder feeding speed; the shaping plate is arranged on the beam of the powder laying mechanism and can move up and down, and the powder bed is flattened after powder feeding; the connecting pipe is connected with the powder storage bin and the powder feeding head.

Example 1

In the embodiment of the invention, the parts printed by FeCrAl alloy powder have excellent performances of uniform structure, high strength, good corrosion resistance and the like, and the nickel metal is coated with Al₂O₃The ceramic is also formed by smooth manufacturing, and the interface contact between the metal ceramic particles is good.

The multi-material additive manufacturing method provided by the embodiment of the invention comprises the following steps:

in step 1, the metal powder is FeCrAl alloy powder, the median particle size is 30 μm, and the ceramic powder is Al₂O₃Having a median particle diameter of20μm；

In the step 1, when vacuum drying is carried out, the drying temperature is set to be 100 ℃, and the vacuum drying is carried out for 6 hours;

in the step 1, a sieve mesh with 400 meshes is selected during sieving.

In the step 2, a chemical plating method is selected as a mode of coating the metal, the plating metal is nickel metal, and the thickness of the plating is 5 microns;

in step 3, the cleaning process of the metalized powder comprises the following steps: putting the metalized powder into absolute ethyl alcohol, setting the ultrasonic cleaning time to be 20min, taking out, adding the absolute ethyl alcohol, washing for 60s, and then flatly laying and standing for 10 min;

in the step 3, the mixed powder cleaning process comprises the following steps: filtering to remove anhydrous ethanol, taking out, adding anhydrous ethanol, washing for 10s, and then spreading and standing for 10 min;

in the step 3, when vacuum drying is carried out, the drying temperature is set to be 100 ℃, and the vacuum drying is carried out for 6 hours;

in the step 3, the sieve mesh number is 400 meshes when sieving.

In step 4, the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power is 200W, the scanning speed is 800mm/s, the range of the scanning distance is 60 μm, the thickness of the printing layer is 30 μm, and the laser scanning strategy is checkerboard scanning;

in the step 4, the introduced protective gas is argon, and the water oxygen content is controlled to be less than 100 ppm;

in the step 4, preheating a formed substrate and powder, wherein the preheating temperature of the substrate is 200 ℃;

in the step 4, the forming process comprises the following steps: spreading the first powder, laser sintering, sucking the redundant first powder, conveying the second powder, carrying out surface leveling treatment, laser sintering and repeating layer by layer.

Referring to fig. 3, in the embodiment of the present invention, a cylindrical test sample with a bottom surface diameter of 12mm and a height of 40mm is processed, and the cross-sectional structure is shown in the figure, the cladding 11 is externally wrapped by the fuel pellet 12, the fuel pellet is provided with the mesopore 13, most of the test samples have uniform structure, few cracks, and good interface contact quality.

Example 2

The multi-material additive manufacturing method provided by the embodiment of the invention is based on the multi-material additive manufacturing and forming system and comprises the following steps of:

respectively putting the various raw material powders which are dried and sieved in vacuum into the plurality of powder storage tanks;

setting forming parameters and importing the forming parameters into a model;

introducing protective gas, preheating, and printing according to a preset forming process.

When the raw material powder is ceramic powder, carrying out surface treatment metallization on the ceramic powder subjected to vacuum drying and sieving to obtain treated ceramic powder; and putting the treated ceramic powder into a powder storage cylinder.

Adopting a film method when the ceramic powder after vacuum drying and sieving is subjected to surface treatment and metallization; wherein the melting point of the metal of the plating layer is lower than that of the ceramic powder, and the thickness of the plating layer is 1 mu m.

Example 3

The difference between the embodiment of the invention and the embodiment 2 is that a thick film method is adopted when the ceramic powder after vacuum drying and sieving is subjected to surface treatment metallization, and the coating thickness is 10 μm.

Example 4

The difference between the embodiment of the invention and the embodiment 2 is that the ceramic powder after vacuum drying and sieving is subjected to surface treatment metallization by adopting a chemical plating method, and the plating thickness is 15 mu m.

Example 5

The multi-material additive manufacturing method provided by the embodiment of the invention is based on the multi-material additive manufacturing and forming system and comprises the following steps of:

respectively putting the various raw material powders which are dried and sieved in vacuum into the plurality of powder storage tanks;

setting forming parameters and importing the forming parameters into a model;

introducing protective gas, preheating, and printing according to a preset forming process.

When the raw material powder is ceramic powder, uniformly mixing the ceramic powder subjected to vacuum drying and sieving with metal powder to obtain treated ceramic powder; and putting the treated ceramic powder into a powder storage cylinder.

When the ceramic powder after vacuum drying and sieving is uniformly mixed with the metal powder, the difference between the median particle size of the metal powder and the median particle size of the ceramic powder is less than 5 mu m, and the metal powder accounts for 5 percent of the mass of the ceramic powder.

Example 6

The difference between the embodiment of the invention and the embodiment 5 is only that when the ceramic powder after vacuum drying and sieving is uniformly mixed with the metal powder, the difference between the median particle size of the metal powder and the median particle size of the ceramic powder is less than 3 mu m, and the metal powder accounts for 30 percent of the mass of the ceramic powder.

Example 7

The embodiment of the invention is different from the embodiment 5 only in that when the ceramic powder after being dried and sieved in vacuum is uniformly mixed with the metal powder, the metal powder accounts for 50 percent of the mass of the ceramic powder.

Example 8

According to the multi-material additive manufacturing method provided by the embodiment of the invention, based on the multi-material additive manufacturing and molding system provided by the invention, multiple raw material powders comprise metal powder and ceramic powder;

the median particle size of the metal powder and the ceramic powder is 15 microns, the median particle size of the ceramic powder is smaller than that of the metal powder by 0.5 microns, and the difference between the median particle sizes of the metal powder and the metal powder or between the median particle size of the ceramic powder and the ceramic powder is less than 5 microns;

the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power is 100W, the scanning speed is 400mm/s, the scanning interval is 20 μm, and the printing layer thickness is 30 μm; the laser scanning strategy is checkerboard scanning;

introducing argon as protective gas, and controlling the water oxygen content to be less than 100 ppm;

the preheating temperature of the substrate is 200 ℃;

the preset forming process comprises the following steps: laying a raw material powder, sintering by laser, and sucking off the redundant raw material powder; and feeding another raw material powder, carrying out surface leveling treatment, carrying out laser sintering, and repeating layer by layer.

Example 9

According to the multi-material additive manufacturing method provided by the embodiment of the invention, based on the multi-material additive manufacturing and molding system provided by the invention, multiple raw material powders comprise metal powder and ceramic powder;

the median particle size of the metal powder and the ceramic powder is 50 microns, the median particle size of the ceramic powder is 5 microns smaller than that of the metal powder, and the difference between the median particle sizes of the metal powder and the metal powder or between the ceramic powder and the ceramic powder is less than 3 microns;

the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power is 300W, the scanning speed is 1000mm/s, the scanning interval is 50 μm, and the printing layer thickness is 50 μm; the laser scanning strategy is checkerboard scanning;

introducing argon as protective gas, and controlling the water oxygen content to be less than 60 ppm;

the preheating temperature of the substrate is 300 ℃;

the preset forming process comprises the following steps: laying a raw material powder, sintering by laser, and sucking off the redundant raw material powder; and feeding another raw material powder, carrying out surface leveling treatment, carrying out laser sintering, and repeating layer by layer.

Example 10

According to the multi-material additive manufacturing method provided by the embodiment of the invention, based on the multi-material additive manufacturing and molding system provided by the invention, multiple raw material powders comprise metal powder and ceramic powder;

the particle size range of the metal powder and the ceramic powder is 75 micrometers, the median particle size of the ceramic powder is 15 micrometers smaller than that of the metal powder, and the difference between the median particle sizes of the metal powder and the metal powder or between the ceramic powder and the ceramic powder is less than 3 micrometers;

the forming parameters include: printing layer thickness, scanning speed, scanning strategy, scanning interval and laser power; wherein the laser power range is 500W, the scanning speed range is 1500mm/s, the scanning interval range is 100 μm, and the printing layer thickness range is 60 μm; the laser scanning strategy is checkerboard scanning;

introducing argon as protective gas, and controlling the water oxygen content to be less than 30 ppm;

the preheating temperature of the substrate is 500 ℃;

the preset forming process comprises the following steps: laying a raw material powder, sintering by laser, and sucking off the redundant raw material powder; and feeding another raw material powder, carrying out surface leveling treatment, carrying out laser sintering, and repeating layer by layer.

In summary, the present invention discloses a multi-material molding system and method, wherein the molding system comprises: the device comprises a laser system, a cavity, an air exchange system, a powder suction system, a substrate and heating system, a powder feeding system, a powder spreading system, other motion mechanisms, an electrical control device and the like. Compared with the traditional selective laser melting equipment, the equipment can realize the printing of two kinds of powder. The first powder adopts a powder spreading mode, and laser selective melting is carried out after a scraper is used for leveling; the second powder adopts a powder feeding mode, and after the powder is fed by a screw rod, the shaping plate is flattened and then is subjected to selective laser melting. The invention discloses a multi-material additive manufacturing method which comprises the following steps: respectively putting the various raw material powders which are dried and sieved in vacuum into the plurality of powder storage tanks; setting forming parameters and importing the forming parameters into a model; introducing protective gas, preheating, and printing according to a preset forming process. Compared with the traditional manufacturing method of metal machining and ceramic sintering forming, the multi-material additive manufacturing method is convenient, fast and efficient, and can realize near-net forming of a complex structure; compared with the traditional single material or composite material laser powder bed melting technology, the method can realize the integrated molding of two different materials, and solves the problem of compatibility of the printing process caused by large difference of different powder properties; compared with the multi-nozzle or coaxial powder feeding laser cladding deposition technology widely researched at present, the method can ensure the compactness of the material, ensure that the organization of the metal part is fine and uniform, and the adhesion of the ceramic part is firm and reliable. Innovatively, in the invention, the ceramic particles are treated, and a layer of metal is coated on the surface of the ceramic particles or the ceramic particles are mixed with metal powder, so that on one hand, the heat conduction in the laser heating process is improved, the integral temperature gradient is reduced, and the temperature distribution is more uniform; on the one hand, the metal acts as a binder for the bonding of the ceramic particles, avoiding the high energy required for melting the ceramic.

Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the claims of the present application.