CN117886613A - Method for preparing silicon nitride ceramics based on laser selective sintering - Google Patents

Abstract

The present invention provides a method for preparing silicon nitride ceramics based on laser selective sintering, which relates to the field of laser processing and ceramic preparation technology, including: mixing silicon nitride powder, sintering aid and binder in a proportion into a stirring device to obtain silicon nitride ceramic slurry; applying the silicon nitride ceramic slurry on a substrate to form a layer to be sintered, and using a laser device to selectively sinter the layer to be sintered; repeating the above operation until silicon nitride ceramics of the desired shape and thickness are obtained. By setting up and using a laser device, the background technology effectively improves the technical problems that traditional silicon nitride ceramic preparation methods, such as hot pressing sintering, pressureless sintering, etc., have long production cycles, high production costs, and low material density.

Description

A method for preparing silicon nitride ceramics based on laser selective sintering

Technical Field

The invention relates to the technical field of laser processing and ceramic preparation, and in particular to a method for preparing silicon nitride ceramics based on laser selective sintering.

Background technique

Laser selective melting forming technology is an advanced manufacturing process used to perform high-precision, high-efficiency and repeatable processing on metal materials. Its basic principle is to use the high energy density of the laser beam to locally heat and melt the metal material, and then control the path and intensity of the laser beam to solidify it into the desired shape in a specific area.

Silicon nitride ceramics have excellent high temperature resistance, corrosion resistance, high strength and good thermal conductivity, and are widely used in aerospace, automobile, electronics, semiconductor and other fields.

Traditional methods for preparing silicon nitride ceramics, such as hot pressing sintering and pressureless sintering, have problems such as long production cycle, high production cost, and low material density. Therefore, it is of great significance to develop a new method for preparing silicon nitride ceramics. Therefore, in view of the above situation, it is urgent to develop a method for preparing silicon nitride ceramics based on laser selective sintering to overcome the shortcomings in current practical applications.

Summary of the invention

The present invention provides a method for preparing silicon nitride ceramics based on laser selective sintering, so as to solve the technical problems raised by the above background technology.

In order to solve the above technical problems, the present invention discloses a method for preparing silicon nitride ceramics based on laser selective sintering, comprising:

Step 1: Mix silicon nitride powder, sintering aid and binder in a proportion in a stirring device to obtain silicon nitride ceramic slurry;

Step 2: Apply silicon nitride ceramic slurry on the substrate to form a layer to be sintered, and use a laser device to perform selective sintering on the layer to be sintered;

Step 3: Repeat the operation of step 2 until a silicon nitride ceramic of a desired shape and thickness is obtained.

Preferably, the sintering aid in step one includes: alumina and yttrium oxide.

Preferably, the binder in step one is polyvinyl alcohol or polyacrylate.

Preferably, the laser device in step 2 can be a carbon dioxide laser.

Preferably, the stirring device is fixedly installed on the laser device on the right side, the belt transmission assembly passes through the stirring device and the laser device, and the transmission direction of the belt transmission assembly is from left to right, and the bottom end of the belt transmission assembly is fixedly installed on the base.

Preferably, the stirring device includes: a stirring box, a feed port is provided at the top of the stirring box, and the input end of the feed port is connected to the stirring chamber, a driving chamber is provided on the right side of the stirring chamber, a driving motor is fixedly installed at one fixed end on the inner wall of the top end of the driving chamber, and a worm is fixedly installed at the output end of the driving motor, and the other end of the worm is rotatably connected to the inner wall of the bottom end of the driving chamber, the worm is cooperatively connected with two sets of worm gears, and the worm gears are fixedly installed on two sets of rotating shafts, and one end of the rotating shaft is rotatably connected to the inner wall of the driving chamber, and the other end of the rotating shaft passes through the stirring chamber and is rotatably connected to its inner wall, and a plurality of stirring rods are fixedly installed on the rotating shaft where the stirring chamber is located.

Preferably, the silicon nitride ceramic slurry in step 2 is applied by a coating mechanism, which is arranged at the bottom of the stirring box and connected to the stirring device, and the coating mechanism includes:

Cavity 1, the top of the cavity 1 is connected to the stirring chamber through a through hole 1, and a solenoid valve is provided in the through hole 1, and the bottom of the cavity 1 is connected to one end of a plurality of connecting hoses, and the other end of the connecting hose passes through the cavity 1 and is connected to the smear rod, and buffer components are symmetrically provided on both sides of the connecting hose;

The buffer assembly includes: a slider 1, which is slidably connected to a slide groove 1 provided in a mixing box, and the front and rear ends of the slider 1 are fixedly mounted on one end of a return spring 1, and the other end of the return spring 1 is fixedly mounted on the inner wall of the slide groove 1, a short rod 1 is hinged on the slider 1, and the other end of the slider 1 is hinged on the smear rod.

Preferably, a ceramic grinding device is also fixedly installed on the right side of the laser device, and the ceramic grinding device includes:

The gear train of claim 1 further comprising a gear that is coupled to the gear train of the motor and the gear train that is coupled to the gear train of the motor. The gear train of the motor is coupled to the gear train of the motor, and the gear train of the motor is coupled to the gear train of the motor.

The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

Fig. 1 is an operation flow chart of the present invention;

Fig. 2 is a schematic diagram of the structure of the present invention;

FIG3 is a left view of the internal structure of the mixing box of the present invention;

FIG. 4 is a left view of the internal structure of the grinding box of the present invention.

In the figure: 1. Laser device; 2. Belt transmission assembly; 3. Mixing box; 4. Feeding port; 5. Mixing chamber; 6. Driving chamber; 7. Driving motor 1; 8. Worm; 9. Worm gear; 10. Rotating shaft 1; 11. Mixing rod; 12. Chamber 1; 13. Solenoid valve; 14. Through hole 1; 15. Connecting hose; 16. Applying rod; 17. Sliding block 1; 18. Sliding groove 1; 19. Reset spring 1; 20. Short rod 1; 21. Base; 22. Polishing box; 23. Two-way driving motor machine; 24, connecting plate; 25, rotating shaft 2; 26, bevel gear 1; 27, cavity 2; 28, bevel gear 2; 29, threaded rod; 30, slider 2; 31, connecting rod 1; 32, liquid storage tank; 33, connecting rod 2; 34, piston; 35, connecting pipe; 36, nozzle; 37, connecting rod 3; 38, grinder; 39, trapezoidal block; 40, roller; 41, adjustment plate; 42, short rod 2; 43, cavity 3; 44, slide 2; 45, push rod; 46, fixed plate.

Detailed ways

The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions and technical features between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

The present invention provides the following embodiments

Example 1

The embodiment of the present invention provides a method for preparing silicon nitride ceramics based on laser selective sintering, as shown in FIG1 , comprising:

Step 1: Mix silicon nitride powder, sintering aid and binder in a proportion in a stirring device to obtain silicon nitride ceramic slurry;

Step 2: Apply silicon nitride ceramic slurry on the substrate to form a layer to be sintered, and use the laser device 1 to perform selective sintering on the layer to be sintered;

Step 3: Repeat the operation of step 2 until a silicon nitride ceramic of a desired shape and thickness is obtained.

Optionally, the sintering aid in step one includes: aluminum oxide and yttrium oxide.

Optionally, the binder in step one is polyvinyl alcohol or polyacrylate.

Optionally, the laser device 1 in step 2 may use a carbon dioxide laser (during the laser sintering process, the light energy generated by the high-power gas laser is absorbed by the material, causing its surface to heat and melt rapidly. At the same time, the external pressure can cause a certain compressive stress to be generated on the surface of the material, thereby promoting the sintering process).

Optionally, the temperature range of the carbon dioxide laser sintering is 200° C. to 1000° C., and the pressure range is 10 5 to 10 7 Pa.

The beneficial effects of the above technical solution are as follows: the present invention mixes silicon nitride powder, sintering aid and binder in a proportion into a stirring device, and fully mixes silicon nitride powder, sintering aid and binder by setting a stirring device, and applies silicon nitride ceramic slurry on a substrate, and then uses a carbon dioxide laser to selectively sinter the sintered layer, thereby effectively preparing silicon nitride ceramics. The present invention effectively improves the technical problems proposed in the background technology by using a laser device 1: traditional silicon nitride ceramic preparation methods, such as hot pressing sintering, pressureless sintering, etc., have long production cycles, high production costs, and low material density.

Example 2

On the basis of Example 1, as shown in Figure 2-3, the right side of the stirring device is fixedly installed on the laser device 1, the belt transmission assembly 2 runs through the stirring device and the laser device 1, and the transmission direction of the belt transmission assembly 2 is from left to right, and the bottom end of the belt transmission assembly 2 is fixedly installed on the base 21.

Optionally, the stirring device includes: a stirring box 3, a feed port 4 is provided at the top of the stirring box 3, and the input end of the feed port 4 is connected to the stirring chamber 5, a driving chamber 6 is provided on the right side of the stirring chamber 5, a driving motor 7 is fixedly installed at the fixed end on the inner wall of the top end of the driving chamber 6, and a worm 8 is fixedly installed at the output end of the driving motor 7, and the other end of the worm 8 is rotatably connected to the inner wall of the bottom end of the driving chamber 6, the worm 8 is cooperatively connected with two sets of worm gears 9, and the worm gears 9 are fixedly installed on two sets of rotating shafts 10, and one end of the rotating shaft 10 is rotatably connected to the inner wall of the driving chamber 6, and the other end of the rotating shaft 10 passes through the stirring chamber 5 and is rotatably connected to its inner wall, and a plurality of stirring rods 11 are fixedly installed on the rotating shaft 10 where the stirring chamber 5 is located.

Optionally, the silicon nitride ceramic slurry in step 2 is applied by a coating mechanism, which is arranged at the bottom of the stirring box 3 and connected to the stirring device, and the coating mechanism includes:

A cavity 12, wherein the top of the cavity 12 is connected to the stirring cavity 5 via a through hole 14, and an electromagnetic valve 13 is provided in the through hole 14, and the bottom of the cavity 12 is connected to one end of a plurality of connecting hoses 15, and the other end of the connecting hoses 15 penetrates the cavity 12 and is connected to the smear rod 16, and buffer components are symmetrically provided on both sides of the connecting hoses 15;

The buffer assembly includes: a slider 17, which is slidably connected to a slide groove 18 provided in the mixing box 3, and the front and rear ends of the slider 17 are fixedly installed on one end of a return spring 19, and the other end of the return spring 19 is fixedly installed on the inner wall of the slide groove 18, a section of a short rod 20 is hinged on the slider 17, and the other end of the slider 17 is hinged on the smear rod 16.

The working principle of the above technical solution is as follows: first, the substrate is placed on the belt conveyor assembly 2, and then the substrate is moved to the bottom of the stirring box 3 by the movement of the belt conveyor assembly 2, and then the silicon nitride powder, sintering aid and binder are poured into the feeding port 4 in proportion, and then the driving motor 7 is started, and the driving motor 7 drives the worm 8 to rotate, and the rotation of the worm 8 drives the worm gear 9 meshing with it to rotate, and the rotation of the worm gear 9 drives the two rotating shafts 10 fixedly connected to it to rotate, and the rotation of the rotating shaft 10 drives a plurality of stirring rods 11 to rotate accordingly, and the stirring rods 11 rotate, so that the silicon nitride powder, sintering aid and binder in the stirring chamber 5 are mixed. The mixed liquid is fully stirred and mixed, and the electromagnetic valve 13 is opened, so that the silicon nitride ceramic slurry is transported to the cavity 12 through the through hole 14, and then the silicon nitride ceramic slurry in the cavity 12 is connected to the coating rod 16 through the connecting hose 15 by gravity, so that the silicon nitride ceramic slurry is coated on the substrate through the coating rod 16, and then the belt conveyor assembly 2 is moved to the bottom of the laser device 1 for laser sintering. When the sintering is completed, the belt conveyor assembly 2 is controlled to reverse, so that the substrate is moved to the bottom of the mixing box 3 again, so that it is coated for the second time and sintered again, and the above operation is repeated until the ceramic preparation is completed.

The beneficial effects of the above technical solution are as follows: by setting the belt transmission component 2, it is conducive to driving the substrate to move left and right, so as to achieve full coating and sintering thereof, and by automatically controlling the movement, automatic operation is achieved to prevent human operation from affecting the ceramic sintering; by setting the driving motor 7, it is conducive to achieving full mixing of silicon nitride powder, sintering aid and binder through stirring; by setting a plurality of stirring rods 11, it is conducive to effectively stirring the mixed slurry of silicon nitride powder, sintering aid and binder, and fully crushing the large particles in the slurry; by setting the electromagnetic valve 13, it is conducive to controlling the amount of slurry entering the cavity 12; by setting the coating mechanism, it is conducive to coating the slurry on the substrate through the transmission action of the belt transmission component 2, and it is conducive to laser sintering the coated substrate; by setting the buffer component, it is conducive to adjusting the upper and lower positions of substrates of fixed thickness, and by setting a plurality of reset springs 19, it is conducive to resetting the coating rod 16, which is very convenient and practical.

Example 3

On the basis of Example 1 or 2, as shown in FIG4 , a method for preparing silicon nitride ceramics based on laser selective sintering is provided, wherein a ceramic grinding device is fixedly installed on the right side of the laser device 1, and the ceramic grinding device comprises:

The polishing box 22, the left end of which is fixedly connected to the laser device 1, the bidirectional drive motor 23 is fixedly mounted on the connecting plate 24, and the front and rear ends of the connecting plate 24 are fixedly mounted on the inner wall of the cavity 27 provided in the polishing box 22, the front and rear ends of the output shaft of the bidirectional drive motor 23 are fixedly mounted with a rotating shaft 25, and a bevel gear 1 26 is fixedly mounted on the rotating shaft 25, the bevel gear 1 26 is meshed with the bevel gear 28, and the bottom end of the bevel gear 28 is fixedly mounted on a threaded rod 29. The threaded rod 29 has a first end and a second end, and the other end of the threaded rod 29 passes through the connecting plate 24 and is rotatably connected to the inner wall of the bottom end of the cavity 27, and a slider 2 30 is threadedly connected to the threaded rod 29, and a connecting rod 1 31 is fixedly installed between the sliders 2 30, and the front and rear ends of the connecting rod 1 31 pass through the cavity 27 and are connected to the ceramic fixing mechanism, one end of the connecting rod 37 is fixedly connected to the connecting rod 1 31, and the other end of the connecting rod 2 33 passes through the liquid storage tank 32 and the cavity 27 and is connected to a grinder 38 (the grinder 38 can refer to CN 106607728 A, a wall construction grinder for construction), and the grinder 38 contacts the top of the ceramic, and a grinding and cleaning mechanism is also provided on the inner wall of the cavity 27 at the bottom of the connecting rod 1 31.

Optionally, the polishing and cleaning mechanism includes: a liquid storage tank 32, the liquid storage tank 32 is fixedly mounted on the inner wall of the bottom end of the cavity 27, one end of a plurality of connecting rods 33 is fixedly mounted on the connecting rod 1 31, the other end of the connecting rod 33 passes through the liquid storage tank 32 and is fixedly connected to the piston 34, and the bottom ends of both sides of the liquid storage tank 32 are connected to one end of a connecting pipe 35, and the other end of the connecting pipe 35 passes through the cavity 27 and is connected to the nozzle 36.

Optionally, the ceramic fixing mechanism is symmetrically arranged at the front and rear ends of the connecting rod 1 31, and the ceramic fixing mechanism includes:

A trapezoidal block 39, one end of which is fixedly mounted on the connecting rod 1 31, the inclined surface at the other end of the trapezoidal block 39 contacts the roller 40, and the roller 40 is movably connected to the adjustment plate 41, and the adjustment plate 41 is hinged at one end of a short rod 2 42, the other end of the short rod 2 42 is fixedly mounted on the inner wall of a cavity 3 43 provided at the front and rear ends of the grinding box 22, and the adjustment plate 41 is provided with a slide groove 2 44, one end of a push rod 45 is movably connected in the slide groove 2 44, and the other end of the push rod 45 passes through the cavity 3 43 and is fixedly connected to a fixed plate 46.

The working principle of the above technical solution is as follows: when the ceramic is prepared, it is transported to the bottom end of the polishing box 22 through the belt conveyor assembly 2, and then the bidirectional driving motor 23 is started, and the bidirectional driving motor 23 rotates to drive the rotating shaft 25 to rotate, and the rotating shaft 25 rotates to drive the bevel gear 1 26 fixedly connected thereto to rotate, and the bevel gear 1 26 rotates to drive the bevel gear 28 meshing therewith to rotate, and the bevel gear 28 rotates to drive the threaded rod 29 fixedly connected thereto to rotate, and the threaded rod 29 rotates to drive the slider 2 30 threadedly connected thereto to move downward, and the slider 2 30 moves downward to drive the trapezoidal block 39 to move downward, and the trapezoidal block 39 moves downward to drive the roller 40 and the adjusting plate 41 in contact therewith to move outward, and the other end of the adjusting plate 41 moves inward at the bottom under the action of the short rod 2 42, thereby moving the push rod 45 and the fixed plate 46 fixedly connected to the push rod 45 inward, thereby effectively fixing the ceramic placed on the belt conveyor assembly 2;

When the connecting rod 1 31 moves downward, it drives the connecting rod 2 33 and the connecting rod 3 37 fixed thereto to move downward (the grinder 38 is in the started state at this time). The connecting rod 3 37 moves downward and drives the grinder 38 to move, thereby moving the grinder 38 to the surface of the silicon nitride ceramic for grinding it. At this time, the connecting rod 2 33 moves downward and drives the piston 34 to move accordingly, thereby pressurizing the water stored in the liquid storage tank 32, and then through the action of the connecting pipe 35, it is sprayed onto the surface of the silicon nitride ceramic through the nozzle 36, thereby assisting the grinder 38 to grind the surface of the silicon nitride ceramic.

The beneficial effects of the above technical scheme are as follows: by setting a bidirectional drive motor 23, it is beneficial to realize the automatic operation of the device under the action of the bidirectional drive motor 23, which is very convenient and practical; by setting a threaded rod 29 and a slider 30, it is beneficial to realize its up and down movement while changing the driving direction of the bidirectional drive motor 23; by setting a ceramic fixing mechanism, it is beneficial to effectively fix the silicon nitride ceramic during the grinding process to prevent it from rotating with the grinder 38 during the grinding process; by setting a liquid storage tank 32, it is beneficial to spray the water in the liquid storage tank 32 through the connecting pipe 35 and the nozzle 36 onto the surface of the silicon nitride ceramic, thereby not only effectively cooling the grinder 38, but also effectively cleaning the grinding dirt during the grinding process, which is very convenient and practical.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (8)

1. A method for preparing silicon nitride ceramics based on laser selective sintering, which is characterized by comprising the following steps:

Step one: mixing silicon nitride powder, a sintering aid and a binder in proportion into a stirring device to obtain silicon nitride ceramic slurry;

Step two: coating silicon nitride ceramic slurry on a base material to form a layer to be sintered, and carrying out zone-selection sintering on the layer to be sintered by using a laser device (1);

Step three: repeating the operation of the second step until the silicon nitride ceramic with the required shape and thickness is obtained.

2. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 1, wherein the sintering aid in the first step comprises: alumina, yttria.

3. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 1, wherein the binder in the first step is polyvinyl alcohol or polyacrylate.

4. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 1, wherein the laser device (1) in the second step is a carbon dioxide laser.

5. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 1, wherein the right side of the stirring device is fixedly arranged on the laser device (1), the belt conveying assembly (2) penetrates through the stirring device and the laser device (1), the transmission direction of the belt conveying assembly (2) is from left to right, and the bottom end of the belt conveying assembly (2) is fixedly arranged on the base (21).

6. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 5, wherein the stirring device comprises: stirring case (3), stirring case (3) top is provided with feed inlet (4), just the input and the stirring chamber (5) intercommunication of feed inlet (4), stirring chamber (5) right side is equipped with driving chamber (6), driving motor one (7) fixed mounting is on driving chamber (6) top inner wall, just driving motor one (7)'s output fixed mounting has worm (8), worm (8) other end rotation is connected on driving chamber (6) bottom inner wall, worm (8) are connected with two sets of worm wheel (9) cooperation, just worm wheel (9) fixed mounting is on two sets of pivots one (10), and pivot one (10) one end rotation is connected on driving chamber (6) inner wall, just pivot one (10) other end runs through stirring chamber (5) and rotates to be connected on its inner wall, and is located stirring chamber (5) place in pivot one (10) fixedly mounted with a plurality of puddler (11).

7. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 1, wherein the silicon nitride ceramics slurry in the second step is coated by a coating mechanism, the coating mechanism is arranged at the bottom end inside the stirring tank (3) and is connected with the stirring device, and the coating mechanism comprises:

The stirring device comprises a first cavity (12), wherein the top end of the first cavity (12) is connected with the stirring cavity (5) through a first through hole (14), an electromagnetic valve (13) is arranged in the first through hole (14), the bottom end of the first cavity (12) is communicated with one ends of a plurality of connecting hoses (15), the other ends of the connecting hoses (15) penetrate through the first cavity (12) and are connected with a smearing rod (16), and buffer assemblies are symmetrically arranged on two sides of the connecting hoses (15);

The cushioning assembly includes: the first sliding block (17), sliding connection around in spout one (18) that agitator tank (3) set up, just both ends fixed mounting around slider one (17) are in reset spring one (19) one end, and reset spring one (19) other end fixed mounting is on spout one (18) inner wall, and a section of quarter butt one (20) articulates on slider one (17), and slider one (17) other end articulates on smearing rod (16).

8. The method for preparing silicon nitride ceramics based on selective laser sintering according to claim 5, wherein a ceramic polishing device is fixedly installed on the right side of the laser device (1), and the ceramic polishing device comprises:

The grinding box (22), the left end of the grinding box (22) is fixedly connected with the laser device (1), the bidirectional driving motor (23) is fixedly installed on the connecting plate (24), the front end and the rear end of the connecting plate (24) are fixedly installed on the inner wall of a cavity II (27) formed by the grinding box (22), a rotating shaft II (25) is fixedly installed on the front end and the rear end output shaft of the bidirectional driving motor (23), a bevel gear I (26) is fixedly installed on the rotating shaft II (25), the bevel gear I (26) is meshed with the bevel gear II (28), the bottom end of the bevel gear II (28) is fixedly installed at one end of a threaded rod (29), the other end of the threaded rod (29) penetrates through the connecting plate (24) and is in rotary connection with the inner wall of the bottom end of the cavity II (27), a sliding block II (30) is in threaded connection with the threaded rod II (29), a connecting rod I (31) is fixedly installed between the sliding block II (30), the front end and the rear end of the connecting rod I (31) penetrates through the cavity II (27) to be connected with a ceramic fixing mechanism, a connecting rod III (37) is fixedly connected with one end of the connecting rod II (31) and one end of the connecting rod II (38) fixedly connected with the ceramic cavity II (38), and a polishing and cleaning mechanism is further arranged on the inner wall of the cavity II (27) at the bottom end of the connecting rod I (31).