Silicon nitride ceramic sheet and preparation process thereof

Abstract

The present invention discloses a silicon nitride ceramic sheet and a preparation process thereof, and relates to the field related to silicon nitride ceramic sheets, including ceramic sheets and coating structures. The present invention coats the top of the ceramic sheet with a coating structure, and simultaneously introduces conductive, thermal and anti-wear functions into the coating structure, and adopts a reasonable multi-layer design to optimize the matching of each layer. Aluminum oxide is used as the bottom layer, which can enhance the adhesion between the coating and the silicon nitride ceramic substrate, and provide high hardness and corrosion resistance; silicon carbide is used as the middle layer, which has excellent thermal conductivity and high temperature resistance, and improves the thermal management ability of the material; titanium nitride is used as the surface layer, which has excellent anti-wear, anti-oxidation and anti-corrosion properties, ensuring the long-term stability and durability of the coating in harsh environments. This combination of multi-layer coating structures greatly enhances the functionality and durability of silicon nitride ceramics.

Description

Technical Field

[0001] The invention relates to the field related to silicon nitride ceramic slices, and in particular to a silicon nitride ceramic slice and a preparation process thereof. Background Art

[0002] Silicon nitride ceramic sheets are made of silicon nitride materials, which have excellent mechanical properties, high temperature resistance, corrosion resistance and good thermal conductivity. They are hard, strong and light, and are widely used in electronics, aerospace, automobile and manufacturing industries, especially in high temperature environments, structural parts, insulation materials, and support and isolation layers in semiconductor manufacturing. Silicon nitride ceramic sheets can also maintain good electrical insulation and wear resistance at high temperatures.

[0003] Chinese patent application number: CN202111518751.9 is a preparation process for in-situ polymerization-formed silicon nitride ceramic sheets, and the production steps include mixing one or several liquid acrylic monomers, one or several low molecular weight and low viscosity liquid epoxy resins, and an appropriate proportion of free radical initiator at room temperature, and then adding high-purity micro-nano silicon nitride powder, dispersant, and inorganic sintering aid together, and thoroughly mixing in a planetary mixer or a screw kneader. The in-situ polymerization-formed silicon nitride production process of the present invention does not use organic solvents, has no drying and discharge process, uses liquid acrylic ester monomers and low molecular weight epoxy resins as dispersion media, has low energy consumption, high speed, and small equipment footprint. The manufactured green embryos have precise dimensions, few defects, and high yield.

[0004] The above patents and prior art have the following problems in actual practice: the protective property of the prepared silicon nitride ceramic sheets is weak, and the added coating has a relatively simple functionality, which leads to problems such as easy damage during use; and during the processing, manual scraping and post-processing polishing are required, which is labor-intensive and reduces work efficiency. Summary of the invention

[0005] Therefore, in order to solve the above-mentioned shortcomings, the present invention provides a silicon nitride ceramic sheet and a preparation process thereof.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a silicon nitride ceramic sheet and its preparation process, including a ceramic sheet, a coating structure is provided on the top of the ceramic sheet, the coating structure includes a transition layer coated on the ceramic sheet, a functional layer is coated on the other side of the transition layer, and a protective layer is coated on the other side of the functional layer; the transition layer is aluminum oxide, the functional layer is silicon carbide, and the protective layer is titanium nitride.

[0007] Preferably, the steps are as follows:

[0008] S1 Raw material preparation: silicon nitride powder, magnesium oxide sintering aid, polyvinyl alcohol dispersant, polyvinyl pyrrolidone binder and lubricant;

[0009] S2 batching and mixing: mix silicon nitride powder with sintering aid, use ball mill to wet mill the raw materials for 12-24 hours, add appropriate amount of dispersant, binder and lubricant;

[0010] S3 molding: Use the tape casting method to evenly coat the mixed slurry on the substrate to form a ceramic sheet. The thickness of the formed sheet is 100-500μm. The formed sheet is dried in a drying oven and completed with a surface treatment device. The temperature is controlled at 80℃ to ensure water evaporation;

[0011] S4 degreasing and pre-sintering: The dried ceramic body is degreased at 200-400°C to remove organic additives, and then pre-sintered in an atmospheric environment at a temperature of 800-1200°C for 2-4 hours;

[0012] S5 high temperature sintering: hot pressing sintering is adopted, the sintering temperature is controlled at 1700-1900℃, the sintering time is 2-6 hours, and the high temperature sintering process needs to maintain nitrogen protection. The sintered ceramic sheet reaches high density and the porosity is less than 1%;

[0013] S6 subsequent processing: The sintered ceramic slices are subjected to surface grinding and polishing, which is completed with the surface treatment device to ensure that the surface roughness of the slices is less than 0.5μm. Finally, the slices are cut using laser equipment;

[0014] Preparation of S7 coating structure:

[0015] S701 bottom coating: transition layer, aluminum oxide is selected, and the sol-gel method is used to dissolve aluminum isopropanol in an alcohol solvent, and the pH value is adjusted to generate a sol, and then the sol is evenly coated on the surface of the silicon nitride sheet. The coating thickness is 100-200nm, and then dried at 80℃, and then annealed at 500-700℃;

[0016] S702 intermediate layer coating: functional layer, silicon carbide is selected, physical vapor deposition method is used, material evaporation deposition is carried out in a vacuum environment, and the intermediate functional layer is evenly deposited on the bottom coating, and the thickness is controlled at 1-10μm;

[0017] S703 surface protection layer coating: titanium nitride is used, and magnetron sputtering deposition process is adopted. Magnetron sputtering is performed in a vacuum chamber to deposit titanium nitride on the intermediate functional layer to form a protective layer with a thickness of 500nm-1μm. After the deposition is completed, heat treatment is performed, and the temperature is controlled at 400-600℃;

[0018] S8 Heat treatment and annealing: After all coatings are deposited, the coating structure is placed in an inert atmosphere for heat treatment at a temperature of 500-700°C for 1-2 hours, which helps densification of the coating and bonding between layers.

[0019] Preferably, the surface treatment device includes a fixed box, a movable door arranged at the left front end of the fixed box, a positioning mechanism arranged at the lower end of the fixed box, a first motor arranged at the top of the fixed box and connected to the positioning mechanism, and a contact processing mechanism arranged at the bottom of the positioning mechanism.

[0020] Preferably, the positioning mechanism includes a base plate arranged at the lower end of the fixed box, a rotating shaft arranged at the upper left of the base plate and connected to the output shaft of the first motor, support blocks arranged at the upper and lower ends of the outer side of the rotating shaft, a rotating member arranged at the lower end of the outer side of the rotating shaft, a connecting rod hinged to the other end of the rotating member, a pull rod hinged to the other end of the connecting rod, a connecting member arranged in the middle of the hinge position of the pull rod and the connecting rod, a screw threadedly connected to the connecting member and the lower end of the rotating shaft, a sliding member hinged to the other end of the pull rod, a connecting member arranged at the bottom of the sliding member, a cylinder arranged at the top of the sliding member and the bottom push rod connected to the connecting member, a guide rod passing through the upper and lower positions of the rear end of the sliding member, and a support fixed to both sides of the guide rod and the bottom fixed to the top of the base plate.

[0021] Preferably, a strip groove is provided at the bottom of the substrate, and the bottom of the connector passes through the strip groove and is connected to the contact processing mechanism.

[0022] Preferably, the left side of the support block is fixed to the inner side of the fixing box through a bracket.

[0023] Preferably, the contact processing mechanism includes a connecting plate connected to the connecting piece, a second motor arranged on the right side of the connecting plate, support rods arranged at the four ends of the bottom of the connecting plate, a support piece connecting the bottom of the support rod, a guide piece arranged at the bottom of the support piece, a follower contact piece arranged at the bottom of the guide piece, a driving pulley connected to the output shaft of the second motor, a synchronous belt arranged on the outside of the driving pulley, a driven pulley connected to the other end of the synchronous belt, an arm arranged on the inner side of the driven pulley, a sliding block arranged at the right end of the arm, and a connecting frame connected to the top of the sliding block, the lower end of the inner side of the connecting frame is fixed to the contact piece, the middle part of the bottom end of the support piece protrudes, and a guide piece is movably embedded in the protruding position, and the two are matched, and the bottom of the guide piece matches the follower contact piece in the same way, but the two sets of matching positions are staggered.

[0024] Preferably, the bottom of the sliding block is convex, and the top of the sliding block is connected to the connecting frame. A square sliding groove is opened in the middle of the top of the support member, and the four inner corners of the sliding groove are chamfered. The protruding position of the sliding block is movably embedded in the sliding groove.

[0025] Preferably, the follower contact member includes a box body whose top matches the guide member, nozzles opened at both ends of the bottom of the box body, two groups of access ports arranged at the front end of the box body, a contact roller arranged in the middle of the box body, and a third motor arranged on the left side of the box body and connected to the contact roller, and the nozzle is connected to the two groups of access ports.

[0026] Preferably, a grinding piece is embedded in the upper end of the contact roller, a scraping piece is embedded in the bottom of the contact roller, a rotating shaft is arranged in the middle of the contact roller, and the left side of the rotating shaft passes through the box body and is connected to the output shaft of the third motor.

[0027] Beneficial effects of the present invention:

[0028] The present invention coats a coating structure on the top of a ceramic sheet, and simultaneously introduces conductive, thermal and wear-resistant functions into the coating structure, and adopts a reasonable multi-layer design to optimize the matching of each layer. Aluminum oxide is used as the bottom layer to enhance the adhesion between the coating and the silicon nitride ceramic substrate, and provide high hardness and corrosion resistance; silicon carbide is used as the middle layer, and has excellent thermal conductivity and high temperature resistance, thereby improving the thermal management capability of the material; titanium nitride is used as the surface layer, and has excellent anti-wear, anti-oxidation and anti-corrosion properties, thereby ensuring the long-term stability and durability of the coating in harsh environments. This combination of multi-layer coating structures greatly enhances the functionality and durability of silicon nitride ceramics.

[0029] The present invention is completed by adopting a surface treatment device during the thin slice drying and post-processing grinding process. The surface treatment device is equipped with a contact treatment mechanism. The contact treatment mechanism is provided with switchable grinding parts and scraping parts. The contact treatment mechanism cooperates with external hot air and water supply equipment and a transmission component inside the mechanism to perform efficient scraping and grinding. The top of the contact treatment mechanism is connected to a positioning mechanism. The positioning mechanism can carry the contact treatment mechanism to perform left and right reciprocating motion, and the movement speed can be adjusted. The auxiliary surface treatment effect is good, manual operation is saved, and work efficiency is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the present invention;

[0031] Figure 2 It is a schematic structural diagram of the surface treatment device of the present invention;

[0032] Figure 3 It is a schematic diagram of the structure of the positioning mechanism of the present invention;

[0033] Figure 4 It is a schematic diagram of the structure of the contact processing mechanism of the present invention;

[0034] Figure 5 It is a schematic diagram of the support member connection structure of the present invention;

[0035] Figure 6It is a schematic diagram of the structure of the follower contact of the present invention;

[0036] Figure 7 It is a schematic diagram of the contact roller structure of the present invention.

[0037] Among them: ceramic sheet-a, coating structure-b, transition layer-b1, functional layer-b2, protective layer-b3, fixed box-1, movable door-2, adjustment mechanism-3, first motor-4, contact processing mechanism-5, substrate-31, rotating shaft-32, support block-33, rotating member-34, connecting rod-35, connecting member-36, screw-37, pull rod-38, sliding member-39, connecting member-310, cylinder-311, guide rod-312, support-3 13. Connecting plate 51, second motor 52, support rod 53, support member 54, connecting frame 55, guide member 56, follower contact member 57, driving pulley 58, synchronous belt 59, driven pulley 510, support arm 511, sliding block 512, box body 571, nozzle 572, access port 573, contact roller 574, third motor 575, grinding member 574a, scraping member 574b, rotating shaft 574c. DETAILED DESCRIPTION

[0038] In order to further explain the technical solution of the present invention, it is described in detail below through specific embodiments.

[0039] See also Figure 1 The present invention provides a silicon nitride ceramic sheet, including a ceramic sheet a, a coating structure b is coated on the top of the ceramic sheet a, the coating structure b includes a transition layer b1, the transition layer b1 is aluminum oxide, which is prepared by a sol-gel method and coated on the top of the ceramic sheet a, a functional layer b2 is deposited on the top of the transition layer b1 by physical vapor deposition technology, the functional layer b2 is silicon carbide and has thermal conductivity, and a protective layer b3 prepared by titanium nitride is deposited on the top of the functional layer b2 by a magnetron sputtering deposition process, so as to provide wear resistance, oxidation resistance and corrosion resistance for the silicon nitride ceramic sheet.

[0040] A preparation process of a silicon nitride ceramic sheet, the steps are as follows:

[0041] S1 Raw material preparation: silicon nitride powder, magnesium oxide sintering aid, polyvinyl alcohol dispersant, polyvinyl pyrrolidone binder and lubricant; S2 Batching and mixing: Mix silicon nitride powder with sintering aid, use ball mill to wet mill the raw materials for 18 hours, add appropriate amount of dispersant, binder and lubricant; S3 Molding: Use tape casting method to evenly coat the mixed slurry on the substrate to form a ceramic sheet. The thickness of the formed sheet is 300μm. The formed sheet is dried in a drying oven and completed with surface treatment device. The temperature is controlled at 80℃, to ensure the evaporation of water; S4 degreasing and pre-sintering: the dried ceramic body is degreased at 300℃ to remove organic additives, and then pre-sintered in an atmospheric environment, the temperature is controlled at 1000℃, and the pre-sintering time is 3 hours; S5 high-temperature sintering: hot pressing sintering is adopted, the sintering temperature is controlled at 1800℃, the sintering time is 4 hours, and the high-temperature sintering process needs to maintain nitrogen protection. The sintered ceramic slices reach high density and the porosity is less than 1%; S6 subsequent processing: the surface of the sintered ceramic slices is ground and polished, and the surface treatment device is used for Complete, ensure that the surface roughness of the thin film is less than 0.5μm, and finally use laser equipment to cut the thin film; S7 Preparation of coating structure b: S701 Bottom layer coating: transition layer b1, select aluminum oxide, use sol-gel method, dissolve aluminum isopropanol in alcohol solvent, adjust the pH value to generate sol, and then evenly coat the sol on the surface of silicon nitride thin film, the coating thickness is 150nm, then dry at 80℃, and then anneal at 600℃; S702 Intermediate layer coating: functional layer b2, select silicon carbide, use physical vapor deposition method, evaporate the material in a vacuum environment Deposition, the middle functional layer is evenly deposited on the bottom coating, and the thickness is controlled at 5μm; S703 surface protection layer b3 coating: titanium nitride is used, and magnetron sputtering deposition process is adopted. Magnetron sputtering is carried out in a vacuum chamber to deposit titanium nitride on the middle functional layer to form a protective layer with a thickness of 750nm. After the deposition is completed, heat treatment is carried out and the temperature is controlled at 500℃; S8 heat treatment and annealing: after all coatings are deposited, the coating structure is placed in an inert atmosphere for heat treatment, and the temperature is controlled at 600℃ for 1.5 hours, which helps the densification of the coating and the bonding between the layers.

[0042] See also Figure 2The surface treatment device includes a fixed box 1, a movable door 2 is installed at the left end of the front end surface of the fixed box 1, a positioning mechanism 3 is arranged at the lower end of the fixed box 1, the left end of the top of the positioning mechanism 3 is connected to the first motor 4, the first motor 4 is installed on the top of the fixed box 1, and a contact processing mechanism 5 is arranged at the right end of the bottom of the positioning mechanism 3. The positioning mechanism 3 can adjust the position of the contact processing mechanism 5, and the contact processing mechanism 5 can process the surface of the thin sheet passing through the bottom, and can assist in scraping and drying during the drying process and perform grinding treatment during the post-processing process.

[0043] See also Figure 3 The positioning mechanism 3 includes a base plate 31 for supporting and fixing at the lower end of the fixed box 1. A rotating shaft 32 is arranged on the upper left of the base plate 31. The top of the rotating shaft 32 passes through the fixed box 1 and is connected to the output shaft of the first motor 4. Support blocks 33 are arranged at the upper and lower ends of the outer side of the rotating shaft 32. The left side of the support block 33 can be fixed to the inner side of the fixed box 1 through an external bracket. The lower end of the outer side of the rotating shaft 32 is connected to a rotating member 34. The other end of the rotating member 34 is hinged to a connecting rod 35. The other end of the connecting rod 35 is hinged to a pull rod 38. A connecting member 36 is arranged in the middle of the hinged position of the two. A screw 37 is threadedly connected to the middle of the connecting member 36 and the lower end of the rotating shaft 32. By opening the movable door 2 The screw rod 37 can be rotated and adjusted, and the other end of the pull rod 38 is hinged to the sliding member 39. A connecting piece 310 is arranged at the bottom of the sliding member 39, and the bottom of the connecting piece 310 is connected to the contact processing mechanism 5. A cylinder 311 is installed on the top of the sliding member 39, and the push rod at the bottom of the cylinder 311 penetrates the sliding member 39 and connects the connecting piece 310. Sleeves are arranged at the upper and lower ends of the back side of the sliding member 39, and the two groups of sleeves are respectively penetrated by two groups of guide rods 312. The guide rod 312 is fixed at the front end of the support 313, and the bottom of the support 313 is fixed to the top of the substrate 31. A strip groove is opened at the bottom of the substrate 31, and the bottom of the connecting piece 310 penetrates the strip groove and is connected to the contact processing mechanism 5.

[0044] See also Figure 4-Figure 5The contact processing mechanism 5 includes a connecting plate 51 connected to the connecting member 310, and a second motor 52 is locked on the right side of the connecting plate 51. The four ends of the bottom of the connecting plate 51 are connected to the supporting member 54 through the support rod 53. The middle part of the bottom end of the supporting member 54 protrudes, and a guide member 56 is movably embedded in the protruding position. The two are matched, and the bottom of the guide member 56 is matched with the follower contact member 57 in the same way, but the two sets of matching positions are staggered and not parallel. The upper ends of the front and rear ends of the follower contact member 57 are locked with a connecting frame 55, and the output shaft at the bottom of the second motor 52 is connected to the driving pulley 5 8. The outer side of the driving pulley 58 rotates synchronously with the driven pulley 510 through the synchronous belt 59. A support arm 511 is welded and fixed to the middle part of the inner side of the driven pulley 510. The middle part of the support arm 511 is connected to the support member 54 through a shaft rod. A sliding block 512 is sleeved on the right end of the support arm 511. The bottom of the sliding block 512 is convex, and the top of the sliding block 512 is connected to the connecting frame 55. A square-shaped sliding groove is opened in the middle part of the top of the support member 54. The four corners of the inner side of the sliding groove are chamfered. The protruding position of the sliding block 512 can be movably embedded in the sliding groove for sliding.

[0045] See also Figure 6 The follower contact member 57 includes a box body 571 whose middle part matches the guide member 56, and nozzles 572 are provided at the left and right ends of the bottom of the box body 571. Two groups of access ports 573 communicating with the nozzles 572 are provided at the lower end of the front end surface of the box body 571. The two groups of access ports 573 are respectively connected to external water supply and hot air supply equipment, which can be used for spraying during the grinding process and heating during the drying process, and valves must be installed in the access ports 573, which cannot be used synchronously. A groove is provided in the middle part of the bottom end of the box body 571, and a contact roller 574 is provided inside the groove. A third motor 575 connected to the contact roller 574 is provided on the left side of the box body 571.

[0046] See also Figure 7 A grinding piece 574a for grinding is embedded in the upper end of the contact roller 574, a scraping piece 574b for scraping is embedded in the bottom of the contact roller 574, and a rotating shaft 574c is arranged in the middle of the contact roller 574. The left side of the rotating shaft 574c passes through the box body 571 and is connected to the output shaft of the third motor 575.

[0047] The specific implementation process is as follows:

[0048] When the surface treatment device is needed to process the thin sheet processing, the surface treatment device is first installed above the thin sheet conveying and placing device, and the thin sheet can be prepared for processing;

[0049] If it is necessary to flatten the surface of the sheet and heat and dry it during the drying process, the cylinder 311 is started, and the push rod at the bottom of the cylinder 311 brings the connecting piece 310 to adjust the height position of the contact processing mechanism 5, so that it moves downward, allowing the flattening piece 574b to contact the surface of the sheet. At this time, the external hot air supply device is started, and the hot air enters from the inlet 573 and is ejected from the nozzle 572;

[0050] Then, the first motor 4 is started to work, and the first motor 4 drives the rotating shaft 32 to rotate. During the rotation of the rotating shaft 32, the rotating member 34 causes the connecting rod 35 to rotate accordingly, and the pull rod 38 can move accordingly. The sliding member 39 connected to the other end of the pull rod 38 can move left and right on the guide rod 312. During the movement, the contact processing mechanism 5 is moved accordingly through the connecting member 310 at the bottom, and the scraping member 574b at the bottom starts to scrape the surface of the sheet flat. If it is necessary to adjust the left and right movement speed, the movable door 2 is opened, and then the screw rod 37 is rotated to adjust the angles of the connecting rod 35 and the rotating member 34, so as to complete the adjustment of the sliding speed of the sliding member 39.

[0051] During the scraping process, the second motor 52 is started to work, and the second motor 52 drives the driving pulley 58 to rotate. During the rotation of the driving pulley 58, the driven pulley 510 is rotated through the synchronous belt 59, and the support arm 511 in the middle of the driven pulley 510 follows the rotation, and during the rotation, the sliding block 512 slides in the direction groove along the top of the support member 54, and then acts on the connecting frame 55 to move. The connecting frame 55 drives the follower contact member 57 to follow the movement, and cooperates with the upper guide member 56 and the bottom of the support member 54 to reciprocate in a square track, and cooperates with the scraping member 574b to perform uniform scraping work;

[0052] If grinding work is required, start the third motor 575, and the third motor 575 drives the rotating shaft 574c to rotate the contact roller 574, turn the grinding piece 574a downward, and then turn off the hot air supply device, start the external water supply device, spray water or grinding liquid from the nozzle 572, adjust the position in the same way as the scraping process, and reciprocate to start uniform grinding.

[0053] The above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surface treatment device for a silicon nitride ceramic wafer, characterized in that: The surface treatment device comprises a fixed box, a movable door arranged at the left front end of the fixed box, a positioning mechanism arranged at the lower end of the fixed box, a first motor arranged at the top of the fixed box and connected to the positioning mechanism, and a contact processing mechanism arranged at the bottom of the positioning mechanism; The positioning mechanism includes a base plate arranged at the lower end of the fixed box, a rotating shaft arranged at the upper left of the base plate and connected to the output shaft of the first motor, support blocks arranged at the upper and lower ends of the outer side of the rotating shaft, a rotating member arranged at the lower end of the outer side of the rotating shaft, a connecting rod hinged to the other end of the rotating member, a pull rod hinged to the other end of the connecting rod, a connecting member arranged in the middle of the hinge position of the pull rod and the connecting rod, a screw threadedly connected to the connecting member and the lower end of the rotating shaft, a sliding member hinged to the other end of the pull rod, a connecting member arranged at the bottom of the sliding member, a cylinder arranged at the top of the sliding member and the bottom push rod connecting the connecting member, a guide rod passing through the upper and lower positions of the rear end of the sliding member, and a support fixed to both sides of the guide rod and the bottom fixed to the top of the base plate; The bottom of the base plate is provided with a strip groove, and the bottom of the connector passes through the strip groove and is connected to the contact processing mechanism; The contact processing mechanism includes a connecting plate connected to the connecting piece, a second motor arranged on the right side of the connecting plate, support rods arranged at the four ends of the bottom of the connecting plate, a support piece connecting the bottom of the support rod, a guide piece arranged at the bottom of the support piece, a follower contact piece arranged at the bottom of the guide piece, a driving pulley connected to the output shaft of the second motor, a synchronous belt arranged on the outside of the driving pulley, a driven pulley connected to the other end of the synchronous belt, an arm arranged on the inner side of the driven pulley, a sliding block arranged at the right end of the arm, and a connecting frame connected to the top of the sliding block, the lower end of the inner side of the connecting frame is fixed to the contact piece, the middle part of the bottom end of the support piece protrudes, and a guide piece is movably embedded in the protruding position, and the two are matched, and the bottom of the guide piece matches the follower contact piece in the same way, but the two sets of matching positions are staggered.

2. The surface treatment device for a silicon nitride ceramic sheet according to claim 1, characterized in that: The left side of the support block is fixed to the inner side of the fixing box through a bracket.

3. The surface treatment device for a silicon nitride ceramic sheet according to claim 1, characterized in that: The bottom of the sliding block is convex, and the top of the sliding block is connected to the connecting frame. A square sliding groove is opened in the middle of the top of the support member. The four inner corners of the sliding groove are chamfered, and the protruding position of the sliding block is movably embedded in the sliding groove.

4. The surface treatment device for a silicon nitride ceramic sheet according to claim 3, characterized in that: The follower contact member includes a box body whose top matches the guide member, nozzles opened at both ends of the bottom of the box body, two groups of access ports arranged at the front end of the box body, a contact roller arranged in the middle of the box body, and a third motor arranged on the left side of the box body and connected to the contact roller, and the nozzle is connected to the two groups of access ports.

5. The surface treatment device for a silicon nitride ceramic sheet according to claim 4, characterized in that: A grinding piece is embedded in the upper end of the contact roller, a flattening piece is embedded in the bottom of the contact roller, a rotating shaft is arranged in the middle of the contact roller, and the left side of the rotating shaft penetrates the box body and is connected to the output shaft of the third motor.

6. A process for preparing a silicon nitride ceramic sheet, using the surface treatment device as described in any one of claims 1 to 5, characterized in that: Here are the steps: S1 Raw material preparation: silicon nitride powder, magnesium oxide sintering aid, polyvinyl alcohol, polyvinyl pyrrolidone and lubricant; S2 batching and mixing: mix silicon nitride powder with sintering aid, use ball mill to wet mill the raw materials for 12-24 hours, add appropriate amount of dispersant, binder and lubricant; S3 molding: Use the tape casting method to evenly coat the mixed slurry on the substrate to form a ceramic sheet. The thickness of the formed sheet is 100-500 μm. The formed sheet is dried in a drying oven and completed with a surface treatment device. The temperature is controlled at 80°C to ensure water evaporation; S4 degreasing and pre-sintering: the dried ceramic body is degreased at 200-400°C to remove organic additives, and then pre-sintered in an atmospheric environment at a temperature of 800-1200°C for 2-4 hours; S5 high temperature sintering: hot pressing sintering is adopted, the sintering temperature is controlled at 1700-1900°C, the sintering time is 2-6 hours, and nitrogen protection is required during the high temperature sintering process. The sintered ceramic sheet reaches high density and the porosity is less than 1%; S6 subsequent processing: The sintered ceramic slices are subjected to surface grinding and polishing, which is completed with the surface treatment device to ensure that the surface roughness of the slices is less than 0.5 μm. Finally, the slices are cut using laser equipment; Preparation of S7 coating structure: S701 bottom coating: transition layer, aluminum oxide is selected, and aluminum isopropanol is dissolved in an alcohol solvent by sol-gel method, and the pH value is adjusted to generate sol, and then the sol is evenly coated on the surface of silicon nitride wafer, the coating thickness is 100-200 nm, and then dried at 80°C, and then annealed at 500-700°C; S702 intermediate layer coating: functional layer, silicon carbide is selected, physical vapor deposition method is used, material evaporation deposition is carried out in a vacuum environment, and the intermediate functional layer is evenly deposited on the bottom coating, and the thickness is controlled at 1-10 μm; S703 surface protection layer coating: titanium nitride is used, and magnetron sputtering deposition process is adopted. Magnetron sputtering is performed in a vacuum chamber to deposit titanium nitride on the intermediate functional layer to form a protective layer with a thickness of 500 nm-1 μm. After the deposition is completed, heat treatment is performed, and the temperature is controlled at 400-600°C; S8 Heat treatment and annealing: After all coatings are deposited, the coating structure is placed in an inert atmosphere for heat treatment at a temperature of 500-700°C for 1-2 hours, which helps densification of the coating and bonding between layers.

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