Process for preparing silicon nitride green body through on-line cutting

Abstract

The invention relates to the technical field of silicon nitride material preparation, in particular to a process for preparing a silicon nitride green body through on-line cutting, which comprises the following steps: mixing nano silicon nitride, nano yttrium oxide and a solvent, performing ball milling treatment, adding an adhesive and a plasticizer, and performing secondary ball milling to obtain slurry; then carrying out tape casting and drying on the slurry, then carrying out on-line cutting treatment, and then carrying out glue discharging treatment to obtain a silicon nitride green body; the online cutting treatment comprises the steps that a silicon nitride blank is placed on a cutting device, after the silicon nitride blank is fixed, transverse cutting is conducted through picosecond laser, cooling is conducted through cooling liquid at the same time, and then tension-free rolling is conducted. The online cutting process with higher fineness is matched with the cooling liquid with higher cooling capacity prepared from water, the wetting agent, the dispersing agent, the solubilizer, the water-based paraffin emulsion and the inhibitor in a specific proportion, so that a silicon nitride green body has higher forming rate and precision.

Description

Technical Field

[0001] The invention relates to the technical field of silicon nitride material preparation, and in particular to an online cutting process for preparing silicon nitride green bodies. Background Art

[0002] Silicon nitride is a high-performance semiconductor material with good thermal conductivity, electrical insulation, high temperature resistance and chemical stability. Therefore, it is widely used in heat dissipation devices in the fields of electronics, aerospace and automobiles.

[0003] In the manufacturing process of silicon nitride related products, silicon nitride needs to be cut. At present, mortar cutting technology or diamond wire cutting technology is usually used for the above cutting. The principle of mortar cutting technology is to use cutting steel wire to drive mortar, and use the SiC particles in the mortar to rub against the crystal rod to achieve the purpose of cutting. The working principle of the currently widely used diamond wire cutting technology is to use electroplating or resin bonding methods to attach diamond particles to the surface of the steel wire matrix to form a diamond wire, and use water and a small amount of organic matter as cutting fluid to perform directionally grinding and cutting on silicon ingots.

[0004] The existing silicon nitride preparation method still has the problem of cracks in the green body during cutting and low cutting accuracy. Therefore, how to improve the integrity and cutting accuracy of the green body during cutting while ensuring the performance of silicon nitride is an important problem facing the current silicon nitride preparation technology. In order to solve this technical problem, technicians in this field have proposed many solutions, such as the patent technical document CN116587440A discloses a silicon nitride wire cutting method, which includes: installing a ring diamond wire saw on the diamond wire cutting device and tensioning it, and fixing the silicon nitride blank sample to be cut on the support platform with a clamp; starting the motor to drive the guide wheel to rotate and drive the ring diamond wire saw to move; controlling the lifting device to lift the silicon nitride blank sample, so as to use the ring diamond wire saw to cut the silicon nitride blank sample; solving the problem that the existing silicon nitride wire cutting process uses reciprocating diamond wire cutting, and the cutting speed and cutting accuracy need to be improved. However, the green body forming rate and accuracy cut by these prior art methods still need to be improved.

[0005] Therefore, according to the above-mentioned related technologies, it is urgent to develop an online cutting process for preparing silicon nitride green bodies. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide an online cutting process for preparing silicon nitride green bodies and a preparation method thereof, so as to solve the problem of low forming rate and precision of green bodies prepared by the prior art.

[0007] Based on the above purpose, the present invention provides a process for preparing silicon nitride green bodies by online cutting.

[0008] A process for preparing silicon nitride green body by online cutting, the preparation process is as follows:

[0009] Step A1: mixing nano silicon nitride, nano yttrium oxide and a solvent and subjecting the mixture to ball milling, then adding a binder and a plasticizer and subjecting the mixture to secondary ball milling to obtain a slurry;

[0010] Step A2: tape-casting the slurry and drying it to obtain a silicon nitride blank;

[0011] Step A3: firstly perform an online cutting process on the silicon nitride blank, and then perform a binder removal process to obtain a silicon nitride green blank;

[0012] The online cutting process in step A3 is to first place the silicon nitride blank on the cutting device, fix it, and then perform cross-cutting with a picosecond laser while cooling it with a coolant, and then perform tension-free winding;

[0013] The cooling liquid is prepared from water, a wetting agent, a dispersant, a solubilizing agent, an aqueous paraffin emulsion and an inhibitor.

[0014] Preferably, the wetting agent is any one or more of fatty alcohol sodium sulfate and octylphenol polyoxyethylene ether;

[0015] The dispersant is any one or more of alkylphenol polyoxyethylene polyoxypropylene ether and allyl polyoxyethylene polyoxypropylene ether;

[0016] The solubilizing agent is any one or more of ethylene glycol, diethylene glycol, propylene glycol, diethylene glycol monobutyl ether, and polyethylene glycol 400;

[0017] The inhibitor is any one or more of triethanolamine, sodium nitrite, benzotriazole, and di-n-butyl phosphite;

[0018] The mass ratio of the water, the wetting agent, the dispersant, the solubilizer, the aqueous paraffin emulsion and the inhibitor is 75-100: 15-30: 2-5: 2-5: 1-4: 1-3.

[0019] Preferably, the coolant preparation method is as follows:

[0020] A wetting agent, a dispersant, a solubilizer, an aqueous paraffin emulsion and an inhibitor are sequentially added into water and mixed evenly to obtain a coolant.

[0021] Preferably, the solvent in step A1 is any one or more of ethanol, xylene, and n-butanol;

[0022] The adhesive in step A1 is a modified chlorinated polypropylene adhesive;

[0023] The plasticizer in step A1 is butyl benzyl phthalate;

[0024] The mass ratio of nano silicon nitride, nano yttrium oxide, solvent, binder and plasticizer in step A1 is 150-200: 10-15: 100-120: 9-14: 4-8.

[0025] Preferably, the debinding process in step A3 is as follows:

[0026] After the debinding furnace is evacuated, a gradient temperature increase is performed to debind the binder first, and then a protective gas is filled into the debinding furnace to make the pressure in the furnace reach 0.07-0.1Mpa, and then ultra-high temperature treatment and temperature control and cooling treatment are carried out in sequence, and finally the furnace is cooled to room temperature to obtain a silicon nitride green body.

[0027] Preferably, the gradient temperature debinding is to first heat the temperature to 150-200°C at 1-3°C / min and keep it for 0.5-1h, then heat the temperature to 300-350°C / min at 1-3°C / min for a second time and keep it for 1-2h, and finally heat the temperature to 550-600°C at 2-5°C / min for a third time and keep it for 1-2h.

[0028] Preferably, the ultra-high temperature treatment is to increase the temperature to 1100-1150° C. at a rate of 4-6° C. / min and keep the temperature for 2-6 hours.

[0029] Preferably, the temperature control and cooling treatment is to cool the temperature to 150-200°C at a rate of 2-5°C / min.

[0030] Preferably, the vacuum degree in the debinding furnace after evacuation is 30-150Pa.

[0031] Preferably, the protective gas is any one of nitrogen and argon.

[0032] Beneficial effects of the present invention:

[0033] The present invention provides an online cutting process for preparing silicon nitride green body and a preparation method thereof. The present invention mixes nano silicon nitride, nano yttrium oxide and solvent and then performs ball milling treatment, then adds a binder and a plasticizer, performs secondary ball milling to obtain a slurry; then the slurry is tape cast and dried to obtain a silicon nitride blank; the silicon nitride blank is firstly subjected to online cutting treatment, and then subjected to binder removal treatment to obtain a silicon nitride green body; the online cutting treatment is to first place the silicon nitride blank on a cutting device, fix it, and then use a picosecond laser to perform cross-cutting while cooling it with a coolant, and then perform tension-free winding. The online cutting process of the present invention with higher precision is combined with a coolant with a strong cooling capacity prepared by the present invention using a specific proportion of water, a wetting agent, a dispersant, a solubilizer, an aqueous paraffin emulsion and an inhibitor, so that the silicon nitride green body prepared by the online cutting process of the present invention has a higher forming rate and precision than the silicon nitride green body prepared by the prior art solution. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0035] The sources and properties of some of the raw materials used in the present invention are as follows:

[0036] Fatty alcohol sodium sulfate was purchased from Hubei Wonder Chemical Co., Ltd., CAS: 68891-38-3;

[0037] Octylphenol polyoxyethylene ether was purchased from Hubei Wande Chemical Co., Ltd., CAS: 9036-15-9; alkylphenol polyoxyethylene polyoxypropylene ether was purchased from Wuhan Nengren Pharmaceutical Chemical Co., Ltd.; allyl polyoxyethylene polyoxypropylene ether was purchased from Nantong Chenrun Chemical Co., Ltd.; ethylene glycol was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; diethylene glycol was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; propylene glycol was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; diethylene glycol monobutyl ether was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; polyethylene glycol 400 was purchased from Shandong Xinheng Chemical Co., Ltd.; triethanolamine was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; sodium nitrite was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; benzotriazole was purchased from Wuhan Yingyuanbei Trading Co., Ltd.; di-n-butyl phosphite was purchased from Wuhan Jiyesheng Chemical Co., Ltd.; aqueous paraffin emulsion was purchased from Dongguan Xuyihua Chemical Co., Ltd.; modified chlorinated polypropylene adhesive was purchased from Beijing Zhongke Optical Analysis Chemical Technology Research Institute; butyl benzyl phthalate was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0038] Example 1: A process for preparing silicon nitride green body by online cutting is as follows:

[0039] S1: add 15g of sodium sulfate of fatty alcohol, 2g of alkylphenol polyoxyethylene polyoxypropylene ether, 2g of ethylene glycol, 1g of aqueous paraffin emulsion and 1g of triethanolamine to 75g of water in sequence, mix well and obtain a coolant;

[0040] S2: 150 g of nano silicon nitride, 10 g of nano yttrium oxide, and 100 g of ethanol were mixed and ball-milled, and then 9 g of modified chlorinated polypropylene adhesive and 4 g of butyl benzyl phthalate were added and ball-milled for a second time to obtain a slurry;

[0041] S3: tape-casting the slurry and drying it to obtain a silicon nitride blank;

[0042] S4: firstly perform online cutting processing on the silicon nitride blank, and then perform binder removal processing to obtain a silicon nitride green blank;

[0043] The online cutting process is to first place the silicon nitride blank on the cutting device, fix it, and then use picosecond laser to perform cross-cutting while using coolant to perform cooling treatment, and then perform tension-free winding;

[0044] The debinding process comprises first evacuating the debinding furnace and then performing gradient temperature debinding, then filling nitrogen into the debinding furnace to make the pressure in the furnace reach 0.07 MPa, then performing ultra-high temperature treatment and temperature control and cooling treatment in sequence, and finally cooling the furnace to room temperature to obtain a silicon nitride green body;

[0045] The gradient heating debinding process is to first heat the temperature to 150°C at 1°C / min and keep it for 0.5h, then heat the temperature to 300°C / min at 1°C / min and keep it for 1h, and finally heat the temperature to 550°C at 2°C / min for three times and keep it for 1h.

[0046] The ultra-high temperature treatment is to increase the temperature to 1100°C at 4°C / min and keep the temperature for 2h;

[0047] The temperature control and cooling treatment is to cool the temperature to 150°C at 2°C / min;

[0048] The vacuum degree in the debinding furnace after evacuation is 30Pa;

[0049] Example 2: A process for preparing silicon nitride green body by online cutting is as follows:

[0050] S1: add 20g of octylphenol polyoxyethylene ether, 3g of alkylphenol polyoxyethylene polyoxypropylene ether, 3g of diethylene glycol, 2g of aqueous paraffin emulsion and 1.5g of sodium nitrite to 80g of water in sequence, mix well and obtain a coolant;

[0051] S2: 160 g of nano silicon nitride, 11 g of nano yttrium oxide, and 105 g of xylene were mixed and ball-milled, and then 10 g of modified chlorinated polypropylene adhesive and 5 g of butyl benzyl phthalate were added and ball-milled for a second time to obtain a slurry;

[0052] S3: tape-casting the slurry and drying it to obtain a silicon nitride blank;

[0053] S4: firstly perform online cutting processing on the silicon nitride blank, and then perform binder removal processing to obtain a silicon nitride green blank;

[0054] The online cutting process is to first place the silicon nitride blank on the cutting device, fix it, and then use picosecond laser to perform cross-cutting while using coolant to perform cooling treatment, and then perform tension-free winding;

[0055] The debinding process comprises first evacuating the debinding furnace and then performing gradient temperature debinding, then filling nitrogen into the debinding furnace to make the pressure in the furnace reach 0.08 MPa, then performing ultra-high temperature treatment and temperature control and cooling treatment in sequence, and finally cooling the furnace to room temperature to obtain a silicon nitride green body;

[0056] The gradient heating debinding method is to first heat the temperature to 160°C at 2°C / min and keep it for 0.6h, then heat the temperature to 310°C / min at 2°C / min and keep it for 1.2h, and finally heat the temperature to 560°C at 3°C / min for three times and keep it for 1.2h.

[0057] The ultra-high temperature treatment is to increase the temperature to 1110°C at 5°C / min and keep the temperature for 3h;

[0058] The temperature control and cooling treatment is to cool the temperature to 160°C at 3°C / min;

[0059] The vacuum degree in the debinding furnace after evacuation is 60Pa;

[0060] Example 3: A process for preparing silicon nitride green body by online cutting is as follows:

[0061] S1: 25 g of octylphenol polyoxyethylene ether, 4 g of alkylphenol polyoxyethylene polyoxypropylene ether, 2 g of ethylene glycol, 2 g of diethylene glycol monobutyl ether, 1-4 g of aqueous paraffin emulsion, 1 g of triethanolamine, and 1 g of benzotriazole are added to 90 g of water in sequence, and the mixture is evenly mixed to obtain a coolant;

[0062] S2: 180 g of nano silicon nitride, 13 g of nano yttrium oxide, and 110 g of n-butanol were mixed and ball-milled, and then 12 g of modified chlorinated polypropylene adhesive and 6 g of butyl benzyl phthalate were added and ball-milled for a second time to obtain a slurry;

[0063] S3: tape-casting the slurry and drying it to obtain a silicon nitride blank;

[0064] S4: firstly perform online cutting processing on the silicon nitride blank, and then perform binder removal processing to obtain a silicon nitride green blank;

[0065] The online cutting process is to first place the silicon nitride blank on the cutting device, fix it, and then use picosecond laser to perform cross-cutting while using coolant to perform cooling treatment, and then perform tension-free winding;

[0066] The debinding process comprises first evacuating the debinding furnace and then performing gradient temperature debinding, then filling argon gas into the debinding furnace to make the pressure in the furnace reach 0.09 MPa, then performing ultra-high temperature treatment and temperature control and cooling treatment in sequence, and finally cooling the furnace to room temperature to obtain a silicon nitride green body;

[0067] The gradient heating debinding method is to first heat the temperature to 180°C at 2°C / min and keep it for 0.8h, then heat the temperature to 330°C / min at 2°C / min and keep it for 1.5h, and finally heat the temperature to 580°C at 4°C / min for three times and keep it for 1.5h.

[0068] The ultra-high temperature treatment is to increase the temperature to 1130°C at 5°C / min and keep the temperature for 4 hours;

[0069] The temperature control and cooling treatment is to cool the temperature to 180°C at 4°C / min;

[0070] The vacuum degree in the debinding furnace after evacuation is 90Pa;

[0071] Example 4: A process for preparing silicon nitride green body by online cutting is as follows:

[0072] S1: 15 g of sodium sulfate of fatty alcohol, 10 g of octylphenol polyoxyethylene ether, 2 g of alkylphenol polyoxyethylene polyoxypropylene ether, 2 g of allyl polyoxyethylene polyoxypropylene ether, 1 g of propylene glycol, 1 g of diethylene glycol monobutyl ether, 2 g of polyethylene glycol 400, 3 g of aqueous paraffin emulsion, 1 g of benzotriazole, and 1 g of di-n-butyl phosphite are added to 95 g of water in sequence, and the mixture is evenly mixed to obtain a coolant;

[0073] S2: 190 g of nano silicon nitride, 14 g of nano yttrium oxide, 50 g of xylene, and 65 g of n-butanol were mixed and ball-milled, and then 13 g of modified chlorinated polypropylene adhesive and 7 g of butyl benzyl phthalate were added and ball-milled for a second time to obtain a slurry;

[0074] S3: tape-casting the slurry and drying it to obtain a silicon nitride blank;

[0075] S4: firstly perform online cutting processing on the silicon nitride blank, and then perform binder removal processing to obtain a silicon nitride green blank;

[0076] The online cutting process is to first place the silicon nitride blank on the cutting device, fix it, and then use picosecond laser to perform cross-cutting while using coolant to perform cooling treatment, and then perform tension-free winding;

[0077] The debinding process comprises first evacuating the debinding furnace and then performing gradient temperature debinding, then filling argon gas into the debinding furnace to make the pressure in the furnace reach 0.09 MPa, then performing ultra-high temperature treatment and temperature control and cooling treatment in sequence, and finally cooling the furnace to room temperature to obtain a silicon nitride green body;

[0078] The gradient heating debinding method is to first heat the temperature to 190°C at 2°C / min and keep it for 0.9h, then heat the temperature to 340°C / min at 2°C / min and keep it for 1.8h, and finally heat the temperature to 590°C at 4°C / min for three times and keep it for 1.8h.

[0079] The ultra-high temperature treatment is to increase the temperature to 1140°C at 5°C / min and keep the temperature for 5 hours;

[0080] The temperature control and cooling treatment is to cool the temperature to 190°C at 4°C / min;

[0081] The vacuum degree in the debinding furnace after evacuation is 120Pa;

[0082] Example 5: A process for preparing silicon nitride green body by online cutting is as follows:

[0083] S1: 15 g of sodium sulfate of fatty alcohol, 15 g of octylphenol polyoxyethylene ether, 2 g of alkylphenol polyoxyethylene polyoxypropylene ether, 3 g of allyl polyoxyethylene polyoxypropylene ether, 2 g of ethylene glycol, 1 g of diethylene glycol, 1 g of propylene glycol, 1 g of diethylene glycol monobutyl ether, 4 g of aqueous paraffin emulsion, 1 g of triethanolamine, 1 g of sodium nitrite and 1 g of benzotriazole were added to 100 g of water in sequence, and the mixture was evenly mixed to obtain a coolant;

[0084] S2: 200 g of nano silicon nitride, 15 g of nano yttrium oxide, 40 g of ethanol, 40 g of xylene, and 40 g of n-butanol were mixed and ball-milled, and then 14 g of modified chlorinated polypropylene adhesive and 8 g of butyl benzyl phthalate were added and ball-milled for a second time to obtain a slurry;

[0085] S3: tape-casting the slurry and drying it to obtain a silicon nitride blank;

[0086] S4: firstly perform online cutting processing on the silicon nitride blank, and then perform binder removal processing to obtain a silicon nitride green blank;

[0087] The online cutting process is to first place the silicon nitride blank on the cutting device, fix it, and then use picosecond laser to perform cross-cutting while using coolant to perform cooling treatment, and then perform tension-free winding;

[0088] The debinding process comprises first evacuating the debinding furnace and then performing gradient temperature debinding, then filling argon gas into the debinding furnace to make the pressure in the furnace reach 0.1 MPa, then performing ultra-high temperature treatment and temperature control and cooling treatment in sequence, and finally cooling the furnace to room temperature to obtain a silicon nitride green body;

[0089] The gradient heating debinding process is to first heat the temperature to 200°C at 3°C / min and keep it for 1 hour, then heat the temperature to 350°C / min at 3°C / min and keep it for 2 hours, and finally heat the temperature to 600°C at 5°C / min for three times and keep it for 2 hours.

[0090] The ultra-high temperature treatment is to increase the temperature to 1150°C at 6°C / min and keep the temperature for 6 hours;

[0091] The temperature control and cooling treatment is to cool the temperature to 200°C at 5°C / min;

[0092] The vacuum degree in the debinding furnace after evacuation is 150Pa;

[0093] Comparative Example 1:

[0094] Compared with Example 1, this comparative example only replaces the "fatty alcohol sodium sulfate salt" added in the coolant preparation process with "water", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally obtains a silicon nitride green body;

[0095] Comparative Example 2:

[0096] Compared with Example 1, this comparative example only replaces the "aqueous paraffin emulsion" added in the coolant preparation process with "water", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally obtains a silicon nitride green body;

[0097] Comparative Example 3:

[0098] Compared with Example 1, this comparative example only replaces "75g water, 15g sodium salt of fatty alcohol sulfate, 2g alkylphenol polyoxyethylene polyoxypropylene ether, 2g ethylene glycol, 1g aqueous paraffin emulsion and 1g triethanolamine" added in the coolant preparation process with "95.1g water, 0.5g sodium salt of fatty alcohol sulfate, 0.1g alkylphenol polyoxyethylene polyoxypropylene ether, 0.1g ethylene glycol, 0.1g aqueous paraffin emulsion and 0.1g triethanolamine", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally a silicon nitride green body is obtained;

[0099] Comparative Example 4:

[0100] Compared with Example 1, this comparative example only replaces the "picosecond laser cross-cutting" used in the online cutting process with "diamond wire cutting", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally a silicon nitride green body is obtained;

[0101] Comparative Example 5:

[0102] Compared with Example 1, this comparative example only replaces the "tensionless winding" in the online cutting process with "conventional winding", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally obtains a silicon nitride green body;

[0103] Performance Test:

[0104] Determination of green body forming rate:

[0105] The percentage of silicon nitride green bodies without cracks, deformation or damage among 150,000 silicon nitride green bodies prepared in each embodiment and comparative example under the same process conditions was calculated as the green body forming rate (%). The measurement results are shown in Table 1.

[0106] Determination of green body precision:

[0107] The length deviation percentage and width deviation percentage of 150,000 silicon nitride green bodies without cracks, deformation or breakage and with a size of 182 mm×182 mm were prepared in various embodiments and comparative examples under the same process conditions. The sum of the length deviation percentage and the width deviation percentage was calculated as the green body deviation (%), and the difference between 100% and the green body deviation (%) was calculated as the green body accuracy. The measurement results are shown in Table 1.

[0108] Table 1

[0109] project Green forming rate / % Green billet accuracy / % Example 1 98.16 99.99 Example 2 97.24 99.99 Example 3 97.71 99.99 Example 4 98.73 99.99 Example 5 97.69 99.99 Comparative Example 1 96.43 99.99 Comparative Example 2 95.17 99.99 Comparative Example 3 95.32 99.99 Comparative Example 4 94.72 98.97 Comparative Example 5 94.94 99.92

[0110] Data Analysis:

[0111] It can be seen from Table 1 that the silicon nitride green body prepared by the online cutting process of the present invention has a higher forming rate and precision;

[0112] This may be because the picosecond laser cross-cutting process used in the present invention not only has a faster cutting speed and a smaller heat-affected zone, but also a finer cutting seam compared to traditional diamond wire cutting; combined with the coolant with strong lubrication and cooling capabilities prepared by the present invention's liquid using specific proportions of water, wetting agent, dispersant, solubilizer, aqueous paraffin emulsion and inhibitor, and the tension-free winding method, the forming rate and accuracy of the cut green body are further guaranteed. Therefore, the silicon nitride green body prepared by the online cutting process of the present invention has a higher forming rate and accuracy.

[0113] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0114] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A process for preparing silicon nitride green bodies by online cutting, characterized in that: The preparation process is as follows: Step A1: mixing nano silicon nitride, nano yttrium oxide and a solvent and subjecting the mixture to ball milling, then adding a binder and a plasticizer and subjecting the mixture to secondary ball milling to obtain a slurry; Step A2: tape-casting the slurry and drying it to obtain a silicon nitride blank; Step A3: firstly perform an online cutting process on the silicon nitride blank, and then perform a binder removal process to obtain a silicon nitride green blank; The online cutting process in step A3 is to first place the silicon nitride blank on the cutting device, fix it, and then perform cross-cutting with a picosecond laser while cooling it with a coolant, and then perform tension-free winding; The cooling liquid is prepared from water, a wetting agent, a dispersant, a solubilizing agent, an aqueous paraffin emulsion and an inhibitor.

2. The process for preparing silicon nitride green bodies by online cutting according to claim 1, characterized in that: The wetting agent is any one or more of fatty alcohol sodium sulfate and octylphenol polyoxyethylene ether; The dispersant is any one or more of alkylphenol polyoxyethylene polyoxypropylene ether and allyl polyoxyethylene polyoxypropylene ether; The solubilizing agent is any one or more of ethylene glycol, diethylene glycol, propylene glycol, diethylene glycol monobutyl ether, and polyethylene glycol 400; The inhibitor is any one or more of triethanolamine, sodium nitrite, benzotriazole, and di-n-butyl phosphite; The mass ratio of the water, the wetting agent, the dispersant, the solubilizer, the aqueous paraffin emulsion and the inhibitor is 75-100: 15-30: 2-5: 2-5: 1-4: 1-3.

3. The process for preparing silicon nitride green body by online cutting according to claim 1, characterized in that: The coolant preparation method is as follows: A wetting agent, a dispersant, a solubilizer, an aqueous paraffin emulsion and an inhibitor are sequentially added into water and mixed evenly to obtain a coolant.

4. The process for preparing silicon nitride green body by online cutting according to claim 1, characterized in that: The solvent in step A1 is any one or more of ethanol, xylene, and n-butanol; The adhesive in step A1 is a modified chlorinated polypropylene adhesive; The plasticizer in step A1 is butyl benzyl phthalate; The mass ratio of nano silicon nitride, nano yttrium oxide, solvent, binder and plasticizer in step A1 is 150-200: 10-15: 100-120: 9-14: 4-8.

5. The process for preparing silicon nitride green body by online cutting according to claim 1, characterized in that: The debinding process in step A3 is as follows: After the debinding furnace is evacuated, a gradient temperature increase is performed to debind the binder first, and then a protective gas is filled into the debinding furnace to make the pressure in the furnace reach 0.07-0.1Mpa, and then ultra-high temperature treatment and temperature control and cooling treatment are carried out in sequence, and finally the furnace is cooled to room temperature to obtain a silicon nitride green body.

6. The process for preparing silicon nitride green body by online cutting according to claim 5, characterized in that: The gradient temperature debinding is firstly to heat to 150-200°C at 1-3°C / min and keep warm for 0.5-1h, then to heat to 300-350°C / min at 1-3°C / min and keep warm for 1-2h, and finally to heat to 550-600°C at 2-5°C / min for 3 times and keep warm for 1-2h.

7. The process for preparing silicon nitride green body by online cutting according to claim 5, characterized in that: The ultra-high temperature treatment is to increase the temperature to 1100-1150° C. at a rate of 4-6° C. / min and keep the temperature for 2-6 hours.

8. The process for preparing silicon nitride green body by online cutting according to claim 5, characterized in that: The temperature control and cooling treatment is to cool the temperature to 150-200°C at 2-5°C / min.

9. The process for preparing silicon nitride green body by online cutting according to claim 5, characterized in that: The vacuum degree in the debinding furnace after evacuation is 30-150Pa. The process for preparing silicon nitride green bodies by online cutting according to claim 5 is characterized in that: The protective gas is any one of nitrogen and argon.