CN117069483A - Method for preparing high-performance ceramic by recycling ceramic casting film waste - Google Patents

Abstract

The invention relates to a method for preparing high-performance ceramic by recycling ceramic casting film waste, which comprises the following steps: (1) Volatilizing residual solvent in the ceramic casting film waste until the weight is no longer changed, so as to obtain a material to be treated; (2) Carrying out liquid nitrogen brittle fracture treatment or hardening treatment on a material to be treated, and crushing to obtain a particle raw material; (3) Mixing the obtained particle raw material with a solvent to obtain mixed slurry; (4) Casting the obtained mixed slurry to obtain a ceramic casting film; (5) And (3) performing at least one process of trimming, laminating and metallizing on the obtained ceramic casting film, and performing debonding and sintering to obtain the high-performance ceramic.

Description

A method for reusing ceramic cast film waste to prepare high-performance ceramics

Technical field

The present invention relates to a method for preparing high-performance ceramics (including mechanical properties, thermal conductivity, etc.), specifically a method for preparing high-performance ceramics by reusing ceramic cast film waste, and belongs to the technical field of ceramic preparation.

Background technique

Tape casting is an important process for preparing ceramic thick films. It can produce large-area ceramic films cheaply and quickly, with high production efficiency, good product consistency, stable performance, and easy to achieve continuous and automated preparation. Tape casting technology can be applied to ceramic substrates, LTCC, MTCC, HTCC and other fields, including high thermal conductivity heat dissipation substrates such as high thermal conductivity aluminum nitride and silicon nitride, and electronic packaging of HTCC multi-layer interconnect devices such as aluminum nitride and aluminum oxide. Fields, molding and preparation of YAG multilayer composite ceramic lasers, ZnO pressure-sensitive ceramics, porous SiC ceramics, etc.

Although tape casting technology is used in different fields, the green film after tape casting inevitably undergoes trimming and other process operations. At the same time, the tape casting green films with defects such as pinholes and craters need to be removed, which is extremely problematic. Big waste. At the same time, a large amount of organic matter, such as macromolecular binders such as polyvinyl butyral, is often added to the cast film, which is not easy to degrade, and the cast film is directly discarded, causing environmental pollution. In addition, certain alkali metal/alkaline earth metal oxides, rare earth oxides, etc. will be added to the ceramic slurry that is liquid-phase sintering. Direct waste will also cause environmental pollution and increase the cost of material preparation. In the past, recycled materials were used to directly obtain secondary casting slurry through high-temperature and strong stirring. However, in the actual production and preparation process, this process is difficult to operate and the feasibility is not high.

Contents of the invention

In view of the above problems, the present invention proposes a method for processing and using casting waste, which can reduce the waste of casting waste and maximize its effect. Specifically, the present invention proposes to harden the recycled material and prepare the secondary slurry after obtaining the powder. This can increase the contact area between the particles and the solvent, so that the organic matter can be quickly dissolved and the ceramic particles can be effectively dispersed again, thereby achieving Rapid preparation of secondary slurry.

On the one hand, the present invention provides a method for reusing ceramic cast film waste to prepare high-performance ceramics, including:

(1) Evaporate the residual solvent in the ceramic cast film waste until the weight no longer changes, and obtain the material to be processed;

(2) The materials to be processed are first subjected to liquid nitrogen embrittlement treatment or hardening treatment, and then crushed to obtain granular raw materials;

(3) Mix the obtained granular raw materials and solvent to obtain a mixed slurry;

(4) The obtained mixed slurry is cast and molded to obtain a ceramic cast film;

(5) The obtained ceramic cast film is subjected to at least one process of trimming, lamination, and metallization, and then debonding and sintering to obtain high-performance ceramics.

Preferably, in step (1): the cast film waste includes scraps of ceramic cast films and defective ceramic cast films; the main components of the ceramic cast film include alumina powder and aluminum nitride powder. , silicon nitride powder, silicon powder and silicon carbide powder.

The temperature of the volatilization treatment is 50-70°C, and the time is 12-24 hours.

Preferably, in step (2): the liquid nitrogen embrittlement treatment is to fully immerse the material to be treated in liquid nitrogen (temperature is -196°C) and maintain it for 5 to 15 seconds;

The hardening treatment is performed in a blast drying oven at 30-50°C for 6-24 hours.

Preferably, in step (2): the crushing is mechanical crushing; the particle size of the crushed raw material is 0.1 mm to 2 mm.

Preferably, in step (3): the solvent is selected from at least one of ethanol, butanone, ethyl acetate and xylene;

The added amount of the solvent is 20-40wt% of the particle raw material;

The mixing method is ball mill mixing, the rotation speed of the ball mill mixing is 40 to 80 rpm, the time is 48 to 72 hours, and the ball to material ratio is (0.5 to 2):1, preferably 1:1.

Preferably, in step (4): the parameters of the tape casting include: the height of the scraper is 300-1200 μm, and the drying temperature is 25-70°C.

Preferably, in step (5): the metallization parameters include: after the cast film is punched, metal slurries such as Ag, W, Mo, etc. are used to obtain the metal layer through screen printing technology, and the metal layer is obtained through lamination. Forming completes the metallization process.

Preferably, in step (5): the debonding parameters include: the temperature is 600-900°C, and the holding time is 1-4 hours; preferably, the heating rate range of the debonding is 1-30°C/ minute;

When the ceramic cast film waste contains silicon powder, it is debonded and then nitrided; the temperature of the nitriding treatment is 1380-1450°C, the time is 4-12 hours, and the atmosphere is nitrogen or nitrogen/hydrogen mixture gas; preferably, the temperature rising rate of the nitriding treatment ranges from 1 to 30°C/minute.

Preferably, in step (5): the sintering temperature is 1000-2100°C and the time is 0.5-24 hours; preferably, the sintering temperature rise rate ranges from 1-30°C/minute.

On the other hand, the present invention provides a high-performance ceramic prepared according to the above method.

Beneficial effects:

According to the present invention, ceramic cast film waste can be used to obtain ceramic materials with excellent performance, making full use of raw materials, reducing waste and avoiding environmental pollution.

Description of the drawings

Figure 1 is a photo of the re-cast film obtained in Example 2;

Figure 2 is an SEM image of the sample prepared by sintering in Example 3.

Detailed ways

The present invention will be further described below through the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention but not to limit the present invention.

The invention relates to a method for preparing high-performance ceramic materials using casting waste, which includes: vacuum drying the collected ceramic casting film waste in a temperature range of 50 to 70°C for 12 to 24 hours. The above materials are subjected to liquid nitrogen embrittlement or hardening treatment and then crushed to obtain granular raw materials with uniform size. Then add solvent in an amount of 20-40wt% of the weight of the above raw materials, mix and ball mill for 48-72 hours. The ball-milled slurry is cast again to obtain a ceramic cast film with uniform performance. The ceramic blank is sequentially subjected to processes such as edge trimming, lamination, or metallization, and then debonding and sintering steps are performed to finally prepare a corresponding ceramic product.

In the following, the method for preparing various ceramic materials of the present invention is exemplified.

In the present invention, a variety of ceramic cast film waste materials are used as raw materials. Including but not limited to aluminum oxide, aluminum nitride, silicon carbide, silicon, silicon nitride, ZnO, YAG and other cast films. For example, in the field of preparing high-performance silicon nitride ceramic substrates, the original cast film waste is made of silicon powder. The particle size of the raw material ranges from 0.5 to 15 μm. Within this range, the silicon powder can be completely nitrided, thereby ensuring that dense silicon nitride ceramic materials are obtained during later sintering, which can effectively improve the thermal conductivity of the material. The oxygen content of silicon powder can range from 0.32 to 0.88wt%, which can effectively control the lattice oxygen content in the sintered sample. It is preferred to use high-purity silicon powder as the raw material, and the purity can be above 99.99%, which can improve the material quality. thermal conductivity.

Weigh a certain weight of cast film waste (to avoid contaminating the material), place it loosely in an oven for drying (i.e., volatilization treatment, the temperature is 50-70°C, and the holding time is 12-24 hours) until the material weight no longer Variety. Among them, the purpose of drying is to fully volatilize the residual solvent, which plays two roles. One is to prevent the recycled materials from adhering during crushing, resulting in insufficient granulation, and the other is to facilitate the later control of the solid content of the slurry.

The dried waste material is fully exposed to liquid nitrogen or hardened, and then crushed to obtain granular materials with small and uniform particle size. The hardening treatment is performed in a blast drying oven at 30-50°C for 6-24 hours. Among them, the purpose of hardening is to solidify the organic matter in the recycled material, making it less ductile and improving the crushing efficiency.

The crushed granular raw materials and solvent are mixed evenly according to a certain proportion, and after ball milling, a ceramic casting slurry with uniform properties is obtained. It can be based on 100% of the total ingredients mass, 60-80% (mass percentage) of the processed powdery material and 20-40% (mass percentage) of the solvent are evenly mixed.

The mixed slurry is cast again to prepare a ceramic cast film. The casting process is operated according to the casting parameters of the original cast film, including steps such as degassing, casting and drying, to obtain a cast film blank with stable performance.

The cast film green body is debinded (low temperature debinding) to obtain a debinded ceramic body. The debinding temperature may be 600-900°C (eg 900°C). The holding time can be 1 to 4 hours. The temperature rise rate of the low-temperature debinding process can range from 1 to 30°C/minute, so that organic matter can be completely decomposed. The cooling rate can range from 1 to 30°C/minute or with furnace cooling. The atmosphere of the low-temperature debinding process can be vacuum, air, inert gas, etc. depending on the material system.

In an optional embodiment, when silicon powder is selected as the raw material to prepare silicon nitride, the debonded green body is nitrided at a certain temperature to obtain a corresponding silicon nitride ceramic green body. The temperature of nitriding can be 1380~1450℃. The nitriding reaction time can be 4 to 12 hours. The temperature rising rate of the nitriding reaction process ranges from 1 to 30°C/minute. The atmosphere of the nitriding reaction process can be nitrogen or a nitrogen-hydrogen mixed gas, where the volume ratio of the mixed gas can be nitrogen:hydrogen=90:10. The body obtained by debinding can be placed in a carbon tube furnace for nitriding to obtain a nitrided silicon nitride ceramic body. In addition, the cooling rate during the nitriding reaction process can range from 1 to 30°C/minute or can be lowered along with the furnace.

The ceramic body is sintered at a certain temperature. Depending on the raw material system, the sintering temperature can range from 1000 to 2100°C. The sintering heat preservation time can be 0.5 to 24 hours. The heating rate can range from 1 to 30°C/minute. The sintering atmosphere can be at least one of argon, nitrogen, helium, air, vacuum, etc., and finally a ceramic material with excellent performance is obtained. In addition, the sintering temperature reduction rate ranges from 1 to 30°C/min or with furnace cooling.

Thus, high-performance ceramic materials are obtained. For example, the prepared silicon nitride ceramic material has excellent mechanical properties and high thermal conductivity, including a relative density of more than 99%, and has high thermal conductivity (greater than 85W/(m·K)), high fracture toughness and high Characteristics of bending strength.

The present invention finally prepares ceramic materials with excellent performance by processing cast film waste. The process is simple and stable, and the conditions are easy to control. At the same time, it can maximize the utilization rate of raw materials and reduce environmental pollution.

Test Methods:

Density: calculated using the drainage method and Archimedes' principle;

Thermal conductivity: tested using a laser pulse meter (LFA427 Nanoflash, NETZSCH Instruments Co. Ltd., Selb, Germany);

Fracture toughness: Using indentation method, Willson-wolpert 2100B (Instron, USA) Vickers hardness tester was used.

The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above contents of the present invention all belong to the present invention. scope of protection. The specific process parameters in the following examples are only an example of the appropriate range, that is, those skilled in the art can make selections within the appropriate range through the description herein, and are not limited to the specific values exemplified below.

In the following examples and comparative examples, among the main raw materials required for the preparation of the original cast film, Si powder was purchased from Shanghai Xiangtian Nano Co., Ltd., with a median particle size of 5 μm. Si ₃ N ₄ powder was purchased from UBE, Japan, with a median particle size of 0.5 μm. AlN powder was obtained from Tokuyama, Japan, with a median particle size of 0.5 μm. Al ₂ O ₃ was purchased from Shanghai Fenghe, with a median particle size of 0.5 μm. SiC, MgO and CaO were purchased from Qinhuangdao Yinuo High-tech Materials Development Co., Ltd. with a purity of 99.9%. Y ₂ O ₃ and lanthanide rare earth oxides were purchased from Shanghai Yuekai Metal Materials Co., Ltd. with a purity of 99.9%; blast drying oven LC-223 (Shanghai Aspec Environmental Equipment Co., Ltd.).

Example 1:

(1) Place 100g of alumina cast film waste in a 55°C oven to dry for 24 hours. The weight does not change and is 97.5g;

(2) Place the obtained material in a 40°C blast drying oven for hardening treatment for 12 hours, then place the final material in a crushing equipment, and take out the powdered material after crushing for 30 minutes. The particle size of the obtained powdery material is 0.5-1mm;

(3) Weigh 80g of the above-mentioned powdery waste, add 24g of solvent (Methyl Keto/Ethanol = 66/34wt%), stir evenly and perform ball milling at a speed of 60 rpm. After ball milling for 48 hours, a mixed slurry is obtained;

(4) Cast the mixed slurry and dry the cast film;

(5) After the obtained cast film is sliced and laminated, the ceramic blank is placed in a carbon tube furnace. Under vacuum, the temperature is raised to 600°C at a heating rate of 10°C/min. After debinding for 2 hours, the air atmosphere is used. , heated to 1600°C for 2 hours at a heating rate of 10°C/min and sintered to obtain a dense alumina ceramic. The relative density and fracture toughness of the material were 98.25% and 4.15±0.64MPa·m ^1/2 respectively.

Example 2:

(1) Place 100g of silicon nitride cast film waste in a 60°C vacuum oven to dry for 24 hours. The weight does not change and is 98.0g;

(2) Place the material in a 40°C blast drying oven for hardening treatment for 12 hours, then place the final material in a crushing equipment, and take out the powdered material after crushing for 30 minutes. The particle size of the obtained powdery material is 0.2-0.5mm;

(3) Weigh 80g of the above-mentioned powdery waste, add 32g of solvent (Methyl Keto/Ethanol = 66/34wt%), stir evenly and perform ball milling at a speed of 60 rpm. After ball milling for 48 hours, a mixed slurry is obtained;

(4) Cast the obtained mixed slurry and dry the cast film;

(5) After slicing and laminating the obtained cast film, place the ceramic blank in a carbon tube furnace. Under vacuum, heat it to 600°C at a heating rate of 10°C/min. After debinding for 2 hours, use a nitrogen atmosphere. , heated to 1800°C for 2 hours at a heating rate of 10°C/min and sintered to obtain a dense silicon nitride ceramic. The relative density and fracture toughness of the material were 99.32% and 6.35±0.64MPa·m ^1/2 respectively.

Figure 1 shows an optical photograph of the cast film again in Example 2. It can be seen that the surface of the cast film is smooth, has excellent strength, and is easy to curl and store.

Example 3:

(1) Place 100g of silicon cast film waste in a 55°C vacuum oven to dry for 48 hours. The weight does not change and is 97.8g;

(2) Place the material in a 40°C blast drying oven for hardening treatment for 12 hours, then place the final material in a crushing equipment, and take out the powdered material after crushing for 30 minutes. The particle size of the obtained powdery material is 0.5-1.5mm;

(3) Weigh 80g of the above-mentioned powdery waste material, add 16g of solvent (Methyl Keto/Ethanol = 66/34wt%), stir evenly and perform ball milling at a speed of 60 rpm. After ball milling for 72 hours, a mixed slurry is obtained;

(4) Cast the obtained mixed slurry and dry the cast film;

(5) After the obtained cast film is sliced and laminated, the ceramic blank is placed in a carbon tube furnace. Under vacuum, the temperature is raised to 600°C at a heating rate of 10°C/min. After debinding for 2 hours, nitrogen is used as the In a protective atmosphere, the temperature was raised to 1420°C and nitrided for 6 hours at a heating rate of 10°C/min to obtain a silicon nitride ceramic body with a nitridation rate of 96% and a relative density of 69.8%. The air pressure sintering process is to raise the temperature to 1900°C under a nitrogen atmosphere with a pressure of 0.6MPa and a heating rate of 10°C/min, hold the temperature for 2 hours, and then cool down with the furnace. The relative density and thermal conductivity of the material are 99.12% and 85W/(m·K) respectively, and the fracture toughness and flexural strength are 7.95±0.29MPa·m ^1/2 and 821±10.2MPa respectively.

Figure 2 shows the microstructure of the silicon nitride ceramic prepared by silicon powder casting film in Example 3. It can be seen that there are no obvious pores inside the material and the large grain size is the main reason for its high thermal conductivity and high toughness.

Example 4:

(1) Place 100g of silicon carbide cast film waste in a 60°C vacuum oven to dry for 24 hours. The weight does not change and is 95.0g;

(2) Place the material in a 40°C blast drying oven for hardening treatment for 24 hours, then place the final material in the crushing equipment, and take out the powdered material after crushing for 30 minutes. The particle size of the obtained powdery material is 0.5-1mm;

(3) Weigh 80g of the above-mentioned powdery waste, add 30g of solvent (butanone), stir evenly and perform ball milling at a speed of 60 rpm. After ball milling for 72 hours, a mixed slurry is obtained;

(4) Cast the obtained mixed slurry and dry the cast film;

(5) After the obtained cast film is sliced and laminated, the ceramic blank is placed in a carbon tube furnace. Under vacuum, the temperature is raised to 900°C at a heating rate of 10°C/min. After debinding for 2 hours, argon gas is used. In the atmosphere, the temperature was raised to 2050°C for 2 hours at a heating rate of 10°C/min, and a dense silicon carbide ceramic was obtained. The relative density and fracture toughness of the material were 98.5% and 3.13±0.24MPa·m ^1/2 respectively.

Example 5

The preparation process of high-performance ceramics in Example 5 is as shown in Example 2. The only difference is that in step (2), the obtained material is placed in liquid nitrogen for 15 seconds and then placed in a crushing equipment. After crushing for 10 minutes, the powder is taken out. Material. The particle size of the obtained powdery material is 0.1-0.3mm.

Example 6

The preparation process of high-performance ceramics in Example 6 is similar to Example 2. The only difference is that in step (2), the material is placed in a 30°C blast drying oven for hardening treatment for 12 hours, and then the finally obtained material is placed in a crushing chamber. In the equipment, take out the powdery material after crushing for 30 minutes. The particle size of the obtained powdery material is 1.5-2mm;

Example 7

The preparation process of high-performance ceramics in Example 7 is similar to that of Example 2. The only difference is that in step (2), the material is placed in a 50°C blast drying oven for hardening treatment for 12 hours, and then the final material is placed in a crusher. In the equipment, take out the powdery material after crushing for 30 minutes. The particle size of the obtained powdery material is 0.5-0.9mm;

Example 8

The preparation process of high-performance ceramics in Example 9 is similar to Example 2. The only difference is that in step (2), the material is placed in a 60°C blast drying oven for hardening treatment for 12 hours, and then the finally obtained material is placed in a crusher. In the equipment, the granular material is taken out after crushing for 30 minutes. Particle size is 1.5-3mm;

Comparative example 1

The preparation process of high-performance ceramics in Comparative Example 1 is as shown in Example 2. The only difference is that in step (2), the dried material is directly placed in the crushing equipment. After crushing for 30 minutes, the final material is placed in the crushing equipment. Medium, take out the granular material after crushing for 30 minutes. Particle size is 3-5mm;

Comparative example 2

The preparation process of high-performance ceramics in Comparative Example 2 is as shown in Example 2. The only difference is that in step (2), the material without drying is directly placed in a 40°C oven for hardening treatment for 12 hours and then crushed for 30 minutes. , because the solvent is not completely evaporated, causing the cast film to stick, and powdery raw materials cannot be obtained.

Table 1 shows the preparation and performance parameters of high-performance ceramics:

Claims (10)

1. A method of reusing ceramic cast film waste to prepare high-performance ceramics, which is characterized by including: (1) Evaporate the residual solvent in the ceramic cast film waste until the weight no longer changes, and obtain the material to be processed; (2) The materials to be processed are first subjected to liquid nitrogen embrittlement treatment or hardening treatment, and then crushed to obtain granular raw materials; (3) Mix the obtained granular raw materials and solvent to obtain a mixed slurry; (4) The obtained mixed slurry is cast and molded to obtain a ceramic cast film; (5) The obtained ceramic cast film is subjected to at least one process of trimming, lamination, and metallization, and then debonding and sintering to obtain high-performance ceramics. 2. The method according to claim 1, characterized in that in step (1): the cast film waste includes scraps of ceramic cast films and defective ceramic cast films; The main ingredients include alumina powder, aluminum nitride powder, silicon nitride powder, silicon powder and silicon carbide powder; The temperature of the volatilization treatment is 50-70°C, and the time is 12-24 hours. 3. The method according to claim 1 or 2, characterized in that in step (2): the liquid nitrogen embrittlement treatment is to fully immerse the material to be treated in liquid nitrogen (temperature is -196°C) and maintain 5～15s; The hardening treatment is performed in a blast drying oven at 30-50°C for 6-24 hours. 4. The method according to any one of claims 1 to 3, characterized in that in step (2): the crushing is mechanical crushing; the particle size of the granular raw material is 0.1 mm to 2 mm. 5. The method according to any one of claims 1 to 4, characterized in that, in step (3): the solvent is selected from at least one of ethanol, butanone, ethyl acetate and xylene; The added amount of the solvent is 20-40wt% of the particle raw material; The mixing method is ball mill mixing, the rotation speed of the ball mill mixing is 40 to 80 rpm, the time is 48 to 72 hours, and the ball to material ratio is (0.5 to 2):1, preferably 1:1. 6. The method according to any one of claims 1 to 5, characterized in that in step (4): the parameters of the tape casting include: the scraped height is 300-1200 μm, and the drying temperature is 25 ~70℃. 7. The method according to any one of claims 1-6, characterized in that in step (5): the metallization parameters include: after the cast film is punched, Ag metal slurry, W Metal paste and Mo metal paste are used to obtain the metal layer through screen printing technology, and the metallization process is completed through lamination molding. 8. The method according to any one of claims 1 to 7, characterized in that in step (5): the debonding parameters include: a temperature of 600-900°C, and a holding time of 1-4 hours; Preferably, the debonding heating rate range is 1 to 30°C/min; when the ceramic cast film waste contains silicon powder, after debonding, it is then nitrided; the nitriding temperature is 1380°C ~1450°C, the time is 4 to 12 hours, and the atmosphere is nitrogen or nitrogen/hydrogen mixed gas; preferably, the temperature rise rate of the nitriding treatment ranges from 1 to 30°C/minute. 9. The method according to any one of claims 1 to 8, characterized in that in step (5): the sintering temperature is 1000~2100°C and the time is 0.5~24 hours; preferably, the sintering The sintering temperature rise rate ranges from 1 to 30°C/minute. 10. A high-performance ceramic prepared according to the method of any one of claims 1-9.