A method for producing a multilayer composite crosslinked ceramic tape casting web

Abstract

The application discloses a preparation method of a multilayer composite crosslinking ceramic flow-casting green tape, which comprises the following steps: inputting slurry into multiple interval-mounted material boxes of a flow-casting machine, making the carrier tape pass through the material boxes and making the slurry in the material boxes be stacked on the carrier tape layer by layer to be flow-cast into a multilayer composite crosslinking flow-casting green tape; the slurry comprises silicon nitride ceramic powder, a sintering aid, a solvent, a binder, a dispersing agent, a plasticizer and a crosslinking agent; the plasticizer is at least one of cashew phenol Mannich tiglic acid ester, dibutyl phthalate, dimethyl phthalate and polyethylene glycol, and the dispersing agent is at least one of fish oil, castor oil and polyvinylpyrrolidone. The obtained green tape is uniform, smooth and flat, free of cracks, wrinkles and bubbles, has good toughness and high strength, is not easy to deform, and has adjustable thickness, and the problem that a crosslinking system ceramic green tape is difficult to flow thick is solved.

Description

Technical Field

[0001] This invention relates to the field of ceramic tape production technology, and more specifically, to a method for preparing multilayer composite cross-linked ceramic tape. Background Technology

[0002] Silicon nitride ceramic substrates are high-performance ceramic materials with excellent mechanical and thermal properties. Using silicon nitride as the main material, they exhibit high strength, high hardness, high-temperature stability, and corrosion resistance. Silicon nitride ceramic substrates are commonly used in high-temperature, high-pressure, and corrosive environments, such as high-temperature reactors, rocket engines, and chemical reactors. They are also widely used in semiconductor manufacturing, electronic component manufacturing, and fiber optic communications. Due to their excellent insulation and high-temperature resistance, silicon nitride ceramic substrates can operate stably in various extreme environments, thus attracting widespread attention and application. Furthermore, they possess a low coefficient of thermal expansion and good thermal conductivity, contributing to improved equipment performance and reliability.

[0003] To obtain high-quality silicon nitride ceramic substrates, high-quality green tape is crucial. Flatness, high density, and low organic content are all important indicators for evaluating green tape. Flatness largely determines the flatness of the sintered sample, while high density helps the sintered sample achieve high density, thereby improving the strength and thermal conductivity of the silicon nitride ceramic substrate. Low organic content reduces the possibility of defects in the sintered sample and is also an important measure for cost savings and environmental protection.

[0004] Furthermore, the introduction of the crosslinking system significantly improves the smoothness, density, and reduction of organic components in the green body. This is because the addition of the crosslinking agent reduces the gaps between ceramic powder particles, increasing the density of the green body. At the same time, the crosslinking system provides higher green body strength, thereby reducing the required organic components. This not only further increases the density of the green body but also benefits subsequent sintering processes such as debonding and porosity.

[0005] However, a necessary condition for high density is high shrinkage. If the shrinkage strength is greater than the body strength or the shrinkage is uneven, cracking will occur. This means that while the crosslinking system brings higher density, it also brings the biggest problem—the inability to produce thick cast bodies. Therefore, how to obtain high-density and thick ceramic cast bodies is a major challenge. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a multilayer composite cross-linked ceramic tape. The resulting tape has a uniform, smooth, crack-free, wrinkle-free, and bubble-free surface, good toughness, high strength, and is not easily deformed. Moreover, its thickness is adjustable, which solves the problem that cross-linked ceramic tape is difficult to thicken.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a multilayer composite crosslinked ceramic casting tape involves feeding slurry into multiple spaced-apart boxes in a casting machine, and using the casting machine to pass a carrier belt through each box and stack the slurry in each box onto the carrier belt layer by layer to form a multilayer composite crosslinked casting tape.

[0009] The slurry comprises, by weight (100%), 27-50 wt% silicon nitride ceramic powder, 4-10 wt% sintering aid, 38-60 wt% solvent, 3-15 wt% binder, 1-5.5 wt% dispersant, 2-8 wt% plasticizer, and 0.5-1 wt% crosslinking agent; the plasticizer is at least one of mannich crotonate, dibutyl phthalate, dimethyl phthalate, and polyethylene glycol; and the dispersant is at least one of fish oil, castor oil, and polyvinylpyrrolidone.

[0010] Furthermore, during the tape casting process, the slurry in the first hopper is cast onto the surface of the carrier tape to form a green ceramic tape body and then dried. Subsequently, the slurry in the hopper is cast onto the surface of the previous green ceramic tape body to form the next green ceramic tape body and then dried. Each green ceramic tape body is dried after being cast before the next green ceramic tape body is cast. The thickness of each layer of green ceramic tape body formed by tape casting is 0.15-0.7 mm.

[0011] Furthermore, multiple of the aforementioned material boxes are installed every 6 meters.

[0012] Furthermore, the casting speed of the slurry in each material box is 200-250 mm / min.

[0013] Furthermore, each green porcelain body is dried by hot air, with the drying temperature controlled to gradually increase from the beginning to the end of the drying process, starting at 30°C and ending at 90°C.

[0014] Further, the solvent is divided into 3 parts. The binder and 1 / 3 part of the solvent are pre-dissolved and dispersed in a high-speed disperser to obtain a pre-dissolved material. The silicon nitride ceramic powder is poured into a ball mill jar, and then the remaining solvent, all sintering aids, dispersants and plasticizers are added. The material-to-ball ratio is controlled at 2-5. After mixing, the mixture is ball-milled for 8-24 hours. After adding the pre-dissolved material, the mixture is ball-milled for another 8-12 hours. The ball-milled slurry is filtered and then put into a degassing tank. A crosslinking agent is added and the mixture is vacuum degassed for 8-12 hours to obtain a slurry.

[0015] Furthermore, the adhesive is a hydroxyl-containing PVB resin, wherein the hydroxyl content ranges from 15 to 21 wt%, and the viscosity in a 10 wt% ethanol solution is 9 to 15 mPa·s.

[0016] Furthermore, the solvent is ethanol.

[0017] Furthermore, the crosslinking agent is at least one of blocked isocyanate, carbodiimide, and KH-560.

[0018] Furthermore, the sintering aid is at least one of yttrium oxide and magnesium oxide.

[0019] The beneficial effects of this invention are:

[0020] This invention obtains ceramic cast strips with adjustable thickness, uniform and smooth surface, no cracks, wrinkles, or bubbles, good toughness, high strength, and resistance to deformation by adjusting the number of casting layers and the thickness of each casting. The introduction of a cross-linking system into the ceramic casting slurry can increase the density of the green body, reduce sintering shrinkage, improve the performance of the finished product, reduce the difficulty of debinding, reduce raw material input, and reduce environmental pollution and raw material waste. At the same time, through multi-layer casting and drying, the problem of the cross-linked system ceramic cast strip being difficult to cast to a thick thickness is solved, and the interlayer strength of the originally non-cross-linked system is improved, further improving the strength of the cast strip. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The multilayer composite cross-linked ceramic casting tape prepared by this invention has a uniform, smooth, crack-free, wrinkle-free, and bubble-free surface, good toughness, high strength, and is not easily deformed. Furthermore, its thickness is adjustable, solving the problem of difficulty in achieving thick castings in cross-linked ceramic casting systems. The preparation method of the multilayer composite cross-linked ceramic casting tape is as follows:

[0023] (a) Preparation of slurry

[0024] The solvent is divided into 3 parts. The binder and 1 / 3 part of the solvent are pre-dissolved and dispersed in a high-speed disperser to obtain a pre-dissolved material. The silicon nitride ceramic powder is poured into a ball mill jar, and then the remaining solvent, all sintering aids, dispersants and plasticizers are added. The material-to-ball ratio is controlled at 2-5. After mixing, the mixture is ball-milled for 8-24 hours. After adding the pre-dissolved material, the mixture is ball-milled for another 8-12 hours. The ball-milled slurry is filtered and then put into a degassing tank. A crosslinking agent is added and the mixture is vacuum degassed for 8-12 hours to obtain a slurry.

[0025] Based on 100% of the total mass of the slurry, the slurry comprises 27–50 wt% silicon nitride ceramic powder, 4–10 wt% sintering aid, 38–60 wt% solvent, 3–15 wt% binder, 1–5.5 wt% dispersant, 2–8 wt% plasticizer, and 0.5–1 wt% crosslinking agent. The average particle size of the silicon nitride ceramic powder is 0.5–3 μm, and the specific surface area can be 8–20 m². 2 / g; the plasticizer is at least one of cashew mannich crotonate, dibutyl phthalate, dimethyl phthalate, and polyethylene glycol; the dispersant is at least one of fish oil, castor oil, and polyvinylpyrrolidone; the binder is a hydroxyl-containing PVB resin, wherein the hydroxyl content ranges from 15-21 wt%, and the viscosity in a 10 wt% ethanol solution is 9-15 mPa·s; the solvent is ethanol; the crosslinking agent is at least one of blocked isocyanate, carbodiimide, and KH-560; the sintering aid is at least one of yttrium oxide and magnesium oxide.

[0026] (b) Casting

[0027] The slurry is fed into multiple spaced material boxes installed at intervals in the casting machine (the multiple material boxes are installed every 6 meters). The casting machine causes the carrier belt to pass through each material box and the slurry in each material box is stacked layer by layer on the carrier belt to form a multi-layer composite cross-linked cast tape (the casting speed of the slurry in each material box is 200-250 mm / min), thus obtaining a multi-layer composite cross-linked cast tape. During the tape casting process, the slurry in the first cartridge is cast onto the carrier tape surface to form a green ceramic tape body, which is then dried. Subsequent cartridges then cast slurry onto the surface of the previous green ceramic tape body to form the next green ceramic tape body, which is also dried. (Each green ceramic tape body is dried by hot air; the drying temperature is controlled to gradually increase from the start to the end of drying, starting at 30℃ and ending at 90℃. This means the same casting and drying area is set from the outlet of the previous cartridge (30℃) to the outlet of the next cartridge (90℃), and from the outlet of the last cartridge.) The thickness of each layer of green ceramic tape body formed by tape casting is 0.15-0.7mm. Microwave drying can be used in conjunction with hot air drying, with the temperature controlled between 25 and 140℃. Microwave drying allows for more even and comprehensive heating of the green ceramic tape body during the drying process, reducing the temperature difference between the sides and the middle, and between the surface and the interior.

[0028] The specific implementation method is as follows:

[0029] Example 1

[0030] The preparation of multilayer composite cross-linked ceramic cast tape includes the following steps:

[0031] Step 1: Weigh the slurry raw materials. Based on 100% of the total slurry mass, the slurry includes 40 wt% silicon nitride ceramic powder, 5 wt% yttrium oxide sintering aid, 42.5 wt% ethanol solvent, 4 wt% hydroxyl-containing PVB resin binder (with a hydroxyl content of 18 wt% and a viscosity of 12 mPa·s in a 10 wt% ethanol solution), 3 wt% castor oil dispersant, 5 wt% dibutyl phthalate plasticizer, and 0.5 wt% carbodiimide crosslinking agent.

[0032] Step 2: Divide the solvent into 3 parts. Disperse the binder and 1 / 3 part of the solvent using a high-speed disperser to obtain a pre-dissolved material. Pour the silicon nitride ceramic powder into a ball mill jar, then add the remaining solvent, all sintering aids, dispersants, and plasticizers. Control the material-to-ball ratio to 3. After mixing, ball mill for 8 hours. Add the pre-dissolved material and continue ball milling for 8 hours. Filter the ball-milled slurry through a 300-mesh sieve and enter a degassing tank. Add a crosslinking agent and vacuum degas for 8 hours to obtain the slurry.

[0033] Step 3, Casting: The slurry is fed into multiple spaced-apart hoppers on the casting machine (the hoppers are spaced 6 meters apart). The casting machine passes the carrier belt through each hopper, and the slurry in each hopper is layered and cast onto the carrier belt to form a multi-layered composite cross-linked cast green tape. During casting, the slurry in the first hopper is cast onto the surface of the carrier belt to form a green ceramic tape preform and then dried. Afterward, the slurry in each hopper is cast onto the surface of the previous green ceramic tape preform to form the next green ceramic tape preform and then dried (each green ceramic tape preform is dried with hot air; the drying temperature is controlled to gradually increase from the beginning to the end of drying, starting at 30℃ and ending at 90℃). The thickness of each layer of cast green ceramic tape preform is 0.5mm.

[0034] Comparative Example 1

[0035] Ceramic cast tapes were prepared according to the method of Example 1, but with an equal amount of ethanol instead of the crosslinking agent (i.e., no crosslinking agent was added).

[0036] Comparative Example 2

[0037] The ceramic tape was prepared according to the method of Example 1, but the tape casting step was changed to: tape casting in one step using a tape casting machine (the tape casting machine includes a material box into which the slurry is fed), tape casting speed of 200 mm / min, drying by blowing hot air inside the tape casting machine, the temperature gradually increasing from front to back, the initial drying point temperature of 30°C, and the final drying point temperature of 90°C (the exhaust air in the tape casting drying tunnel is greater than the inlet air, forming a slight negative pressure inside the tape casting machine), thus obtaining the ceramic tape casting.

[0038] Example 1 and Comparative Examples 1-2 above represent cross-linked multilayer casting, uncross-linked multilayer casting, uncross-linked single-layer casting, and cross-linked single-layer casting schemes, respectively. Cast tape products with cracking reaching the maximum thickness were prepared in batches using these four schemes, and the performance test results are shown in Table 1. As can be seen from the data in Table 1, the multilayer cross-linked system (Example 1) has significant advantages in both maximum thickness and final product performance.

[0039] Table 1

[0040]

[0041]

[0042] Example 2

[0043] Ceramic cast tape was prepared according to the method in Example 1, but the plasticizer was replaced with an equal amount of self-made cashew phenol Mannich crotonate (synthesis method is described in: Synthesis of cashew phenol-based plasticizer and its effect on the mechanical properties of PVC [J]. Journal of Qinghai University. 2023, 41(03)).

[0044] Example 3

[0045] The ceramic casting tape was prepared according to the method of Example 1, but the dispersant was replaced with an equal amount of crotonic acid copolymer CA-SMS-MC dispersant (prepared according to the method described in the paper (Synthesis and properties of crotonic acid copolymer dispersants [J]. Yan Jie; Wang Bin; Pang Hao et al. Coating Industry. 2014, 44(04))).

[0046] Example 4

[0047] The ceramic casting tape was prepared according to the method of Example 1, but the plasticizer was replaced with an equal amount of self-made cashew phenol Mannich crotonate, and the dispersant was replaced with an equal amount of crotonic acid copolymer CA-SMS-MC dispersant.

[0048] Cast tape products with cracking reaching the maximum thickness were prepared using the schemes in Examples 2-4 above. Performance tests revealed that the maximum thicknesses of the cast tapes prepared in Examples 2-4 were 3.75, 3.52, and 5.08 mm, respectively; the thermal conductivity was 86.71, 84.9, and 91.64 m*K, respectively; and the three-point bending strength was 731, 764, and 776 MPa, respectively. None of the cast tapes prepared in Examples 2-4 showed cracking.

[0049] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a multilayer composite cross-linked ceramic cast tape, characterized in that, The slurry is fed into multiple spaced boxes in the casting machine. The casting machine then passes the carrier belt through each box and stacks the slurry in each box onto the carrier belt layer by layer to form a multi-layer composite cross-linked casting tape. Based on 100% of the total mass of the slurry, the slurry includes 40 wt% silicon nitride ceramic powder, 5 wt% yttrium oxide sintering aid, 42.5 wt% ethanol solvent, 4 wt% hydroxyl-containing PVB resin binder, 3 wt% castor oil, 5 wt% mannich crotonate plasticizer, and 0.5 wt% carbodiimide crosslinking agent.

2. The method for preparing a multilayer composite cross-linked ceramic cast tape according to claim 1, characterized in that, During tape casting, the slurry in the first hopper is cast onto the surface of the carrier tape to form a green ceramic tape blank and then dried. After that, the slurry in the hopper is cast onto the surface of the previous green ceramic tape blank to form the next green ceramic tape blank and then dried. Each green ceramic tape blank is dried after being cast before the next green ceramic tape blank is cast. The thickness of each layer of green ceramic tape blank is 0.15-0.7 mm.

3. The method for preparing a multilayer composite cross-linked ceramic cast tape according to claim 1, characterized in that, Multiple of the aforementioned material boxes are installed at 6-meter intervals.

4. The method for preparing a multilayer composite cross-linked ceramic cast tape according to claim 1, characterized in that, The casting speed of the slurry in each material box is 200-250 mm / min.

5. The method for preparing a multilayer composite cross-linked ceramic cast tape according to claim 1, characterized in that, Each ceramic blank is dried by hot air, and the drying temperature is controlled to gradually increase from the beginning to the end of the drying process, with the starting drying temperature at 30℃ and the ending drying temperature at 90℃.

6. The method for preparing a multilayer composite cross-linked ceramic cast tape according to claim 1, characterized in that, The solvent is divided into 3 parts. The binder and 1 / 3 part of the solvent are pre-dissolved and dispersed in a high-speed disperser to obtain a pre-dissolved material. The silicon nitride ceramic powder is poured into a ball mill jar, and then the remaining solvent, all sintering aids, dispersants and plasticizers are added. The material-to-ball ratio is controlled at 2-5. After mixing, the mixture is ball-milled for 8-24 hours. After adding the pre-dissolved material, the mixture is ball-milled for another 8-12 hours. The ball-milled slurry is filtered and then put into a degassing tank. A crosslinking agent is added and the mixture is vacuum degassed for 8-12 hours to obtain a slurry.

7. The method for preparing a multilayer composite cross-linked ceramic cast tape according to claim 1, characterized in that, The adhesive is a hydroxyl-containing PVB resin, wherein the hydroxyl content ranges from 15 to 21 wt%, and the viscosity in a 10 wt% ethanol solution is 9 to 15 mPa·s.

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