Accurate drying control method for ceramic slurry tape casting process

Abstract

The invention discloses an accurate drying control method for a ceramic slurry tape casting technology, and belongs to the technical field of ceramic slurry tape casting. The method comprises the steps that a flow guide cover is installed in a drying chamber, and a heating piece is arranged on the flow guide cover; the interior of the drying chamber is sequentially divided into a natural leveling area, a rapid skinning area, a slow volatilization area, a forced drying area and an extension area from the starting point to the end point, and the rapid skinning area, the slow volatilization area and the forced drying area are each provided with a heating piece; sampling the green body at the starting point and the ending point of each drying area, and calculating the solvent residual rate of the sample; calculating the solvent volatilization rate of each drying area; and judging whether the solvent volatilization rate of each drying area meets the condition or not, and if not, adjusting the related temperature control condition. According to the whole drying process, the drying quality is remarkably improved through partition control, organic matter in the dried product ceramic green bodies is evenly distributed, the problems of distortion and cracking are avoided, bubbles are extremely few, the quality consistency of the same batch of products is good, and the percent of pass is high.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic slurry tape casting, and in particular relates to a precise drying control method for a ceramic slurry tape casting process. Background Art

[0002] Ceramic slurry tape casting is used to make ceramic green tapes, which are then further laminated, degreased, and sintered to form ceramic sheets for use in electronic substrates, multilayer capacitors, multilayer packaging, piezoelectric ceramics, etc., and gradually expanded to metals, alloys, and organic materials, etc., providing more options for the miniaturization of electronic components and electronic equipment and ultra-large-scale integrated circuits. Ceramic slurry tape casting technology has the advantages of a wide range of applications, small green body defect size, high production efficiency, and stable product performance. It can produce ceramic green tapes of 1um-1500μm.

[0003] The ceramic slurry tape casting process is a process of removing the solvent from the ceramic slurry to obtain a ceramic green body with a certain toughness and plasticity, including ball milling mixing, degassing, molding, drying, stripping the base tape and other process flows. Among them, the drying step is the most critical production process for manufacturing ceramic slurry into ceramic green body.

[0004] The tape-cast drying process involves the comprehensive effects of mass transfer, heat transfer, aerodynamics and other disciplines. It is not only affected by the temperature, humidity, flow rate and other factors of the drying medium, but also varies due to the different slurry components and internal structures. During tape-casting, the ceramic slurry flows from the material trough of the tape-casting machine to the base belt. Driven by the motor, the base belt and the scraper produce relative movement to form a wet body. The thickness of the wet body is controlled by adjusting the height between the scraper and the base belt. During drying, the wet body is dried together with the base belt in the drying chamber of the tape-casting machine. During the evaporation of the solvent, the ceramic particles are bonded together by the film-forming effect of the binder to form a ceramic green body (also called a tape-cast membrane) with certain flexibility and strength.

[0005] In the traditional drying process of ceramic slurry tape casting process, the ceramic slurry is dried by introducing hot air from the back to the front. The basic principle is to dry at low temperature first, then at medium temperature, and finally at high temperature, and finally to achieve the purpose of evaporating almost all the solvent. This traditional drying method has the following defects: there is no fine segmentation control of the drying area, and there is no set of more accurate parameter control methods to evaluate the pros and cons of the tape casting drying process. Therefore, the dried ceramic green body is prone to uneven distribution of internal organic matter, distortion, cracking, more bubbles and other quality problems. In addition, the product quality is greatly affected by the experience of the operator. The quality consistency of the same batch of products is poor and the qualified rate is low. The reason is that the flow direction of the hot air is opposite to the forward direction of the tape casting, which leads to The temperature of the heated air drops significantly after passing through the heat absorption of the green body and the drying oven. The amount of solvent volatilization of the wet green body in the initial stage of drying is insufficient. In the middle and late stages of drying, a large amount of solvent evaporates rapidly and concentratedly under high temperature conditions, thereby driving the binder in the green body to migrate from the bottom to the surface, resulting in uneven distribution of organic matter inside the cast film. The solvent is heated but has no time to diffuse, and its vapor pressure exceeds the saturated vapor pressure, thereby generating more bubbles in the green body and on its surface. Moreover, the volatilization rate of the solvent on the green body surface and the diffusion rate inside the green body are unbalanced, resulting in different shrinkage rates in different parts of the green body, which easily generates stress inside the green body, causing the powder particles inside the green body to move and reorient, resulting in further shrinkage, and ultimately leading to deformation and cracking of the film tape with more bubbles. Summary of the invention

[0006] The purpose of the present invention is to provide a precise drying control method for ceramic slurry tape casting process with good drying quality and high qualified rate in order to solve the above problems.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0008] A precise drying control method for a ceramic slurry tape-casting process, which is used to tape-dry a wet green body through a drying chamber of a tape-casting machine, wherein the wet green body is formed by flattening the ceramic slurry with a scraper used to control the height of the wet green body, and the wet green body placed on a conveyor belt moves from the starting point of the drying chamber to the end point, wherein the scraper is located at the starting point of the drying chamber, with the starting point of the drying chamber as the front and the end point as the rear, a first hot air pipe for introducing hot air is installed at the rear of the drying chamber, a first exhaust pipe for exhausting air and a second hot air pipe for introducing hot air are installed in the middle of the drying chamber, and a second exhaust pipe for exhausting air is installed at the front of the drying chamber, and the hot air flows from the back to the front. The precise drying control method for a ceramic slurry tape-casting process comprises the following steps:

[0009] Step 1: A guide cover is installed in the drying chamber at a position behind and close to the exhaust pipe, the guide cover is located above the conveyor belt, and a heating element is provided on the guide cover;

[0010] Step 2, dividing the drying chamber from the starting point to the end point into the following five drying zones: a natural leveling zone, a rapid skinning zone, a slow volatilization zone, a forced drying zone and an extension zone, wherein the natural leveling zone is the area from the scraper to the second exhaust pipe, the rapid skinning zone is the area from the second exhaust pipe to the rear end of the air guide cover, the slow volatilization zone is the area from the rear end of the air guide cover to the second hot air pipe, the forced drying zone is the area from the second hot air pipe to the first hot air pipe, and the extension zone is the area from the first hot air pipe to the end point of the drying chamber; the rapid skinning zone, the slow volatilization zone and the forced drying zone are respectively provided with heating elements;

[0011] Step 3: Sample the green body at the starting point and the end point of each drying zone and calculate the solvent residual rate of the sample. The calculation formula is as follows:

[0012]

[0013] Wherein, α is the residual solvent rate of the sample, M is the wet weight of the sample, i.e., the actual mass of the sample after sampling and unprocessed, which is also the sum of the solid mass of the sample and the mass of the solvent, and m is the dry weight of the sample, i.e., the actual mass of the sample after sampling and high drying treatment, which is also the solid mass of the sample. The method of high drying treatment is: placing the sample in an oven at a temperature 5-20°C higher than the boiling point of the solvent and drying it for 1-3h;

[0014] Step 4: Calculate the solvent volatilization rate of each drying zone according to the following formula:

[0015]

[0016] Wherein, η is the solvent volatilization rate of a certain drying area, α0 is the solvent residual rate of the starting point sample of the natural leveling area, and α 起 is the solvent residual rate of the corresponding sample at the starting point of the drying zone, α 止 is the solvent residual rate of a corresponding sample at the end point of the drying zone;

[0017] Step 5, determine whether the solvent volatilization rate η1 of the natural leveling zone is not less than 1% and not more than 6.5%, if yes, keep the status quo, if not, adjust the sealing degree of the natural leveling zone until the condition is met; determine whether the solvent volatilization rate η2 of the rapid skinning zone is not less than 14.5% and not more than 27%, if yes, keep the status quo, if not, change the heating value of the rapid skinning zone and the heating element in the guide cover until the condition is met; determine whether the solvent volatilization rate η3 of the slow volatilization zone is not less than 25% and not more than 37.5%, if yes, keep the status quo, if If not, change the temperature and / or wind speed of the second hot air duct and the wind speed of the second exhaust duct, and change the heating value of the heating element in the slow volatilization zone until the condition is met; judge whether the solvent volatilization rate η4 in the forced drying zone is not less than 28.5% and not more than 45.5%, and judge whether the solvent residual rate of the endpoint sample in the forced drying zone is less than 0.7%. If yes, keep the status quo; if not, change the temperature and / or wind speed of the first hot air duct and the wind speed of the first exhaust duct, and change the heating value of the heating element in the forced drying zone until the condition is met. The specific adjustment method or change method of adjusting the sealing degree of the natural leveling zone, changing the heating value of the heating element in the rapid skinning zone and the air guide cover, changing the temperature and / or wind speed of the second hot air duct, changing the wind speed of the first exhaust duct, changing the wind speed of the second exhaust duct, changing the heating value of the heating element in the slow volatilization zone, changing the temperature and / or wind speed of the first hot air duct, and changing the heating value of the heating element in the forced drying zone, depends on actual needs, as long as the above requirements can be met. There are many variations in the specific methods, and they are not within the scope of research and protection of the present invention.

[0018] Preferably, in order to achieve a more precise control effect to further improve the drying quality, in the step 2, the slow volatilization zone is divided into the following three drying sections from front to back: a first slow volatilization zone, a second slow volatilization zone, and a third slow volatilization zone; the forced drying zone is divided into the following four drying sections from front to back: a first strong drying zone, a second strong drying zone, a third strong drying zone, and a fourth strong drying zone; the first slow volatilization zone, the second slow volatilization zone, the third slow volatilization zone, the first strong drying zone, the second strong drying zone, the third strong drying zone, and the fourth strong drying zone are respectively provided with heating elements; in the step 3, in the slow volatilization zone, the starting points and end points of the first slow volatilization zone, the second slow volatilization zone, and the third slow volatilization zone are respectively sampled and the samples are cleaned. The product is subjected to the calculation of the solvent residual rate, in the forced drying zone, the starting points and end points of the first strong drying zone, the second strong drying zone, the third strong drying zone and the fourth strong drying zone are respectively sampled and the solvent residual rate of the samples is calculated; in the step 4, the calculation of the solvent volatilization rate of the slow volatilization zone also includes the calculation of the solvent volatilization rate of the first slow volatilization zone, the second slow volatilization zone and the third slow volatilization zone, and the calculation of the solvent volatilization rate of the forced drying zone also includes the calculation of the solvent volatilization rate of the first strong drying zone, the second strong drying zone, the third strong drying zone and the fourth strong drying zone; in the step 5, the specific method for judging whether the solvent volatilization rate of the slow volatilization zone meets the corresponding conditions is: judging the solvent volatilization rate of the first slow volatilization zone Whether it is not less than 8% and not more than 12%, the solvent volatility of the second section of the slow evaporation zone is judged Whether it is not less than 8% and not more than 12.5%, the solvent volatility of the three sections of the slow evaporation zone is judged is not less than 9% and not more than 13%, if yes, keep the status quo, if not, change the temperature and / or wind speed of the second hot air pipe and the wind speed of the second exhaust pipe, and change the heating value of the heating elements of each drying section of the slow volatilization zone at the same time, until the condition is met; the specific method for judging whether the solvent volatilization rate of the forced drying zone meets the corresponding condition is: judging the solvent volatilization rate of a section of the strong drying zone Whether it is not less than 17.5% and not more than 23.5%, judge the solvent volatility of the strong dry zone Whether it is not less than 8% and not more than 12%, judge the solvent volatility of the strong dry area Whether it is not less than 2% and not more than 7%, judge the solvent volatility of the strong dry area Whether it is not less than 1% and not more than 3%, and whether the residual solvent rate of the end point sample of the forced drying zone is less than 0.7%. If yes, keep the status quo; if not, change the temperature and / or wind speed of the first hot air pipe and the wind speed of the first exhaust pipe, and change the heating value of the heating element of each drying section of the forced drying zone until the condition is met. In order to facilitate intuitive understanding, the solvent volatilization rate of the blank in different drying zones and drying sections is finally plotted into a solvent volatilization rate curve of the tape casting drying process.

[0019] Preferably, in order to facilitate the rapid application of the later drying process, the step 5 further includes the following:

[0020] Step 6: Plot the solvent volatilization rate of the green body in different drying zones and drying sections into a solvent volatilization rate curve of the tape casting drying process.

[0021] Preferably, in order to achieve a better rapid crusting effect and facilitate rapid control of the heating element's heating value, the air guide cover includes two interconnected heating elements, and the front heating element is in a horizontal direction, and the rear heating element is in an inclined direction gradually tilted upward from front to back; all of the heating elements are electric heating plates, and except for the two electric heating plates arranged on the air guide cover, all other electric heating plates are placed under the conveyor belt, and the power input terminal of each electric heating plate is respectively connected to the control output terminal of the controller.

[0022] The beneficial effects of the present invention are:

[0023] The present invention installs a guide cover at a position behind the exhaust pipe in the drying chamber and installs a heating element on the guide cover, so as to divide the drying chamber into a plurality of drying zones and respectively arrange heating elements in the slow volatilization zone and the forced drying zone, so that the wet blank is naturally microscopically leveled in the closed, windless and non-heating state in the natural leveling zone, the blank is rapidly and strongly dried in the rapid crusting zone and a crusting layer with a certain sealing function is formed on the surface of the blank, and the internal solvent is slowly volatilized in the slow volatilization zone due to the presence of a dense crusting layer, thereby reducing the shrinkage difference inside the blank, thereby reducing the quality problems such as distortion, cracking, and bubbles caused by particle movement and reorientation, and because the solvent volatilizes slowly, the adhesive will not evaporate with the solvent. The solvent evaporates and migrates to the upper surface, so the organic matter in the dried ceramic green body (i.e., cast film) is more evenly distributed. After the solvent evaporates slowly, the green body enters the forced drying zone. Since the solvent content in the green body is already low, the vapor pressure generated by the volatilization is small, so it is suitable to adopt forced drying conditions with high temperature and fast air flow rate to improve the drying efficiency and produce very few bubbles. Finally, the green body is naturally dried in the extension zone, so that the solvent residual rate is finally less than 0.7%, achieving the purpose of high-quality drying. The entire drying process significantly improves the drying quality through zoning control. After drying, the organic matter in the product ceramic green body is evenly distributed, there is no distortion or cracking problem and there are very few bubbles. The quality consistency of the same batch of products is good, and the qualified rate is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the main structure of a drying and forming production equipment mainly including a drying chamber corresponding to the ceramic slurry tape casting process of the present invention;

[0025] Figure 2 is a three-dimensional diagram of the air deflector of the present invention;

[0026] Figure 3 It is the solvent volatilization rate curve of the green body during the tape casting and drying process described in the embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0028] like Figure 1As shown, the drying and forming production equipment mainly based on the drying chamber involved in the present invention includes a material trough 2, a scraper 3, a conveyor belt 6, a first hot air pipe 11, a first exhaust pipe 10, a second hot air pipe 9, a second exhaust pipe 5, a guide cover 7 and multiple heating elements, all of which are preferably electric heating plates 8, and the shape and size of each electric heating plate 8 are determined according to specific needs. The ceramic slurry 1 in the material trough 2 is scraped flat when passing under the scraper 3 to form a wet body 4. The wet body 4 becomes a dry body after passing through all the drying zones, that is, the dried product ceramic green body 12 (i.e., cast film). The ceramic green body 12 contains a very small amount of unvolatile solvent and a relatively large amount of binder, so that the ceramic green body 12 has a certain flexibility and can be bent for easy application; whether it is a wet body or a dry body, or a semi-wet and semi-dry body, they are collectively referred to as bodies.

[0029] Combination Figure 1 The precise drying control method for ceramic slurry tape casting molding process of the present invention is used to tape-dry a wet green body 4 through a drying chamber of a tape casting machine. The wet green body 4 is formed by flattening the ceramic slurry 1 with a scraper 3 for controlling the height of the wet green body 4. The wet green body 4 placed on a conveyor belt 6 moves from the starting point of the drying chamber to the end point. The scraper 3 is located at the starting point of the drying chamber, with the starting point of the drying chamber as the front ( Figure 1 The left side of the center), the end point is the back ( Figure 1 The first hot air pipe 11 for introducing hot air is installed in the rear of the drying chamber, the first exhaust pipe 10 for exhausting air and the second hot air pipe 9 for introducing hot air are installed in the middle of the drying chamber, and the second exhaust pipe 5 for exhausting air is installed in the front of the drying chamber. The hot air flows from the back to the front. The precise drying control method for the ceramic slurry tape casting process includes the following steps:

[0030] Step 1: Figure 1 and Figure 2 As shown, a deflector 7 is installed in the drying chamber at a position behind and close to the exhaust pipe 5, and the deflector 7 is located above the conveyor belt 6. Two heating elements are arranged on the deflector 7, and the two heating elements are preferably two electric heating plates 8. The two electric heating plates 8 connected to each other are arranged in a horizontal direction at the front and in an inclined direction gradually tilted upward from front to back at the rear.

[0031] Step 2, divide the drying chamber from the starting point to the end point into the following five drying zones: a natural leveling zone, a rapid skinning zone, a slow volatilization zone, a forced drying zone and an extension zone, wherein the natural leveling zone is the area from the scraper 3 to the second exhaust pipe 5, the rapid skinning zone is the area from the second exhaust pipe 5 to the rear end of the air guide 7, the slow volatilization zone is the area from the rear end of the air guide 7 to the second hot air pipe 9, the slow volatilization zone is divided into the following three drying sections from front to back: a slow volatilization zone section 1, a slow volatilization zone section 2, and a slow volatilization zone section 3, the forced drying zone is the area from the second hot air pipe 9 to the first hot air pipe 10, and the forced drying zone is divided into the following three drying sections from front to back: a slow volatilization zone section 1, a slow volatilization zone section 2, and a slow volatilization zone section 3. It is divided into the following four drying sections: strong drying zone section 1, strong drying zone section 2, strong drying zone section 3, and strong drying zone section 4. The extension zone is the area from the first hot air pipe 10 to the end point in the drying chamber; the quick crusting zone, the slow waving zone section 1, the slow waving zone section 2, the slow waving zone section 3, the strong drying zone section 1, the strong drying zone section 2, the strong drying zone section 3, and the strong drying zone section 4 are respectively provided with heating elements, and these heating elements are preferably electric heating plates 8. Except for the two electric heating plates 8 provided on the guide cover 7, all other electric heating plates 8 are placed under the conveyor belt 6, and the power input end of each electric heating plate 8 is respectively connected to the control output end of the controller (not shown in the figure);

[0032] Step 3: Take samples of the green body at the starting point and the end point of each drying zone and each drying section, and calculate the residual solvent rate of the samples. The calculation formula is as follows:

[0033]

[0034] Wherein, α is the residual solvent rate of the sample, M is the wet weight of the sample, i.e., the actual mass of the sample after sampling and unprocessed, which is also the sum of the solid mass of the sample and the mass of the solvent, and m is the dry weight of the sample, i.e., the actual mass of the sample after sampling and high drying treatment, which is also the solid mass of the sample. The method of high drying treatment is: placing the sample in an oven at a temperature 5-20°C higher than the boiling point of the solvent and drying it for 1-3h;

[0035] Step 4: Calculate the solvent volatilization rate of each drying zone and each drying section according to the following formula:

[0036]

[0037] Wherein, η is the solvent volatilization rate of a certain drying area, α0 is the solvent residual rate of the starting point sample of the natural leveling area, and α 起 is the solvent residual rate of the corresponding sample at the starting point of the drying zone, α 止 is the solvent residual rate of a corresponding sample at the end point of the drying zone;

[0038] Step 5, determine whether the solvent volatilization rate η1 of the natural leveling zone is not less than 1% and not more than 6.5%, if yes, keep the status quo, if not, adjust the sealing degree of the natural leveling zone until the condition is met; determine whether the solvent volatilization rate η2 of the rapid skinning zone is not less than 14.5% and not more than 27%, if yes, keep the status quo, if not, change the heating value of the electric heating plate 8 in the rapid skinning zone and the guide cover 7 until the condition is met; determine the solvent volatilization rate of the slow volatilization zone Whether it is not less than 8% and not more than 12%, the solvent volatility of the second section of the slow evaporation zone is judged Whether it is not less than 8% and not more than 12.5%, the solvent volatility of the three sections of the slow evaporation zone is judged Is it not less than 9% and not more than 13%? If yes, keep the status quo; if not, change the temperature and / or wind speed of the second hot air pipe 9 and the wind speed of the second exhaust pipe 5, and change the heating value of the electric heating plate 8 of each drying section of the slow volatilization zone until the condition is met; judge the solvent volatilization rate of the strong drying zone Whether it is not less than 17.5% and not more than 23.5%, judge the solvent volatility of the strong dry zone Whether it is not less than 8% and not more than 12%, judge the solvent volatility of the strong dry area Whether it is not less than 2% and not more than 7%, judge the solvent volatility of the strong dry area is not less than 1% and not more than 3%, and at the same time, judge whether the solvent residual rate of the endpoint sample of the forced drying zone is less than 0.7%, if yes, keep the status quo, if not, change the temperature and / or wind speed of the first hot air pipe 11 and the wind speed of the first exhaust pipe 10, and at the same time change the heating value of the electric heating plate 8 of each drying section of the forced drying zone until the condition is met;

[0039] Step 6: Plot the solvent volatilization rate of the green body in different drying zones and drying sections into a solvent volatilization rate curve of the tape casting drying process.

[0040] In order to verify the drying quality of the present invention, the present invention is further described in detail with multiple embodiments below:

[0041] Embodiment 1:

[0042] Combination Figure 1 and Figure 2In the above-mentioned precise drying control method for ceramic slurry tape casting molding process of the present invention, the wet green body 4 is dried. In step 5, the drying conditions are controlled as follows: the natural leveling area is in the best sealing state, the wind speed of the second exhaust pipe 5 is 0.6m / s, the temperature of the electric heating plate 8 in the inclined direction of the guide cover 7 is 50℃, the temperature of the electric heating plate 8 in the horizontal direction of the guide cover 7 is 50℃, the temperature of the electric heating plate 8 in the rapid skinning area is 35℃, the temperature of the electric heating plate 8 in the first section of the slow waving area is 35℃, and the temperature of the electric heating plate 8 in the second section of the slow waving area is Temperature: 40°C, temperature of the electric heating plate 8 in the third section of the slow evaporation zone: 40°C, temperature of the hot air in the second hot air pipe 9: 60°C, wind speed of the hot air: 0.9m / s, wind speed of the first exhaust pipe 10: 1.8m / s, temperature of the electric heating plate 8 in the first section of the strong drying zone: 50°C, temperature of the electric heating plate 8 in the second section of the strong drying zone: 60°C, temperature of the electric heating plate 8 in the third section of the strong drying zone: 70°C, temperature of the electric heating plate 8 in the fourth section of the strong drying zone: 80°C, temperature of the hot air in the first hot air pipe 11: 110°C, wind speed of the hot air: 2.4m / s.

[0043] Under the above conditions, the solvent volatilization rate of each drying zone and drying section was tested: the solvent volatilization rate η1 of the natural leveling zone was 1%, the solvent volatilization rate η2 of the rapid skinning zone was 27%, and the solvent volatilization rate of the slow volatilization zone was The solvent volatilization rate in the second slow volatilization zone is 8%. The solvent volatilization rate of the three sections of the slow volatilization zone is 8%. The solvent volatilization rate in the strong dry zone is 9%. The solvent volatilization rate of the second stage of the strong drying zone is 23.5%. The solvent volatilization rate of the three sections of the strong drying area is 12%. The solvent volatilization rate of the fourth section of the strong drying zone is 7%. The solvent volatilization rate η5 of the tape-casting drying process is 3%, the solvent volatilization rate η5 of the tape-casting drying process is 1%, and the solvent residual rate of the end sample of the four sections of the strong drying zone is 0.5%. Finally, the solvent volatilization rate of the green body in different drying zones and drying sections is plotted into a solvent volatilization rate curve of the tape-casting drying process, such as Figure 3 shown.

[0044] Embodiment 2:

[0045] Combination Figure 1 and Figure 2In the above-mentioned precise drying control method for ceramic slurry tape casting molding process of the present invention, the wet green body 4 is dried. In step 5, the drying conditions are controlled as follows: the natural leveling area is in the best sealing state, the wind speed of the second exhaust pipe 5 is 0.6m / s, the temperature of the electric heating plate 8 in the inclined direction of the guide cover 7 is 40℃, the temperature of the electric heating plate 8 in the horizontal direction of the guide cover 7 is 40℃, the temperature of the electric heating plate 8 in the rapid skinning area is 30℃, the temperature of the electric heating plate 8 in the first section of the slow waving area is 40℃, and the temperature of the electric heating plate 8 in the second section of the slow waving area is Temperature: 45°C, temperature of the electric heating plate 8 in the third section of the slow evaporation zone: 50°C, temperature of the hot air in the second hot air pipe 9: 60°C, wind speed of the hot air: 0.9m / s, wind speed of the first exhaust pipe 10: 1.8m / s, temperature of the electric heating plate 8 in the first section of the strong drying zone: 50°C, temperature of the electric heating plate 8 in the second section of the strong drying zone: 60°C, temperature of the electric heating plate 8 in the third section of the strong drying zone: 70°C, temperature of the electric heating plate 8 in the fourth section of the strong drying zone: 80°C, temperature of the hot air in the first hot air pipe 11: 110°C, wind speed of the hot air: 2.4m / s.

[0046] Under the above conditions, the solvent volatilization rate of each drying zone and drying section was tested: the solvent volatilization rate η1 of the natural leveling zone was 1%, the solvent volatilization rate η2 of the rapid skinning zone was 14.5%, and the solvent volatilization rate of the slow volatilization zone was The solvent volatilization rate in the second slow volatilization zone is 12%. The solvent volatilization rate of the third section of the slow volatilization zone is 12.5%. The solvent volatilization rate in the strong dry zone is 13%. The solvent volatilization rate of the second stage of the strong drying zone is 23.5%. The solvent volatilization rate of the three sections of the strong drying area is 12%. The solvent volatilization rate of the fourth section of the strong drying zone is 7%. The solvent volatilization rate η5 of the tape-casting drying process is 3%, the solvent volatilization rate η5 of the tape-casting drying process is 1%, and the solvent residual rate of the end sample of the four sections of the strong drying zone is 0.6%. Finally, the solvent volatilization rate of the green body in different drying zones and drying sections is plotted into a solvent volatilization rate curve of the tape-casting drying process, such as Figure 3 shown.

[0047] Embodiment 3:

[0048] Combination Figure 1 and Figure 2In the above-mentioned precise drying control method for ceramic slurry tape casting molding process of the present invention, the wet green body 4 is dried. In step 5, the drying conditions are controlled as follows: the natural leveling area is in the worst sealing state, the wind speed of the second exhaust pipe 5 is 1.6 m / s, the temperature of the electric heating plate 8 in the inclined direction of the guide cover 7 is 45°C, the temperature of the electric heating plate 8 in the horizontal direction of the guide cover 7 is 45°C, the temperature of the electric heating plate 8 in the rapid skinning area is 30°C, the temperature of the electric heating plate 8 in the first section of the slow evaporation area is 35°C, and the temperature of the electric heating plate 8 in the second section of the slow evaporation area is Temperature: 40°C, temperature of the electric heating plate 8 in the third section of the slow evaporation zone: 40°C, temperature of the hot air in the second hot air pipe 9: 60°C, wind speed of the hot air: 0.9m / s, wind speed of the first exhaust pipe 10: 1.8m / s, temperature of the electric heating plate 8 in the first section of the strong drying zone: 50°C, temperature of the electric heating plate 8 in the second section of the strong drying zone: 60°C, temperature of the electric heating plate 8 in the third section of the strong drying zone: 70°C, temperature of the electric heating plate 8 in the fourth section of the strong drying zone: 80°C, temperature of the hot air in the first hot air pipe 11: 110°C, wind speed of the hot air: 2.4m / s.

[0049] Under the above conditions, the solvent volatilization rate of each drying zone and drying section was tested: the solvent volatilization rate η1 of the natural leveling zone was 6.5%, the solvent volatilization rate η2 of the rapid skinning zone was 21.5%, and the solvent volatilization rate of the slow volatilization zone was The solvent volatilization rate in the second slow volatilization zone is 8%. The solvent volatilization rate of the three sections of the slow volatilization zone is 8%. The solvent volatilization rate in the strong dry zone is 9%. The solvent volatilization rate of the second stage of the strong drying zone is 23.5%. The solvent volatilization rate of the three sections of the strong drying area is 12%. The solvent volatilization rate of the fourth section of the strong drying zone is 7%. The solvent volatilization rate η5 of the tape-casting drying process is 3%, the solvent volatilization rate η5 of the tape-casting drying process is 1%, and the solvent residual rate of the end sample of the four sections of the strong drying zone is 0.55%. Finally, the solvent volatilization rate of the green body in different drying zones and drying sections is plotted into a solvent volatilization rate curve of the tape-casting drying process, such as Figure 3 shown.

[0050] Embodiment 4:

[0051] Combination Figure 1 and Figure 2In the above-mentioned precise drying control method for ceramic slurry tape casting molding process of the present invention, the wet green body 4 is dried. In step 5, the drying conditions are controlled as follows: the natural leveling area is in the worst sealing state, the wind speed of the second exhaust pipe 5 is 1.6 m / s, the temperature of the electric heating plate 8 in the inclined direction of the guide cover 7 is 50°C, the temperature of the electric heating plate 8 in the horizontal direction of the guide cover 7 is 50°C, the temperature of the electric heating plate 8 in the rapid skinning area is 35°C, the temperature of the electric heating plate 8 in the first section of the slow evaporation area is 40°C, and the temperature of the electric heating plate 8 in the second section of the slow evaporation area is Temperature: 45°C, temperature of the electric heating plate 8 in the third section of the slow evaporation zone: 50°C, temperature of the hot air in the second hot air pipe 9: 60°C, wind speed of the hot air: 0.9m / s, wind speed of the first exhaust pipe 10: 1.4m / s, temperature of the electric heating plate 8 in the first section of the strong drying zone: 50°C, temperature of the electric heating plate 8 in the second section of the strong drying zone: 55°C, temperature of the electric heating plate 8 in the third section of the strong drying zone: 60°C, temperature of the electric heating plate 8 in the fourth section of the strong drying zone: 65°C, temperature of the hot air in the first hot air pipe 11: 100°C, wind speed of the hot air: 1.8m / s.

[0052] Under the above conditions, the solvent volatilization rate of each drying zone and drying section was tested: the solvent volatilization rate η1 of the natural leveling zone was 6.5%, the solvent volatilization rate η2 of the rapid skinning zone was 27%, and the solvent volatilization rate of the slow volatilization zone was The solvent volatilization rate in the second slow volatilization zone is 12%. The solvent volatilization rate of the third section of the slow volatilization zone is 12.5%. The solvent volatilization rate in the strong dry zone is 13%. The solvent volatilization rate of the second stage of the strong drying zone is 17.5%. The solvent volatilization rate of the three sections of the strong drying area is 8%. The solvent volatilization rate of the fourth section of the strong drying zone is 2%. The solvent volatilization rate η5 of the tape-casting drying process is 1%, the solvent volatilization rate η5 of the tape-casting drying process is 0%, and the solvent residual rate of the end sample of the four sections of the strong drying zone is 0.52%. Finally, the solvent volatilization rate of the green body in different drying zones and drying sections is plotted into a solvent volatilization rate curve of the tape-casting drying process, such as Figure 3 shown.

[0053] The appearance quality of the dry green bodies, i.e., the ceramic green bodies 12 (in the embodiment, the aluminum nitride cast membrane) produced in batches in the above four embodiments is statistically analyzed, and the average value of each data is taken. The results are shown in the following table:

[0054]

[0055] From the analysis of the above table, it can be seen that the products obtained in Examples 1 to 4 have the advantages of no distortion, no cracking problems and very few bubbles, and the quality consistency of the same batch of products is good and the qualified rate is high; among them, the drying quality of the products obtained in Examples 1 and 4 is relatively better.

[0056] Compared with Example 1, in Example 2, the volatilization rate of the solvent in the rapid skinning zone is lower, and the volatilization rate in the slow volatilization zone is higher. As the solvent evaporates, the amount of binder to the upper surface of the body is relatively large, which ultimately causes the puncture strength of the upper surface of the ceramic green body 12 to be significantly greater than the puncture strength of the lower surface.

[0057] Compared with Example 1, in Example 3, the vapor pressure of the solvent in the natural leveling zone is lower, the solvent volatilization rate on the body surface is relatively high, and the natural leveling effect of the ceramic slurry is slightly poor, which ultimately leads to slightly poor thickness consistency of the ceramic green body 12.

[0058] Compared with Example 1, in Example 4, the volatilization rate of the solvent in the forced drying zone is lower, the vapor pressure generated by the volatilization of the solvent inside the green body is smaller, and the number of bubbles in the final ceramic green body 12 is smaller, but the thickness consistency is slightly worse.

[0059] Note: In practical applications of the present invention, if the quantity of the same batch of green bodies is relatively large, the relevant temperature control parameters can be adjusted by the method of the present invention. After the adjustment, most of the products have not been dried, and the high-quality drying effect of the batch of products can be achieved; if the quantity of the same batch of green bodies is relatively small, green bodies with the same proportion and humidity can be used as test products. After the relevant temperature control parameters are adjusted by the method of the present invention, the batch of green bodies can be dried using the relevant parameters, and the high-quality drying effect of the batch of products can be achieved.

[0060] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A precise drying control method for a ceramic slurry tape-casting process, which is used to tape-dry a wet green body through a drying chamber of a tape-casting machine, wherein the wet green body is formed by flattening the ceramic slurry with a scraper for controlling the height of the wet green body, and the wet green body placed on a conveyor belt moves from the starting point of the drying chamber to the end point, wherein the scraper is located at the starting point of the drying chamber, with the starting point of the drying chamber as the front and the end point as the rear, a first hot air pipe for introducing hot air is installed in the rear of the drying chamber, a first exhaust pipe for exhausting air and a second hot air pipe for introducing hot air are installed in the middle of the drying chamber, and a second exhaust pipe for exhausting air is installed in the front of the drying chamber, and the hot air flows from the back to the front, characterized in that: The precise drying control method for ceramic slurry tape casting process comprises the following steps: Step 1: A guide cover is installed in the drying chamber at a position behind the second exhaust pipe and close to the exhaust pipe, the guide cover is located above the conveyor belt, and a heating element is provided on the guide cover; Step 2, dividing the drying chamber from the starting point to the end point into the following five drying zones: a natural leveling zone, a rapid skinning zone, a slow volatilization zone, a forced drying zone and an extension zone, wherein the natural leveling zone is the area from the scraper to the second exhaust pipe, the rapid skinning zone is the area from the second exhaust pipe to the rear end of the air guide cover, the slow volatilization zone is the area from the rear end of the air guide cover to the second hot air pipe, the forced drying zone is the area from the second hot air pipe to the first hot air pipe, and the extension zone is the area from the first hot air pipe to the end point of the drying chamber; the rapid skinning zone, the slow volatilization zone and the forced drying zone are respectively provided with heating elements; Step 3: Sample the green body at the starting point and the end point of each drying zone and calculate the solvent residual rate of the sample. The calculation formula is as follows: Wherein, α is the residual solvent rate of the sample, M is the wet weight of the sample, i.e., the actual mass of the sample after sampling and unprocessed, which is also the sum of the solid mass of the sample and the mass of the solvent, and m is the dry weight of the sample, i.e., the actual mass of the sample after sampling and high drying treatment, which is also the solid mass of the sample. The method of high drying treatment is: placing the sample in an oven at a temperature 5-20°C higher than the boiling point of the solvent and drying it for 1-3h; Step 4: Calculate the solvent volatilization rate of each drying zone according to the following formula: Wherein, η is the solvent volatilization rate of a certain drying area, α0 is the solvent residual rate of the starting point sample of the natural leveling area, and α 起 is the solvent residual rate of the corresponding sample at the starting point of the drying zone, α 止 is the solvent residual rate of a corresponding sample at the end point of the drying zone; Step 5, determine whether the solvent volatilization rate η1 of the natural leveling zone is not less than 1% and not more than 6.5%, if yes, keep the status quo, if not, adjust the sealing degree of the natural leveling zone until the condition is met; determine whether the solvent volatilization rate η2 of the rapid skinning zone is not less than 14.5% and not more than 27%, if yes, keep the status quo, if not, change the heating value of the rapid skinning zone and the heating element in the guide cover until the condition is met; determine whether the solvent volatilization rate η3 of the slow volatilization zone is not less than 25% and not more than 37.5%, if yes, keep the status quo, if If not, change the temperature and / or wind speed of the second hot air duct and the wind speed of the second exhaust duct, and change the heating value of the heating element in the slow volatilization zone until the condition is met; judge whether the solvent volatilization rate η4 in the forced drying zone is not less than 28.5% and not more than 45.5%, and judge whether the solvent residual rate of the endpoint sample in the forced drying zone is less than 0.7%. If yes, keep the status quo; if not, change the temperature and / or wind speed of the first hot air duct and the wind speed of the first exhaust duct, and change the heating value of the heating element in the forced drying zone until the condition is met.

2. The precise drying control method for ceramic slurry tape casting process according to claim 1, characterized in that: In the step 2, the slow volatilization zone is divided into the following three drying sections from front to back: a slow volatilization zone section 1, a slow volatilization zone section 2, and a slow volatilization zone section 3; the forced drying zone is divided into the following four drying sections from front to back: a strong drying zone section 1, a strong drying zone section 2, a strong drying zone section 3, and a strong drying zone section 4; the slow volatilization zone section 1, the slow volatilization zone section 2, the slow volatilization zone section 3, the strong drying zone section 1, the strong drying zone section 2, the strong drying zone section 3, and the strong drying zone section 4 are respectively provided with heating elements; in the step 3, in the slow volatilization zone, the starting points and end points of the slow volatilization zone section 1, the slow volatilization zone section 2, and the slow volatilization zone section 3 are respectively sampled and the solvent residual rate of the samples is calculated; in the forced drying zone, ... In the drying zone, the starting points and end points of the first strong drying zone, the second strong drying zone, the third strong drying zone and the fourth strong drying zone are respectively sampled and the solvent residual rate of the samples is calculated; in the step 4, the calculation of the solvent volatilization rate of the slow volatilization zone also includes the calculation of the solvent volatilization rate of the first slow volatilization zone, the second slow volatilization zone and the third slow volatilization zone, and the calculation of the solvent volatilization rate of the forced drying zone also includes the calculation of the solvent volatilization rate of the first strong drying zone, the second strong drying zone, the third strong drying zone and the fourth strong drying zone; in the step 5, the specific method for judging whether the solvent volatilization rate of the slow volatilization zone meets the corresponding conditions is: judging the solvent volatilization rate η of the first slow volatilization zone 31 Whether it is not less than 8% and not more than 12%, the solvent volatility η of the second section of the slow evaporation zone is judged 32 Whether it is not less than 8% and not more than 12.5%, the solvent volatility η of the three sections of the slow evaporation zone is judged 33 is not less than 9% and not more than 13%, if yes, keep the status quo, if not, change the temperature and / or wind speed of the second hot air pipe and the wind speed of the second exhaust pipe, and change the heating value of the heating elements of each drying section of the slow volatilization zone at the same time, until the condition is met; the specific method for judging whether the solvent volatilization rate of the forced drying zone meets the corresponding condition is: judging the solvent volatilization rate η of one section of the strong drying zone 41 Whether it is not less than 17.5% and not more than 23.5%, the solvent volatility η of the strong dry zone is judged 42 Whether it is not less than 8% and not more than 12%, the solvent volatility η of the strong dry zone is judged 43 Whether it is not less than 2% and not more than 7%, the solvent volatility η of the strong dry zone is judged 44 Whether it is not less than 1% and not more than 3%, and at the same time, determine whether the solvent residual rate of the endpoint sample in the forced drying zone is less than 0.7%. If so, keep the status quo; if not, change the temperature and / or wind speed of the first hot air duct and the wind speed of the first exhaust duct, and at the same time change the heating value of the heating elements of each drying section in the forced drying zone until the condition is met.

3. The precise drying control method for ceramic slurry tape casting process according to claim 2, characterized in that: The step 5 further includes the following: Step 6: Plot the solvent volatilization rate of the green body in different drying zones and drying sections into a solvent volatilization rate curve of the tape casting drying process.

4. The precise drying control method for ceramic slurry tape casting process according to any one of claims 1 to 3, characterized in that: The deflector includes two interconnected heating elements, and the front heating element is in a horizontal direction, while the rear heating element is in an inclined direction gradually tilted upward from front to back; all of the heating elements are electric heating plates, and except for the two electric heating plates arranged on the deflector, all other electric heating plates are placed under the conveyor belt, and the power input end of each electric heating plate is respectively connected to the control output end of the controller.

Images