Beryllium oxide ceramic structural member sintering method

Abstract

The invention discloses a beryllium oxide ceramic structural part sintering method in the technical field of ceramic processing, which comprises the following steps: S1, selecting sagger kiln furniture which adapts to the size of a product green body and has a flat bottom, and paving a layer of ceramic balls at the bottom of the sagger kiln furniture; s2, a green gasket is arranged at the upper end of the ceramic ball, the size of the green gasket is matched with that of the product green, and the shrinkage coefficient is the same as that of the product green; s3, arranging a layer of isolation powder at the upper end of the green gasket; s4, the product green body is placed at the upper end of the isolation powder, and a sintered whole is formed; s5, the sintered whole is moved into a sintering furnace to be sintered; according to the method, the large beryllium oxide structural member can be obtained, and compared with a traditional sintering method, the sintering success rate is greatly increased, and the deformation and cracking risks in the product sintering process are greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic processing, and in particular to a sintering method for a beryllium oxide ceramic structural part. Background Art

[0002] Beryllium oxide (BeO) ceramics are widely used in electronic components, thermal management materials and high-temperature insulators due to their excellent thermal conductivity, electrical insulation and mechanical strength. Due to their excellent performance, beryllium oxide ceramics also have important application prospects in high-tech fields such as aerospace, electronics and nuclear industry.

[0003] However, beryllium oxide ceramics have a large shrinkage rate during the sintering process, which makes it easy to produce stress concentration and cause deformation and cracking when preparing beryllium oxide ceramic structural parts, seriously affecting the quality and reliability of the product. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the technical problem to be solved by the present invention is: how to improve the deformation and cracking phenomenon caused by stress concentration during the sintering process of beryllium oxide ceramic structural parts.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] The sintering method of beryllium oxide ceramic structural parts comprises the following steps:

[0007] S1: Select a sagger kiln that is suitable for the size of the product green body and has a flat bottom, and lay a layer of ceramic balls on the bottom of the sagger kiln;

[0008] S2: a green spacer is arranged on the upper end of the ceramic ball, the size of the green spacer is adapted to the size of the product green spacer and the shrinkage coefficient is the same as that of the product green spacer;

[0009] S3: placing a layer of isolation powder on the upper end of the green gasket;

[0010] S4: placing the green body of the product on the top of the isolation powder to form a sintered whole;

[0011] S5: The sintered body is moved into a sintering furnace for sintering.

[0012] Furthermore, in step S2, a layer of cooked gasket is first laid on the upper end of the ceramic ball, and a green gasket is laid on the upper end of the cooked gasket.

[0013] Furthermore, in step S4, after placing the green body of the product on the upper end of the isolation powder, slightly shake the part above the green body gasket. If the part above the green body gasket slides relative to the ceramic ball, proceed to step S5. If the part above the green body gasket does not slide relative to the ceramic ball, adjust the position of the green body gasket and then slightly shake the part above the green body gasket to observe whether the part above the green body gasket slides relative to the ceramic ball, and perform the same operations as the above steps.

[0014] Furthermore, the upper edge of the sagger kiln is higher than the upper edge height of the green product after it is placed on the upper end of the isolation powder.

[0015] Furthermore, the green gasket has a thickness of 10-20 mm and is larger than the green product.

[0016] Furthermore, the isolation powder comprises aluminum oxide particles with a particle size of 5-10 μm.

[0017] Furthermore, the ceramic balls in step S1 are alumina ceramic balls, and the diameter of the alumina ceramic balls is 3-10 mm.

[0018] Furthermore, the laying area of ​​the alumina ceramic balls accounts for 60%-80% of the bottom plane of the sagger kiln.

[0019] Furthermore, the sintering process in step S5 is specifically as follows: after the sintering unit is moved into the sintering furnace, the temperature is raised from room temperature to 200°C at a rate of 2°C / min, and then the temperature is further raised to 350°C at a rate of 2.5°C / min, and kept warm for 2h; then the temperature is further raised to 600°C at a rate of 2.4°C / min, and kept warm for 2h, then the temperature is further raised to 1000°C at a rate of 1°C / min, and the temperature is raised to 1200°C at a rate of 100°C / h, and kept warm for 2h, then the temperature is raised to 1480°C at a rate of 2.5°C / min, and kept warm for 2h, then the temperature is raised to 1620 at a rate of 1°C / min, and kept warm for 3h, then the temperature is lowered to 1450 at a rate of 1°C / min, and kept warm for 3h, then the temperature is lowered to 800°C at a rate of 1.2°C / min, and then the power is turned off to cool down.

[0020] The beneficial effects of the present invention are:

[0021] (1) A layer of ceramic balls is arranged between the ceramic balls and the green body gasket to ensure that the green body of the product can slide relative to the ceramic balls during the sintering process, which is beneficial to dispersing the stress generated by the green body of the product during the sintering process.

[0022] (2) Using green gaskets with the same shrinkage coefficient can ensure that they have a consistent shrinkage coefficient during the sintering process and do not crack due to shrinkage differences, further reducing stress concentration caused by uneven material shrinkage.

[0023] (3) The setting of isolation powder can not only provide sufficient sliding during the sintering process to prevent the product from sticking to the gasket, but also optimize the stress distribution and further reduce the possibility of cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the steps of the method of the present invention;

[0025] Figure 2 It is a schematic diagram of the sintered overall structure of the present invention;

[0026] Marked in the figure, 1-sagger kiln furniture, 2-ceramic ball, 3-cooked body gasket, 4-green body gasket, 5-isolation powder, 6-product green body. DETAILED DESCRIPTION

[0027] Example 1

[0028] The present invention is further described below in conjunction with the accompanying drawings.

[0029] according to Figure 1 , Figure 2 As shown, the embodiment of the present application proposes a sintering method for a beryllium oxide ceramic structure, which is characterized by comprising the following steps:

[0030] S1: Select a sagger kiln 1 that is suitable for the size of the product green body 6 and has a flat bottom, and lay a layer of ceramic balls 2 on the bottom of the above sagger kiln 1; the above sagger kiln 1 is a sagger body with an opening on the upper side and a surrounding baffle, and the size must be smaller than the size of the sintering furnace and larger than the size of the product green body 6. Place the sagger on a platform with good flatness, check that the sagger is not deformed, and then add the ceramic balls 2, and evenly lay the ceramic balls 2 on the bottom of the sagger.

[0031] The ceramic ball 2 is an alumina ceramic ball, and the diameter of the alumina ceramic ball is 3-10 mm.

[0032] S2: A green sheet gasket 4 is arranged on the upper end of the ceramic ball 2. The size of the green sheet gasket 4 is adapted to the size of the product green sheet 6 and the shrinkage coefficient is the same as that of the product green sheet 6. The thickness of the green sheet gasket 4 is 10-20 mm and the size is larger than the product green sheet 6, ensuring that the bottom of the product green sheet 6 is completely placed on the upper end of the green sheet gasket 4.

[0033] In order to ensure the overall support stability, a layer of cooked gasket 3 is first laid on the upper end of the ceramic ball 2. The cooked gasket 3 should meet the requirement that beryllium oxide will not deform after high-temperature sintering at 1750°C. A green gasket 4 is laid on the upper end of the above-mentioned cooked gasket 3. The placement area of ​​the cooked gasket is roughly equivalent to the area of ​​the green gasket 4, and a gap of 10-30mm is left between the gaskets; specifically, the green gasket 4 is a granulated material that is the same as the product green body 6, which is first dry-pressed and then isostatically pressed to obtain the beryllium oxide ceramic green gasket 4, and the green gasket 4 is placed above the cooked gasket 3 layer; the dry pressing pressure is 1.5-2.5T / cm3, the isostatic pressing pressure is 180-220Mpa, and the holding time is 5-8 minutes; the dry-pressed product green body 6 can be formed according to the actual needs of the product.

[0034] S3: a layer of isolation powder 5 is provided on the upper end of the green gasket 4; the thickness of the alumina powder layer should be 2-5 mm, and the alumina powder is γ alumina particles of 5 μm-10 μm. In specific operation, the γ alumina powder is evenly spread on the beryllium oxide green gasket 4, and the alumina powder should be spread as flat as possible.

[0035] The isolation powder 5 does not react with the beryllium oxide green body 6 and the green body gasket 4 below, and plays a good isolation role. It can also avoid the shrinkage difference between the beryllium oxide green body 6 and the green body gasket 4, and can slide freely when the shrinkage difference occurs.

[0036] S4: Place the product green body 6 on the upper end of the isolation powder 5 to form a sintered whole; after placing the product green body 6 on the upper end of the isolation powder 5, slightly shake the part above the green body gasket 4. If the part above the green body gasket 4 slides relative to the ceramic ball 2, a high-temperature sintering process is performed; if the part above the green body gasket 4 does not slide relative to the ceramic ball 2, adjust the position of the green body gasket 4 and then slightly shake the part above the green body gasket 4 to observe whether the part above the green body gasket 4 slides relative to the ceramic ball 2, and perform the same operation as the above steps. That is, by applying a force to the product green body 6, the product green body 6 drives the green body gasket 4 to shake together, which indicates that the sintered whole can proceed to the next high-temperature sintering process, which can ensure that the stress of the product green body 6 is dispersed under the action of the sliding structure during the sintering process.

[0037] S5: Move the sintered body to the sintering furnace for sintering. The specific sintering process is: after the sintered body is moved to the sintering furnace, the temperature is raised from room temperature to 200°C at a rate of 2°C / min, and then the temperature is further raised to 350°C at a rate of 2.5°C / min, and kept at this temperature for 2 hours; then the temperature is further raised to 600°C at a rate of 2.4°C / min, and kept at this temperature for 2 hours, and then the temperature is further raised to 1000°C at a rate of 1°C / min, and the temperature is raised to 1200°C at a rate of 100°C / h, and kept at this temperature for 2 hours, and then the temperature is raised to 1480°C at a rate of 2.5°C / min, and kept at this temperature for 2 hours, and then the temperature is raised to 1620 at a rate of 1°C / min, and kept at this temperature for 3 hours, and then the temperature is lowered to 1450 at a rate of 1°C / min, and kept at this temperature for 3 hours, and then the temperature is lowered to 800°C at a rate of 1.2°C / min, and then the power is turned off for cooling.

[0038] A layer of ceramic balls 2 is arranged between the ceramic balls 2 and the green gasket 4 to ensure that the product green body 6 can slide relative to the ceramic balls 2 during the sintering process, which is beneficial to dispersing the stress generated by the product green body 6 during the sintering process; using green gaskets 4 with the same shrinkage coefficient can ensure that they have a consistent shrinkage coefficient during the sintering process and do not crack due to shrinkage differences, further reducing the stress concentration caused by uneven material shrinkage; the provision of the isolation powder 5 can not only provide sufficient sliding properties during the sintering process to avoid adhesion between the product and the gasket, but also optimize the stress distribution and further reduce the possibility of cracking.

[0039] In this embodiment, specifically, a product green body 6 is first obtained from the previous process. The size of the product green body 6 is Φ220mm×100mm, and the center of the circle contains a through hole of Φ45×100mm, and 16 through holes of Φ20mm×100mm are arranged around the center of the circle.

[0040] Secondly, it is necessary to clarify which batch of granulated materials is used for the green product 6. In the current embodiment, the green product 6 uses material number 20230425ANE. This batch of granulated materials is used to form a green gasket 4 by dry pressing and isostatic pressing. The size of the green gasket 4 is a Φ300mm×20mm disc. The dry pressing pressure is 2T / cm3, the isostatic pressing pressure is 220Mpa, and the holding time is 8 minutes; then the green gasket is placed. First, a sagger is selected. According to the size of the current green product 6, the selected sagger size is 350mm×350mm×200mm. Φ3mm alumina ceramic balls are laid at the bottom of the sagger, and the proportion of alumina ceramic balls accounts for 70% of the bottom; a cooked gasket 3 is laid above the alumina ceramic balls. The placement area of ​​the cooked gasket is roughly equivalent to the area of ​​the green gasket 4, and a 10-30mm gap is left between the gaskets. Then lay the formed green sheet 4 on the alumina ceramic ball, and then lay the prepared γ alumina powder evenly on the green sheet 4, with a thickness of 5mm, and good uniformity is required. Finally, put the prepared green sheet 6, put the green sheet 6 on the top layer, and shake it gently by hand. If the product drives the green sheet 4 to shake together, there is no problem.

[0041] Place the prepared sagger containing the green body 6 in the sintering furnace and raise the temperature from room temperature to 200°C at a rate of 2°C / min, and continue to raise the temperature to 350°C at a rate of 2.5°C / min, and keep it for 2h; then continue to raise the temperature to 600°C at a rate of 2.4°C / min, keep it for 2h, continue to raise the temperature to 1000°C at a rate of 1°C / min, raise the temperature to 1200°C at a rate of 100°C / h, keep it for 2h, then raise the temperature to 1480°C at a rate of 2.5°C / min, keep it for 2h, then raise the temperature to 1620 at a rate of 1°C / min, keep it for 3h, and then lower the temperature to 1450 at a rate of 1°C / min, keep it for 3h, and then lower the temperature to 800°C at a rate of 1.2°C / min. Then turn off the power to cool the furnace.

[0042] After sintering, liquid permeability test, bulk density test and appearance test are carried out to ensure that the product is porcelain-like and has no defects in appearance.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that in this embodiment, the size of the product green body 6 is a regular hexagon with a side length of 120 mm. The green body gasket 4 is formed by dry isostatic pressing, and the green body gasket 4 is homogeneous beryllium oxide or aluminum oxide with the same shrinkage coefficient as beryllium oxide, and the size of the green body gasket 4 is a Φ300mm×20mm disc.

[0045] At the same time, the blanks are placed. First, the sagger is selected. According to the size of the current green blank 6, the selected sagger size is 320mm×320mm×180mm. Alumina ceramic balls of Φ3mm are laid at the bottom of the sagger, and the proportion of alumina ceramic balls accounts for 70% of the bottom; the cooked blank gasket 3 is laid above the alumina ceramic balls, and then the formed green blank gasket 4 is laid on the alumina ceramic balls, and then the prepared γ alumina powder is evenly laid on the green blank gasket 4, with a thickness of 3mm, and good uniformity is required. Finally, put the green blank 6 prepared in advance, put the green blank 6 on the top layer, and shake it gently with your hand. The product should drive the green blank gasket 4 to shake together, then there is no problem.

[0046] Place the prepared sagger containing the green body 6 in the sintering furnace and raise the temperature from room temperature to 200°C at a rate of 2°C / min, and continue to raise the temperature to 350°C at a rate of 2.5°C / min, and keep it for 2h; then continue to raise the temperature to 600°C at a rate of 2.4°C / min, keep it for 2h, continue to raise the temperature to 1000°C at a rate of 1°C / min, raise the temperature to 1200°C at a rate of 100°C / h, keep it for 2h, then raise the temperature to 1480°C at a rate of 2.5°C / min, keep it for 2h, then raise the temperature to 1620 at a rate of 1°C / min, keep it for 3h, and then lower the temperature to 1450 at a rate of 1°C / min, keep it for 3h, and then lower the temperature to 800°C at a rate of 1.2°C / min. Then turn off the power to cool the furnace.

[0047] After sintering, liquid permeability test, bulk density test and appearance test are carried out to ensure that the product is porcelain-like and has no defects in appearance.

[0048] Example 3

[0049] The difference between this embodiment and Embodiment 1 and Embodiment 2 is that the size of the product green body 6 is a cylinder with a side length of Φ140mm*250mm, and the green body gasket 4 is formed by dry isostatic pressing, and the size of the green body gasket 4 is a Φ180mm×20mm disc.

[0050] Then, the blanks are placed. First, a sagger is selected. According to the size of the current green blank 6, the size of the selected sagger is 320mm×320mm×280mm. Alumina ceramic balls of Φ3mm are laid at the bottom of the sagger, and the proportion of alumina ceramic balls accounts for 70% of the bottom. Then, the formed green blank gasket 4 is laid on the alumina ceramic balls, and then the prepared γ-alumina powder is evenly laid on the green blank gasket 4, with a thickness of 5mm, and good uniformity is required. Finally, the prepared green blank 6 is placed on the top layer, and the green blank 6 is gently shaken by hand. The product should drive the green blank gasket 4 to shake together, and there is no problem.

[0051] Place the prepared sagger containing the green body 6 in the sintering furnace and raise the temperature from room temperature to 200°C at a rate of 2°C / min, and continue to raise the temperature to 350°C at a rate of 2.5°C / min, and keep it for 2h; then continue to raise the temperature to 600°C at a rate of 2.4°C / min, keep it for 2h, continue to raise the temperature to 1000°C at a rate of 1°C / min, raise the temperature to 1200°C at a rate of 100°C / h, keep it for 2h, then raise the temperature to 1480°C at a rate of 2.5°C / min, keep it for 2h, then raise the temperature to 1620 at a rate of 1°C / min, keep it for 3h, and then lower the temperature to 1450 at a rate of 1°C / min, keep it for 3h, and then lower the temperature to 800°C at a rate of 1.2°C / min. Then turn off the power to cool the furnace.

[0052] After sintering, liquid permeability test, bulk density test and appearance test are carried out to ensure that the product is porcelain-like and has no defects in appearance.

[0053] In summary, the present invention proposes a sintering method for beryllium oxide ceramic structural parts. Alumina ceramic balls have a certain rolling coefficient, which can relieve stress concentration during the sintering process; using green gaskets 4 with the same shrinkage coefficient can ensure that they have a consistent shrinkage coefficient during the sintering process, and will not crack due to shrinkage differences, further reducing stress concentration caused by uneven material shrinkage; the γ-alumina ball powder used can not only provide sufficient sliding properties during the sintering process to avoid adhesion between the product and the gasket, but also optimize stress distribution and further reduce the possibility of cracking. Under this method, large beryllium oxide structural parts can be obtained. Compared with traditional sintering methods, the firing success rate is greatly improved, and the risk of deformation and cracking during the firing process of the product is greatly reduced.

Claims

1. A method for sintering a beryllium oxide ceramic structure, characterized in that: The following steps are involved: S1: Select a sagger kiln that is suitable for the size of the product green body and has a flat bottom, and lay a layer of ceramic balls on the bottom of the sagger kiln; S2: a green spacer is arranged on the upper end of the ceramic ball, wherein the size of the green spacer is adapted to the size of the product green spacer and the shrinkage coefficient is the same as that of the product green spacer; S3: disposing a layer of isolation powder on the upper end of the green gasket; S4: placing the green body of the product on the top of the isolation powder to form a sintered whole; S5: The sintered body is moved into a sintering furnace for sintering.

2. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: In step S2, a layer of cooked gasket is first laid on the upper end of the ceramic ball, and the green gasket is laid on the upper end of the cooked gasket.

3. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: In step S4, after placing the green body of the product on the upper end of the isolation powder, slightly shake the part above the green body gasket. If the part above the green body gasket slides relative to the ceramic ball, proceed to step S5. If the part above the green body gasket does not slide relative to the ceramic ball, adjust the position of the green body gasket and then slightly shake the part above the green body gasket to observe whether the part above the green body gasket slides relative to the ceramic ball, and repeat the above steps.

4. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: The upper edge of the sagger kiln is higher than the upper edge height of the product green body after being placed on the upper end of the isolation powder.

5. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: The green body gasket has a thickness of 10-20 mm and a size larger than the bottom size of the green body of the product.

6. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: The isolation powder includes aluminum oxide particles with a particle size of 5-10 μm.

7. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: The ceramic balls in step S1 are alumina ceramic balls, and the diameter of the alumina ceramic balls is 3-10 mm.

8. The method for sintering a beryllium oxide ceramic structure according to claim 7, characterized in that: The laying area of ​​the alumina ceramic balls occupies 60%-80% of the bottom plane of the sagger kiln.

9. The sintering method of beryllium oxide ceramic structure according to claim 1, characterized in that: The sintering process in step S5 is specifically as follows: after the sintered body is moved into the sintering furnace, the temperature is raised from room temperature to 200°C at a rate of 2°C / min, and then the temperature is further raised to 350°C at a rate of 2.5°C / min, and kept warm for 2h; then the temperature is further raised to 600°C at a rate of 2.4°C / min, and kept warm for 2h, and then the temperature is further raised to 1000°C at a rate of 1°C / min, and the temperature is raised to 1200°C at a rate of 100°C / h, and kept warm for 2h, and then the temperature is raised to 1480°C at a rate of 2.5°C / min, and kept warm for 2h, and then the temperature is raised to 1620 at a rate of 1°C / min, and kept warm for 3h, and then the temperature is lowered to 1450 at a rate of 1°C / min, and kept warm for 3h, and then the temperature is lowered to 800°C at a rate of 1.2°C / min, and then the power is turned off for cooling.

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