CN210030482U - MAX phase ceramic part sintering device based on gel casting - Google Patents
MAX phase ceramic part sintering device based on gel casting Download PDFInfo
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- CN210030482U CN210030482U CN201920509715.8U CN201920509715U CN210030482U CN 210030482 U CN210030482 U CN 210030482U CN 201920509715 U CN201920509715 U CN 201920509715U CN 210030482 U CN210030482 U CN 210030482U
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Abstract
The utility model provides a MAX looks ceramic parts sintering device based on gel casting belongs to ceramic technology field. In the device, a sintering table is positioned in the center of a protective cover, MAX phase ceramics are positioned in the center of the sintering table, the protective cover is positioned in the center of an alumina crucible, the lower part in the protective cover is provided with melting A, the upper part is provided with gas phase A, and the protective cover is completely buried by powder. And during sintering, placing the MAX phase green body on a sintering table, placing the MAX phase green body in a sintering furnace after the device is assembled, sealing the sintering furnace, vacuumizing and filling protective gas, and heating to raise the temperature to obtain the MAX phase ceramic part with a large size and a complex shape. The method adopts A-rich protective atmosphere sintering, and powder embedding is isolated, so that MAX-phase ceramic parts with large size and complex shape characteristics can be prepared, the density of a sintered product is greater than 95%, and the surface is not decomposed. The MAX phase ceramic part sintered by the method is resistant to irradiation, high temperature, oxidation, abrasion and corrosion, and can be used as a high-temperature structure candidate material in a complex and harsh service environment.
Description
Technical Field
The utility model relates to a jumbo size, complicated shape ceramic parts processing preparation technical field especially indicate a MAX looks ceramic parts sintering device based on gel casting.
Background
MAX phase ceramics are ternary layer compounds Mn+1AXnAnd (N-1-3), wherein M is a transition metal element, A is a main group element, X is C or N, and N-1, 2 or 3. The MAX phases have covalent and metallic bonds, so that they have both metal-like properties, such as high electrical and thermal conductivity, and thermal shock resistance, and ceramic-like properties, such as high hardness, good wear, corrosion, irradiation and oxidation resistance, and still maintain good mechanical properties at high temperatures. These characteristics make them promising for extremely demanding service environments, particularly as a candidate for reactor core high temperature structures.
The unique crystal structure of the MAX phase ceramic endows the MAX phase ceramic with special chemical bond characteristics, and electronic structure researches show that M-X is combined with strong covalent bonds and ionic bonds, M-A is combined with weak covalent bonds and metal bonds, and M-M is combined with metal bonds. The M atom and the A atom are combined by a strong covalent bond to form a Ti-C-Ti-C-Ti covalent bond chain, so that the MAX phase ceramic has high strength and elastic modulus, the Ti-C-Ti-C-Ti chain and the A atom are combined by a weaker covalent bond, and the unique chemical bond characteristic in the MAX phase is that MX is combined by the strong covalent bond, and an MX sheet layer and an A atom surface are combined by the weaker covalent bond, so that the A atom is easy to break loose the binding of the MX sheet layer, and an MX nanometer sheet layer is left.
Gel casting is a novel method for forming a ceramic material with a near net size, has obvious advantages in the aspect of manufacturing large-size ceramic parts with complex shapes, and is ideal for forming the MAX-phase ceramic parts with the large-size and complex shapes by using a gel casting process. However, due to the unique valence bond structure of the MAX phase ceramic, the intermediate element A is easily decomposed and lost in the high-temperature sintering process of the MAX phase ceramic part green body, so that the service performance of the material is fluctuated and even fails. Foreign scholars Murugaiah in the article "Barsum, Tape Casting, pressure Sintering Sinterng, and gain Growth in Ti3SiC2 composites" protect the MAX phase green compact by placing molten Si near the MAX phase, but the protection effect of the Si vapor generated in the open environment is limited, the MAX phase still decomposes and loses the intermediate element A in the Sintering process, and in addition, the MAX phase also decomposes the carbon element generated in the high-temperature heating process of the graphite resistance furnace in the open environment. Chinese patent (CN 108046806A), utilizing a tube furnace to sinter the MAX phase green compact, the tube furnace can isolate carbon or other elements generated by the heating electrode at high temperature, thereby playing a certain protection role in MAX sintering, but the sintering of the MAX phase in the tube furnace still cannot avoid the main phase decomposition caused by the loss of the intermediate element a.
The utility model discloses a rich A protective atmosphere sintering under the closed environment makes the isolated powder that buries of back unburnt earthenware that comes unstuck with the safety cover simultaneously, and MAX looks ceramic parts of making can satisfy the requirement of being on active service under nuclear power heap waiting high temperature, high corrosion, high abrasion, the high irradiation environmental condition.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model is to provide a MAX looks ceramic parts sintering device based on gel casting, MAX looks ceramic parts that make have jumbo size (be greater than or equal to 200mm), complicated shape and have technical characteristics such as resistant irradiation, high temperature resistant, anti-oxidant, wear-resisting corrosion, corrosion-resistant.
The device includes the sintering platform, safety cover and alumina crucible, the sintering platform is located the central point of safety cover, MAX looks pottery is located the central point of sintering platform, the safety cover is located the central point of alumina crucible, the lower part is melting A in the safety cover, upper portion is gaseous phase A in the safety cover, melting A's liquid level height is no longer than the mesa height of sintering platform, MAX looks pottery's width is no longer than the mesa width of sintering platform, the powder buries the safety cover completely, the powder height is no longer than 2 times of safety cover height. The powder is MX powder or AX powder.
The protective cover is made of one of zirconium, molybdenum, tantalum, niobium and tungsten, and preferably molybdenum; the protective cover has a gap, is not sealed at low temperature (lower than 1000 ℃), and gas in the protective cover can penetrate through the powder and enter a furnace chamber of the sintering furnace.
The powder is agglomerated and contracted at the high temperature of more than 1000 ℃, the protective cover is sealed, and carbon or other impurities volatilized at the high temperature when the furnace chamber is heated cannot enter the protective cover to decompose the MAX phase. During the high-temperature sintering process, volatile components generated by MX powder and AX powder can enter the protective cover to inhibit surface decomposition during the MAX phase sintering process. The decomposition of the MAX phase can also be suppressed by melting the gas phase A generated during the sintering process of A and by filling the protective cover with argon and helium.
The method adopting the device comprises the following steps:
s1: placing the degummed large-size MAX phase green compact with the complex shape on a sintering table in a protective cover in a sintering device, and completing the construction and assembly of the sintering device;
s2: placing the sintering device assembled in S1 into a sintering furnace, sealing the sintering furnace, vacuumizing to below 10-1000 Pa, filling argon or helium into the sintering furnace until the pressure in the sintering furnace is restored to the atmospheric pressure, repeating the steps of vacuumizing and filling argon or helium for two to three times, exhausting oxygen and nitrogen in the sintering furnace, and filling argon or helium in the sintering furnace;
s3: and heating the sintering furnace to raise the temperature, and sintering the MAX-phase part green body to obtain the MAX-phase ceramic part with a large size and a complex shape.
And in the process of vacuumizing and filling argon or helium in the S2, other parts in the protective cover can be replaced by argon or helium through the protective cover gap.
The sintering temperature in S3 is 1300-1800 ℃; the constant temperature time is 0.5-10 h, preferably 2 h; the heating rate is 2-20 ℃/min, and 8 ℃/min is preferred.
The utility model discloses an above-mentioned technical scheme's beneficial effect as follows:
(1) the sintering in the atmosphere rich in A can inhibit the surface decomposition caused by the loss of the element A in the MAX phase sintering process.
(2) By adopting the powder embedding sintering process, the decomposition of MAX phase by carbon or other impurities volatilized by the heating electrode can be avoided, and meanwhile, the volatile components of MX powder and XA powder in the high-temperature sintering process can enter the protective cover to inhibit the decomposition of MAX phase.
(3) The protective cover is introduced to build the sintering platform, so that the MAX phase green compact with low strength can be prevented from being in direct contact with MX powder or XA powder, and the green compact is prevented from being disintegrated in the sintering process. Meanwhile, the protective cover can also prevent the gas phase A from escaping, thereby better supplementing the element A lost in the MAX phase sintering process.
(4) The MAX-phase ceramic part with the diameter larger than 200mm and the complex shape characteristics can be prepared, the density of the part can reach more than 95%, the surface of the part is not decomposed, and the service requirements of nuclear reactors and other nuclear reactors under the environmental conditions of high temperature, high corrosion and high irradiation are met.
Drawings
Fig. 1 is the utility model discloses a MAX looks ceramic parts non-pressure solid phase sintering device structure sketch map based on gel injection molding.
Wherein: 1-melting A; 2-sintering table; 3-a protective cover; 4-gas phase a; 5-MAX phase ceramics; 6-alumina crucible; 7-powder.
Detailed Description
In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.
The utility model provides a MAX looks ceramic parts sintering equipment based on gel casting.
As shown in FIG. 1, the apparatus comprises a sintering table 2, a protective cover 3 and an alumina crucible 6, wherein the sintering table 2 is positioned at the central position of the protective cover 3, MAX-phase ceramics 5 is positioned at the central position of the sintering table 2, the protective cover 3 is positioned at the central position of the alumina crucible 6, the lower part in the protective cover 3 is fused A1, the upper part in the protective cover 3 is gaseous phase A4, the liquid level height of the fused A1 is not more than the table top height of the sintering table 2, the width of the MAX-phase ceramics 5 is not more than the table top width of the sintering table 2, the protective cover 3 is completely buried by powder 7, and the height of the powder 7 is not more. Wherein, the powder 7 is MX powder or AX powder.
The method for applying the device comprises the following steps:
s1: placing the degummed large-size MAX phase green compact with the complex shape on a sintering table 2 in a protective cover 3 in a sintering device, and completing the construction and assembly of the sintering device;
s2: placing the sintering device assembled in S1 into a sintering furnace, sealing the sintering furnace, vacuumizing to below 10-1000 Pa, filling argon or helium into the sintering furnace until the pressure in the sintering furnace is restored to the atmospheric pressure, repeating the steps of vacuumizing and filling argon or helium for two to three times, exhausting oxygen and nitrogen in the sintering furnace, and filling argon or helium in the sintering furnace;
s3: and heating the sintering furnace to raise the temperature, and sintering the MAX-phase part green body to obtain the MAX-phase ceramic part with a large size and a complex shape.
The following description is given with reference to specific examples.
Example 1
(1) Placing the degummed large-size MAX phase green blank with the complex shape on a sintering table in a protective cover, completing the construction and assembly of a sintering device according to the diagram shown in figure 1, and burying powder to select MX powder. Wherein, the sintering table 2 is positioned at the central position of the protective cover 3, the MAX phase ceramics 5 is positioned at the central position of the sintering table, the protective cover 3 is positioned at the central position of the alumina crucible 6, the height of the liquid level of the melting A1 is not more than the table top height of the sintering table 2, the width of the MAX phase ceramics 5 is not more than the table top width of the sintering table 2, the protective cover 3 is completely buried by the powder 7, and the height of the powder is not more than 2 times of the height of the protective cover 3;
(2) putting the sintering device assembled in the step (1) into a sintering furnace, then sealing the sintering furnace, vacuumizing to below 10Pa, filling argon into the sintering furnace until the pressure returns to atmospheric pressure, vacuumizing to below 10Pa, repeating the steps twice, exhausting oxygen and nitrogen in the sintering furnace, and filling protective inert gas argon;
(3) heating and raising the temperature to finish sintering the green body of the part to obtain the MAX-phase ceramic part with large size and complex shape.
Further, the material of the protective cover in the step (1) can be molybdenum, the protective cover is not sealed at low temperature, and gas in the protective cover can penetrate MX powder to enter the furnace chamber;
in the process of changing the sintering furnace into protective atmosphere argon, nitrogen and oxygen in the protective cover can be changed into argon through the protective cover gap;
the sintering temperature in the step (3) is 1600 ℃; keeping the temperature for 2 h; the heating rate is 8 ℃/min. The MX powder is agglomerated and contracted at the high temperature of 1000 ℃, the protective cover is sealed, and carbon or other impurities volatilized at the high temperature by heating in the furnace chamber cannot enter the protective cover to decompose the MAX phase. During the high-temperature sintering process, volatile components generated by MX powder can enter the protective cover to inhibit surface decomposition during the MAX phase sintering process. The decomposition of the MAX phase can also be suppressed by melting the gas phase A generated during the sintering process and the argon gas filled in the protective cover.
Finally, the obtained MAX phase ceramic part has no decomposition on the surface, compact and uniform microstructure, 96 percent of relative density, 411MPa of bending strength and 6.4 MPa.m of fracture toughness1/2And the diameter of the parts (centrifugal pump parts) is 225mm, the corrosion resistance is good, and the service requirement of the nuclear reactor core structural material on the MAX-phase ceramic parts is met.
Example 2
As shown in fig. 1, the method comprises the following steps:
(1) placing the degummed large-size MAX phase green blank with the complex shape on a sintering table in a protective cover, completing the construction and assembly of a sintering device according to the diagram shown in figure 1, and burying powder to select MX powder. Wherein, the sintering table 2 is positioned at the central position of the protective cover 3, the MAX phase ceramics 5 is positioned at the central position of the sintering table, the protective cover 3 is positioned at the central position of the alumina crucible 6, the height of the liquid level of the melting A1 is not more than the table top height of the sintering table 2, the width of the MAX phase ceramics 5 is not more than the table top width of the sintering table 2, the protective cover 3 is completely buried by the powder 7, and the height of the powder is not more than 2 times of the height of the protective cover 3;
(2) putting the sintering device assembled in the step (1) into a sintering furnace, then sealing the sintering furnace, vacuumizing to below 50Pa, filling argon into the sintering furnace until the pressure returns to atmospheric pressure, vacuumizing to below 50Pa, repeating the steps twice, exhausting oxygen and nitrogen in the sintering furnace, and filling protective inert gas argon;
(3) heating and raising the temperature to finish sintering the green body of the part to obtain the MAX-phase ceramic part with large size and complex shape.
Further, the material of the protective cover in the step (1) can be niobium, the protective cover is not sealed at low temperature, and gas in the protective cover can penetrate MX powder to enter the furnace chamber;
in the process of changing the sintering furnace into protective atmosphere argon, nitrogen and oxygen in the protective cover can be changed into argon through the protective cover gap;
step (3), sintering temperature is 1550 ℃; keeping the temperature for 3 hours; the heating rate is 10 ℃/min. The MX powder is agglomerated and contracted at the high temperature of 1100 ℃, the protective cover is sealed, and carbon or other impurities volatilized at the high temperature by heating in the furnace chamber cannot enter the protective cover to decompose the MAX phase. During the high-temperature sintering process, volatile components generated by MX powder can enter the protective cover to inhibit surface decomposition during the MAX phase sintering process. The decomposition of the MAX phase can also be suppressed by melting the gas phase A generated during the sintering process and the argon gas filled in the protective cover.
Finally, the obtained MAX phase ceramic part has no decomposition on the surface of the part, compact and uniform microstructure, 97 percent of relative density, 403MPa of bending strength and 6.5 MPa.m of fracture toughness1/2And the diameter of the part (centrifugal pump part) is 230mm, the corrosion resistance is good, and the service requirement of the nuclear reactor core structural material on the MAX phase ceramic part is met.
Example 3
(1) Placing the degummed large-size MAX phase green body with the complex shape on a sintering table in a protective cover, completing the construction and assembly of a sintering device according to the diagram shown in figure 1, and burying powder to select XA powder. Wherein, the sintering table 2 is positioned at the central position of the protective cover 3, the MAX phase ceramics 5 is positioned at the central position of the sintering table, the protective cover 3 is positioned at the central position of the alumina crucible 6, the height of the liquid level of the melting A1 is not more than the table top height of the sintering table 2, the width of the MAX phase ceramics 5 is not more than the table top width of the sintering table 2, the protective cover 3 is completely buried by the powder 7, and the height of the powder is not more than 2 times of the height of the protective cover 3;
(2) putting the sintering device assembled in the step (1) into a sintering furnace, then sealing the sintering furnace, vacuumizing to below 50Pa, filling helium into the sintering furnace until the pressure returns to atmospheric pressure, vacuumizing to below 50Pa, repeating the steps twice, exhausting oxygen and nitrogen in the sintering furnace, and filling protective inert gas helium;
(3) heating and raising the temperature to finish sintering the green body of the part to obtain the MAX-phase ceramic part with large size and complex shape.
Further, the protective cover in the step (1) can be made of tungsten, the protective cover is not sealed at low temperature, and gas in the protective cover can penetrate XA powder to enter the furnace chamber;
in the process of replacing and filling protective atmosphere helium in the sintering furnace, nitrogen and oxygen in the protective cover can be replaced and filled into helium through the protective cover gap;
the sintering temperature of the step (3) is 1650 ℃; keeping the temperature for 1 h; the heating rate is 12 ℃/min. The XA powder is agglomerated and shrunk at 1050 ℃, the protective cover is sealed, and carbon or other impurities volatilized at high temperature when the furnace chamber is heated cannot enter the protective cover to decompose MAX phase. In the high-temperature sintering process, volatile matters generated by XA powder can enter the protective cover to inhibit surface decomposition in the MAX phase sintering process. The decomposition of the MAX phase can also be suppressed by melting the gas phase A generated during the sintering process of A and the helium gas filled in the protective cover.
Finally, the obtained MAX phase ceramic part has no decomposition on the surface of the part, compact and uniform microstructure, 96.5 percent of relative density, 409MPa of bending strength and 6.8 MPa.m.times.of fracture toughness1/2The diameter of the parts (parts of the centrifugal pump) is 260mm, the corrosion resistance is good, and the service requirement of the nuclear reactor core structural material on the MAX-phase ceramic parts is met.
The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.
Claims (3)
1. The utility model provides a MAX looks ceramic parts sintering equipment based on gel casting which characterized in that: including sintering table (2), safety cover (3) and alumina crucible (6), sintering table (2) are located the central point of safety cover (3), MAX looks pottery (5) are located the central point of sintering table (2), safety cover (3) are located the central point of alumina crucible (6), lower part is melting A (1) in safety cover (3), upper portion is gaseous phase A (4) in safety cover (3), the mesa height of melting A (1) is no longer than sintering table (2), the mesa width of MAX looks pottery (5) is no longer than sintering table (2), powder (7) bury safety cover (3) completely, powder (7) height is no longer than 2 times of safety cover (3) height.
2. A gel injection moulding based MAX phase ceramic component sintering device according to claim 1 characterised in that: the protective cover (3) is made of one of zirconium, molybdenum, tantalum, niobium and tungsten, a gap exists in the protective cover, the protective cover is not sealed when the temperature is lower than 1000 ℃, and gas in the protective cover can penetrate through the powder (7) and enter a furnace chamber of the sintering furnace.
3. A gel injection moulding based MAX phase ceramic component sintering device according to claim 1 characterised in that: the powder (7) is MX powder or AX powder.
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| CN201920509715.8U CN210030482U (en) | 2019-04-16 | 2019-04-16 | MAX phase ceramic part sintering device based on gel casting |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110028326A (en) * | 2019-04-16 | 2019-07-19 | 北京科技大学 | MAX phase ceramics components sintering equipment and method based on gel casting forming |
| CN116178019A (en) * | 2022-09-08 | 2023-05-30 | 合肥工业大学 | Method for preparing porous MAX phase ceramic material by pressureless wrapping calcination |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110028326A (en) * | 2019-04-16 | 2019-07-19 | 北京科技大学 | MAX phase ceramics components sintering equipment and method based on gel casting forming |
| CN116178019A (en) * | 2022-09-08 | 2023-05-30 | 合肥工业大学 | Method for preparing porous MAX phase ceramic material by pressureless wrapping calcination |
| CN116178019B (en) * | 2022-09-08 | 2023-12-22 | 合肥工业大学 | Method for preparing porous MAX phase ceramic material by pressureless wrapping calcination |
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