CN109761587B - Preparation of Al2O3-GdAlO3-ZrO2Method for preparing ternary eutectic ceramics - Google Patents

Preparation of Al2O3-GdAlO3-ZrO2Method for preparing ternary eutectic ceramics Download PDF

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CN109761587B
CN109761587B CN201910170459.9A CN201910170459A CN109761587B CN 109761587 B CN109761587 B CN 109761587B CN 201910170459 A CN201910170459 A CN 201910170459A CN 109761587 B CN109761587 B CN 109761587B
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gdalo
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苏海军
刘海方
申仲琳
张军
刘林
郭敏
傅恒志
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Northwestern Polytechnical University
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Preparation of Al2O3‑GdAlO3‑ZrO2The method of the ternary eutectic ceramics adopts a laser near-net forming method, and Al with different shapes and sizes which are difficult to prepare in the prior art can be obtained by layer-by-layer manufacturing/layer-by-layer accumulation2O3‑GdAlO3‑ZrO2Ternary eutectic ceramics. In preparation, the invention realizes Al by reciprocating scanning the upper surface of the sample by gradually reducing the laser power2O3‑GdAlO3‑ZrO2The temperature compensation of the ternary eutectic ceramic in the cooling process slows down the cooling rate of the sample, so that the temperature of the sample is gradually reduced after the sample is formed, thereby reducing the thermal stress in the cooling process and inhibiting the formation of cracks. The invention has high forming speed, does not need to use an expensive Mo crucible or an expensive Ir crucible, avoids the pollution possibly caused by the crucible, reduces the production cost, and obtains the Al2O3‑GdAlO3‑ZrO2The solidification structure of the ternary eutectic ceramic is more than 25 times finer than that of a sample obtained by a Bridgman method, the size of the obtained sample is 2-3 times that of the sample obtained by a laser suspension zone melting method, and the application range of the material is widened.

Description

Preparation of Al2O3-GdAlO3-ZrO2Method for preparing ternary eutectic ceramics
Technical Field
The invention relates to a laser additive manufacturing field of high-performance oxide eutectic ceramic materialIn particular to a method for preparing Al by utilizing a laser near-net forming method2O3-GdAlO3-ZrO2A method for preparing a ternary eutectic ceramic rod-shaped sample.
Background
Al2O3-GdAlO3The eutectic ceramic has excellent high-temperature mechanical property, outstanding structural thermal stability and natural oxidation resistance, and is considered to be an ultra-high-temperature structural material for aerospace with wide application potential. The documents "Narihito Nakagawa, Hideki Ohtsubo, Atsuyuki Mitani, Kazutoshi Shimizu, Yoshiharu Waku.H.high temperature strand and thermal stability for melt growth composite [ J]Journal of the European Ceramic Society,2005,25:1251-2O3-GdAlO3Eutectic ceramic columnar ingots, and the high-temperature mechanical properties of the eutectic ceramic columnar ingots are examined. The research result shows that: the bending strength of the material can be kept from room temperature to 1600 ℃; after the sample is thermally exposed for 500 hours at 1700 ℃ in the atmospheric atmosphere, the strength is basically kept unchanged, the solidification structure is not obviously coarsened, and the size, the surface roughness and the weight of the sample are basically unchanged. The estimation shows that the oxide eutectic ceramics are applied to the nozzle blade of the gas turbine, and the thermal efficiency of the gas turbine is expected to be improved by 9 percent. However, when used as a structural material, Al is required to have not only high strength but also high toughness2O3-GdAlO3Eutectic ceramics belong to typical brittle materials, and the low fracture toughness greatly restricts the application prospect of the materials.
The document "Leo Mazeroles, Nicolas Piquet, Marie-France Trichet,
Figure BDA0001987756280000011
Perrière,Denis Boivin,Michel Parlier.New microstructures in ceramic materials from the melt for high temperature applications[J]aerospace Science and Technology,2008,12:499-2O3-GdAlO3Isobinary eutectic ceramic and added ZrO2Mechanical properties of the latter ternary eutectic ceramics, resultsIs shown that ZrO2The addition of (2) can obviously improve the fracture toughness of the sample. However, the maximum forming rate of the preparation method is 20mm/h, the preparation period is too long, and an expensive Mo crucible or Ir crucible is required, which not only may pollute the ceramic melt, but also greatly increases the production cost. In addition, the resulting sample had a coarse texture and eutectic layer spacing>5 μm, resulting in limited mechanical properties. Therefore, development of new Al is urgently required2O3-GdAlO3-ZrO2A preparation process of ternary eutectic ceramics.
The documents "Weidan Ma, Jun Zhang, Haijun Su, Qun Ren, Bin Yao, Lin Liu, Hengzhi Fu. Microtrecution transformation from irregular electronic to complex electronic in direct software Al2O3/GdAlO3/ZrO2ceramics by laser floating zone melting[J]Journal of the European Ceramic Society,2016,36:1447-2O3-GdAlO3-ZrO2Ternary eutectic ceramics. The method does not need to use a crucible, not only avoids the pollution possibly caused by the crucible, but also greatly reduces the production cost. In addition, the high-energy laser beam is used as a heat source, so that the temperature gradient in the processing process is up to 10 DEG4K/cm, so that the coagulation rate can be adjusted in a wider range. The preparation method has the advantages that the coagulation rate can reach 100 mu m/s (6mm/min) as fast as possible, the preparation method is far faster than the preparation methods such as a Bridgman method, and the tissue size of the obtained sample can reach submicron scale. However, the method needs to firstly press the preform by a special grinding tool, then the preform obtains certain processing strength by sintering, and finally the eutectic ceramic sample is prepared by melting the preform by laser, so that the preparation process is complicated, and the sample size is small and is only phi 3mm x 40mm at most.
The documents "Haifang Liu, Haijun Su, Zhonglin Shen, Enyuan Wang, Di Zhoo, Min Guo, Jun Zhang, Lin Liu, Hengzhi Fu. direct formation of Al2O3/GdAlO3/ZrO2ternary eutectic ceramics by selective laser melting:Microstructure evolutions[J].Journal of the European Ceramic Society,2018,38:5144-5152.' preparation of Al by direct processing of ceramic powder by selective laser melting technique at a scanning rate of 6mm/min2O3-GdAlO3-ZrO2Ternary eutectic ceramic samples. The method does not need to prepare a prefabricated body, greatly simplifies the preparation process, however, the process is not mature at present, and only can prepare a single-channel single-layer sample with a simple shape.
The laser near-net forming technology is a laser additive manufacturing technology based on synchronous powder feeding, the shape and the size of a sample to be processed are not limited, and the target sample is manufactured layer by layer and stacked layer by adopting a manufacturing concept of dimension increasing until the target sample is obtained. The technology uses high-energy laser beam as heat source, and the temperature gradient in the forming process can reach 10%4K/cm, therefore, the coagulation rate can be adjusted in a wider range, so that the regulation of the coagulated tissue and the obtaining of the coagulated tissue in a nanometer scale are realized. In addition, auxiliary equipment such as a preheating furnace can be added according to experimental needs to reduce thermal stress during forming and further inhibit the generation of cracks. Therefore, if the laser near-net-shape technique can be applied to Al2O3-GdAlO3-ZrO2In the preparation of the ternary eutectic ceramic, the method is expected to break through the difficulty in preparing Al with a complex structure in the prior art2O3-GdAlO3-ZrO2The bottleneck problem of the ternary eutectic ceramic sample piece is solved, so that the application potential of the material is released to a certain extent and the application range of the material is widened.
In patent publication No. CN102557596A, a method for preparing alumina-based eutectic ceramic by laser powder feeding is disclosed, in which a laser surface atmosphere heating furnace is used to assist in heating the eutectic ceramic, thereby reducing the thermal stress during zone melting and further suppressing the formation of cracks during powder melting. However, the eutectic ceramic prepared by the method has irregular shape, poor forming quality and low forming speed which is only 0.6-6 mm/min.
The documents "Fangyong Niu, Dongjiang Wu, Guingyi Ma, Jiangtian Wang, Minhai Guo, Bi Zhang. nanosized microstructure of Al2O3-ZrO2(Y2O3)eutectics fabricated by laser engineered net shaping[J].Scripta Materialia 2015,95:39-41, utilizing laser near-net shaping technology to prepare columnar and arc-shaped wall Al with nano-scale solidification structure2O3-ZrO2The binary eutectic ceramic sample proves the feasibility of preparing oxide eutectic ceramics with various shapes by utilizing a laser near-net forming technology. However, Al is present during the preparation2O3And ZrO2The two raw materials are respectively conveyed into the molten pool by a multi-barrel powder feeder, and the two components can be mixed unevenly in the rapid solidification process. Furthermore, it is uncertain whether the method is applicable to other eutectic systems and more constituent elements such as ternary eutectic systems.
Disclosure of Invention
To overcome the existing Al2O3-GdAlO3-ZrO2The invention provides a method for preparing Al, which solves the problems of long processing period, high production cost, complicated process and the like of a forming process of ternary eutectic ceramics2O3-GdAlO3-ZrO2A method of ternary eutectic ceramics.
The specific process of the invention is as follows:
step 1, preparing eutectic component Al2O3-Gd2O3-ZrO2Spherical powder particles.
Adopting a centrifugal spray drying method to fully and uniformly mix Al according to eutectic mixture ratio2O3-Gd2O3-ZrO2The ceramic powder is prepared into spherical powder particles.
The particle size distribution of the obtained spherical powder particles is 30-100 mu m.
Step 2, charging
And filling the obtained spherical powder particles into a powder conveying barrel of a powder feeder for standby.
Step 3, preparing Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
Melting and solidifying the spherical powder particles obtained in the step 1 by using a laser near-net forming method, and stacking and forming layer by layer to prepare Al2O3-GdAlO3-ZrO2The preparation process of the ternary eutectic ceramic comprises the following steps:
firstly, placing heating Al in a preheating furnace2O3A substrate.
The Al placed in the preheating furnace2O3The vertical distance between the upper surface of the substrate and the laser nozzle is 10 mm; the Al2O3The temperature at which the substrate was heated was 700 ℃.
And secondly, setting the scanning technological parameters.
The scanning process parameters comprise laser power of a laser nozzle, scanning speed, one-way scanning distance, single-layer lifting height of the laser nozzle and the number of processing layers of a sample; the laser power of the laser nozzle is 200-400W, the scanning speed is 48-192 mm/min, the single-pass scanning distance is 2-4 mm, the single-layer lifting height of the laser nozzle is 0.1-0.2 mm, and the number of sample layers is 300-1000;
third step, preparing Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics. And taking the current position of the laser nozzle as a starting point. And starting the laser and the powder feeder. The laser beam is output through the laser head and radiated to Al2O3Surface of substrate, Al2O3The substrate melts by absorbing the laser energy and forms a molten pool that extends with the movement of the laser nozzle. Meanwhile, spherical powder particles are conveyed to a powder feeding port from a powder feeding barrel through a rotary powder feeding disc, and are finally conveyed out from a powder channel of the laser nozzle through a conveying pipeline under the pushing of powder feeding gas, enter a dissolving pool below the laser nozzle and are melted; when the laser beam leaves, the temperature of the melt in the molten pool is reduced and the melt is solidified to form the Al2O3-GdAlO3-ZrO2First layer of Al in ternary eutectic ceramics2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
When the laser nozzle moves for a single pass, a scanning length is finished. The laser nozzle moves upwards by a lifting height and then moves linearly towards the starting point direction to obtain the first layer Al2O3-GdAlO3-ZrO2The surface of the ternary eutectic ceramic continues to scan. In the scanning, the first layer Al2O3-GdAlO3-ZrO2The surface of the ternary eutectic ceramic melts to form a molten pool and extends with the movement of the laser nozzle. Meanwhile, spherical powder particles are sent into the dissolving tank through a laser nozzle and are melted; when the laser beam leaves, the temperature of the melt in the molten pool is reduced and solidified to form a second Al layer2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
Repeating the preparation of the first layer of Al2O3-GdAlO3-ZrO2Ternary eutectic ceramic and second layer of Al2O3-GdAlO3-ZrO2The process of ternary eutectic ceramics is carried out until the designed preparation layer number is finished, and Al is obtained2O3-GdAlO3-ZrO2Ternary eutectic ceramic samples.
Step 4, Al2O3-GdAlO3-ZrO2And (4) compensation cooling of the ternary eutectic ceramic sample.
Gradually cooling the laser nozzle to the Al2O3-GdAlO3-ZrO2Compensating and cooling the ternary eutectic ceramic sample; the method comprises the following steps:
to obtain Al2O3-GdAlO3-ZrO2After the ternary eutectic ceramic sample, the powder feeder was turned off, and the laser nozzle was moved up by 10mm at a speed of 1000mm/min and maintained at that height. The laser nozzle faces the Al2O3-GdAlO3-ZrO2The upper surface of the ternary eutectic ceramic sample was scanned. In the scanning process, every time the laser nozzle moves for a single scanning length, the laser power is reduced by 10W until the laser power of the laser nozzle is reduced to 50W. The laser power is gradually reduced in the scanning process through the laser nozzle, and Al in cooling is treated2O3-GdAlO3-ZrO2Temperature compensation is carried out on the ternary eutectic ceramic sample to ensure that the Al is2O3-GdAlO3-ZrO2The temperature of the ternary eutectic ceramic sample is gradually reduced, so that the thermal stress in the cooling process is reduced, and the formation of cracks is inhibited.
In the compensation cooling process, the laser power of the laser nozzle is 200-400W, and the scanning speed is 48-192 mm/min.
When the laser power is reduced to 50W, the laser is closed, the preheating furnace is closed, and the substrate and the forming sample piece on the substrate are naturally cooled along with the preheating furnace to obtain Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
The invention scans the upper surface of the sample in a reciprocating way by the method for gradually reducing the laser power, can slow down the cooling rate of the sample, and gradually reduces the temperature of the sample after forming, thereby reducing the thermal stress in the cooling process and inhibiting the formation of cracks.
Compared with the prior art, the invention has the following outstanding characteristics:
(1) the process is simple and the forming speed is high. The method does not need to use an expensive Mo crucible or an expensive Ir crucible, thereby not only avoiding the pollution possibly brought by the crucible, but also reducing the production cost. In addition, the invention does not need to press and sinter the prefabricated body, adopts the concept of additive manufacturing, directly processes ceramic powder particles by using high-energy laser beams, and forms Al with the relative density of more than 98 percent near net shape2O3-GdAlO3-ZrO2The ternary eutectic ceramic sample simplifies the processing procedure. Further, Al in the invention2O3-GdAlO3-ZrO2The forming speed of the ternary eutectic ceramic can reach 192mm/min at most, and Al is prepared by other methods2O3-GdAlO3-ZrO2When the ternary eutectic ceramic is used, the reported fastest forming speed is 6mm/min, and the preparation period is greatly shortened.
(2) Can prepare Al which has no crack formation and has large-size and fine structure2O3-GdAlO3-ZrO2Ternary eutectic ceramic samples. The invention combines two modes of continuously preheating the substrate by the bottom preheating furnace and continuously scanning the upper surface of the obtained sample by gradually reducing the laser power after the processing is finished, thereby reducing the thermal stress in the forming process and the cooling process and effectively inhibiting the formation of cracks. The obtained rod-shaped Al has no crack formation2O3-GdAlO3-ZrO2The ternary eutectic ceramic test specimens are shown in fig. 1. In the prior art, the method has the defects that,al prepared by Bridgman method2O3-GdAlO3-ZrO2Coarse texture of ternary eutectic ceramic, and spacing between eutectic layers>5 μm, resulting in limited mechanical properties; al with submicron structure prepared by laser suspension zone melting method2O3-GdAlO3-ZrO2The size of the obtained sample is small, the reported maximum size is phi 3mm multiplied by 40mm, and the method can only prepare a rod-shaped sample with a single shape, so that the application range and the application prospect of the material are greatly restricted. Al currently prepared by the invention2O3-GdAlO3-ZrO2The solidification structure of the ternary eutectic ceramic is fine, the spacing between eutectic layers can reach 0.2 mu m, as shown in figure 2, the structure of the ternary eutectic ceramic is more than 25 times finer than that of a sample obtained by a Bridgman method, and the size of the obtained sample is 2-3 times that of the sample obtained by a laser suspension zone melting method, as shown in figure 1. In addition, the laser near-net forming technology used by the invention has no limitation on the shape and the size of a target sample, so that the Al with larger size and more complex shape is hopeful to be prepared with the subsequent continuous optimization process2O3-GdAlO3-ZrO2The ternary eutectic ceramic sample can widen the application range of the material and release the application potential of the material.
Drawings
FIG. 1 shows a rod-like Al prepared by the present invention2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
FIG. 2 shows Al prepared by the present invention2O3-GdAlO3-ZrO2And (3) a ternary eutectic ceramic microstructure diagram.
Fig. 3 is a flow chart of the present invention.
Detailed Description
The invention relates to a method for manufacturing Al by adopting laser near-net forming2O3-GdAlO3-ZrO2The method of the ternary eutectic ceramic comprises the following steps:
step 1, preparing eutectic component Al2O3-Gd2O3-ZrO2Spherical powder particles.
Adopting a centrifugal spray drying method to fully and uniformly mix Al according to eutectic mixture ratio2O3-Gd2O3-ZrO2The ceramic powder is prepared into spherical powder particles.
The eutectic mixture ratio is as follows: al (Al)2O358% of powder and Gd2O3Powder 19%, ZrO2The powder content was 23%.
The ratio is in mole percent.
The method for preparing the spherical powder particles is disclosed in the invention with the application number of CN201810640599, and the specific process is as follows:
firstly, obtaining eutectic component oxide ceramic powder which is fully and uniformly mixed;
the eutectic component oxide ceramic powder is made of Al2O3Powder of Gd2O3Powder and ZrO2The powder is used as an initial raw material;
weighing initial raw materials according to the mol percentage, adding a polyvinyl alcohol solution and absolute ethyl alcohol into the initial raw materials, and then ball-milling for 5 hours at the rotating speed of 550r/min to fully and uniformly mix the initial raw materials to obtain mixed slurry;
putting the obtained mixed slurry into a drying oven, and drying for 2 hours at 100 ℃ to obtain eutectic component oxide ceramic powder;
secondly, preparing slurry;
adding distilled water into the eutectic component oxide ceramic powder obtained in the first step, and fully stirring to obtain uniformly mixed slurry;
thirdly, spray granulation;
preparing eutectic component oxide ceramic spherical particles by using a centrifugal spray dryer, wherein the specific preparation process comprises the following steps:
starting a centrifugal spray dryer, setting the inlet air temperature to be 350 ℃, and setting the lower limit value of the outlet air temperature to be 140 ℃; starting a centrifugal fan; starting an air heater, and heating air entering a centrifugal spray dryer to the set inlet air temperature of 350 ℃ and the set outlet air temperature of 140 ℃;
II, starting a motor to drive the centrifugal spray head to rotate; starting a feeding pump, and feeding the uniformly mixed slurry obtained in the second step into a centrifugal spray head through a feeding pipe of the centrifugal spray head; the rotating speed of the feeding pump is 10-20 r/min; adjusting the frequency of the motor within 20-25 Hz;
the slurry fed into the centrifugal spray head is uniformly and continuously dripped into a centrifugal disc at the bottom end of the centrifugal spray head through a feed liquid distributor in the centrifugal spray head, and is dispersed into uniform atomized liquid drops under the action of centrifugal force generated when the centrifugal spray head rotates; after the atomized liquid drops are contacted with hot air in a centrifugal spray dryer, 95-98% of water is instantaneously evaporated and dried in 8-10 s to form spherical oxide ceramic particles keeping a liquid drop shape; the spherical oxide ceramic particles enter a pollinator at the bottom of the centrifugal spray dryer;
III, after the slurry is processed, closing the centrifugal fan, unloading the pollinator, and collecting spherical oxide ceramic particles; the particle size of the obtained spherical oxide ceramic particles is 30-100 mu m;
fourthly, removing glue;
and (3) putting the spherical oxide ceramic particles obtained in the third step into a box type sintering furnace, and preserving the heat for 30min at 500 ℃ to discharge the polyvinyl alcohol in the spherical oxide ceramic particles to obtain the spherical oxide ceramic particles with pure eutectic components.
The particle size distribution of the obtained spherical powder particles is 30-100 mu m.
Step 2, charging
And (3) filling the spherical powder particles obtained in the step (1) into a powder feeding barrel of a powder feeder for standby.
Step 3, preparing Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
Melting and solidifying the spherical powder particles obtained in the step 1 by using a laser near-net forming method, and stacking and forming layer by layer to prepare Al2O3-GdAlO3-ZrO2The preparation process of the ternary eutectic ceramic comprises the following steps:
in a first step, a shaft-type preheating furnace is opened and a block of Al of 100mm by 10mm is placed in the preheating furnace2O3A substrate.Adding the Al2O3The substrate was heated to 700 ℃. Moving the laser nozzle to Al2O3Adjusting the laser nozzle and Al directly above the substrate2O3The vertical distance between the upper surfaces of the substrates was 10 mm.
And secondly, setting technological parameters. Setting the laser power of a laser nozzle to be 200-400W, the scanning speed to be 48-192 mm/min, the single-pass scanning length to be 2-4 mm, the single-pass lifting height of the laser nozzle to be 0.1-0.2 mm, and the number of processing layers to be 300-1000.
And controlling the opening and closing of the laser, the movement track of the laser nozzle and the technological parameters in the processing process by a control program consisting of CNC control codes.
Third step, preparing Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics. And taking the current position of the laser nozzle as a starting point. And starting the laser and the powder feeder. The laser beam is output through the laser head and radiated to Al2O3Surface of substrate, Al2O3The substrate melts by absorbing the laser energy and forms a molten pool that extends with the movement of the laser nozzle. Meanwhile, spherical powder particles are conveyed to a powder feeding port from a powder feeding barrel through a rotary powder feeding disc, and are finally conveyed out from a powder channel of the laser nozzle through a conveying pipeline under the pushing of powder feeding gas, enter a dissolving pool below the laser nozzle and are melted; when the laser beam leaves, the temperature of the melt in the molten pool is reduced and the melt is solidified to form the Al2O3-GdAlO3-ZrO2First layer of Al in ternary eutectic ceramics2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
When the laser nozzle moves for a single pass, a scanning length is finished. The laser nozzle moves upwards by a lifting height and then moves linearly towards the starting point direction to obtain the first layer Al2O3-GdAlO3-ZrO2The surface of the ternary eutectic ceramic continues to scan. In the scanning, the first layer Al2O3-GdAlO3-ZrO2The surface of the ternary eutectic ceramic melts to form a molten pool and extends with the movement of the laser nozzle. At the same time, sphericalPowder particles are fed into the dissolving tank through a laser nozzle and melted; when the laser beam leaves, the temperature of the melt in the molten pool is reduced and solidified to form a second Al layer2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
Repeating the preparation of the first layer of Al2O3-GdAlO3-ZrO2Ternary eutectic ceramic and second layer of Al2O3-GdAlO3-ZrO2The process of ternary eutectic ceramics is carried out until the designed preparation layer number is finished, and Al is obtained2O3-GdAlO3-ZrO2Ternary eutectic ceramic samples.
The laser and the powder feeder both adopt the prior art.
Step 4, Al2O3-GdAlO3-ZrO2And (4) compensation cooling of the ternary eutectic ceramic sample.
Gradually cooling the laser nozzle to the Al2O3-GdAlO3-ZrO2The ternary eutectic ceramic sample is compensated and cooled, and specifically comprises the following steps:
to obtain Al2O3-GdAlO3-ZrO2After the ternary eutectic ceramic sample, the powder feeder was turned off, and the laser nozzle was moved up by 10mm at a speed of 1000mm/min and maintained at that height. The laser nozzle is along the obtained Al2O3-GdAlO3-ZrO2The upper surface of the ternary eutectic ceramic sample makes linear reciprocating motion to the Al2O3-GdAlO3-ZrO2The upper surface of the ternary eutectic ceramic sample was scanned. In the scanning process, every time the laser nozzle moves for a single scanning length, the laser power is reduced by 10W until the laser power of the laser nozzle is reduced to 50W. The laser power is gradually reduced in the scanning process through the laser nozzle, and Al in cooling is treated2O3-GdAlO3-ZrO2Temperature compensation is carried out on the ternary eutectic ceramic sample to ensure that the Al is2O3-GdAlO3-ZrO2The temperature of the ternary eutectic ceramic sample is gradually reduced, so that the thermal stress in the cooling process is reduced, and the formation of cracks is inhibited.
In the compensation cooling process, the laser power of the laser nozzle is 200-400W, and the scanning speed is 48-192 mm/min.
When the laser power is reduced to 50W, the laser is closed, the preheating furnace is closed, and the substrate and the forming sample piece on the substrate are naturally cooled along with the preheating furnace to obtain Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
The invention describes the concrete process in detail through six embodiments, and the implementation process of each embodiment is the same, and the difference lies in the process parameters of each embodiment.
Table 1: process parameters of the examples
Examples Laser power Scanning rate Rotational speed of powder feeding disc Length of single scan Single layer lift height Number of processing layers
1 400W 192mm/min 20rpm 4mm 0.1mm 1000
2 350W 168mm/min 18rpm 3mm 0.15mm 800
3 300W 144mm/min 16rpm 2mm 0.1mm 600
4 250W 96mm/min 14rpm 3mm 0.2mm 500
5 200W 96mm/min 12rpm 4mm 0.15mm 400
6 300W 48mm/min 10rpm 2mm 0.2mm 300
Note: by regulating and controlling the combination of all process parameters, the ceramic powder fed into a molten pool in the forming process is ensured to be completely melted, and the distance between a laser nozzle and a processing surface is ensured to be kept at 10mm all the time, so that a sample with good forming quality and without cracks and air holes is obtained.

Claims (2)

1. Preparation of Al2O3-GdAlO3-ZrO2The method of the ternary eutectic ceramic is characterized by comprising the following specific steps:
step 1, preparing eutectic component Al2O3-Gd2O3-ZrO2Spherical powder particles:
fully and uniformly mixing Al according to eutectic ratio2O3-Gd2O3-ZrO2Preparing spherical powder particles from ceramic powder;
the particle size distribution of the obtained spherical powder particles is 30-100 mu m;
step 2, charging:
filling the obtained spherical powder particles into a powder feeding barrel of a powder feeder for later use;
step 3, preparing Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics:
melting and solidifying the spherical powder particles obtained in the step 1 by using a laser near-net forming method, and stacking and forming layer by layer to prepare Al2O3-GdAlO3-ZrO2The preparation process of the ternary eutectic ceramic comprises the following steps:
firstly, placing heating Al in a preheating furnace2O3A substrate;
the Al placed in the preheating furnace2O3Substrate upper surface and laserThe vertical distance between the spray heads is 10 mm; adding the Al2O3Heating the substrate to 700 ℃;
secondly, setting scanning technological parameters;
the scanning process parameters comprise laser power of a laser nozzle, scanning speed, one-way scanning distance, single-layer lifting height of the laser nozzle and the number of processing layers of a sample; the laser power of the laser nozzle is 200-400W, the scanning speed is 48-192 mm/min, the single-pass scanning distance is 2-4 mm, the single-layer lifting height of the laser nozzle is 0.1-0.2 mm, and the number of sample layers is 300-1000;
third step, preparing Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics; taking the current position of the laser nozzle as a starting point; starting a laser and a powder feeder; the laser beam is output through the laser head and radiated to Al2O3Surface of substrate, Al2O3The substrate is melted by absorbing laser energy and forms a molten pool extending along with the movement of the laser nozzle; meanwhile, spherical powder particles are conveyed to a powder feeding port from a powder feeding barrel through a rotary powder feeding disc, and are finally conveyed out from a powder channel of the laser nozzle through a conveying pipeline under the pushing of powder feeding gas, enter a molten pool below the laser nozzle and are melted; when the laser beam leaves, the temperature of the melt in the molten pool is reduced and the melt is solidified to form the Al2O3-GdAlO3-ZrO2First layer of Al in ternary eutectic ceramics2O3-GdAlO3-ZrO2Ternary eutectic ceramics;
when the laser nozzle moves for a single pass, a scanning length is finished; the laser nozzle moves upwards by a lifting height and then moves linearly towards the starting point direction to obtain the first layer Al2O3-GdAlO3-ZrO2Continuously scanning the surface of the ternary eutectic ceramic; in the scanning, the first layer Al2O3-GdAlO3-ZrO2Melting the surface of the ternary eutectic ceramic to form a molten pool and extending along with the movement of the laser nozzle; meanwhile, spherical powder particles are fed into the molten pool through a laser nozzle and are melted; after the laser beam leaves, the molten pool meltsThe temperature of the body is reduced and the body is solidified to form a second Al layer2O3-GdAlO3-ZrO2Ternary eutectic ceramics;
repeating the preparation of the first layer of Al2O3-GdAlO3-ZrO2Ternary eutectic ceramic and second layer of Al2O3-GdAlO3-ZrO2The process of ternary eutectic ceramics is carried out until the designed preparation layer number is finished, and Al is obtained2O3-GdAlO3-ZrO2A ternary eutectic ceramic sample;
step 4, Al2O3-GdAlO3-ZrO2And (3) compensation cooling of the ternary eutectic ceramic sample:
gradually cooling the laser nozzle to the Al2O3-GdAlO3-ZrO2Compensating and cooling the ternary eutectic ceramic sample; the method comprises the following steps:
to obtain Al2O3-GdAlO3-ZrO2After the ternary eutectic ceramic sample is obtained, the powder feeder is closed, and the laser nozzle moves up by 10mm at the speed of 1000mm/min and keeps the height; the laser nozzle faces the Al2O3-GdAlO3-ZrO2Scanning the upper surface of the ternary eutectic ceramic sample; in the scanning process, every time the laser nozzle moves for a one-way scanning length, the laser power is reduced by 10W until the laser power of the laser nozzle is reduced to 50W; the laser power is gradually reduced in the scanning process through the laser nozzle, and Al in cooling is treated2O3-GdAlO3-ZrO2Temperature compensation is carried out on the ternary eutectic ceramic sample to ensure that the Al is2O3-GdAlO3-ZrO2The temperature of the ternary eutectic ceramic sample is gradually reduced, so that the thermal stress in the cooling process is reduced, and the formation of cracks is inhibited; when the laser power is reduced to 50W, the laser is closed, the preheating furnace is closed, and the substrate and the forming sample piece on the substrate are naturally cooled along with the preheating furnace to obtain Al2O3-GdAlO3-ZrO2Ternary eutectic ceramics.
2. Al according to claim 12O3-GdAlO3-ZrO2The method for preparing the ternary eutectic ceramic is characterized in that in compensation cooling, the laser power of a laser nozzle is 200-400W, and the scanning speed is 48-192 mm/min.
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