CN-122010550-A - Method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering

Abstract

The invention discloses a method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering, which comprises the following steps of S1 mixing ethanolamine, magnesium acetate tetrahydrate and water according to a certain proportion to obtain a mixed solution A, S2 mixing citric acid, aluminum isopropoxide and water according to a certain proportion to obtain a mixed solution B, S3 slowly adding the mixed solution A into the solution B in the step S2 to form uniform colloid, S4 drying colloid liquid to obtain a dried precursor, S5 calcining the precursor at low temperature to obtain nano-magnesia-alumina spinel powder, S6 performing ball milling and spray granulation to obtain spherical granulating powder with uniform grain size, S7 performing dry press forming and cold isostatic press forming to obtain ceramic biscuit to be sintered, and S8 performing sintering in a muffle furnace to obtain final magnesia-alumina spinel ceramic. The powder is subjected to ball milling, spray granulation, dry pressing and cold isostatic pressing, and the compact fine-grain magnesia-alumina spinel ceramic prepared by low-temperature sintering is realized.

Inventors

• DAI PEIJUN
• WANG JUN

Assignees

• 广漠科技(苏州)有限公司

Dates

Publication Date

20260512

Application Date

20260206

Claims (10)

1. 1. A method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering is characterized by comprising the following steps: s1, mixing ethanolamine, magnesium acetate tetrahydrate and water according to a certain proportion to obtain a mixed solution A; s2, mixing citric acid, aluminum isopropoxide and water according to a certain proportion to obtain a mixed solution B; s3, slowly adding the mixed solution A obtained in the step S1 into the solution B obtained in the step S2 to form uniform colloid; s4, drying the colloid liquid obtained in the step S3 to obtain a dried precursor; S5, calcining the precursor obtained in the step S4 at a low temperature to obtain nano magnesia-alumina spinel powder; s6, ball milling and spray granulating the magnesia-alumina spinel powder obtained in the step S5 to obtain spherical granulated powder with uniform particle size; S7, carrying out dry press molding and cold isostatic pressing molding on the magnesia-alumina spinel granulating powder obtained in the step S6 to obtain a ceramic biscuit to be sintered; And S8, placing the ceramic biscuit formed in the step S7 on an alumina firing plate, and sintering in a muffle furnace to obtain the final magnesia-alumina spinel ceramic.
2. 2. The method for preparing dense fine-grain magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the mass ratio of ethanolamine, magnesium acetate tetrahydrate and water in the step S1 is 1 (1-20): (30-100); in the step S2, the mass ratio of the citric acid to the aluminum isopropoxide to the water is 1 (10-60): 30-100; the mass ratio of the ethanolamine in the solution A to the aluminum isopropoxide in the solution B is 1 (10-60).
3. 3. The method for preparing dense fine-grained magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the mixing reaction temperature is 30-100 ℃ and the reaction time is 1-60 h in the step S1.
4. 4. The method for preparing dense fine-grained magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the mixing reaction temperature is 30-100 ℃ and the reaction time is 1-60 h in the step S2.
5. 5. The method for preparing dense fine-grain magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the reaction time in the step S3 is 1-60 h.
6. 6. The method for preparing dense fine-grained magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the drying temperature in the step S4 is 30-100 ℃ and the drying time is 1-60 h.
7. 7. The method for preparing dense fine-grained magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the calcination temperature is 700-1200 ℃ and the calcination time is 1-10 h in the step S5.
8. 8. The method for preparing dense fine-grain magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the ball milling mode in the step S6 is planetary ball milling, the ball milling speed is 200-400 rpm, and the ball milling time is 10-30 h.
9. 9. The method for preparing dense fine-grained magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the dry-pressing molding pressure in the step S7 is 10-50 MPa, the cold isostatic pressing pressure is 200-300 MPa, and the pressure is maintained for 5min.
10. 10. The method for preparing dense fine-grained magnesia-alumina spinel ceramic by low-temperature sintering according to claim 1, wherein the sintering temperature is 1200-1400 ℃ and the sintering time is 1-10 h in the step S8.

Description

Method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering Technical Field The invention belongs to the technical field of ceramic preparation, and particularly relates to a method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering. Background Magnesia alumina spinel ceramics have wide application in transparent armor, high temperature window, semiconductor industry, refractory materials and other fields due to their excellent mechanical properties and chemical stability. However, practical applications of magnesia-alumina spinel ceramics still face problems such as high purity raw materials being expensive, sintering temperatures typically above 1600 ℃ and the addition of a certain amount of sintering aid often being required, resulting in low material purity and inability to meet the requirements of semiconductor applications. In addition, high temperature sintering generally means coarsening of grains, and the grain size of magnesia-alumina spinel ceramics is generally above a few microns, resulting in the mechanical properties of the material being affected. In addition, the addition of the sintering aid makes it easy for second phase impurities to be generated at the grain boundaries, thereby reducing the grain boundary strength. Therefore, there is an urgent need for high purity, high sintering activity magnesia-alumina spinel powder, which can prepare high purity, dense, fine-grained magnesia-alumina spinel ceramics at low temperature. Disclosure of Invention The invention mainly solves the technical problem of providing a method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering, wherein the compact fine-grain magnesia-alumina spinel ceramic is prepared by low-temperature sintering in normal pressure and air atmosphere after powder is subjected to ball milling, spray granulation, dry pressing and cold isostatic pressing. In order to solve the technical problems, the invention adopts a technical scheme that the method for preparing compact fine-grain magnesia-alumina spinel ceramic by low-temperature sintering comprises the following steps: s1, mixing ethanolamine, magnesium acetate tetrahydrate and water according to a certain proportion to obtain a mixed solution A; s2, mixing citric acid, aluminum isopropoxide and water according to a certain proportion to obtain a mixed solution B; s3, slowly adding the mixed solution A obtained in the step S1 into the solution B obtained in the step S2 to form uniform colloid; s4, drying the colloid liquid obtained in the step S3 to obtain a dried precursor; S5, calcining the precursor obtained in the step S4 at a low temperature to obtain nano magnesia-alumina spinel powder; s6, ball milling and spray granulating the magnesia-alumina spinel powder obtained in the step S5 to obtain spherical granulated powder with uniform particle size; S7, carrying out dry press molding and cold isostatic pressing molding on the magnesia-alumina spinel granulating powder obtained in the step S6 to obtain a ceramic biscuit to be sintered; And S8, placing the ceramic biscuit formed in the step S7 on an alumina firing plate, and sintering in a muffle furnace to obtain the final magnesia-alumina spinel ceramic. Further, in the step S1, the mass ratio of the ethanolamine, the magnesium acetate tetrahydrate and the water is 1 (1-20): 30-100; in the step S2, the mass ratio of the citric acid to the aluminum isopropoxide to the water is 1 (10-60): 30-100; the mass ratio of the ethanolamine in the solution A to the aluminum isopropoxide in the solution B is 1 (10-60). Further, in the step S1, the mixing reaction temperature is 30-100 ℃ and the reaction time is 1-60 h. Further, in the step S2, the mixing reaction temperature is 30-100 ℃ and the reaction time is 1-60 h. Further, in the step S3, the reaction time is 1 to 60 hours. Further, in the step S4, the drying temperature is 30-100 ℃ and the drying time is 1-60 h. Further, in the step S5, the calcination temperature is 700-1200 ℃ and the calcination time is 1-10 hours. Further, in the step S6, the ball milling mode is planetary ball milling, the ball milling rotating speed is 200-400 rpm, and the ball milling time is 10-30 hours. Further, in the step S7, the dry-pressing molding pressure is 10-50 MPa, the cold isostatic pressing pressure is 200-300 MPa, and the pressure is maintained for 5min. Further, in the step S8, the sintering temperature is 1200-1400 ℃ and the sintering time is 1-10 h. The beneficial effects of the invention are at least as follows: The invention prepares high-purity superfine magnesia-alumina spinel powder, and after ball milling, spray granulation, dry pressing and cold isostatic pressing, the powder is sintered at low temperature in normal pressure and air atmosphere to prepare compact fine-grain magnesia-alumina spinel ceramic. Drawings FIG. 1 is an XRD pattern of the magnesia-alum