Sintering method of 3D printing zirconia ceramic

Abstract

The invention provides a sintering method of 3D printing zirconia ceramic, and belongs to the technical field of ceramic. The sintering method provided by the invention comprises the following steps: sequentially carrying out glue removal and microwave sintering on a 3D printing zirconium oxide green body to obtain the 3D printing zirconium oxide ceramic, the temperature of the microwave sintering is 1400-1500 DEG C, and the heat preservation time of the microwave sintering is 8-12 min. According to the method, the 3D printing zirconium oxide green body is sequentially subjected to glue discharging and microwave sintering, the temperature and time of microwave sintering are controlled, the compactness of the zirconium oxide ceramic is improved, and then the hardness and bending strength of the zirconium oxide ceramic are improved. The result of the embodiment shows that the hardness of the zirconia ceramic prepared by the sintering method disclosed by the invention is more than 12GPa, and the bending strength is more than 930MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramics, and in particular relates to a sintering method for 3D printed zirconia ceramics. Background Art

[0002] Zirconia ceramics have the advantages of high toughness, high hardness, high temperature resistance, corrosion resistance, good insulation, etc., and are widely used in many fields. Zirconia ceramics with complex shapes and structures can be obtained through 3D printing. 3D printed zirconia ceramics obtain zirconia ceramic green bodies through 3D printing, and then perform binder removal and sintering to obtain zirconia ceramics. The conventional sintering method is mainly muffle furnace sintering, but this method not only has a long sintering time, but also the hardness and flexural strength of the zirconia ceramics obtained by sintering are low. Therefore, how to improve the hardness and flexural strength of 3D printed zirconia ceramics has become a difficult problem in the prior art. Summary of the invention

[0003] The object of the present invention is to provide a sintering method for 3D printed zirconia ceramics. The zirconia ceramics prepared by the method of the present invention have high hardness and high bending strength.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a sintering method for 3D printed zirconia ceramics, comprising:

[0006] The 3D printed zirconia green body is sequentially subjected to binder removal and microwave sintering to obtain a 3D printed zirconia ceramic; the microwave sintering temperature is 1400-1500° C., and the microwave sintering insulation time is 8-12 minutes.

[0007] Preferably, the debinding temperature is 450-550°C.

[0008] Preferably, the debinding temperature is 500°C.

[0009] Preferably, the process of heating up to the debinding temperature includes a two-stage heating process or a three-stage heating process.

[0010] Preferably, the two-stage heating process is: heating from room temperature to 200-300°C at a heating rate of 15-25°C / min, and then heating from 200-300°C to the debinding temperature at a heating rate of 6-7°C / min.

[0011] Preferably, the two-stage heating process is: heating from room temperature to 250°C at a heating rate of 15-25°C / min, and then heating from 250°C to the debinding temperature at a heating rate of 6-7°C / min.

[0012] Preferably, the three-stage heating process is: heating from room temperature to 200-300°C at a heating rate of 15-25°C / min, then heating from 200-300°C to 320-380°C at a heating rate of 2-3°C / min, and then heating from 320-380°C to the debinding temperature at a heating rate of 10-20°C / min.

[0013] Preferably, the three-stage heating process is: heating from room temperature to 250°C at a heating rate of 15-25°C / min, then heating from 250°C to 350°C at a heating rate of 2-3°C / min, and then heating from 350°C to the debinding temperature at a heating rate of 10-20°C / min.

[0014] Preferably, the process of heating from the debinding temperature to the microwave sintering temperature includes: heating from the debinding temperature to 800-1000°C at a heating rate of 38-42°C / min, heating from 800-1000°C to 1150-1250°C at a heating rate of 28-32°C / min, heating from 1150-1250°C to 1280-1320°C at a heating rate of 8-12°C / min, and heating from 1280-1320°C to the first temperature at a heating rate of 5-10°C / min; the first temperature is ≥ the microwave sintering temperature, when the first temperature is equal to the microwave sintering temperature, the first temperature is the microwave sintering temperature; when the first temperature is greater than the microwave sintering temperature, it also includes a process of cooling from the first temperature to the microwave sintering temperature.

[0015] Preferably, the cooling rate from the first temperature to the microwave sintering temperature is 20-30° C. / min.

[0016] The present invention provides a sintering method for 3D printed zirconia ceramics, comprising: debinding and microwave sintering the 3D printed zirconia green body in sequence to obtain the 3D printed zirconia ceramics; the temperature of the microwave sintering is 1400-1500°C, and the holding time of the microwave sintering is 8-12 minutes. The present invention sequentially debinds and microwaves the 3D printed zirconia green body, controls the temperature and time of microwave sintering, improves the density of the zirconia ceramics, and further improves the hardness and flexural strength of the zirconia ceramics. The results of the embodiment show that the hardness of the zirconia ceramics prepared by the sintering method of the present invention is above 12GPa, and the flexural strength is above 930MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a SEM image of the zirconia ceramic prepared in Example 2;

[0018] Figure 2 This is a SEM image of the zirconia ceramic prepared in Example 4;

[0019] Figure 3 This is a SEM image of the zirconia ceramic prepared in Comparative Example 2;

[0020] Figure 4 This is a SEM image of the zirconia ceramic prepared in Comparative Example 3;

[0021] Figure 5 The hardness indentation of the zirconia ceramic prepared in Example 2;

[0022] Figure 6 The hardness indentation of the zirconia ceramic prepared in Example 3;

[0023] Figure 7 This is the hardness indentation of the zirconia ceramic prepared in Example 4. DETAILED DESCRIPTION

[0024] The present invention provides a sintering method for 3D printed zirconia ceramics, comprising:

[0025] The 3D printed zirconia green body is sequentially subjected to binder removal and microwave sintering to obtain a 3D printed zirconia ceramic; the microwave sintering temperature is 1400-1500° C., and the microwave sintering insulation time is 8-12 minutes.

[0026] The present invention has no special limitation on the specific preparation method and parameters of the 3D printed zirconia green body, and the zirconia green body can be obtained by using a 3D printing method well known to those skilled in the art.

[0027] In the present invention, the 3D printing method for 3D printing the zirconia green body preferably includes inkjet 3D printing or light-curing 3D printing.

[0028] In an embodiment of the present invention, the preparation method of the 3D printed zirconia green body is as follows: 3Y-ZrO2 (D50 is 150nm, particle size is 50-200nm) zirconia powder is mixed with a solvent (water and ethylene glycol in a mass ratio of 1:9), a dispersant (BYKJET-9133), a surfactant (Sasol NovelutionS70), an anti-settling agent (fumed nano-silica, 1-10nm), acetic acid and acrylic resin (the mass ratio of zirconia powder, solvent, dispersant, surfactant, anti-settling agent, acetic acid and acrylic resin is 30:35:2:0.6:0.2:0.2:0.2), stirred for 30min, ultrasonicated for 6h, heated to 100°C for 1h, cooled to room temperature, filtered, and zirconia ink was obtained; and a 3D printed zirconia green body of 30mm*4mm*1.2mm was prepared by inkjet 3D printing.

[0029] In the present invention, the debinding temperature is preferably 450-550°C, more preferably 480-520°C, and further preferably 500°C.

[0030] In the present invention, the process of heating to the debinding temperature preferably includes a two-stage heating process or a three-stage heating process.

[0031] In the present invention, the two-stage heating process is preferably: heating from room temperature to 200-300°C at a heating rate of 15-25°C / min, and then heating from 200-300°C to the debinding temperature at a heating rate of 6-7°C / min, more preferably: heating from room temperature to 250°C at a heating rate of 15-25°C / min, and then heating from 250°C to the debinding temperature at a heating rate of 6-7°C / min; further preferably: heating from room temperature to 250°C at a heating rate of 22.5°C / min, and then heating from 250°C to the debinding temperature at a heating rate of 6.25°C / min.

[0032] In the present invention, the three-stage heating process is preferably: heating from room temperature to 200-300°C at a heating rate of 15-25°C / min, then heating from 200-300°C to 320-380°C at a heating rate of 2-3°C / min, and then heating from 320-380°C to the debinding temperature at a heating rate of 10-20°C / min; more preferably: heating from room temperature to 250-380°C at a heating rate of 15-25°C / min. ℃, then increase the temperature from 250℃ to 350℃ at a heating rate of 2-3℃ / min, and then increase the temperature from 350℃ to the debinding temperature at a heating rate of 10-20℃ / min; further preferably: increase the temperature from room temperature to 250℃ at a heating rate of 22.5℃ / min, then increase the temperature from 250℃ to 350℃ at a heating rate of 2.5℃ / min, and then increase the temperature from 350℃ to the debinding temperature at a heating rate of 15℃ / min.

[0033] In the present invention, the temperature of the microwave sintering is 1400-1500° C. In an embodiment of the present invention, the temperature of the microwave sintering may specifically be 1400° C., 1410° C., 1420° C., 1430° C., 1440° C., 1450° C., 1460° C., 1470° C., 1480° C., 1490° C. or 1500° C.

[0034] In the present invention, the holding time of the microwave sintering is 8 to 12 minutes. In an embodiment of the present invention, the holding time of the microwave sintering can be specifically 8 minutes, 9 minutes, 10 minutes, 11 minutes or 12 minutes.

[0035] In the present invention, the process of heating from the debinding temperature to the microwave sintering temperature preferably includes: heating from the debinding temperature to 800-1000°C at a heating rate of 38-42°C / min, heating from 800-1000°C to 1150-1250°C at a heating rate of 28-32°C / min, heating from 1150-1250°C to 1280-1320°C at a heating rate of 8-12°C / min, and heating from 1280-1320°C to the first temperature at a heating rate of 5-10°C / min; the first temperature is ≥ the microwave sintering temperature, when the first temperature is equal to the microwave sintering temperature, the first temperature is the microwave sintering temperature; when the first temperature is greater than the microwave sintering temperature, it also includes a process of cooling from the first temperature to the microwave sintering temperature.

[0036] In the present invention, the cooling rate from the first temperature to the microwave sintering temperature is preferably 20-30° C. / min.

[0037] In an embodiment of the present invention, the process of heating from the debinding temperature to the microwave sintering temperature can be specifically as follows: heating from the debinding temperature to 900°C at a heating rate of 40°C / min, heating from 900°C to 1200°C at a heating rate of 30°C / min, heating from 1200°C to 1300°C at a heating rate of 10°C / min, heating from 1300°C to 1400°C at a heating rate of 10°C / min, and heating from 1400°C to 1500°C at a heating rate of 6.67°C / min.

[0038] In an embodiment of the present invention, the process of heating from the debinding temperature to the microwave sintering temperature can also be specifically as follows: heating from the debinding temperature to 900°C at a heating rate of 40°C / min, heating from 900°C to 1200°C at a heating rate of 30°C / min, heating from 1200°C to 1300°C at a heating rate of 10°C / min, heating from 1300°C to 1400°C at a heating rate of 10°C / min, and heating from 1400°C to 1500°C at a heating rate of 5°C / min.

[0039] In an embodiment of the present invention, the process of heating from the debinding temperature to the microwave sintering temperature can also be specifically as follows: heating from the debinding temperature to 900°C at a heating rate of 40°C / min, heating from 900°C to 1200°C at a heating rate of 30°C / min, heating from 1200°C to 1300°C at a heating rate of 10°C / min, heating from 1300°C to 1400°C at a heating rate of 10°C / min, and heating from 1400°C to 1450°C at a heating rate of 5°C / min.

[0040] In an embodiment of the present invention, the process of heating from the debinding temperature to the microwave sintering temperature can also be specifically as follows: heating from the debinding temperature to 900°C at a heating rate of 40°C / min, heating from 900°C to 1200°C at a heating rate of 30°C / min, heating from 1200°C to 1300°C at a heating rate of 10°C / min, heating from 1300°C to 1400°C at a heating rate of 10°C / min, heating from 1400°C to 1450°C at a heating rate of 5°C / min, and cooling from 1450°C to 1400°C at a cooling rate of 25°C / min.

[0041] After the microwave sintering is completed, the present invention preferably cools the microwave sintered product along with the furnace to obtain a 3D printed zirconia ceramic.

[0042] In the present invention, the furnace cooling time is preferably 150 to 200 minutes.

[0043] In the present invention, the debinding and microwave sintering are preferably performed in a microwave sintering furnace. The present invention has no particular limitation on the type of microwave sintering furnace, and commercially available equipment known to those skilled in the art can be used.

[0044] The present invention adopts microwave sintering, which can directly act on the inside of the material and does not rely on external heat transfer methods such as conduction and convection. The heating rate is significantly higher than that of the traditional sintering method, and the material can be heated to the sintering temperature in a short time, thereby greatly shortening the sintering time. Microwave heating avoids the heat loss to the environment in the traditional heating method by directly converting electromagnetic energy into thermal energy. During the microwave sintering process, due to the rapid heating and the direct action of energy on the material, energy consumption can be significantly reduced, energy utilization efficiency can be improved, energy saving and environmental protection can be achieved, and production costs can be reduced. Due to its special heating mechanism, microwave sintering often shows higher sintering activity in the microwave field. Compared with traditional sintering, microwave sintering can achieve the same or even higher density and performance at a relatively low temperature, reduce material overburning or unnecessary grain growth, and improve the mechanical strength of the material. The whole process can be controlled within 6 hours; microwave heating is a volume heating, unlike traditional sintering, which transfers heat from the outside to the inside, but the entire material volume absorbs energy and heats up simultaneously inside and outside. Therefore, when sintering samples with larger volumes, microwave sintering can effectively reduce the temperature gradient, ensure sintering uniformity, and reduce the internal stress and thermal deformation of the samples, which is especially effective for samples with larger thicknesses.

[0045] The invention controls the temperature and time of microwave sintering, improves the density of zirconia ceramics, and further improves the hardness and bending strength of the zirconia ceramics.

[0046] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The preparation method of the 3D printed zirconia green body in each embodiment and comparative example is as follows: 3Y-ZrO2 (D50 is 150 nm, particle size is 50-200 nm) zirconia powder is mixed with a solvent (water and ethylene glycol in a mass ratio of 1:9), a dispersant (BYKJET-9133), a surfactant (Sasol Novelution S70), an anti-settling agent (fumed nano-silica, 1-10 nm), acetic acid and acrylic resin (the mass ratio of zirconia powder, solvent, dispersant, surfactant, anti-settling agent, acetic acid and acrylic resin is 30:35:2:0.6:0.2:0.2:0.2), stirred for 30 minutes, ultrasonicated for 6 hours, heated to 100 ° C for 1 hour, cooled to room temperature, filtered, and zirconia ink was obtained; and a 3D printed zirconia green body of 30 mm * 4 mm * 1.2 mm was prepared by inkjet 3D printing.

[0048] Example 1

[0049] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from room temperature (25℃) to 250℃ (heating time 10min) at a heating rate of 22.5℃ / min in a microwave sintering furnace, and then heated from 250℃ to 500℃ (heating time 40min) at a heating rate of 6.25℃ / min for debinding, and then heated from 500℃ to 900℃ (heating time 10min) at a heating rate of 40℃ / min, and then heated from 900℃ to 1000℃ at a heating rate of 30℃ / min. The temperature was raised from 0°C to 1200°C (heating time: 10 min), then from 1200°C to 1300°C at a heating rate of 10°C / min (heating time: 10 min), then from 1300°C to 1400°C at a heating rate of 10°C / min (heating time: 10 min), then from 1400°C to 1500°C at a heating rate of 6.67°C / min (heating time: 15 min), then microwave sintered at 1500°C for 10 min, and cooled with the furnace to obtain 3D printed zirconia ceramics.

[0050] Example 2

[0051] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from room temperature (25℃) to 250℃ (heating time 10min) at a heating rate of 22.5℃ / min in a microwave sintering furnace, then heated from 250℃ to 350℃ (heating time 40min) at a heating rate of 2.5℃ / min, and then heated from 350℃ to 500℃ (heating time 10min) at a heating rate of 15℃ / min for debinding, and then heated from 500℃ to 900℃ (heating time 10min) at a heating rate of 40℃ / min. in), heated from 900°C to 1200°C at a heating rate of 30°C / min (heating time 10min), heated from 1200°C to 1300°C at a heating rate of 10°C / min (heating time 10min), heated from 1300°C to 1400°C at a heating rate of 10°C / min (heating time 10min), heated from 1400°C to 1500°C at a heating rate of 5°C / min (heating time 20min), microwave sintered at 1500°C for 10min, and cooled with the furnace to obtain 3D printed zirconia ceramics.

[0052] Example 3

[0053] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from room temperature (25℃) to 250℃ (heating time 10min) at a heating rate of 22.5℃ / min in a microwave sintering furnace, then heated from 250℃ to 350℃ (heating time 40min) at a heating rate of 2.5℃ / min, and then heated from 350℃ to 500℃ (heating time 10min) at a heating rate of 15℃ / min for debinding, and then heated from 500℃ to 900℃ (heating time 10min) at a heating rate of 40℃ / min. in), heated from 900°C to 1200°C at a heating rate of 30°C / min (heating time 10 min), heated from 1200°C to 1300°C at a heating rate of 10°C / min (heating time 10 min), heated from 1300°C to 1400°C at a heating rate of 10°C / min (heating time 10 min), heated from 1400°C to 1450°C at a heating rate of 5°C / min (heating time 10 min), microwave sintered at 1450°C for 10 min, and cooled with the furnace to obtain 3D printed zirconia ceramics.

[0054] Example 4

[0055] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from room temperature (25℃) to 250℃ (heating time 10min) at a heating rate of 22.5℃ / min in a microwave sintering furnace, then heated from 250℃ to 350℃ (heating time 40min) at a heating rate of 2.5℃ / min, and then heated from 350℃ to 500℃ (heating time 10min) at a heating rate of 15℃ / min for debinding, then heated from 500℃ to 900℃ (heating time 10min) at a heating rate of 40℃ / min, and then heated from 900℃ to 1000℃ (heating time 10min) at a heating rate of 30℃ / min. The temperature was increased from 100℃ to 1200℃ (heating time 10min), the temperature was increased from 1200℃ to 1300℃ at a heating rate of 10℃ / min (heating time 10min), the temperature was increased from 1300℃ to 1400℃ at a heating rate of 10℃ / min (heating time 10min), the temperature was increased from 1400℃ to 1450℃ at a heating rate of 5℃ / min (heating time 10min), the temperature was decreased from 1450℃ to 1400℃ at a cooling rate of 25℃ / min (cooling time 2min), microwave sintering was carried out at 1400℃ for 10min, and the furnace was cooled to obtain 3D printed zirconia ceramics.

[0056] Comparative Example 1

[0057] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from 25°C to 500°C (heating time 24h) in a muffle furnace for debinding, then heated from 500°C to 1200°C (heating time 6h), kept at 1200°C for 1h, then heated from 1200°C to 1500°C (heating time 2h), kept at 1500°C for 4h, and sintered with the furnace cooling to obtain zirconia ceramics.

[0058] Comparative Example 2

[0059] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from room temperature (25℃) to 250℃ (heating time 10min) at a heating rate of 22.5℃ / min in a microwave sintering furnace, then heated from 250℃ to 350℃ (heating time 40min) at a heating rate of 2.5℃ / min, and then heated from 350℃ to 500℃ (heating time 10min) at a heating rate of 15℃ / min for debinding, and then heated from 500℃ to 900℃ (heating time 20min) at a heating rate of 20℃ / min. The material was heated from 900°C to 1200°C at a heating rate of 15°C / min (heating time: 20min), heated from 1200°C to 1400°C at a heating rate of 10°C / min (heating time: 20min), heated from 1400°C to 1500°C at a heating rate of 5°C / min (heating time: 20min), cooled from 1500°C to 1450°C at a cooling rate of 12.5°C / min (cooling time: 4min), sintered at 1450°C for 20min, and cooled in the furnace to obtain zirconia ceramics.

[0060] Comparative Example 3

[0061] The 3D printed zirconia green body (30mm*4mm*1.2mm) was heated from room temperature (25℃) to 250℃ (heating time 5min) at a heating rate of 45℃ / min in a microwave sintering furnace, then heated from 250℃ to 350℃ (heating time 10min) at a heating rate of 10℃ / min, and then heated from 350℃ to 500℃ (heating time 5min) at a heating rate of 30℃ / min for debinding, and then heated from 40℃ / min to 500℃ (heating time 5min) at a heating rate of 40℃ / min. The temperature was raised from 500°C to 900°C (heating time: 10 min), then raised from 900°C to 1200°C at a heating rate of 30°C / min (heating time: 10 min), then raised from 1200°C to 1400°C at a heating rate of 10°C / min (heating time: 20 min), then lowered from 1400°C to 1350°C at a cooling rate of 25°C / min (cooling time: 2 min), and microwave sintered at 1350°C for 10 min. The zirconia ceramics were then cooled in the furnace to obtain.

[0062] The 3D printed zirconia ceramics prepared in Example 2 were observed using a scanning electron microscope, and the obtained SEM image is as follows: Figure 1 As shown; the 3D printed zirconia ceramics prepared in Example 4 were observed using a scanning electron microscope, and the obtained SEM image is as shown Figure 2 The zirconia ceramics prepared in Comparative Example 2 were observed using a scanning electron microscope, and the SEM image obtained was as shown Figure 3 The zirconia ceramics prepared in Comparative Example 3 were observed using a scanning electron microscope, and the SEM image obtained was as shown Figure 4As shown. Figures 1 to 4 It can be seen that the grain size of the 3D printed zirconia ceramic prepared by the present invention is very small and the density is very high, while the grain size of the zirconia ceramic prepared in the comparative example is larger or the density is lower.

[0063] The hardness of the zirconia ceramics prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was tested according to GB / T 16534-2007 "Test Method for Vickers Hardness of Fine Ceramics". The force used in the test was 1 kg. The test indentations of the zirconia ceramics prepared in Examples 2 to 4 were as follows: Figures 5 to 7 The hardness of the zirconia ceramics prepared in Examples 1 to 4 and Comparative Examples 1 to 3 is shown in Table 1.

[0064] Table 1 Hardness of zirconia ceramics prepared in Examples 1 to 4 and Comparative Examples 1 to 3

[0065] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Hardness / GPa 12.20 12.16 13.48 14.02 9.58 10.05 8.75

[0066] The flexural strength of the zirconia ceramics prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was tested in accordance with GB / T 6569-2006 "Test method for flexural strength of fine ceramics". The size used in the test was 30*4*1.2 mm. The flexural strength of the zirconia ceramics prepared in Examples 1 to 4 and Comparative Examples 1 to 3 is shown in Table 2.

[0067] Table 2 Bending strength of zirconia ceramics prepared in Examples 1 to 4 and Comparative Examples 1 to 3

[0068] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Bending strength / MPa 934 1040 1090 1170 648 785 578

[0069] It can be seen from Table 1 and Table 2 that the present invention controls the temperature and time of microwave sintering, thereby improving the hardness and bending strength of microwave sintered zirconia ceramics.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A sintering method for 3D printed zirconia ceramics, comprising: The 3D printed zirconia green body is sequentially subjected to binder removal and microwave sintering to obtain a 3D printed zirconia ceramic; The temperature of the microwave sintering is 1400-1500° C., and the heat preservation time of the microwave sintering is 8-12 minutes.

2. The sintering method according to claim 1, characterized in that: The debinding temperature is 450-550°C.

3. The sintering method according to claim 2, characterized in that: The debinding temperature is 500°C.

4. The sintering method according to claim 2 or 3, characterized in that: The process of heating up to the debinding temperature includes a two-stage heating process or a three-stage heating process.

5. The sintering method according to claim 4, characterized in that: The two-stage heating process is: heating from room temperature to 200-300°C at a heating rate of 15-25°C / min, and then heating from 200-300°C to the debinding temperature at a heating rate of 6-7°C / min.

6. The sintering method according to claim 5, characterized in that: The two-stage heating process is: heating from room temperature to 250°C at a heating rate of 15-25°C / min, and then heating from 250°C to the debinding temperature at a heating rate of 6-7°C / min.

7. The sintering method according to claim 4, characterized in that: The three-stage heating process is as follows: heating from room temperature to 200-300°C at a heating rate of 15-25°C / min, then heating from 200-300°C to 320-380°C at a heating rate of 2-3°C / min, and then heating from 320-380°C to the debinding temperature at a heating rate of 10-20°C / min.

8. The sintering method according to claim 7, characterized in that: The three-stage heating process is: heating from room temperature to 250°C at a heating rate of 15-25°C / min, then heating from 250°C to 350°C at a heating rate of 2-3°C / min, and then heating from 350°C to the debinding temperature at a heating rate of 10-20°C / min.

9. The sintering method according to claim 2, characterized in that: The process of heating from the debinding temperature to the microwave sintering temperature includes: heating from the debinding temperature to 800-1000°C at a heating rate of 38-42°C / min, heating from 800-1000°C to 1150-1250°C at a heating rate of 28-32°C / min, heating from 1150-1250°C to 1280-1320°C at a heating rate of 8-12°C / min, and heating from 1280-1320°C to the first temperature at a heating rate of 5-10°C / min; the first temperature is ≥ the microwave sintering temperature, when the first temperature is equal to the microwave sintering temperature, the first temperature is the microwave sintering temperature; when the first temperature is greater than the microwave sintering temperature, it also includes a process of cooling from the first temperature to the microwave sintering temperature.

10. The sintering method according to claim 9, characterized in that: The cooling rate from the first temperature to the microwave sintering temperature is 20-30°C / min.

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