Non-metallic mineral matter cordierite type microwave dielectric ceramic and preparation method thereof

Abstract

The application discloses a non-metallic mineral matter cordierite type microwave dielectric ceramic material, which is sintered from the following raw materials: black talc powder, coal-based kaolin ore powder, bauxite powder and Sm-Mn composite sintering additives, wherein the Sm-Mn composite sintering additives are prepared by pre-sintering Sm2O3 and Mn(NO3)2.4H2O, and the mass percentage of each raw material in the total amount of black talc powder, coal-based kaolin ore powder, bauxite powder, Sm2O3 and Mn(NO3)2.4H2O is as follows: the black talc powder accounts for 46-49%, the coal-based kaolin ore powder accounts for 15-19%, the bauxite powder accounts for 27-31%, the Sm2O3 accounts for 0.5-1.5%, and the Mn(NO3)2.4H2O accounts for 4.5-5.5%, and the main phase of the non-metallic mineral matter cordierite type microwave dielectric ceramic material is cordierite Mg2Al4Si5O 18 12, the secondary phase is SmMn2O5 and MnO2. The application further discloses a preparation method, wherein the Sm-Mn composite sintering additives are sintered first, and then mixed with the mineral raw materials in proportion to prepare by a solid phase sintering method. The non-metallic mineral matter microwave dielectric ceramic material prepared by the application solves the problem of microwave dielectric performance deterioration caused by impurities in the mineral raw materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic materials, in particular to a non-metallic mineral cordierite type microwave dielectric ceramic material and a preparation method thereof BACKGROUND

[0002] In recent years, with the iteration and rapid development of mobile communication technology, microwave dielectric ceramic materials are widely used in 5G communication systems. The performance of microwave dielectric ceramic is mainly determined by three parameters: dielectric constant, which affects the size of the device and the transmission speed of the signal; quality factor, high quality factor is conducive to reducing the loss of the device; resonance frequency temperature coefficient, which represents the temperature stability of the device in use. Silicate ceramics have a low dielectric constant and are excellent candidate materials for dielectric substrates, among which cordierite type microwave dielectric ceramic (Mg2Al4Si5O 18 ) can be used as a dielectric antenna substrate, filter and resonator in low latency (0.1-1ms) 5G / 6G application scenarios. High-performance cordierite type microwave dielectric ceramic material requires high-purity chemical powder raw materials, and the increase in raw material cost cannot meet the competitive market environment.

[0003] Non-metallic minerals such as black talc, coal-based kaolin and bauxite contain a large amount of Mg, Al and Si elements, which can form cordierite phase (Mg2Al4Si5O 18 ) under high temperature, but impurities in the minerals can cause deterioration of microwave dielectric properties. SUMMARY

[0004] In view of the above technical defects, the present application aims to provide a non-metallic mineral cordierite type microwave dielectric ceramic and a preparation method thereof, to solve the problem of deterioration of microwave dielectric properties caused by mineral impurities when sintering non-metallic minerals to form cordierite phase ceramic materials.

[0005] A non-metallic mineral cordierite type microwave dielectric ceramic material sintered from the following raw materials: black talc powder, coal-based kaolin powder, bauxite powder and Sm-Mn composite sintering aid, the Sm-Mn composite sintering aid is made by pre-sintering Sm2O3 and Mn(NO3)2·4H2O, and the mass percentage of each raw material is calculated based on the total amount of black talc powder, coal-based kaolin powder, bauxite powder, Sm2O3 and Mn(NO3)2·4H2O, black talc powder accounts for 46-49%, coal-based kaolin powder accounts for 15-19%, bauxite powder accounts for 27-31%, Sm2O3 accounts for 0.5-1.5%, and Mn(NO3)2·4H2O accounts for 4.5-5.5%, the main phase of the non-metallic mineral cordierite type microwave dielectric ceramic material is cordierite Mg2Al4Si5O 18The secondary phase is SmMn2O5 and MnO2.

[0006] Further, the non-metallic mineral quality cordierite type microwave dielectric ceramic material has a relative dielectric constant of 5.82-6.32, a quality factor of 73420-89231 GHz, and a resonance frequency temperature coefficient of 2-5 ppm / ℃.

[0007] Another technical scheme of the present application is a preparation method of a non-metallic mineral quality cordierite type microwave dielectric ceramic, comprising the following steps:

[0008] The black talc ore, coal-based kaolin ore and bauxite are pretreated to obtain mixed ore powder;

[0009] The Sm2O3 and Mn(NO3)2·4H2O are mixed and ground, and then calcined to obtain a composite sintering aid;

[0010] The composite sintering aid and the mixed ore powder are wet ball milled, and then dried after the ball milling is completed;

[0011] The dried powder is prepared into a blank and then high-temperature sintered to obtain a non-metallic mineral quality cordierite type microwave dielectric ceramic material.

[0012] Further, the Sm2O3 and Mn(NO3)2·4H2O are weighed according to the proportion, uniformly mixed by grinding, and then calcined, the calcination temperature is 600-800℃, and the holding time is 2-4h.

[0013] Further, the pretreatment of the black talc ore, coal-based kaolin ore and bauxite is as follows: the bauxite is mixed with the black talc ore and the coal-based kaolin ore respectively, and then crushed and refined, and then the two kinds of mixed powders are uniformly mixed by dry rolling to obtain the mixed ore powder.

[0014] Further, the particle size of the mixed powder after the crushing and refining is less than 45μm, the rolling speed of the dry rolling is 100-150r / min, and the rolling time is 18-24h.

[0015] Further, the deionized water and PVA binder are added when the composite sintering aid and the mixed ore powder are wet ball milled.

[0016] Further, the addition amount of the PVA binder is 0.5-1% of the mass of the deionized water.

[0017] Further, the ball milling time of the wet ball milling is 8-12h, and the rotating speed is 250-300r / min.

[0018] Further, the high-temperature sintering process is: increasing temperature to 400-600 DEG C at 5-10 DEG C / min for 2-4h to remove glue, then increasing temperature to 1150-1250 DEG C at 3-5 DEG C / min for sintering, and the holding time is 5-8h, and cooling down with furnace after holding.

[0019] Compared with the prior art, the application has the advantages of:

[0020] 1. Black mica, coal-based kaolin and bauxite are used as main raw materials to realize low-cost microwave dielectric ceramic material preparation with cordierite as main phase.

[0021] 2. (SmMn2O5+MnO2) Sm-Mn composite sintering aid is introduced into non-metallic mineral cordierite type microwave dielectric ceramic material, which not only increases Qxf value, but also improves resonance frequency temperature coefficient, and comprehensively improves microwave dielectric properties of the material.

[0022] 3. Sm2O3 and Mn (NO3) 2 are selected as raw materials, and (SmMn2O5+MnO2) Sm-Mn composite sintering aid is synthesized by solid phase calcination method in one step, which is simple in process and convenient in operation. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 XRD of non-metallic mineral cordierite type microwave dielectric ceramic material prepared in example 3. DETAILED DESCRIPTION

[0024] The application will be further described in combination with examples, but not as limitation to the application.

[0025] The component analysis of black mica, coal-based kaolin and bauxite powder used in each embodiment of the application is as follows

[0026]

[0027]

[0028] Example 1

[0029] Take 46g of black talc ore powder, 17g of coal-based kaolin ore powder, 31g of bauxite powder, mix half of the bauxite powder 15.5g with the black talc ore powder, and the other half with the coal-based kaolin ore powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 100r / min, the rolling time is 18h, and the mixed ore powder is obtained. In addition, 1.5g of Sm2O3 powder and 4.5g of Mn(NO3)2·4H2O powder are mixed uniformly by manual grinding method, the grinding time is 15min, and after mixing, the powder is placed in a muffle furnace for calcination, the calcination temperature is 600℃, and the holding time is 2h, and the Sm-Mn composite sintering aid is obtained. The mixed ore powder, Sm-Mn composite sintering aid, PVA binder and deionized water are mixed in proportion, then wet ball milling, the addition amount of PVA binder is 1g, the addition amount of deionized water is 200g, the ball milling time is 8h, and the rotating speed is 250r / min. After wet ball milling, the powder is dried and pressed into a green body, which is then sintered in a high-temperature muffle furnace, heated to 400℃ at a rate of 5℃ / min for 2h, then heated to 1150℃ at a rate of 3℃ / min, and sintered for 5h, and then cooled in the furnace after holding, to obtain the non-metallic mineral cordierite type microwave dielectric ceramic material of the application.

[0030] Example 2

[0031] Take 46g of black talc ore powder, 17g of coal-based kaolin ore powder, 31g of bauxite powder, mix half of the bauxite powder 15.5g with the black talc ore powder, and the other half with the coal-based kaolin ore powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 100r / min, the rolling time is 18h, and the mixed ore powder is obtained. In addition, 1.5g of Sm2O3 powder and 4.5g of Mn(NO3)2·4H2O powder are mixed uniformly by manual grinding method, the grinding time is 15min, and after mixing, the powder is placed in a muffle furnace for calcination, the calcination temperature is 600℃, and the holding time is 2h, and the Sm-Mn composite sintering aid is obtained. The mixed ore powder, Sm-Mn composite sintering aid, PVA binder and deionized water are mixed in proportion, then wet ball milling, the addition amount of PVA binder is 1g, the addition amount of deionized water is 200g, the ball milling time is 8h, and the rotating speed is 250r / min. After wet ball milling, the powder is dried and pressed into a green body, which is then sintered in a high-temperature muffle furnace, heated to 400℃ at a rate of 5℃ / min for 2h, then heated to 1150℃ at a rate of 3℃ / min, and sintered for 5h, and then cooled in the furnace after holding, to obtain the non-metallic mineral cordierite type microwave dielectric ceramic material of the application.

[0032] Example 3

[0033] Take 48 g of black tourmaline ore powder, 16 g of coal-based kaolin ore powder, and 29 g of bauxite powder. Mix half of the bauxite powder (14.5 g) with the black tourmaline ore powder, and mix the other half with the coal-based kaolin ore powder. Then, respectively crush and refine, pass through a 325 mesh sieve, and mix the two kinds of mixed powders uniformly by dry rolling method. The rotation speed of the rolling mill is 150 r / min, and the rolling time is 24 h. Sm2O3 powder 1.5 g and Mn(NO3)2·4H2O powder 5.5 g are mixed uniformly by manual grinding method, and the grinding time is 30 min. After mixing, the powder is placed in a muffle furnace for calcination. The calcination temperature is 700℃, and the holding time is 3 h. The Sm-Mn composite sintering aid is obtained. The mixed ore powder, Sm-Mn composite sintering aid, PVA binder, and deionized water are mixed in proportion, and then wet ball milling is performed. The addition amount of PVA binder is 1.5 g, the addition amount of deionized water is 200 g, the ball milling time is 12 h, and the rotation speed is 300 r / min. After wet ball milling, the powder is dried and pressed into a compact, which is then sintered in a high-temperature muffle furnace. The temperature is raised to 600℃ at a rate of 10℃ / min for 4 h to remove the binder, and then the temperature is raised to 1250℃ at a rate of 5℃ / min to the sintering temperature. The holding time is 8 h. After holding, the compact is cooled in the furnace. The non-metallic mineral cordierite type microwave dielectric ceramic material of the application is obtained.

[0034] Example 4

[0035] Take 49g of black talc ore powder, 15g of coal series kaolin ore powder, 30g of bauxite powder, mix half of the bauxite powder 15g with the black talc ore powder, and mix the other half with the coal series kaolin ore powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 120r / min, the rolling time is 22h, and the mixed ore powder is obtained. In addition, take 1g of Sm2O3 powder and 5g of Mn(NO3)2·4H2O powder, mix them uniformly by hand grinding method, the grinding time is 25min, after mixing, the powder is placed in a muffle furnace for calcination, the calcination temperature is 750℃, and the holding time is 2h, and the Sm-Mn composite sintering aid is obtained. The mixed ore powder, Sm-Mn composite sintering aid, PVA binder and deionized water are mixed in proportion, then wet ball milling is carried out, the addition amount of PVA binder is 1.8g, the addition amount of deionized water is 200g, the ball milling time is 10h, and the rotating speed is 300r / min. After wet ball milling, the powder is dried and pressed into a green body, and then sintered in a high-temperature muffle furnace, the temperature is raised to 500℃ at a speed of 7℃ / min for 3h, then the temperature is raised to 1200℃ at a speed of 4℃ / min, and the sintering temperature is 7h, and then the furnace is cooled after holding, and the non-metallic mineral cordierite type microwave dielectric ceramic material of the application is obtained.

[0036] Example 5

[0037] Take 49g of black talc ore powder, 15g of coal series kaolin ore powder, 30g of bauxite powder, mix half of the bauxite powder 15g with the black talc ore powder, and mix the other half with the coal series kaolin ore powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 120r / min, the rolling time is 22h, and the mixed ore powder is obtained. In addition, take 1g of Sm2O3 powder and 5g of Mn(NO3)2·4H2O powder, mix them uniformly by hand grinding method, the grinding time is 25min, after mixing, the powder is placed in a muffle furnace for calcination, the calcination temperature is 750℃, and the holding time is 2h, and the Sm-Mn composite sintering aid is obtained. The mixed ore powder, Sm-Mn composite sintering aid, PVA binder and deionized water are mixed in proportion, then wet ball milling is carried out, the addition amount of PVA binder is 1.8g, the addition amount of deionized water is 200g, the ball milling time is 10h, and the rotating speed is 300r / min. After wet ball milling, the powder is dried and pressed into a green body, and then sintered in a high-temperature muffle furnace, the temperature is raised to 500℃ at a speed of 7℃ / min for 3h, then the temperature is raised to 1200℃ at a speed of 4℃ / min, and the sintering temperature is 7h, and then the furnace is cooled after holding, and the non-metallic mineral cordierite type microwave dielectric ceramic material of the application is obtained.

[0038] Example 6

[0039] Take 47 g of black tourmaline powder, 19 g of coal-based kaolin powder, 28 g of bauxite powder, mix half of the bauxite powder 14 g with the black tourmaline powder, and mix the other half with the coal-based kaolin powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45 μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 150 r / min, the rolling time is 18 h, and the mixed powder is obtained. In addition, take 0.8 g of Sm2O3 powder and 5.2 g of Mn(NO3)2·4H2O powder, mix uniformly by hand grinding method, the grinding time is 20 min, and after mixing, the powder is placed in a muffle furnace for calcination, the calcination temperature is 800℃, and the holding time is 4 h, and the Sm-Mn composite sintering aid is obtained. The mixed powder, Sm-Mn composite sintering aid, PVA binder and deionized water are mixed in proportion, then wet ball milling is carried out, the addition amount of PVA binder is 1.5 g, the addition amount of deionized water is 200 g, the ball milling time is 12 h, and the rotating speed is 250 r / min. After wet ball milling, the powder is dried and pressed into a green body, which is then sintered in a high-temperature muffle furnace, heated to 450℃ at a rate of 10℃ / min for 4 h, then heated to 1150℃ at a rate of 5℃ / min, and sintered for 5 h, and then cooled in the furnace after holding, to obtain the non-metallic mineral cordierite type microwave dielectric ceramic material.

[0040] Comparative Example 1

[0041] Take 48 g of black tourmaline powder, 16 g of coal-based kaolin powder, and 29 g of bauxite powder, mix half of the bauxite powder 14.5 g with the black tourmaline powder, and mix the other half with the coal-based kaolin powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45 μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 150 r / min, the rolling time is 24 h, and the mixed powder is obtained. The mixed powder, PVA binder and deionized water are mixed in proportion, then wet ball milling is carried out, the addition amount of PVA binder is 1.5 g, the addition amount of deionized water is 200 g, the ball milling time is 12 h, and the rotating speed is 300 r / min. After wet ball milling, the powder is dried and pressed into a green body, which is then sintered in a high-temperature muffle furnace, heated to 600℃ at a rate of 10℃ / min for 4 h, then heated to 1250℃ at a rate of 5℃ / min, and sintered for 8 h, and then cooled in the furnace after holding, to obtain the non-metallic mineral cordierite type microwave dielectric ceramic material.

[0042] Comparative Example 2

[0043] Take 48 g of black talc ore powder, 16 g of coal series kaolin ore powder, 29 g of bauxite powder, mix half of the bauxite powder 14.5 g with the black talc ore powder, mix the other half with the coal series kaolin ore powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45 μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 150 r / min, the rolling time is 24 h, to obtain a mixed ore powder. In addition, take 5.5 g of Mn(NO3)2·4H2O powder, place it in a muffle furnace for calcination, the calcination temperature is 700℃, and the holding time is 3 h, to obtain MnO2 single additive. Mix the mixed ore powder, MnO2 additive, PVA binder and deionized water in proportion, then perform wet ball milling, the addition amount of PVA binder is 1.5 g, the addition amount of deionized water is 200 g, the ball milling time is 12 h, and the rotating speed is 300 r / min. After the wet ball milling, the powder is dried and pressed into a pellet, and then sintered in a high-temperature muffle furnace, the temperature is increased to 600℃ at a speed of 10℃ / min for 4 h, then increased to 1250℃ at a speed of 5℃ / min, and the sintering temperature is kept for 8 h, and then cooled in the furnace after holding, to obtain the non-metallic mineral cordierite type microwave dielectric ceramic material.

[0044] Comparative Example 3

[0045] Take 48 g of black talc ore powder, 16 g of coal series kaolin ore powder, 29 g of bauxite powder, mix half of the bauxite powder 14.5 g with the black talc ore powder, mix the other half with the coal series kaolin ore powder, then respectively crush and refine, pass through a 325 mesh sieve, the particle size of the two mixed powders is less than 45 μm, then mix the two powders uniformly by dry rolling method, the rolling speed is 150 r / min, the rolling time is 24 h, to obtain a mixed ore powder. In addition, take 5.5 g of Mn(NO3)2·4H2O powder, place it in a muffle furnace for calcination, the calcination temperature is 700℃, and the holding time is 3 h, to obtain MnO2 single additive. Mix the mixed ore powder, MnO2 additive, PVA binder and deionized water in proportion, then perform wet ball milling, the addition amount of PVA binder is 1.5 g, the addition amount of deionized water is 200 g, the ball milling time is 12 h, and the rotating speed is 300 r / min. After the wet ball milling, the powder is dried and pressed into a pellet, and then sintered in a high-temperature muffle furnace, the temperature is increased to 600℃ at a speed of 10℃ / min for 4 h, then increased to 1250℃ at a speed of 5℃ / min, and the sintering temperature is kept for 8 h, and then cooled in the furnace after holding, to obtain the non-metallic mineral cordierite type microwave dielectric ceramic material.

[0046] The properties of the materials obtained in each example and comparative example are as follows

[0047]

[0048] In the above-mentioned embodiments, the ceramic sample prepared in Example 3 has the highest quality factor and the temperature coefficient of resonant frequency close to zero, and the phase composition thereof is shown in Table 1. Figure 1 The main phase is cordierite Mg2Al4Si5O 18 , and the secondary phases are SmMn2O5 and MnO2. On the basis of Example 3, the ceramic sample without any additives is synthesized in Comparative Example 1, the ceramic sample with only MnO2 additives is synthesized in Comparative Example 2, and in Comparative Example 3, the Sm-Mn composite sintering aid is not pre-synthesized, but Mn(NO3)2·4H2O and Sm2O3 are directly mixed with the mineral material and sintered. It can be seen from the results that the addition and sintering of the Sm-Mn composite sintering aid can achieve a substantial increase in the quality factor and a temperature coefficient of resonant frequency close to zero.

Claims

1. A non-metallic mineral matter cordierite-type microwave dielectric ceramic material, characterized by, The non-metallic mineral cordierite type microwave dielectric ceramic material is sintered from the following raw materials: black talc powder, coal-based kaolin ore powder, bauxite powder and Sm-Mn composite sintering additives prepared by pre-sintering of Sm2O3 and Mn(NO3)2·4H2O, and the mass percentage of each raw material in the total amount of black talc powder, coal-based kaolin ore powder, bauxite powder, Sm2O3 and Mn(NO3)2·4H2O is 46-49% of black talc powder, 15-19% of coal-based kaolin ore powder, 27-31% of bauxite powder, 0.5-1.5% of Sm2O3 and 4.5-5.5% of Mn(NO3)2·4H2O, the main phase of the non-metallic mineral cordierite type microwave dielectric ceramic material is cordierite Mg2Al4Si5O 18 , and the secondary phase is SmMn2O5 and MnO2.

2. The non-metallic mineral cordierite-type microwave dielectric ceramic material according to claim 1, characterized in that, The cordierite type microwave dielectric ceramic material has a relative dielectric constant of 5.82-6.32, a quality factor of 73420-89231 GHz, and a resonance frequency temperature coefficient of 2-5 ppm / ℃.

3. A method for producing a non-metallic mineral cordierite-type microwave dielectric ceramic material according to claim 1 or 2, characterized by, The method comprises the following steps: The black talc ore, the coal-based kaolin ore and the bauxite are pretreated to obtain mixed ore powder; Sm2O3 and Mn(NO3)2·4H2O are mixed and ground, and then calcined to obtain a Sm-Mn composite sintering aid; The composite sintering aid and the mixed ore powder are wet ball milled, and then dried; The dried powder is prepared into a blank and then high-temperature sintered to obtain a non-metallic mineral cordierite type microwave dielectric ceramic material.

4. The method of claim 3, wherein the non-metallic mineral cordierite-type microwave dielectric ceramic material is prepared by the steps of: preparing a mixed powder by mixing a cordierite-type ceramic powder, a glass frit, and a binder; and forming a green body by pressing the mixed powder. The Sm2O3 and Mn(NO3)2·4H2O are weighed according to the proportion, mixed and ground uniformly, and then calcined at a temperature of 600-800 ℃ for 2-4 h.

5. The method of claim 3, wherein the non-metallic mineral cordierite-type microwave dielectric ceramic material is prepared by the steps of: preparing a mixed powder by mixing a cordierite-type ceramic powder, a glass frit, and a binder; and forming a green body by pressing the mixed powder. The pretreatment of the black talc ore, the coal-based kaolin ore and the bauxite is as follows: the bauxite is mixed with the black talc ore and the coal-based kaolin ore respectively, and then crushed and refined, and then the two kinds of mixed powders are mixed uniformly by dry rolling to obtain the mixed ore powder.

6. The method of claim 5, wherein the non-metallic mineral cordierite-type microwave dielectric ceramic material is prepared by the steps of: preparing a mixed powder by mixing a cordierite-type ceramic powder, a glass frit, and a binder; and forming a green body by pressing the mixed powder. The particle size of the mixed powder after the crushing and refining is less than 45 μm, the rolling speed of the dry rolling is 100-150 r / min, and the rolling time is 18-24 h.

7. The method of claim 3, wherein the non-metallic mineral cordierite type microwave dielectric ceramic material is prepared by the steps of: preparing a mixed powder of a cordierite type ceramic material and a glass frit; and sintering the mixed powder at a temperature of 1,200°C to 1,300°C for 2 to 4 hours. Deionized water and PVA binder are added during the wet ball milling of the composite sintering aid and the mixed ore powder.

8. The method for preparing non-metallic cordierite-type microwave dielectric ceramic material according to claim 7, characterized in that, The addition amount of the PVA binder is 0.5-1% of the mass of the deionized water.

9. The method for preparing non-metallic cordierite-type microwave dielectric ceramic material according to claim 7, characterized in that, The ball milling time of the wet ball milling is 8-12 h, and the rotating speed is 250-300 r / min.

10. The method for preparing the non-metallic cordierite-type microwave dielectric ceramic material according to claim 3, characterized in that, The high-temperature sintering process is as follows: the temperature is raised to 400-600 ℃ at a rate of 5-10 ℃ / min, the glue is discharged for 2-4 h, the temperature is raised to 1150-1250 ℃ at a rate of 3-5 ℃ / min, the temperature is kept for 5-8 h, and then the furnace is cooled after the temperature keeping.

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