Lithium-free low-temperature ceramic sintering aid, preparation method and application thereof

Abstract

The application provides a lithium-free low-temperature ceramic sintering aid and a preparation method and application thereof, and relates to the technical field of lithium-free low-temperature ceramic sintering aids and the preparation method and application thereof.The lithium-free low-temperature ceramic sintering aid is composed of raw materials such as quartz, Al2O3, CaO, MgO, K2O, Na2O and B2O3.The lithium-free low-temperature ceramic sintering aid of the application realizes the preparation of a high-performance low-temperature sintering aid without using lithium-containing raw materials, reduces the cost of the sintering aid, promotes the formation of large continuous phases in the sintering aid during the ceramic sintering process, avoids the generation of crystallization problems, reduces the energy consumption of ceramic production and improves the profit of ceramic production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium-free low-temperature ceramic sintering aids, and particularly relates to a lithium-free low-temperature ceramic sintering aid and a preparation method and application thereof. BACKGROUND

[0002] Research shows that the addition of a low-temperature sintering aid can effectively reduce the sintering temperature of raw ceramic powder, and therefore is widely used in the current ceramic manufacturing field. The main role of the low-temperature sintering aid is to promote crystal growth during the sintering process, thereby reducing the sintering temperature of the ceramic.

[0003] However, the lithium-containing low-temperature sintering aid has the following problems in practical application: (1) due to the excessively rapid grain growth, the movement of the grain boundary and the growth of the grain are not coordinated, thereby forming a gap between the grains and causing crystallization, which reduces the performance of the material; (2) harmful gases and other chemical substances are released during use, which is not conducive to human health and environmental protection; (3) water sources and soil are polluted during the waste discharge process, which affects the ecological balance; (4) as the lithium resource is developed and widely used, the price of lithium continues to rise, and the cost of the lithium-containing low-temperature sintering aid increases significantly. Therefore, it is urgent to develop a new type of lithium-free low-temperature ceramic sintering aid to replace the traditional lithium-containing low-temperature sintering aid to overcome the above problems. SUMMARY

[0004] To solve the above problems, the present application provides a lithium-free low-temperature ceramic sintering aid and a preparation method and application thereof. Compared with the traditional lithium-containing low-temperature sintering aid, the lithium-free low-temperature ceramic sintering aid of the present application realizes the preparation of a high-performance low-temperature sintering aid on the basis of not using lithium-containing raw materials, not only reduces the cost of the sintering aid, but also promotes the formation of a large continuous phase inside the ceramic during the ceramic sintering process, avoids the occurrence of the crystallization problem, reduces the energy consumption of ceramic production, and improves the profit of ceramic production.

[0005] The lithium-free low-temperature ceramic sintering aid according to the present application is composed of the following raw materials in the following weight percentages:

[0006] Quartz 61%, Al2O3 8-10%, CaO 0.1-3%, MgO 0.1-2%, K2O 1-4%, Na2O 4-11%, B2O3 10-15%, and the sum of the weight percentages of the above raw materials is 100%.

[0007] The present application also provides a preparation method of the lithium-free low-temperature ceramic sintering aid, and the steps are as follows: the raw materials are mixed and stirred uniformly, and then calcined to obtain the lithium-free low-temperature ceramic sintering aid.

[0008] Further, the roasting adopts a segmented temperature rising and holding process, specifically: rising from 20 DEG C to 600 DEG C at a temperature rising rate of 3.2 DEG C / min, holding for 20-50 min, rising from 600 DEG C to 920 DEG C at a temperature rising rate of 3.2 DEG C / min, rising from 920 DEG C to 1100 DEG C at a temperature rising rate of 1.5 DEG C / min, holding for 100-150 min.

[0009] Another object of the application is to provide the application of the lithium-free low-temperature ceramic sintering aid, specifically: after the lithium-free low-temperature ceramic sintering aid is crushed to pass through an 80-120 mesh sieve, the ceramic body powder is added and mixed uniformly, an appropriate amount of water is added to the powder, and the ceramic body slurry is obtained by ball milling, the ceramic green body is formed by pouring the slurry into a mold, the ceramic body is obtained after the green body is dried and sintered, and the ceramic body is obtained after the sintering is completed and the temperature is cooled to room temperature.

[0010] Further, the addition amount of the lithium-free low-temperature ceramic sintering aid is 1wt%-5wt% of the ceramic body powder.

[0011] Further, the addition amount of the water is 40wt%-45wt% of the ceramic body powder.

[0012] Further, the roasting adopts a segmented temperature rising and holding process, specifically: rising from 20 DEG C to 600 DEG C at a temperature rising rate of 3.2 DEG C / min, holding for 20-50 min, rising from 600 DEG C to 920 DEG C at a temperature rising rate of 3.2 DEG C / min, rising from 920 DEG C to 1100 DEG C at a temperature rising rate of 1.5 DEG C / min, holding for 100-150 min.

[0013] Further, the ball milling ball ratio is 1:10, the ball milling rotation speed is 50 rpm / min, and the ball milling time is 2 h.

[0014] Further, the drying temperature is 80 DEG C, and the drying time is 24 h.

[0015] Compared with the prior art, the application has the beneficial technical effects of:

[0016] The application can promote the crystal phase transition of the ceramic material during the sintering process by increasing the content of sodium element in the sintering aid, thereby reducing the sintering temperature of the ceramic.

[0017] The sintering aid can promote the crystallization of the ceramic and obtain smaller crystals, improve the uniformity of the crystal dispersion, and further improve the mechanical properties of the ceramic.

[0018] The sintering aid can release sodium ions during the sintering process, promote the dispersion of the ceramic particles, and form an oxide solid phase reaction between the raw material particles, thereby avoiding problems such as crystallization, improving the sintering density of the ceramic material, and further improving the quality and service life of the ceramic. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 This is a SEM image of the ceramic according to Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The technical solution provided by the present invention is further described below in conjunction with the examples. Ceramic body It is composed of the following components: SiO2 67.02wt%, Al2O3 26.94wt%, Fe2O3 1.25 wt%, MgO 0.39 wt%, CaO 1.06wt%, Na2O 0.61wt%, K2O 2.35wt%, and TiO2 0.38wt%.

[0022] Example 1

[0023] (1) Preparation of lithium-free low-temperature ceramic sintering aids:

[0024] Quartz 61wt%, Al2O3 10wt%, CaO 3wt%, MgO 2wt%, K2O 4wt%, Na2O 5wt%, and B2O3 15wt% were mixed and stirred evenly. The mixed raw materials were then poured into an alumina crucible. The crucible was then placed in a muffle furnace. The temperature of the muffle furnace was increased from 20℃ to 600℃ at a heating rate of 3.2℃ / min and kept at this temperature for 30 min. The temperature was then increased from 600℃ to 920℃ at a heating rate of 3.2℃ / min. Then, the temperature was increased from 920℃ to 1100℃ at a heating rate of 1.5℃ / min and kept at this temperature for 120 min. The mixture was then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid.

[0025] (2) Ceramic firing:

[0026] The prepared lithium-free low-temperature ceramic sintering aid was crushed through a 120-mesh sieve and added to the ceramic green body powder at a ratio of 1wt%. After the green body powder and the aid were fully uniform, they were placed in a 10 L ball mill and water accounting for 43% of the green body mass was added. The above whole was ball milled for 2 h at a material-ball ratio of 1:10 and a rotation speed of 50 rpm / min, and then poured into a gypsum mold. After solidification, the mold was removed, and the ceramic sample strip was placed in an oven at 80°C for 24 h. The dried sample strip was placed in a muffle furnace. according to The ceramic body is obtained by sintering according to the sintering process of lithium-free low-temperature ceramic sintering aid and then cooling to room temperature. .

[0027] Example 2

[0028] (1) Preparation of lithium-free low-temperature ceramic sintering aids:

[0029] Quartz 61 wt%, Al203 10 wt%, CaO 3 wt%, MgO 2 wt%, K20 4 wt%, Na20 5 wt%, B203 15 wt% were mixed and stirred uniformly, then the uniformly mixed raw materials were poured into an alumina crucible, then the crucible was placed in a muffle furnace, the muffle furnace was heated from 20 °C to 600 °C at a heating rate of 3.2 °C / min, and held for 30 min, then heated from 600 °C to 920 °C at a heating rate of 3.2 °C / min, then heated from 920 °C to 1100 °C at a heating rate of 1.5 °C / min, and held for 120 min, and then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid.

[0030] (2) Ceramic firing:

[0031] The prepared aid lithium-free low-temperature ceramic sintering aid was crushed to pass through a 120 mesh sieve, and then added to the ceramic body powder at a proportion of 1.5 wt%. After the body powder and the aid were fully and uniformly mixed, they were placed in a 10 L ball mill tank and 43% water by mass of the body was added. The whole was ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after setting, the mold was removed. The ceramic sample strip was placed in an oven at 80 °C and dried for 24 h. After drying, the sample strip was placed in a muffle furnace, and sintered according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After cooling to room temperature, a ceramic body was obtained.

[0032] Example 3

[0033] (1) Preparation of lithium-free low-temperature ceramic sintering aid:

[0034] Quartz 61 wt%, Al203 10 wt%, CaO 3 wt%, MgO 2 wt%, K20 4 wt%, Na20 5 wt%, B203 15 wt% were mixed and stirred uniformly, then the uniformly mixed raw materials were poured into an alumina crucible, then the crucible was placed in a muffle furnace, the muffle furnace was heated from 20 °C to 600 °C at a heating rate of 3.2 °C / min, and held for 30 min, then heated from 600 °C to 920 °C at a heating rate of 3.2 °C / min, then heated from 920 °C to 1100 °C at a heating rate of 1.5 °C / min, and held for 120 min, and then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid.

[0035] (2) Ceramic firing:

[0036] The prepared lithium-free low-temperature ceramic sintering aid is crushed through a 120 mesh sieve and added to the ceramic body powder at a proportion of 2 wt%. After the body powder and the aid are fully and uniformly mixed, they are placed in a 10 L ball mill tank and 43% water by mass of the body is added. The whole is ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after solidification, the mold is removed. The ceramic sample strip is placed in an oven at 80°C for drying for 24 h, and after drying, the sample strip is placed in a muffle furnace and sintered according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After sintering is completed, the ceramic body is cooled to room temperature.

[0037] Example 4

[0038] (1) Preparation of lithium-free low-temperature ceramic sintering aid:

[0039] The quartz 61 wt%, Al2O3 10 wt%, CaO 3 wt%, MgO 2 wt%, K2O 4 wt%, Na2O 5 wt%, and B2O3 15 wt% are mixed and stirred uniformly, then the uniformly mixed raw materials are poured into an alumina crucible, and then the crucible is placed in a muffle furnace. The muffle furnace is heated from 20°C to 600°C at a heating rate of 3.2°C / min, held for 30 min, heated from 600°C to 920°C at a heating rate of 3.2°C / min, and then heated from 920°C to 1100°C at a heating rate of 1.5°C / min, held for 120 min, and cooled to room temperature to obtain the lithium-free low-temperature ceramic sintering aid.

[0040] (2) Ceramic firing:

[0041] The prepared lithium-free low-temperature ceramic sintering aid is crushed through a 120 mesh sieve and added to the ceramic body powder at a proportion of 2.5 wt%. After the body powder and the aid are fully and uniformly mixed, they are placed in a 10 L ball mill tank and 43% water by mass of the body is added. The whole is ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after solidification, the mold is removed. The ceramic sample strip is placed in an oven at 80°C for drying for 24 h, and after drying, the sample strip is placed in a muffle furnace and sintered according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After sintering is completed, the ceramic body is cooled to room temperature.

[0042] Example 5

[0043] (1) Preparation of lithium-free low-temperature ceramic sintering aid:

[0044] Quartz 61 wt%, Al203 10 wt%, CaO 3 wt%, MgO 2 wt%, K20 4 wt%, Na20 5 wt%, B203 15 wt% were mixed and stirred uniformly, then the uniformly mixed raw materials were poured into an alumina crucible, then the crucible was placed in a muffle furnace, the muffle furnace was heated from 20 °C to 600 °C at a heating rate of 3.2 °C / min, and held for 30 min, then heated from 600 °C to 920 °C at a heating rate of 3.2 °C / min, then heated from 920 °C to 1100 °C at a heating rate of 1.5 °C / min, and held for 120 min, and then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid.

[0045] (2) Ceramic firing:

[0046] The prepared aid lithium-free low-temperature ceramic sintering aid was crushed to pass through a 120 mesh sieve, and then added to the ceramic body powder at a proportion of 3 wt%. After the body powder and the aid were fully and uniformly mixed, they were placed in a 10 L ball mill tank and 43% water based on the mass of the body was added. The whole was ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after setting, the mold was removed. The ceramic sample strip was placed in an oven at 80 °C and dried for 24 h. After drying, the sample strip was placed in a muffle furnace, and sintering was carried out according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After cooling to room temperature, a ceramic body was obtained.

[0047] Example 6

[0048] (1) Preparation of lithium-free low-temperature ceramic sintering aid:

[0049] Quartz 61 wt%, Al203 10 wt%, CaO 3 wt%, MgO 2 wt%, K20 4 wt%, Na20 5 wt%, B203 15 wt% were mixed and stirred uniformly, then the uniformly mixed raw materials were poured into an alumina crucible, then the crucible was placed in a muffle furnace, the muffle furnace was heated from 20 °C to 600 °C at a heating rate of 3.2 °C / min, and held for 30 min, then heated from 600 °C to 920 °C at a heating rate of 3.2 °C / min, then heated from 920 °C to 1100 °C at a heating rate of 1.5 °C / min, and held for 120 min, and then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid.

[0050] (2) Ceramic firing:

[0051] The prepared lithium-free low-temperature ceramic sintering aid is crushed through a 120 mesh sieve and added to the ceramic body powder at a proportion of 3.5 wt%. After the body powder and the aid are fully and uniformly mixed, they are placed in a 10 L ball mill tank and 43% water by mass of the body is added. The whole is ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after solidification, the mold is removed. The ceramic sample strip is placed in an oven at 80°C for drying for 24 h, and after drying, the sample strip is placed in a muffle furnace and sintered according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After sintering is completed, the ceramic body is cooled to room temperature.

[0052] Example 7

[0053] (1) Preparation of lithium-free low-temperature ceramic sintering aid:

[0054] The quartz 61 wt%, Al2O3 10 wt%, CaO 3 wt%, MgO 2 wt%, K2O 4 wt%, Na2O 5 wt%, and B2O3 15 wt% are mixed and stirred uniformly, then the uniformly mixed raw materials are poured into an alumina crucible, and then the crucible is placed in a muffle furnace. The muffle furnace is heated from 20°C to 600°C at a heating rate of 3.2°C / min, held for 30 min, heated from 600°C to 920°C at a heating rate of 3.2°C / min, and then heated from 920°C to 1100°C at a heating rate of 1.5°C / min, held for 120 min, and cooled to room temperature to obtain the lithium-free low-temperature ceramic sintering aid.

[0055] (2) Ceramic firing:

[0056] The prepared lithium-free low-temperature ceramic sintering aid is crushed through a 120 mesh sieve and added to the ceramic body powder at a proportion of 4 wt%. After the body powder and the aid are fully and uniformly mixed, they are placed in a 10 L ball mill tank and 43% water by mass of the body is added. The whole is ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after solidification, the mold is removed. The ceramic sample strip is placed in an oven at 80°C for drying for 24 h, and after drying, the sample strip is placed in a muffle furnace and sintered according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After sintering is completed, the ceramic body is cooled to room temperature.

[0057] Example 8

[0058] (1) Preparation of lithium-free low-temperature ceramic sintering aid:

[0059] Quartz 61 wt%, Al203 10 wt%, CaO 3 wt%, MgO 2 wt%, K20 4 wt%, Na20 5 wt%, B203 15 wt% were mixed and stirred uniformly, then the uniformly mixed raw materials were poured into an alumina crucible, then the crucible was placed in a muffle furnace, the muffle furnace was heated from 20°C to 600°C at a heating rate of 3.2°C / min, and kept for 30 min, then heated from 600°C to 920°C at a heating rate of 3.2°C / min, then the muffle furnace was heated from 920°C to 1100°C at a heating rate of 1.5°C / min and kept for 120 min, and then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid.

[0060] (2) Ceramic firing:

[0061] The prepared aid lithium-free low-temperature ceramic sintering aid was crushed to pass through a 120 mesh sieve, and then added to the ceramic body powder at a proportion of 4.5 wt%. After the body powder and the aid were fully and uniformly mixed, they were placed in a 10 L ball mill tank and 43% water based on the mass of the body was added. The whole was ball milled at a material-to-ball ratio of 1:10 and a rotation speed of 50 rpm / min for 2 h, then poured into a gypsum mold, and after solidification, the mold was removed. The ceramic sample strip was placed in an oven at 80°C and dried for 24 h. After drying, the sample strip was placed in a muffle furnace, and sintering was carried out according to the sintering process of the lithium-free low-temperature ceramic sintering aid. After cooling to room temperature, a ceramic body was obtained.

[0062] Comparative Example 1

[0063] The same as Example 1, except that only ceramic firing was carried out, and no lithium-free low-temperature ceramic sintering aid was added.

[0064] Comparative Example 2

[0065] The same as Example 1, except that a commercially available lithium-containing low-temperature sintering aid was used for ceramic firing. The lithium-containing low-temperature sintering aid was 5 wt%.

[0066] Test Example 1

[0067] The ceramic materials prepared by the inventive example and the comparative examples were prepared into samples of the same specification, and the strength, water absorption, flexibility and shrinkage of the samples were tested.

[0068] The test method is as follows:

[0069] Flexural strength: After measuring the size of the sample and determining the span, a universal testing machine test was used, and the maximum force at break was recorded. The three-point flexural strength formula is: P = 3xFxL / 2xaxb 2

[0070] Wherein: P-anti-bending strength, Mpa; F-maximum force, N; L-span, mm; a-width, mm; b-thickness, mm, reference standard: GB / T 6569-2006;

[0071] Water absorption: the dry weight of the sample is recorded as M1, boiled in distilled water for 2 h and soaked for 20 h, and the weight after absorption is measured as M2;

[0072] The absorption rate calculation formula is: W=(M2-M1) / M1×100%

[0073] Wherein: W-absorption rate, %; M1-dry mass, g; M2-saturated mass, g, reference standard: ASTM C373-88(2006);

[0074] Caliper deformation test method: the sample strip of 25 cm×2.3 cm×1 cm is suspended and fired in a 1100℃ muffle furnace, the sample is naturally curved by gravity, the thickness at different positions is measured and averaged as S, and the vertical distance L between the bending vertex and the horizontal line at both ends is measured on the coordinate paper;

[0075] Wq=L×S2 / 100

[0076] Wherein, Wq-bending height, mm; L-vertical distance between the bending vertex and the horizontal line at both ends, cm; S-thickness, mm; the bending height is 14-20 mm, which is qualified;

[0077] Shrinkage: a 10 cm long straight line scratch is etched on the surface of the unsintered ceramic sample strip, and the length of the straight line scratch on the surface of the sintered ceramic sample is measured;

[0078] The shrinkage test formula is: Ws=(10-I)×100%

[0079] Wherein, Ws-shrinkage, %; I-length after sintering, cm, shrinkage <9% is qualified.

[0080] The test results are as follows:

[0081]

[0082] The principles and implementation modes of the present application are described herein by applying specific examples, and the above example description is only used to help understand the method and core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In view of the above, the content of the specification should not be understood as a limitation of the present application.

Claims

1. Application of a lithium-free low-temperature ceramic sintering aid in ceramic firing, characterized in that: The lithium-free low-temperature ceramic sintering aid is composed of the following raw materials in percentage by weight: Quartz 61wt%, Al2O3 10wt%, CaO 3wt%, MgO 2wt%, K2O 4wt%, Na2O 5wt%, B2O3 15wt%; The preparation method of the lithium-free low-temperature ceramic sintering aid is as follows: 61 wt% of quartz, 10 wt% of Al2O3, 3 wt% of CaO, 2 wt% of MgO, 4 wt% of K2O, 5 wt% of Na2O, and 15 wt% of B2O3 were mixed and stirred uniformly, and then the uniformly mixed raw materials were poured into an alumina crucible, and then the crucible was placed in a muffle furnace, and the muffle furnace was heated from 20°C to 600°C at a heating rate of 3.2°C / min and kept warm for 30 min, then heated from 600°C to 920°C at a heating rate of 3.2°C / min, and then heated from 920°C to 1100°C at a heating rate of 1.5°C / min and kept warm for 120 min, and then cooled to room temperature to obtain a lithium-free low-temperature ceramic sintering aid; The amount of the lithium-free low-temperature ceramic sintering aid added is 1wt%-5wt% of the ceramic green body powder; The ceramic body is composed of the following components: SiO2 67.02wt%, Al2O3 26.94wt%, Fe2O3 1.25wt%, MgO 0.39wt%, CaO 1.06wt%, Na2O 0.61wt%, K2O 2.35wt%, and TiO2 0.38wt%.

2. The use according to claim 1, characterized in that The steps are as follows: a lithium-free low-temperature ceramic sintering aid is crushed and passed through an 80-120 mesh sieve, then added to ceramic body powder and mixed evenly; an appropriate amount of water is added to the powder and then ball-milled to obtain a ceramic body slurry; the slurry is poured into a mold to form a ceramic green body; the green body is dried and sintered; and after sintering, the ceramic body is cooled to room temperature to obtain the ceramic body.

3. The use according to claim 2, characterized in that The amount of water added is 40wt%-45wt% of the ceramic green body powder.

4. The use according to claim 2, characterized in that The calcination adopts a staged heating and holding process, specifically: heating from 20°C to 600°C at a heating rate of 3.2°C / min, holding for 20-50 min, heating from 600°C to 920°C at a heating rate of 3.2°C / min, heating from 920°C to 1100°C at a heating rate of 1.5°C / min, and holding for 100-150 min.

5. The use according to claim 2, characterized in that The ball-to-material ratio was 1:10, the ball-milling speed was 50 rpm / min, and the ball-milling time was 2 h.

6. The use according to claim 2, characterized in that The drying temperature is 80° C. and the drying time is 24 h.

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