Lithium-free ceramic formula and production process method thereof

Abstract

A lithium-free ceramic formula and a production process method thereof belong to the technical field of ceramic production, and the formula comprises 32-38% of fused quartz, 25-30% of kaolin, 15-20% of black mud washing mud, 10% of cordierite and 10% of synthetic frit. The fused quartz and the cordierite are selected in the formula, the fused quartz and the cordierite are sintered to form a double-crystal-phase component with a low expansion coefficient, and the fused quartz and the cordierite are crystal phases with a small thermal expansion coefficient, so that the thermal shock resistance of the ceramic material is remarkably improved. In the raw material preparation process, a raw material grain composition control method is adopted, and the raw materials are gradually added into the formula step by step, so that the raw materials are mixed more uniformly, and the grain composition of the slurry is more reasonable. And by setting a reasonable firing temperature curve, the formation of a fired crystal phase is further ensured, inversion of the crystal phase is prevented, and the stability of thermal shock resistance of the ceramic material is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic production, and in particular relates to a lithium-free ceramic formula and a production process thereof. Background Art

[0002] Household ceramic products are widely recognized by the market and consumers for their good cooking performance and health characteristics. Their application scenarios have also rapidly developed from stewing to frying, stir-frying, stewing, braising, steaming, boiling, etc. As the application scenarios gradually expand, the disadvantages of poor thermal shock resistance of traditional ceramic materials are gradually exposed, that is, they cannot withstand frequent thermal fluctuations, and are prone to explosion accidents when used in such scenarios.

[0003] In order to solve this problem, the industry has previously added a certain proportion of lithium to the clay composition of ceramic products to improve the performance. The lithium element is usually obtained by grinding and refining the raw materials together with petalite and spodumene to obtain the clay. The low expansion and high heat resistance of petalite and spodumene greatly improve the thermal shock resistance of traditional ceramic materials.

[0004] Due to the low amount of petalite and spodumene in my country and their poor quality, petalite and spodumene are currently mainly imported from abroad. In recent years, the prices of spodumene and petalite have continued to rise, resulting in high costs for ceramic products containing lithium formulas, which even affects the operation of production enterprises and is difficult to be accepted by consumers, seriously affecting the promotion and application of such high-performance ceramic products. If we rely on spodumene and petalite for a long time to improve the thermal shock resistance of ceramic products, spodumene and petalite will become a "bottleneck" problem.

[0005] Therefore, finding alternative materials to improve the thermal shock resistance of ceramic materials, getting rid of dependence on imported spodumene and petalite raw materials, and making them completely localized has become an urgent problem to be solved. Summary of the invention

[0006] The present invention provides a lithium-free ceramic formula and a production process thereof. In the formula, two components, fused quartz and synthetic frit, are selected to form a dual-phase component after firing. Both are crystal phases with a small thermal expansion coefficient, which significantly improves the thermal shock resistance of the ceramic material. In the raw material preparation process, a raw material particle grading control method is adopted, and the formula is gradually added step by step to make the mixing more uniform, thereby obtaining a higher quality mud. By reasonably setting the firing temperature curve, the crystal phase composition after firing is further ensured, the inversion of the crystal phase is prevented, and the thermal shock resistance of the ceramic material is guaranteed. This solves the problems in the above-mentioned background technology.

[0007] The technical problem solved by the present invention is achieved by adopting the following technical solutions: A lithium-free ceramic formula has two situations: 1. Fused quartz: 32~38%, kaolin: 25~30%, black mud washed mud: 15~20%, cordierite 10%, synthetic frit 10%; 2. Fused quartz: 30~40%, kaolin: 25~35%, black mud washed mud: 25~30%, synthetic frit 8~12%.

[0008] In the above lithium-free ceramic formula, the Al content of kaolin is 2 O 3 >35%, K 2 O+Na 2 O total ≤ 1.5%, black mud washing mud K 2 O+Na 2 Total O content ≤2.0%.

[0009] A production process for a lithium-free ceramic formula: first, the other raw materials except fused quartz and cordierite in the lithium-free ceramic formula are put into a ball mill according to a proportion, and the ball mill is put into a mud pool when the fineness is 0.08% of the residue on a 10,000-hole sieve; then, the fused quartz and cordierite are slowly added to the mud pool in batches and stirred evenly; then, the evenly stirred mud is passed through a 40-mesh sieve to remove iron, filter press, knead mud, and age for use; wherein the fused quartz particle grading is 60-160 mesh, and the cordierite particle grading is 100-200 mesh.

[0010] A firing process for a lithium-free ceramic formula: take lithium-free ceramic clay and heat it at room temperature - 850°C for 220 minutes, 850°C-980°C for 55 minutes, 980°C-1015°C for 30 minutes, 1015°C-1260°C for 165 minutes, and keep it at 1260°C-1260°C for 30-35 minutes. After the insulation, immediately cool it to 1100°C at a cooling rate of 7°C / min, then cool it to 60°C with the furnace and take it out of the kiln. The firing atmosphere is an oxidizing flame firing throughout the process.

[0011] The beneficial effects of the present invention are: The present invention provides a ceramic material formula and production process with completely domestically produced raw materials, which is independently controllable. Fused quartz is used to replace spodumene and petalite in the prior art, thereby getting rid of import dependence. The melting temperature of fused quartz is about 1713℃, the thermal conductivity is low, and the thermal expansion coefficient is almost the smallest among all refractory materials, with a near-zero thermal expansion rate (0.54-0.8×10-6 / ℃), high purity (SiO 2 High content, low content of iron, potassium, sodium, titanium, etc.), has excellent thermal stability, good electrical insulation and good resistance to chemical corrosion.

[0012] In the formula, two components, fused quartz and synthetic frit, are selected to form a dual-phase component after firing. Both are crystal phases with a small thermal expansion coefficient, which significantly improves the thermal shock resistance of the ceramic material.

[0013] During the raw material preparation process, the raw material particle grading control method is adopted, and the formula is gradually added step by step to make the mixing more uniform and obtain higher quality mud.

[0014] By reasonably setting the firing temperature curve, the crystal phase composition after firing can be further ensured, the inversion of the crystal phase can be prevented, and the thermal shock resistance of the ceramic material can be guaranteed. DETAILED DESCRIPTION

[0015] In order to facilitate understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0016] A lithium-free ceramic formula, the components of which are: fused quartz: 32-38%, kaolin: 25-30%, black mud washed mud: 15-20%, cordierite 10%, and synthetic frit 10%.

[0017] Another ratio of a lithium-free ceramic formula, its components are: fused quartz: 30-40%, kaolin: 25-35%, black mud washed mud: 25-30%, synthetic frit 8-12%.

[0018] In the above lithium-free ceramic formula, the Al content of kaolin is 2 O 3 >35%, K 2 O+Na 2 O total ≤ 1.5%, black mud washing mud K 2 O+Na 2 Total O content ≤2.0%.

[0019] A production process for lithium-free ceramic formulation: 1. Put the other raw materials in the lithium-free ceramic formula except fused quartz and cordierite into the ball mill according to the proportion, and grind them to a fineness of 0.08% on a 10,000-hole sieve, then put them into the mud pool; 2. Slowly add fused quartz and cordierite into the above-mentioned mud pool in batches and stir evenly. The particle size of fused quartz is 60-160 mesh, and the particle size of cordierite is 100-200 mesh. 3. After the stirred slurry is passed through a 40-mesh sieve, it is iron-removed, filtered, slurried, and aged for later use. The iron-removal, filtration, slurry-mixing, and aging steps are similar to the conventional ceramic mud preparation process and will not be described in detail here; A firing process for a lithium-free ceramic formula: take the lithium-free ceramic clay prepared above and heat it at room temperature - 850°C for 220 minutes, 850°C-980°C for 55 minutes, 980°C-1015°C for 30 minutes, 1015°C-1260°C for 165 minutes, and keep it at 1260°C-1260°C for 30-35 minutes. After the insulation, immediately cool it to 1100°C at a cooling rate of 7°C / min, then cool it to 60°C with the furnace and take it out of the kiln. The firing atmosphere is an oxidizing flame firing throughout the process.

[0020] The above embodiments mainly illustrate the lithium-free ceramic formulation and its production process of the present invention. Although only limited embodiments and technical features are described, those skilled in the art should understand that the present invention can be implemented in many other forms without departing from its subject matter and scope. Therefore, the embodiments shown are regarded as illustrative rather than restrictive, and the present invention may cover various modifications and replacement schemes without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A lithium-free ceramic formula, characterized in that: The formula is: fused quartz: 32-38%, kaolin: 25-30%, black mud washed mud: 15-20%, cordierite 10%, and synthetic frit 10%.

2. The lithium-free ceramic formulation according to claim 1, characterized in that: The formula is: fused quartz: 30-40%, kaolin: 25-35%, black mud washed mud: 25-30%, and synthetic frit 8-12%.

3. The lithium-free ceramic formulation according to claim 1 or 2, characterized in that: The Al2O3 of the kaolin is greater than 35%, and the total amount of K2O+Na2O is ≤1.5%.

4. The lithium-free ceramic formulation according to claim 1 or 2, characterized in that: The total amount of K2O+Na2O in the black mud washing mud is ≤2.0%.

5. The production process of the lithium-free ceramic formula according to claim 1 or 2, characterized in that: The process is as follows:

1. Putting the other raw materials in the lithium-free ceramic formula except fused quartz and cordierite into a ball mill according to the proportion, and grinding them to a fineness of 0.08% of the residue on a 10,000-hole sieve, and then putting them into a mud pool; 2. Slowly add molten quartz and cordierite into the above-mentioned mud pool in batches and stir evenly. The particle size of molten quartz is 60-160 mesh, and the particle size of cordierite is 100-200 mesh.

3. After the evenly stirred mud is sieved through a 40-mesh sieve, iron is removed, filter pressed, mud kneaded, and aged for later use.

6. The firing process of the clay obtained by the lithium-free ceramic formula production process according to claim 5 is characterized in that: The firing process is as follows: take lithium-free ceramic mud and heat it at room temperature - 850°C for 220 minutes, 850°C - 980°C for 55 minutes, 980°C - 1015°C for 30 minutes, 1015°C - 1260°C for 165 minutes, and keep it at 1260°C - 1260°C for 30-35 minutes. After the heat preservation, immediately cool it to 1100°C at a cooling rate of 7°C / min, then cool it to 60°C with the furnace and take it out of the kiln. The firing atmosphere is oxidizing flame firing throughout the process.