Forming method of graphite crucible

Abstract

The invention provides a graphite crucible forming method which comprises the following steps: S1, graphite, refractory clay and aggregate which are used as raw materials are screened, the graphite is natural graphite or artificial graphite, the specific gravity of the graphite is 45%-55%, and the carbon content of the graphite is 85%-95%; the granularity is required to be below 100 meshes; the content of silicate particles in the refractory clay is 60%-90%; the refractoriness is higher than 1580 DEG C; s2, graphite, refractory clay and aggregate which serve as raw materials are crushed into powder, the crushed graphite powder and refractory clay are subjected to dry mixing, the aggregate is added after dry mixing is completed, heating and wet mixing are conducted, and a mixture is obtained; s3, uniformly pressing the mixture obtained in the step S2, aging for multiple times, scattering and pressing a lump, cutting the lump and beating the lump into a tank, carrying out rotary molding, pre-dry-cleaning the tank, drying, glazing, and sintering to obtain a primary finished product; and S4, inspecting the finished product obtained in the step S3 to obtain a finished product. According to the forming method of the graphite crucible, the preparation technological process is simple, the preparation period is short, the production cost is low, and the comprehensive performance of the graphite crucible is excellent.

Description

Technical Field

[0001] The invention relates to the technical field of graphite crucible forming methods, and in particular to a graphite crucible forming method. Background Art

[0002] Graphite crucible has good thermal conductivity and high temperature resistance. During high temperature use, the thermal expansion coefficient is small, and it has a certain resistance to strain from rapid heating and cooling. At the same time, it has excellent chemical stability and has good resistance to acid and alkaline solutions. In metallurgy, casting, machinery, chemical industry and other industrial sectors, it is widely used in metal smelting, purification of lithium battery negative electrode materials, smelting of polysilicon materials, ingot casting and other operations. Its service life has a great impact on productivity and economic benefits.

[0003] When preparing the graphite crucible, firstly, crystalline natural graphite or artificial graphite is used as the main raw material and asphalt as a binder is stirred and kneaded, and then after kneading, it is pressed into a green body by static pressure process, and then the pressed green body is calcined and heat-treated under vacuum conditions.

[0004] For the finished graphite crucible, the differences in quality and performance are mainly reflected in the differences in raw materials, process operation conditions and other factors. The performance and life of crucibles produced under different technical conditions are inconsistent. Among them, the influence of asphalt in the raw materials on the quality of the finished graphite crucible is mainly reflected in the roasting stage. It can transform the asphalt as a binder into coke during the heat treatment process and be wrapped in the transition layer between the carbon particles. After the asphalt is converted into coke at high temperature, it will build an interface carbon grid layer in the semi-finished product, which has the effect of tower bridge and reinforcement. The performance of the roasted product is good or not, to a large extent, it is determined by the uniformity of the asphalt in the green body after pressing and the change of asphalt during roasting: Among them, the uniformity of the asphalt in the green body directly affects the uniformity of the internal structure of the graphite crucible material after molding. At the same time, the asphalt has rheological properties after softening. The softened asphalt component will flow to the gravity side due to gravity flow in the green body, and then in the subsequent graphitization process, it will cause defects in the internal uniformity of the formed graphite rod, which will also affect the quality of the finished graphite rod. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a method for forming a graphite crucible, comprising:

[0006] S1 screens graphite, refractory clay and aggregate as raw materials, among which,

[0007] The graphite is natural graphite or artificial graphite, the specific gravity of the graphite is 45%-55%, the carbon content is 85%-95%; the particle size is required to be less than 100 mesh;

[0008] The silicate particle content of the refractory clay is 60%-90%; the refractoriness is higher than 1580°C;

[0009] S2: crushing the graphite, refractory clay and aggregate as raw materials into powder, dry-mixing the crushed graphite powder and refractory clay, and adding aggregate after dry-mixing to heat and wet-mix to obtain a mixture;

[0010] S3: the mixed material obtained in step S2 is pressed evenly → aged for multiple times → pressed into a ball → cut into pieces and canned → roto-molded → pre-dry-cleaned → dried → glazed → sintered → initially finished product;

[0011] S4 inspects the finished product of step S3 to obtain the finished product.

[0012] Preferably, the chemical composition mass percentages of the refractory clay are: SiO2 40%-56%, Al2O3 25%-45%, Fe2O3 0.5%-3%, CaO 0.5%-0.8%; MgO 0.2%-0.6%, K2O 0.5%-1%, Na2O 0.5%-0.2%, and the rest are impurities.

[0013] Preferably, the aggregate is pyrophyllite, pyrophyllite, silica and silicon carbide.

[0014] Preferably, before glazing, remove dust and floating objects from the crucible surface, then use a brush to dip the glaze slurry and brush it from top to bottom, then brush it horizontally, and finally smooth it and brush it to keep the glaze evenly covered. After the glaze on the crucible mouth is dry, brush it again.

[0015] Preferably, the thickness of the glaze layer is 1.5 mm-2 mm.

[0016] Preferably, when the sintering temperature reaches the highest temperature in S4, the sintering is stopped and kept warm for 8 hours, and then the temperature is gradually lowered and cooled, and the sintering is taken out of the kiln after 24 hours.

[0017] Beneficial Effects of the Invention

[0018] The invention provides a graphite crucible forming method, which has simple preparation process flow, short preparation cycle, low production cost and excellent comprehensive performance of the graphite crucible. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0020] The present invention provides a method for forming a graphite crucible, comprising:

[0021] S1 screens graphite, refractory clay and aggregate as raw materials, among which,

[0022] The graphite is natural graphite or artificial graphite, the specific gravity of the graphite is 45%-55%, the carbon content is 85%-95%; the particle size is required to be less than 100 mesh;

[0023] The silicate particle content of the refractory clay is 60%-90%; the refractoriness is higher than 1580°C;

[0024] S2: crushing the graphite, refractory clay and aggregate as raw materials into powder, dry-mixing the crushed graphite powder and refractory clay, adding aggregate after dry-mixing, heating and wet-mixing to obtain a mixture;

[0025] S3: the mixed material obtained in step S2 is pressed evenly → aged for multiple times → pressed into a ball → cut into pieces and canned → roto-molded → pre-dry-cleaned → dried → glazed → sintered → initially finished product;

[0026] S4 inspects the finished product of step S3 to obtain the finished product.

[0027] Example 1: To produce large crucibles above 100#, graphite with a particle size of 32 mesh is used.

[0028] Example 2: To produce crucibles of size 100-50, graphite with a particle size of 80 mesh is used.

[0029] The chemical composition mass percentage of the refractory clay is: SiO2 40%-56%, Al2O3 25%-45%, Fe2O3 0.5%-3%, CaO 0.5%-0.8%; MgO 0.2%-0.6%, K2O 0.5%-1%, Na2O 0.5%-0.2%, and the rest are impurities.

[0030] Example 3: The chemical composition mass percentages of the refractory clay are: SiO2 40%, Al2O3 45%, Fe2O3 0.5%, CaO 0.5%; MgO 0.2%, K2O 0.5%, Na2O 0.5%, and the rest are impurities.

[0031] Example 4: The chemical composition mass percentages of the refractory clay are: SiO2 56%, Al2O3 25%, Fe2O3 3%, CaO 0.8%; MgO 0.6%, K2O 1%, Na2O 0.2%, and the rest are impurities.

[0032] Example 5, the chemical composition mass percentage of the refractory clay is: SiO2 55%, Al2O3 23%, Fe2O3 4%, CaO 0.5%; MgO 0.6%, K2O 1%, Na2O 0.11%, and the rest are impurities.

[0033] In one embodiment, the aggregate is pyrophyllite, pyrophyllite, silica and silicon carbide.

[0034] In one embodiment, dust and floating objects on the crucible surface are first removed before glazing. Then, a brush is used to apply glaze slurry from top to bottom, and then horizontally. Finally, the glaze is smoothed and brushed to ensure uniform glaze coverage. The crucible mouth is brushed again after the glaze is dry.

[0035] In one embodiment, the thickness of the glaze layer is 1.5 mm-2 mm.

[0036] In one embodiment, when the sintering temperature reaches the highest temperature in S4, the sintering is stopped and kept warm for 8 hours, and then the temperature is gradually lowered and cooled, and the sintered product is taken out of the kiln after 24 hours.

[0037] Beneficial Effects of the Invention

[0038] The invention provides a graphite crucible forming method, which has simple preparation process flow, short preparation cycle, low production cost and excellent comprehensive performance of the graphite crucible.

[0039] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention.

Claims

1. A method for forming a graphite crucible, characterized in that: include: S1 screens graphite, refractory clay and aggregate as raw materials, among which, The graphite is natural graphite or artificial graphite, the specific gravity of the graphite is 45%-55%, the carbon content is 85%-95%; the particle size is required to be less than 100 mesh; The silicate particle content of the refractory clay is 60%-90%; the refractoriness is higher than 1580°C; S2: crushing the graphite, refractory clay and aggregate as raw materials into powder, dry-mixing the crushed graphite powder and refractory clay, and adding aggregate after dry-mixing to heat and wet-mix to obtain a mixture; S3: the mixed material obtained in step S2 is pressed evenly → aged for multiple times → pressed into a ball → cut into pieces and canned → roto-molded → pre-dry-cleaned → dried → glazed → sintered → initially finished product; S4 inspects the finished product of step S3 to obtain the finished product.

2. The method for forming a graphite crucible according to claim 1, characterized in that: The chemical composition mass percentage of the refractory clay is: SiO2 40%-56%, Al2O3 25%-45%, Fe2O3 0.5%-3%, CaO 0.5%-0.8%; MgO 0.2%-0.6%, K2O 0.5%-1%, Na2O 0.5%-0.2%, and the rest are impurities.

3. The method for forming a graphite crucible according to claim 1, characterized in that: The aggregates are pyrophyllite, pyrophyllite, silica and silicon carbide.

4. The method for forming a graphite crucible according to claim 1, characterized in that: Before applying glaze, first remove dust and floating objects on the surface of the crucible, then use a brush to dip the glaze slurry and brush it from top to bottom, then brush it horizontally, and finally smooth it out and brush it to keep the glaze evenly covered. Brush the crucible mouth again after the glaze is dry.

5. The method for forming a graphite crucible according to claim 4, characterized in that: The thickness of the glaze layer is 1.5mm-2mm.

6. The method for forming a graphite crucible according to claim 1, characterized in that: When the sintering temperature in S4 reaches the highest temperature, stop the fire and keep warm for 8 hours, then gradually cool down and take out of the kiln after 24 hours.