Graphite material for monocrystalline silicon growth thermal field in solar photovoltaic industry and production method thereof

Abstract

The invention relates to a graphite material for a monocrystalline silicon growth thermal field in a solar photovoltaic industry. In the graphite material, an aggregate is calcined petroleum coke, wherein the true density of the calcined petroleum coke is more than or equal to 2.1g / cm <3>, and the ash content of the calcined petroleum coke is less than or equal to 0.3%; a binder is medium temperature pitch, wherein the softening point of the medium temperature pitch is 83-86 DEG C, and the coking value of the medium temperature pitch is more than or equal to 49%; and the volume density of the graphite material is larger than or equal to 1.80g / cm<3>, the resistivity of the graphite material is less than or equal to 7.0 mu omega m, the compression strength of the graphite material is larger than or equal to 38Mpa, the rupture strength of the graphite material is more than or equal to 18Mpa, the porosity of the graphite material is less than or equal to 14%, the ash content of the graphite material is less than or equal to 0.2%, and the thermal expansion coefficient of the graphite material is less than or equal to 2*10<-6> / DEG C. The preparation method of the graphite material comprises the following steps: smashing raw materials, sieving, burdening, kneading, molding, primarily roasting, secondarily roasting, secondarily dipping, and thirdly roasting; and graphitizing, thus obtaining a finished product.

Description

technical field [0001] The invention relates to a graphite material, in particular to a graphite material for a solar photovoltaic industry monocrystalline silicon growth heat field and a manufacturing method thereof. Background technique [0002] Solar energy is a clean, safe and reliable energy source. The best way to use solar energy is photovoltaic conversion, which is to use the photovoltaic effect to make sunlight shine on silicon materials to generate electricity directly. The photovoltaic industry is an industrial chain formed by the application and development of silicon materials, including the production of high-purity monocrystalline silicon and polycrystalline silicon raw materials, solar cell production, solar cell module production, and related production equipment manufacturing. [0003] The thermal field of monocrystalline silicon growth mainly includes quartz crucible, graphite crucible (three-petal pot), heater, guide tube, inner insulation body (lining), ...

AI Technical Summary

Problems solved by technology

[0005] Chinese patent 201010263217.3 discloses a graphite material for solar thermal power generation and energy storage, with a bulk density of ≥1.75g / cm 3 , resistivity ≤ 7.5μΩm, ​​ash content ≤ 0.2%, flexural strength ≥ 18.5Mpa, elastic modulus ≤ 8.8Gpa, thermal expansion coefficient ≤ 2.0×10 -6 / °C -1 , its physical and chemical properties cannot meet the performance requirements of graphite materials for single crystal silicon growth thermal field

[0006] The graphite material disclosed in Chinese patent 200710090789 is made of calcined petroleum coke, crushed graphite and medium-temperature pitch, with a purity of ≥99% and a bulk density of ≥1.68g / cm 3 , and its physical and chemical properties cannot meet the performance requirements of graphite materials for single crystal silicon growth thermal field

The pressure exerted by the isostatic pressing molding technology is relatively high, generally P≥160mpa, and with the increase of product specifications, the pressure requirements are also large; on the other hand, the particle size of the raw material formula is small (0.0425mm), and its subsequent roasting , impregnation, graphitization and other processes, and the process parameters are not easy to grasp. Therefore, the technical content of isostatic pressing products is relatively high, and the technical means are extremely complicated. Correspondingly, the price of isostatic pressing graphite is also very high, which is 150,000 yuan per ton

At present, the technology of isostatic pressing products has been matured and popularized in foreign industrially developed countries such as Japan, Germany, and the United States. However, the manufacturers capable of producing isostatic graphite in my country are very limited, and most of them produce some low-end and small-sized products. The specific performance is that the size is small, the strength and volume density are not enough, and the high-end, large-size and high-performance products are still in the experimental stage.

Due to the insufficient import of isostatic graphite, the product has a large gap in the domestic market

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