Application and Development of C/C Composite Materials in Photovoltaic Field

Carbon/carbon thermal field materials are essential consumables in the production of photovoltaic single crystal furnaces. The main product forms include crucibles, guide tubes, insulation tubes, heaters, etc. for single crystal drawing furnaces. Among different components, graphite thermal field materials mainly composed of isostatic pressed graphite can meet the drawing requirements before 2016. But subsequently, carbon/carbon thermal fields have played an increasingly important role, mainly reflected in:

From Figure 1, it can be seen that there is a trend towards larger thermal fields, and carbon/carbon composite materials provide the possibility for larger thermal fields. The large-sized thermal field component products play a supporting role in the development of the diameter enlargement of monocrystalline silicon rods;

据统计，2022年，P型单晶硅片

The total market share of N-type monocrystalline silicon wafers is about 97.5%, with P-type monocrystalline silicon wafers accounting for 87.5% and N-type monocrystalline silicon wafers accounting for 10%. It is expected that the market share of N-type monocrystalline silicon wafers will increase to 30% by 2023 and may exceed 50% by 2025. The problem of relying on imported key consumables will constrain the development of the industry, therefore, domestic carbon/carbon thermal fields will further replace imported isostatic pressed graphite products in the future, and the penetration rate of carbon/carbon thermal fields will continue to increase.

In terms of raw material costs, carbon fiber preforms are the largest part, accounting for over 80%. Self made preforms can reduce costs, but the technical barrier is relatively high. From the cost composition of carbon/carbon thermal field, manufacturing expenses account for up to 54%, mainly including reaction auxiliary materials, electricity, depreciation, etc. Depreciation is the largest part of manufacturing expenses, accounting for about 60%. The main difference between leading companies and other companies comes from depreciation. The way to reduce depreciation is to increase equipment output per unit time, independently develop and produce equipment, which mainly relies on the technological research and development capabilities of each company. In addition, electricity accounts for about 16% of manufacturing costs (which may vary depending on the process), and the main way to reduce it is to build factories in areas with low electricity prices.

In addition, carbon materials used in the thermal field of crystalline silicon furnaces are susceptible to corrosion in silicon steam. Silicon vapor mainly diffuses into the interior of the material through its pores and defects for corrosion, causing a large number of cracks on the surface of the material and serious damage to the interior of C/C composite materials and hard carbon felt materials. It is necessary to study how to effectively control the peeling of carbon matrix and carbon fiber, as well as issues such as necking and splitting of carbon fiber.

Carbon/carbon composite materials have excellent properties such as light weight, low thermal expansion coefficient, high temperature resistance, corrosion resistance, stable friction coefficient, and good thermal conductivity. In addition to being used to manufacture high-temperature thermal field components, they are also the best candidate materials for friction components and can be widely used in fields such as semiconductor, aerospace, and braking.