Method for removing carbon deposition on inner wall of air inlet pipe in CVD (Chemical Vapor Deposition) grown graphene powder

Abstract

The invention discloses a method for removing carbon deposition on the inner wall of a gas inlet pipe in CVD (Chemical Vapor Deposition) grown graphene powder, which comprises the following steps: S1, inserting a graphite gas inlet pipe into liquid metal, then introducing mixed gas containing carbon source gas / nitrogen into the liquid metal through the graphite gas inlet pipe, and growing graphene powder in the liquid metal, after the graphene powder continuously grows for a preset time, cutting off the carbon source-containing gas, keeping the nitrogen flow unchanged, and suspending the growth of the graphene powder; s2, the temperature of the molten liquid metal is adjusted; s3, a gas outlet of the graphite gas inlet pipe is moved out of the liquid level of the liquid metal, and then oxygen / nitrogen mixed gas is introduced into the graphite gas inlet pipe; and S4, after the oxygen / nitrogen mixed gas is introduced for a set time, the oxygen is cut off, the nitrogen is kept unchanged, and cooling is conducted. According to the method, carbon deposition on the inner wall of the air inlet pipe can be efficiently removed, operation is easy, the interval time from pausing of growth of the graphene powder to re-growth is short, and the growth efficiency of the graphene powder is high.

Description

technical field [0001] The invention belongs to the technical field of graphene, and in particular relates to a method for removing carbon deposits on the inner wall of an intake pipe in a CVD-grown graphene powder. Background technique [0002] Graphene is a two-dimensional honeycomb crystal material composed of carbon atoms hybridized with SP2. Due to its excellent optical, electrical, and mechanical properties, it has important application prospects in the fields of materials science, micro-nano processing, energy, and biomedicine, so it has attracted extensive attention from many researchers. [0003] At present, the preparation methods of graphene powder include mechanical exfoliation method, redox method and CVD (chemical vapor deposition) method; although mechanical exfoliation method can prepare graphene powder with few defects, the number of graphene layers is thick and the preparation cost is high ; Although the redox method can prepare graphene powder at a lower ...

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Problems solved by technology

However, when graphene powder is grown in molten metal by CVD method, as the growth continues, the long-chain by-products of methane cracking will deposit carbon on the inner wall of the inlet nozzle inserted into the molten metal, causing the inlet pipe The inner diameter of the mouth continues to decrease, which eventually causes the airflow to be blocked, so that it is impossible to continue to aerate and grow graphene powder

[0005] Currently commonly used methods to remove carbon deposits in the intake pipe: the first is to use a drill to drill out the carbon deposits on the inner wall of the intake pipe; The rate of carbon deposition on the wall; at present, there are certain defects in both methods: the first method must stop the growth, the temperature in the high-temperature furnace drops to room temperature, open the furnace cover, and take out the intake pipe to use a drill to drill the inner wall of the intake pipe. Carbon drilling, this method not only has a long interval between graphene growth before and after, but also increases energy consumption after repeated heating and cooling, and the powder growth efficiency is low; while the second method can slow down the speed of carbon deposition on the inner wall of the intake pipe, However, the pyrolysis efficiency of carbon-containing gas will also decrease, which will affect the growth efficiency of graphene powder

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