ZHENGSHAN TECHNOLOGY

Graphite electrodes are widely used in molds, crucibles, electrodes, batteries, brushes and other fields because of their high abrasion resistance, high temperature resistance, and good electrical conductivity.However, graphite is strong and brittle, and it is prone to collapse during traditional processing, especially in high temperature and oxidizing environments. Its oxidation resistance is poor, resulting in limited service life.In order to improve the oxidation resistance of graphite electrodes, researchers have adopted a variety of methods. Among them, chemical vapor deposition (CVD) technology is an effective method.

1. Introduction to CVD technology

Chemical vapor deposition (CVD) is a technique for forming a thin film on a solid surface through a chemical reaction in a gaseous precursor.This method has the advantages of simple process, uniform coating, and strong designability, and is widely used in the preparation of coatings of various materials.

2. Application of CVD technology in the oxidation resistance of graphite electrodes

Preparation of SiC/C gradient surface coating

Through CVD technology, a layer of SiC/C gradient surface coating can be formed on the surface of the graphite electrode.In this method, the graphite electrode is first surface pretreated, and then it is fixed in the water-cooled reactor of the CVD equipment for vacuum treatment.Then, the graphite electrode in the reactor is heated and methane (CH4) gas is introduced to form a layer of pyrolytic carbon on the surface of the graphite electrode.Subsequently, the temperature of the furnace chamber is kept unchanged, and the carrier gas hydrogen (H2) is introduced, so that H2 carries silicon tetrachloride (SiCl4) gas, reacts with CH4 gas on the surface of the graphite electrode and deposits it to form a SiC/C gradient coating.Finally, in situ heat treatment is carried out to make the coating more stable.

This SiC/C gradient surface coating can effectively improve the oxidation resistance of graphite electrodes.Due to the good permeability of the coating, it can penetrate into the fine pores on the surface of the graphite electrode, thereby effectively resisting the oxidation of the surface voids.

Multilayer CVD-SiC coating

In order to further improve the oxidation resistance of graphite electrodes, researchers have also developed a multi-layer CVD-SiC coating.This kind of coating is usually composed of multiple layers of SiC materials of different composition, such as CVD-SiC/MoSi2-CrSi2-Si/B-modified SiC and so on.The multi-layer structure can more effectively block the diffusion of oxygen, thereby improving the oxidation resistance of graphite electrodes.

SiC fiber composite coating

In addition to the simple SiC coating, SiC fibers can also be combined with SiC coatings to form SiC fiber composite coatings.This coating combines the advantages of SiC/SiC and CVD-SiC to further improve the oxidation resistance of graphite electrodes.The addition of SiC fiber can enhance the strength and toughness of the coating, making it more wear-resistant and corrosion-resistant.

3. The advantages of CVD technology in the oxidation resistance of graphite electrodes

Improve antioxidant properties

CVD technology can form a dense SiC coating on the surface of the graphite electrode, which can effectively block the diffusion of oxygen, thereby improving the oxidation resistance of the graphite electrode.

Enhanced wear resistance

SiC coating has high hardness and wear resistance, which can significantly improve the wear resistance of graphite electrodes and extend their service life.

Improve thermal stability

SiC coating has good thermal stability and can maintain stable performance in high temperature environments, thereby ensuring the normal operation of graphite electrodes at high temperatures.