569

High Temperature Oxidation Corrosion Characteristics and Protective Performance Analysis of Graphite

2019/7/30

HC Coatings News: Graphite and its products have high temperature and high strength properties. They are mainly used in the metallurgical industry to manufacture graphite crucibles. In steelmaking, graphite is commonly used as a protective agent for steel ingots and the inner liner of metallurgical furnaces. The materials processed by graphite include graphite electrode, graphite crucible, graphite rod, graphite tube, graphite liner, graphite gasket, etc. According to Zhisheng Weihua Antioxidant Coating Laboratory, these amorphous carbon graphite materials start to oxidize at 400 °C. The qualitative carbon element graphite material is oxidized at about 1000 ° C, and the oxidation rate is above 5%. Some graphite materials have an oxidation rate of up to 30% in high temperature heavy metal medium.

The refractory high temperature material is in contact with oxygen or oxidizing medium at high temperature, and the oxidative weight gain of the material increases with the increase of temperature. The oxidation rate of graphite and porous material is proportional to the fourth power of the temperature, and the initial fine grain of the material When the temperature rises and the time is lengthened, the crystal grains become larger and larger, the grain boundary of the material becomes larger, and the contact with oxygen or the oxidizing medium becomes larger, the cracking and oxidation of the material occurs, the high temperature oxidation is fast, and the material has a short service life.

Graphite has good chemical stability. Specially processed graphite, which has the characteristics of corrosion resistance, good thermal conductivity and low permeability, is widely used in the manufacture of heat exchangers, reaction tanks, condensers, combustion towers, absorption towers, coolers, heaters, filters. , pump equipment. Widely used in petrochemical, hydrometallurgy, acid and alkali production, synthetic fiber, paper and other industrial sectors, can save a lot of metal materials, but graphite oxidation can not be ignored. Based on the above high temperature oxidation conditions, Zhisheng Weihua researched and developed anti-oxidation coatings for high temperature metals and porous materials. For different anti-oxidation conditions, Zhisheng Weihua researched and developed ZS high temperature anti-oxidation coatings under four different working conditions.

This type is a high temperature coating for graphite or superficial porous material to prevent oxidation. ZS-1021 (graphite) graphite high temperature anti-oxidation coating. The coating is acidified and synthesized under high temperature and high pressure. The temperature resistance can reach 2600 ° C, and the coating has good curing effect. The coating is dense, and the graphite and porous materials have both physical and chemical bridging, and the matrix forms an integrated structure. The adhesion is good, the coating is smooth and full, self-cleaning and anti-adhesive, and resistant to thermal shock and vibration. It is better, has good self-healing ability for heat expansion and contraction, anti-melting slag and high temperature debris attack and osmosis erosion, anti-oxidation diffusion rate of more than 96%, and the material has long anti-oxidation service life at high temperature.

The second type is ZS-1023 ultra-high temperature metal anti-oxidation coating. It can reach 3000 °C for long-term ultra-high temperature resistance. It can protect metal from oxidation and corrosion at high temperature. It can effectively prevent oxygen from penetrating into the substrate at high temperature. Impact, high linear expansion coefficient and good thermal vibration coefficient. ZS-1023 ultra-high temperature metal anti-oxidation coating research and development technology is at the level of * in the world and has high technical content. The coating can be applied to prevent oxidation from corrosion on high temperature metal surfaces of ultra high temperature equipment.

The third type is ZS-1051 high temperature transparent anti-oxidation coating, which can withstand temperature of 1700 °C for a long time. The coating is water-based inorganic environmental protection coating. The coating is completely transparent. Under the premise of not affecting the color of the substrate, the substrate can be guaranteed not to be at high temperature. Rusting, anti-oxidation, anti-oxidation, effective flame retardant and fireproof, high fireproof grade, effective prevention and control of high temperature materials in high temperature corrosive medium oxidative corrosion;

The fourth type is ZS-1021 high temperature resistant sealing coating. It adopts Zhisheng Weihua high temperature resistant special high temperature resistant solution. The temperature resistance can reach 1800 °C. The coating is dense and hard, the sealing resistance is good, the oxidation resistance is good, the anti-oxidation diffusion is good, and the wear resistance is good. Shock. It can be applied to high temperature metal, graphite and other materials to resist and prevent oxidation. ZS-1021 high temperature resistant sealing coating is mainly used for anticorrosive coating of metal under high temperature.