Application of thermal spraying in papermaking field

       Over the years, thermal spraying technology has been widely used in metallurgy, petroleum, chemical industry, papermaking, aerospace, machinery manufacturing and other industries with its unique surface preparation method. In recent years, there have been many new developments in the application of foreign thermal spray technology in papermaking machinery. Due to equipment, materials, technology and other reasons, it has not been widely promoted and applied in China. Here is a brief description of some applications of thermal spraying ceramics and cermet coatings in papermaking machinery. It is hoped that the surface engineering technology of thermal spraying can be widely promoted in my country's papermaking industry.



Ceramics - generally refers to metal oxides, used for thermal spray coatings, mainly A1203, TiO2, Cr203, Zr02 and a few others. It is suitable for multiple heat-resistant, wear-resistant, corrosion-resistant and electrical insulation conditions. Spraying A1203+TiO2 can form a corrosion-resistant coating that resists strong acid and alkali; spraying Cr203 coating can obtain the densest and hardest ceramics. Wear-resistant surface; and sprayed Zr02 is the best high-temperature resistance among ceramics, and it can work under the working condition of 1600 ℃. Ceramic coatings generally use oxyacetylene flame and plasma spraying methods. Low melting point ceramics can be sprayed with oxyacetylene, while high melting point ceramics must be properly used to be effective.



Cermets usually refer to carbon compounds of metals, and the main ones used for thermal spraying are WC, Cr203, etc. Cermets achieve strong wear resistance with their high hardness. The hardness of the WC spray coating can reach HV1200, which is equivalent to about HRc75. It is mainly used for wear-resistant conditions below 400 °C. The hardness of Cr203 coating can reach HV1000, and it is mainly used for high temperature working conditions of 400~800℃. According to relevant foreign information, the wear resistance of WC coating sprayed with supersonic speed is 10 times that of chilled cast iron. This coating can only be achieved best with sonic spray over explosive spray.