Study On Characteristics Of Composite Ceramic Coatings Preventing Slagging And Corrosion

The high temperature corrosion and slagging on heat exchange tubes of coal-firedboiler has always been a main prolem of power station boiler.Based these problems,multiphase ceramic coating was prepared on the surface of heating surface of steel by thermal chemical reaction.This article experimented the corrosion and slagging resistance property of multiphase ceramic coating,providing theoretical basis of widespread use of multiphase ceramic coating on heat exchange tubes.First,the ceramic coating was prepared on the surface of 20G which is the commonly steel used on water wall.Next,analyzing the coating morphology and thermal shock performance.Then run corrosion and slagging resistance property tests on coatings.The result of SO2 gas corrosion test suggests that ceramic coatings have better corrosion resistance property than 20G base steel.The corrosion resistance property of ceramic coatings improved 2 times,2.3 times and 2.3 times under 400?,450?and 500 ? respectively.The thermal analysis kinetics shows that the SO2 gas corrosion mode function of both coatings and base steel are D2.Then,analyzing the coating morphology by SEM and EDS,finding out the anti-corrosion mechanism of multiphase ceramic coatings.Slagging resistance property tests were divided into two parts,stain resistance and adhesion characteristic test.The result of stain resistance test suggests that ceramic coatings have better stain resistance property than 20G base steel.The stain resistance property ofceramic coatings improved 53 times,51 times and 43 times under the stain of Na2SO4,K2SO4 and Zhundong coal ash respectively.The result of adhesion property test suggests that ceramic coatings reduce the 20G base steel's adhesion ability.The contact angle between the surface of coatings and the molten droplet of Na2SO4 is 118.5°,bigger than 98°,which is between the surface of base steel and the molten droplet.Besides,work of adhesion between the surface of coatings and the molten droplet of Na2SO4 is smaller than that between the surface of base steel and the molten droplet.