Performance Of The Arc Spraying Coatings With Core Wires Used On The CFB Boiler's Water-cooled Wall

The abrasion oftheboiler's water-cooledwall at hightemperaturewas aserious problem on the boiler's operation period. Coatings with FeB and CrBas the metal matrix composites were prepared using core wires designedbased on the analyses of water-cooled wall's invalidation systematically.Carried out high temperature corrosion test, hot corrosion test and hightemperature erosion test referentially. The component and structure of thecoatings brought some influence which was investigated including its actionmechanism. The coatings had obvious layer structures, and the hardcomponentswithdiscretedistributioncouldincreaseintensity ofthecoatings.In addition that metal layer in coatings could increase malleability. Theresults of high temperature corrosion test showed that coatings with sealcoats had excellent oxidation resistance. The Cr element in the CrB coatingwouldbe oxygenizedasCr2O3,whichhaddensestructureandgoodoxidationresistance. In the hot corrosion test, the K-Na-Fe three-element compoundwith low melting point was generated on the surface of some parts of thecoatings, whichcausedhot corrosion. TheCrB coatings showedtheexcellenthot corrosion resistance during the test. In the high temperature erosion test, infection of the factors to the coatings abrasion resistance was investigated.The FeB coating was abraded plastically mostly at high temperature, whosesurface appeared narrow channels as the result of abrasion. Brittle abrasionoccurred when the CrB coating stayed in the same environment, and thecoating's surface appeared tiny impact craters. The hard components in thecoatings prevented particles from striking well. The process of the coatingshigh temperature erosion included three stages, as crack emergence, crackextending, and coatings'separating. The form and mechanism of the crackwere same under different erosion modalities. Plastic abrasion or brittleabrasion occurred based on the capacity and structure of the coatings. Theresults of the field test showed that the CrB coating and FeB coating couldprotect the boiler's water-cooled wall well in high temperature erosionenvironment,andcouldextenditsoperationallifespan.