| Currently most of the world’s iron and steel products should be plated zinc andaluminum to improve the life of use. Plating zinc and aluminum has become the most basicapplication of corrosion of steel, and it is one of the most popular methods. In the process ofplating zinc and aluminum, the requirement of the equipment is very demanding, becausezinc and aluminum could make steel sink roll quickly cankerous perforated and scrapped,that is one of the problem which is being addressed in industry. The sink rolls are frequentreplaced and repaired that reduce the operating rate, raise the cost, bring a lot ofinconvenience to the production and operation.This paper chose four different powders, which are Co-Cr-WC, NiCr-Cr3C2,CoCr-MoB and Co-WC. Spray the four different powders on the predesigned specimen bythe HVOF. Study the porosity, coating hardness, microstructure morphology and ability ofresistance to zinc and aluminum liquid corrosion. By observing SEM photographs of thecoating had found that the CoCr-MoB porosity was maximum. The Co-WC coatinghardness is maximum. There is no crack or other defect on the coatings macro morphologyof four kinds of powders. Corrosion resistance of Co-WC coating is12hours in the etchantof liquid zinc and aluminum at the temperature of650℃. Scanning the SEM and EDSanalysis shows that the coating corrosion mechanism it is that the weak Co element in thecoating first contacts with liquid zinc and starts up dissolving corrosion. It makes the WCloose. Liquid aluminum along the crevice corrosion by zinc enter into the coating, contactwith the base metal, corrode the base metal.At last the coating fall off.According to the dissertation, WC-Co coating shows the best over-all properties. |
PDF Full Text Request