Application Research Of Cermet Composite Coatings On Axial Flow Fan's Blades

Axial flow fan is a main device of the boiler, which has the task of continuous gas transportation. Erosion of the blade by the solid particle of the smoke and gas is the major problem of axial flow fan, which may make axial flow fan reduce power and even stop working. Today with the worldwide attention to energy, study on erosion of axial flow fan becomes more and more important.On the basis of literature search on erosion of axial flow fan's blade, depending on the failure mechanisms, several kinds of coatings were prepared. NiWC35, Ni60, SNi46 and SNi67 spraying and fuzing coatings were prepared by spraying and fuzing. Cermet composite coating of LX88A was prepared by arc spraying. Cermet composite coatings of conventional WC/12Co and nanostructured WC/12Co were prepared by HVOF. The bonding strength, hardness and erosion of coatings were studied by some tests. The mechanisms of erosion were explored by analyzing the microstructure and distribution of element of coatings with the techniques of metallographic analysis, Scanning Electron Microscope (SEM), Electron Probe Micro-Analysis (EPMA) and X-Ray Diffraction (XRD), and the anti-erosion performance of several kinds of coatings above were compared.The study shows that the coatings prepared by three kinds of spraying processes all do well in anti-erosion performance. The coating prepared by HVOF is the best one of them. The coatings prepared by spraying and fuzing are better than the coating prepared by arc spraying. The anti-erosion performance of NiWC35 spraying and fuzing coating is better than other spraying and fuzing coatings because of 35% cermet WC in it. The anti-erosion performance of LX88A cermet composite coating is good because of the cermet Fe₃B which is produced in the process of arc spraying. Nanostructured WC/12Co coating shows better properties in density, hardness, bonding strength, toughness and anti-erosion than the conventional.Considering the results above, four kinds of the cermet coatings possess excellent anti-erosion performance. NiWC35 spraying and fuzing coating and LX88A coating would be applied abroad, because the process is simple and thedepositing can be carried out on the spot. Nanostructured WC/12Co coating is expected abroad applied inland in the prevent of axial flow fan's blade for its best strength, toughness and anti-erosion performances, while the technology of HVOF has been abroad applied overseas.