High Temperature Erosion Mechanisms and Erosion Rate of Hard Coatings for Surface Recovery of Heavy-Fuel Engines

This study aims at evaluating the erosion resistance at temperature of several hard coatings, including: CrC-NiCr by HVOF, Nanosteel by Arc Spray, NiCrBSi by powder flame spraying, and Inconel-718 by Cold Spray.These coatings are to be used for the recovery of highly eroded walls (above 10 mm thickness) of gray cast iron in the exhaust ducts in heavy-fuel engines. The erosion test consists of erosive particles thrown through a high temperature gas jet, for 5 cycles of 5 minutes, according ASTM G211-14. Coated samples of 12.5 mm thickness are kept with a front temperature of 600ºC and a back temperature of 90ºC (water cooled), simulating the actual application. The eroded samples are characterized using XRD, SEM/EDS, and elemental mapping analyses. The results show the erosion rate of each material/system, and their corresponding erosion mechanisms. Thus, the results allows for the selection of an optimum coating for this surface recovery application.