EROSION OF AISI 1018 STEEL AND SEVERAL THERMAL SPRAYED COATINGS UNDER SIMULATED IN-BED TUBE EROSION CONDITIONS OF FLUIDIZED BED COMBUSTORS

摘要

A series of erosion tests was carried out on AM 1018 low carbon steel and several thermal sprayed coating specimens at low elevated temperature (300°C) and low impact velocity (-2.5 m/s) using a nozzle type laboratory erosion tester. Angular SiO{sub}2 quartz particles of average size 742 μm were used as the erodent material for tests at three different impact angles of 30°, 45° and 90° under generally oxidizing conditions for exposure periods up to 96 hours. Material wastage rates were determined from thickness loss measurements of the specimens. Test results were compared with erosion test results from higher velocity test conditions (30 m/s). The morphologies of the specimens were examined by scanning electron microscopy (SEM). It was found that there are some differences on erosion mechanism and behavior of steel and coatings under low velocity from those under high velocity. Also a significant change in the ranking of erosion resistance occurred when steel and coatings were tested under different velocities. The erosion behavior of coatings is related to their composition, microstructure rather than their hardness.