An assessment of the erosion resistance of iron-aluminide cermets at room and elevated temperatures

Abstract

The resistance of FeAl–40 volume percent (v/o)TiB 2, FeAl–80v/oTiC and FeAl–80v/oWC cermets to solid particle erosion was evaluated at 25, 180, 500 and 700 °C and compared to the erosion behavior of WC–6 weight percent (w/o)Co (Co–90v/oWC) cemented carbides at the same temperatures. The relative ranking of the FeAl-cermets to erosion was from the most erosion resistant: FeAl–WC>FeAl–TiB 2>FeAl–TiC to the least erosion resistant. Erosion resistance was related to both cermet microstructure and material removal mechanisms. Even though the WC–Co contained a higher volume fraction of the hard phase, the erosion rates of the FeAl-cermets were roughly of the same magnitude to those of the WC–Co, particularly at the highest test temperature. The erosion rates of the FeAl-cermets were constant (FeAl–TiB 2) or decreased (FeAl–WC, FeAl–TiC) with increasing test temperature; whereas, the erosion rates of the WC–Co increased with increasing test temperature. This behavior was related to the oxidation resistance Co binder as the test temperature was increased. Subsequent impact by the erodent particles easily removed the oxidized material, leading to an increase of about 300% in erosion rate of WC–Co at 700 °C compared to room temperature. The FeAl binder in the FeAl-cermets did not oxidize nearly as much at the elevated temperatures, hence, the erosion rates of these cermets stayed constant or decreased. The results of this study indicate, that once the microstructure (e.g. volume fraction, particle size, particle size distribution, etc., of the hard phase) of the FeAl-cermets is optimized for erosion resistance these materials might make promising candidates for elevated temperature application where erosion is an operative wear mechanisms.