Tribological stability of Al2O3 short fiber reinforced high Cr cast irons

To develop super abrasion resistant materials, Al2O3 short fiber reinforced high Cr cast irons with a range of fiber volume fractions were fabricated by an infiltration process. Abrasion tests were carried out with a Suga-type (two-body) tester and a rubber wheel (three-body) abrasive tester at room temperature, and with a low-stress abrasion tester at 923 K, respectively. Microstructure observations revealed that the presence of alumina fibers greatly refines the solidification structures of the matrix alloys. The results of the wear tests show that the abrasion resistance of high Cr cast irons at both room and elevated temperature was improved by the presence of Al2O3 fibers. In the two-body abrasion tests, the wear rates of the hypo- and hyper-eutectic composites were 92 and 88% of that of the monolithic materials, respectively, while in the three-body abrasion tests, these wear rate ratios were 38 and 88%, respectively. At 923 K, the hypo-eutectic composite with a fiber volume fraction of 20% exhibited the smallest wear rate, and a decrease in wear rate with increasing fiber volume content was demonstrated in the hyper-eutectic composites. It was concluded that the presence of Al2O3 fibers in high Cr cast irons is useful for abrasion resistance.