2004 年 22 巻 1 号 p. 132-140
Cast iron has been widely used for the parts of sliding wear such as cylinder bores of motor engines because of its high resistance, which is mainly due to the fine pearlite structure and the existence of graphite acting as a solid lubricant. These features are derived from the rich carbon content (3-4 mass%). However, under severe sliding conditions such as those in high-power motor engines or exhaust-gas recycle (EGR) engines, cast iron without any treatment is not sufficient for wear resistance. In this study, iron casting with Mo-alloyed and W-alloyed was presented. Effects of the alloying of these metals on the microstructure, the hardness and the wear resistance were studied. Furthermore, surface modification by laser melting was carried out to obtain a chilled microstructure, that is, a non-equilibrium phase. The difference between the equilibrium and the non-equilibrium phases was examined for the tribological characateristics. 3% Mo-alloyed, 8% Mo-alloyed and 8% W-alloyed cast iron with laser melting showed high wear resistance ; on the other hand 16% Mo-alloyed cast iron as cast showed high wear resistance.