High silicon content aluminum alloys are used in machine parts which need weight saving and wear resistance. The application of aluminum alloys in automotive engines is being undertaken. On the other hand, zinc dialkyldithiophosphate (ZnDTP) has been the most widely used lubricant additives in the engine, but it is known that ZnDTP can easily cause sludge and catalyst poisoning. Therefore the development of alternative additives has proceeded. In this study, friction and wear properties of the high silicon content aluminum alloys and CrN (chromium nitride) are investigated by using a block-on-ring type sliding tester in lubricating oils with ZnDTP or sulfur containing anti-wear agents. As a result, the friction coefficient in the case of ZnDTP was higher than that of non-additive. And the friction coefficient in the case of sulfur containing anti-wear agents were lower than that of non-additive. Both ZnDTP and sulfur containing anti-wear agents improved wear resistance. Tribofilms formed by the additive in the wear track affected the friction and wear properties.

Carbon coatings have a keen attention according to its low friction, high hardness and high wear resistance properties. There are needs to apply carbon coatings into ceramic mechanical parts, such as mechanical seal. However the tribological properties of carbon coatings when slid against ceramics are still not investigated sufficiently. Generally tribological behaviors are affected by a counterpart material. Therefore more fundamental researches about counterpart material are necessary. In this research tribological behaviors of carbon coating when slid against various counterpart material, including SiC, SiC(O) that is SiC after annealing at 1000°C, Si₃N₄, Al₂O₃, Al₂O₃(Si) that includes more Si atomic concentration than Al₂O₃ and Si wafer at various temperatures in air have been investigated. Carbon coating when slid against SiC showed the lowest wear rate at 23°C, and carbon coating when slid against Si₃N₄ showed the lowest wear rate at 140°C and carbon coating when slid against SiC(O) showed the lowest friction coefficient at all temperature.