イオン注入によるAl合金の耐摩耗性改善

概要

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In order to investigate the mechanical properties of ion-implanted aluminum alloy, disk samples of AC8A were irradiated with 130keV Ar+, 100keVB+, 100keVN2+, or 200keV N2+ at doses of up to 3×1017, 1×1017, 1.5×1018, or 1.5×1018ions/cm2 respectively.Knoop hardness (load: 98mN) increased with ion implantation, and in the case of N2+ ion implantation, hardness increased from 117 to 165. To measure the tribological property, pin-on-disk tests were performed using steel (SUJ2) balls of 5mm in diameter as pins. Sliding conditions were load: 460mN, speed: 25mm/s, oil lubrication (SAE 7.5W-30). The coefficient of friction for ion implanted AC8A disks was 0.1∼0.2, which was higher than the 0.07 obtained for unimplanted disks. Ion implantation improved the wear resistance of the disks, and in the case of N2+ ion-implanted disks, the wear volume was below the detection limit (<10-4mm3).X-ray diffraction analysis for N2+ ion-implanted samples revealed that AlN formed beneath the sample surface. It is suggested that the formation of AlN improved the wear resistance of N2+ ion-implanted AC8A disks by surface hardening.