Improving the Wear Resistance for Al Alloy by Ion Implantation

Abstract

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.