Fatigue Life Enhancement by Surface Coating of Ni/Cu Multilayered Films
Effect of Ni/Cu multilayer coating on fatigue durability was investigated. The Ni/Cu multilayered films were coated on cylindrical copper specimens by electroplating technique. Thickness of individual component layers was h=20nm and 100nm and the total thickness was 5μm. The specimens with a conventional nickel coating and uncoated specimens were also prepared. Push-pull fatigue tests were carried out in air at room temperature. It was found that the specimens with the Ni/Cu multilayered coatings exhibited the fatigue lives longer than those of the conventional nickel coating. In particular, the fatigue life with the h=100nm multilayer was at least ten times longer than that with the nickel coating at the stress amplitude of 90MPa. From the electron channelling contrast imaging (ECCI) observation of subsurface areas of the copper specimens, dislocation structures peculiar to fatigue deformation was suppressed by the surface coatings.
Young Won Chang, Nack J. Kim and Chong Soo Lee
Y. Kaneko et al., "Fatigue Life Enhancement by Surface Coating of Ni/Cu Multilayered Films", Materials Science Forum, Vols. 561-565, pp. 2393-2398, 2007