Thickness Effect of Interlayer on Fatigue Behavior and Fatigue Fracture A5052 Mechanisms in Aluminum Alloy with DLC/Thermally Sprayed WC-12Co Hybrid Coatings

Abstract

Al A5052-H14 Table 1 2 6mm WC-12Co (high velocity oxygen fuel, HVOF) WC-12Co 25 70 120μm 3 DLC WC-12Co #2000 15μm DLC/WC-12Co A5052 Thickness Effect of Interlayer on Fatigue Behavior and Fatigue Fracture A5052 Mechanisms in Aluminum Alloy with DLC/Thermally Sprayed WC-12Co Hybrid Coatings by Toshifumi KAKIUCHI , Yoshihiko UEMATSU , Makoto TAKEKAWA Takema TERATANI , Yoshifumi KOBAYASHI and Yoshio HARADA WC-12Co was thermally sprayed by a high velocity oxygen fuel (HVOF) method on A5052 aluminum alloy as an interlayer with the thicknesses of 25, 70 and 120μm and subsequently diamond-like carbon (DLC) film was deposited with the thickness of 15μm to fabricate DLC/WC-12Co hybrid coating. Rotary bending fatigue tests were conducted using the specimens with DLC/WC-12Co hybrid coating, DLC single coating, WC-12Co single coating and without coating, and the thickness effect of interlayer on the fatigue behavior was investigated. The fatigue strengths of the specimens with DLC single coating and WC-12Co single coating were higher than those of the substrate specimens. The fatigue strengths in the specimens with WC-12Co single coating increased with increasing the thickness of WC-12Co layer. The specimens with hybrid coating exhibited higher fatigue strengths than the specimens with WC-12Co single coating when the thickness of WC-12Co layer was the same. However the thicker WC-12Co interlayer led to the lower improvement of fatigue strength by hybrid coating. In the specimens with WC-12Co layer, the boundary between WC-12Co layer and substrate was rough and uneven due to the thermal spray process and a fatigue crack initiated at the concave site of substrate on the boundary. In the specimens with hybrid coating, cracking in DLC film and WC-12Co interlayer occurred simultaneously and suddenly near the end of fatigue life. A fatigue crack in the substrate had grown up to a large size and the specimen fractured soon after a crack appeared on the surface.

Effect of Interlayer Thickness on Fatigue Behavior in A5052 Aluminum Alloy with Diamond-Like Carbon/Anodic-Oxide Hybrid Coating

“…3) The authors had developed DLC/WC-12Co hybrid coating on Al 4,5) or magnesium (Mg) 6) substrate, in which WC-12Co was thermally sprayed as an interlayer and subsequently DLC was deposited on it. It had been reported that the resistance against delamination under the contact pressure and fatigue strengths were improved by DLC/WC-12Co hybrid coatings.…”

Fatigue Behavior of Magnesium Alloy with Diamond-Like Carbon/Nickel Plating Hybrid Coating in Laboratory Air and Corrosive Environment

“…They demonstrated that DLC coating did not delaminate under high contact pressure. Furthermore, it was found that DLC/WC-Co hybrid coating could improve fatigue strengths 12), 13) . Thus the concept of hybrid coating 14)- 16) is attractive in terms of improving fatigue strengths.…”

Fatigue behavior of A5052 aluminum alloy with diamond-like carbon/electroless nickel plating hybrid coating

“…In the previous cases of DLC/WC-Co (Kakiuchi et al, 2013, Okada et al, 2010 or DLC/anodic-oxide (Uematsu et al, 2015) hybrid coatings, the thickness of the interlayers varied in the range of 10 ~ 80 μm. Thus the thickness of the plating in the present study was set to be 20 μm for comparison.…”

“…is inserted between DLC coating and soft substrate. The authors had reported about the fabrication of hybrid coatings on Al (Kakiuchi et al, 2013) or magnesium (Mg) (Okada et al, 2010) substrates, in which WC-12Co was thermally sprayed as an interlayer prior to DLC deposition. The hybrid coatings could further improve fatigue strengths of substrates than DLC single coating, and increase the resistance against delamination under the contact pressure.…”