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

Abstract

Fatigue tests using magnesium alloy, AZ80A, were conducted in laboratory air and demineralized water to investigate the effect of diamond-like carbon (DLC)/electroless nickel (Ni) plating hybrid coating on the fatigue performances. The fatigue strengths of Ni plating single-layered specimens were lower than those of the substrate, while DLC single layer could improve fatigue strengths. DLC/Ni plating hybrid coating could further improve fatigue strengths than DLC single layer. The cyclic slip deformation inducing fatigue crack initiation was effectively suppressed by DLC/Ni plating hybrid coating. Fatigue tests in demineralized water revealed that the fatigue strengths decreased irrespective of coatings. DLC/Ni plating hybrid coating had little effect on the fatigue strengths in corrosive environment. Demineralized water could reach substrate through some defects in the coatings, resulting in the degradation of fatigue strengths in demineralized water.