“…14) More recently, several investigators have reported the effect of a Zn interlayer between the substrate and the ZnMg coating on the adhesion strength of the ZnMg/Zn bilayer coating. 4,13,[15][16][17][18] Song et al 15) and Sabooni et al 17) both reported that a Zn interlayer is an essential part for the improvement of the adhesion strength of the Zn-Mg coatings, which confirmed the previous report by Jung et al 11) From the lap shear test results, the Zn interlayer significantly contributed to the improvement of the formability and adhesion of the Zn-Mg coating, showing that the maximum adhesion strength of the Zn-Mg coatings with the Zn interlayer became approximately twice as high as that of the Zn-Mg coatings without the Zn interlayer. 15) A modified Benjamin-Weaver model was suggested to quantify the adhesion strength of PVD ZnMg/ Zn bilayered coatings, and it was reported that the annealing treatment of the double-layer ZnMg/Zn coating was detrimental for the adhesion strength as the thickness of the Zn interlayer decreased below the critical value of 500 nm due to diffusion during the annealing.…”