Effect of the Variation of Film Thickness on the Properties of Multilayered Si-Doped Diamond-Like Carbon Films Deposited on SUS 304, Al and Cu Substrates

Multilayered Si-doped DLC film with thicknesses of 5.5, 10.1, 21.8 and 28.3 μm was deposited on stainless steel, aluminum alloy and copper alloy substrates by plasma-enhanced chemical vapor deposition. The mechanical and tribological properties of multilayered Si-doped DLC films deposited on three different substrates were evaluated in this study. The hardness of the multilayered Si-doped DLC film of different substrates is related to the substrate material and internal stress. In a scratch test, the adhesion of the multilayered Si-doped DLC film increased with the film thickness. The multilayered Si-doped DLC film with a thickness of 28.3 μm on stainless steel substrate has the highest adhesion of 31 N. The adhesion of the multilayered Si-doped DLC film with different thicknesses on the copper alloy is relatively poor. The ball-on-disk friction test results show that the multilayered Si-doped DLC film with thicknesses of 5.5 and 10.1 μm is prone to shear deformation and exhibit high friction coefficient. The uneven stress distribution and surface deformation of the multilayered Si-doped film deposited on the aluminum alloy and the copper alloy cause the fluctuation and rise of the friction coefficient. The wear resistance of multilayered Si-doped DLC films on different substrates is related to stress shielding and adhesion strength.