Amorphous Hydrogenated Silicon Carbide Interlayers: Chemical, Optical, and Tribological Behavior for Improving Adhesion of Carbon‐Based Films to Ferrous Alloy

ABSTRACT Diamond‐like carbon thin films have been gaining attention in the last years due to their unique properties, such as low friction coefficient and high wear resistance. However, the lack of adhesion between DLC coatings and ferrous alloys complicates their wider industrial application. Amorphous hydrogenated silicon carbide (a‐SiC x :H) interlayers can be used as a solution for adhesion issues. Nonetheless, for interlayers produced with tetramethylsilane, deposition temperatures higher than 300°C may degrade the previous heat treatment of the substrate. This work aims to verify the influence of chemical, optical, morphological, and tribological properties in the adhesion of a‐C:H/a‐SiC x :H/AISI 4140 steel structures deposited with 0.8 Pa as background pressure and low interlayer deposition temperatures ( T ≤ 200°C). The results showed that both chemical and morphological properties strongly modify the adhesion behavior at low deposition temperatures. The optical absorption edge of the samples takes place in energies around 3.5 (or ~350 nm) and ~1.5 eV (or ~850 nm) for the a‐SiC x :H interlayer (mainly deposited at 150°C) and a‐C:H film deposited for 60 min, respectively. When the a‐SiC x :H temperature increased from 85°C to 200°C, the oxygen content at the interfaces and in the interlayer decreased as well as the density of defects observed in the a‐C:H surface.