Local transformation of amorphous hydrogenated carbon coating induced by high contact pressure

The development of coatings presenting adaptive characteristics based on mechanical loads would promote improved local characteristics. In this work, the surface modification of an a-C:H coating was analyzed based on the contact pressure using two tribological tests: lubricated reciprocating ball-on-plane and dry micro-scratch tests. Local transformation were evaluated based on Raman spectroscopy and indentation hardness. Results indicated regions presenting a red-shift of the G band and higher indentation hardness. High compressive stress field developed under the contacting region (numerical simulations) coupled to the red-shift of the G band and the increase on indentation hardness inside the tested regions are compatible with the nucleation of sp3 carbon bond sites derived from sp2 bonds, indicating a possible modification of the coating.