TRIBOLOGICAL PROPERTIES OF BIAS VOLTAGE MODULATED A-C-H NANOSCALED MULTILAYERS

Nanoscaled multilayer coatings consisting of alternating layers of har d and soft amorphous hydrogenated carbon (a-C:H) films have been depos ited by modulation of the substrate bias voltage in a plasma activated chemical vapor deposition (PACVD) process. Alternating hard/soft a-C: H nanolayers is a model system to investigate the correlation of the d ifferent layers and interfaces with the final tribological and mechani cal properties. The substrate bias voltage determines the ratio of sp( 2)/sp(3) bonded carbon, the internal stress and the hydrogen content i n the different a-C:H layers, all of which contribute to the mechanica l properties. Different bias voltage functions (sinusoidal, triangular , rectangular, etc.) were used to obtain soft, graded or sharp interfa ces between the layers. The mechanical and tribological behavior of th e multilayer structures have been characterized by tribological tests. (C) 1997 Elsevier Science S.A.