B. Prakash

Ti–B and Ti–B–C coatings deposited by plasma immersion ion implantation and their fretting behavior

Abstract Ti–B and Ti–B–C coatings were deposited by a two-step plasma immersion ion implantation (PIII) process. A structural study revealed that as-deposited PIII Ti–B coatings are amorphous and did not crystallize on vacuum annealing up to 800 °C. The coefficient of friction and the wear rate of such as-deposited and annealed PIII Ti–B coatings sliding against corundum under non-lubricated conditions were found to be higher than the ones for crystalline TiB 2 coatings deposited by PVD. Attempts to decrease friction and wear rate resulted in depositing PIII Ti–B based coatings in a methane atmosphere. Such PIII Ti–B–C coatings contain both hard TiB 2 and lubricating DLC phases. They show in non-lubricated fretting test conditions, a low coefficient of friction and a good wear resistance in comparison to industrial currently available PVD TiB 2 and PVD TiN coatings.

Low-Friction MoSx Coatings Resistant to Wear in Ambient Air of Low and High Relative Humidity

The investigation of the tribological performance of MoS2-based coatings in air of high humidity is critical for the future use of such low-friction and high-wear-resistant coatings in ambient air. Sulfur-deficient MoSx coatings with a basal plane (x = 1.3) and a random (x = 1.8) crystallographic orientation were produced by planar magnetron sputtering. The coefficient of friction and the wear loss of MoSx coatings in comparison with TiN and amorphous TiB2 coatings were investigated in bi-directional sliding fretting tests performed in ambient air of different relative humidity. The wear rate expressed as a volumetric loss per unit of dissipated energy was determined. From these results, the best friction and wear performance was achieved with basal-plane-oriented MoSx coatings tested at a relative humidity in the range of 10-50%. A coefficent of friction of 0.06-0.08 and a wear rate of 4 × 103μm3J-1, at a normal load of 1 N and a fretting frequency of 10 Hz, were recorded for that type of MoSx coatings.

Surface Modification of Materials by Plasma Immersion Ion Implantation

Modification of surfaces is an attractive way to achieve the desired property at the surface or in the near surface region of any bulk material. Surface modifications can be done by alloying/mixing elements at the surface of bulk materials or by an adherent overlayer on bulk materials. Plasma immersion ion implantation (PIII) is one among the surface modification techniques and was developed by Conrad and his co-workers at the University of Wisconsin in 1991 [1] . PIII is an emerging technology for the surface modification of semiconductors, metals, and insulators. Materials to be treated are immersed in a plasma at a given potential. Intricate/complex shapes can be treated rather uniformly with this technique. Indeed, this technology offers a substantially uniform ion bombardment of components, removing the line-of-sight restrictions of conventional ion beam implanters, as well as providing a more simple way to treat large surface areas. As there is no ion beam rastering as in conventional ion implantation, the treatment time can be reduced with PIII. This could support the introduction of PIII into manufacturing processes in a competitive manner compared to conventional ion implanatation. The physics and technology of the PIII process are discussed in Section 4.2 . In Section 4.3 , the potential of this technique for depositing low friction and wear resistant layers is discussed. In addition, the nitriding of stainless steel and the formation of intermixed layers are discussed. Applications of PIII in the fields of microelectronics and medicine are discussed in Sections 4.4 and 4.5 .