Efforts to produce nanocomposite films of soft particles in a hard matrix are reviewed. Films consisting of a hard matrix phase in combination with a soft, lubricious phase grown as either multilayers or composite films show promise as hard, lubricating, wear-resistant coatings. Here we will report on films of TiN or CrN with MoS₂ nanoclusters grown by two deposition techniques: cathodic arc evaporation and magnetron sputter deposition.

The effects of changing the deposition parameters on mechanical properties such as hardness, adhesion and wear behavior have been investigated by nano-indentation, scratch and indent adhesion characterization, pin-on-disk tribometry at both ambient and elevated temperatures, and micro-abrasive wear testing. These results are correlated with changes in film chemistry (XPS and RBS) and film microstructure (X-ray diffraction).

Thin films of hard materials are of prime importance for resistant, protective and decorative coatings. Beside adhesion, hardness is the most often quoted requirement, even if doubts remain on the experimental determination of the hardness values of thin films and on their theoretical interpretations. Transition metal interstitial compounds are extensively used because of their broad range of functional properties in machining, microelectronics, decoration, etc.. The article presents a summary of recent relevant results on the structural, mechanical, electronic and optical properties of fcc TiN, VN, CrN, NbN, MoN, WN and some ternary nitrides in the form of sputtered thin films. The process parameters, e.g. the reactive gas partial pressure and the substrate bias, strongly influence the film properties. The composition and growth parameters influence the morphology, the stress state and other physical properties.

The systematic investigation of the electronic density of states in valence and core states of comparable nitrides provide indications of the degree of covalency in the chemical bonding in relation with properties such as cohesive energy and hardness. For example in molybdenum nitride, the low stability of the cubic MoN phase is related to an increase in the charge transfer of Mo d electrons to nitrogen with increasing stoechiometric ratio N/Mo.

Ellipsometric measurements of the dielectric function interpreted in relation with details of the band structure measure the variation of the density of conduction electrons. Since vacancies and interstitials give specific numbers of electrons to the conduction band, this analysis allows to differentiate the type of defects at various compositions in TiN films, for exemple, for which the reported hardness values spread over a wide range.}

We present our results on different types of nanostructured and alloyed a-C:H coatings reflecting a technology for the design of optimized coatings for a wide range of applications.

Multilayered a-C:H films, composed of a 60 nm Si-a-C:H adhesion layer and 300 nm (hard/soft) multilayer structure have been deposited on 100Cr6 steel by a periodical variation of the sample self-bias voltage during deposition. The single layer thickness has been varied from 4 to 20 nm. The wear rate (determined by pin on disk measurement against a steel ball) of multilayer structures having a single layer thickness in the range of 11 nm to 15 nm, showed a drastic decrease by one decade down to 4 x 10^-18 m³/Nm, compared to the multilayer systems composed of thicker or thinner single layers.

Amorphous hydrogenated carbon films containing titanium in different concentrations (a-C:H/Ti) were deposited on glass substrates by a combined rf-PACVD and DC magnetron sputtering process. By adding titanium to the carbon matrix, cellular reactions like tendential differentiation of osteoblast cells together with a reduced osteoclast cell activity, compared to pure a-C:H or pure Ti, could be obtained . This makes a-C:H/Ti a valuable coating for bone implants, by enhancing bone ingrowth through osteoblast differentiation while reducing bone resorption through osteoclast inhibition.