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Thin ZrC films ( 90%) in the infrared region, characteristic of metallic behavior. Nanoindentation results indicated that films deposited under lower CH4 pressures exhibited slightly higher nanohardness and Young modulus values than films deposited under higher pressures. As a result, tribological characterization revealed that these films exhibited relatively high wear resistance and steady-state friction coefficients on the order of μ = 0.4.

Polytetrafluoroethylene (PTFE) and alumina nanocomposites have been of great interest to the tribological community due to the significant reduction in wear imparted by filling PTFE with low weight percentages of alumina nanofillers. The mechanisms of these three order, four order, and sometimes five order of magnitude reductions in wear have been commonly explored through evaluation of a transfer film. The present article evaluates the tribofilm formed on the wear surface of the polymer. PTFE composites with 2, 5, and 8 wt% alumina fillers were tested to evaluate wear of the polymer and how it is affected by the tribofilms formed on the wear surface of the polymer. Furthermore, the link between a transient “run-in” wear period and the formation of that tribofilm is observed and discussed. Nanomechanical measurements of the tribofilm reveal significant alterations in the mechanical properties of the surface films formed during sliding.

Thin ZrC films were grown on (1 0 0) Si substrates at temperatures from 30 to 500 °C by the pulsed laser deposition technique. Auger electron spectroscopy investigations found that films contained oxygen concentration below 2.0 at%, while X-ray photoelectron spectroscopy investigations showed that oxygen is bonded in an oxy-carbide type of compound. The films’ mass densities, estimated from X-ray reflectivity curve simulations, and crystallinity improved with the increase of the substrate temperature. Williamson–Hall plots and residual-stress measurements using the modified sin 2 ψ method for grazing incidence X-ray diffraction showed that the deposited films are nanostructured, with crystallite sizes from 6 to 20 nm, under high micro-stress and compressive residual stress. Nanoindentation investigations found hardness values above 40 GPa for the ZrC films deposited at substrate temperatures higher than 300 °C. The high density of the deposited films and the nm-size crystallites are the key factors for achieving such high hardness values.

A straightforward approach allowing three-dimensional (3D) visualization of subsurface deformation beneath nanoindents using reconstructed cross-sectional transmission electron microscopy (TEM) data is demonstrated. This approach relies on generating an array of nanoindents, extracting a thin (

TiN films thinner than 400 nm were grown on (1 0 0) Si substrates at room temperature and 300 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser (λ = 248 nm, pulse duration τ = 25 ns, 6.0 J/cm2 fluence, and 40 Hz repetition rate) under various atmospheres. Simulation of X-ray reflectivity curves acquired from films showed they were very dense and smooth, while X-ray diffraction investigations found they were crystalline, with crystallites size from 10 to 35 nm and micro-strain values of 0.6–1.1%. The oxygen content in bulk, measured by Auger electron spectroscopy (AES), was below 3.1 at%. Nanoindentation investigations found hardness values between 35 and 40 GPa, amongst the highest values reported for TiN films. The high laser fluence used for ablation generated energetic ions and atomic species that bombarded the substrate during growth, resulting in the deposition of very dense films, exhibiting high micro-strain values and small crystallite sizes, which could explain the measured hardness values.

The extent of dislocation-based plasticity in ceramics is limited and often accompanied by microcracking. This limitation has precluded the investigation of post-yield plastic response in ceramics. Using low-load nanoindentations and by tracking the hardness of selected grains before and after plastic deformation, the influence of microcracking and variability in microhardness due to grain orientation were minimized and the post-yield response of polycrystalline ZrB 2 ceramic was determined. The observed increase in nanoindentation hardness after plastically deforming isolated ZrB 2 grains indicates conclusively the existence of post-yield strain hardening.

While the signal quality of recording neural electrodes is observed to degrade over time, the degradation mechanisms are complex and less easily observable. Recording microelectrodes failures are attributed to different biological factors such as tissue encapsulation, immune response, and disruption of blood-brain barrier (BBB) and non-biological factors such as strain due to micromotion, insulation delamination, corrosion, and surface roughness on the recording site (Polikov et. al., 2005; Prasad et. al., 2011; Streit et. al., 2012; Prasad et. al., 2012). Strain due to brain micromotion is considered to be one of the important abiotic factors contributing to the failure of the neural implants. To reduce the forces exerted by the electrode on the brain, a high compliance 2D serpentine shaped electrode cable was designed, simulated, and measured using polyimide as the substrate material. Serpentine electrode cables were fabricated using MEMS microfabrication techniques, and the prototypes were subjected to load tests to experimentally measure the compliance. The compliance of the serpentine cable was numerically modeled and quantitatively measured to be up to 10 times higher than the compliance of a straight cable of same dimensions and material.