Damage Accumulation Phenomena in Multilayer (TiAlCrSiY)N/(TiAlCr)N, Monolayer (TiAlCrSiY)N Coatings and Silicon upon Deformation by Cyclic Nanoindentation.

The micromechanism of the low-cycle fatigue of mono- and multilayer PVD coatings on cutting tools was investigated. Multilayer nanolaminate (TiAlCrSiY)N/(TiAlCr)N and monolayer (TiAlCrSiY)N PVD coatings were deposited on the cemented carbide ball nose end mills. Low-cycle fatigue resistance was studied using the cyclic nanoindentation technique.

Why can tiAicrsiYN-based adaptive coatings deliver exceptional performance under extreme frictional conditions?

Adaptive TiAlCrSiYN-based coatings show promise under the extreme tribological conditions of dry ultra-high-speed (500-700 m min-1) machining of hardened tool steels. During high speed machining, protective sapphire and mullite-like tribo-films form on the surface of TiAlCrSiYN-based coatings resulting in beneficial heat-redistribution in the cutting zone. XRD and HRTEM data show that the tribo-films act as a thermal barrier creating a strong thermal gradient.

Hierarchical adaptive nanostructured PVD coatings for extreme tribological applications: the quest for nonequilibrium states and emergent behavior.

Adaptive wear-resistant coatings produced by physical vapor deposition (PVD) are a relatively new generation of coatings which are attracting attention in the development of nanostructured materials for extreme tribological applications. An excellent example of such extreme operating conditions is high performance machining of hard-to-cut materials. The adaptive characteristics of such coatings develop fully during interaction with the severe environment.

Nanoindentation of advanced polymers under non-ambient conditions: creep modelling and tan delta.

The creep modelling approach described in this paper reveals a correlation between the strain rate sensitivity parameter determined from room temperature nanoindentation data and tan delta determined from conventional dynamic mechanical analysis (DMA). With recent advances in nanomechanical instrumentation it is possible to obtain reliable raw data under non-ambient conditions. Nanoindentation tests on polymeric films at elevated temperature provide support for the correlation, with high values of the high strain rate sensitivity parameter only observed in the vicinity of the glass transition temperature.

Elevated temperature nanoindentation and viscoelastic behaviour of thin poly(ethylene terephthalate) films.

A commercial nanoindentation system fitted with a heating stage and heated indenter has been used to investigate how the elevated temperature nanoscale mechanical properties of poly(ethylene terephthalate) films vary with their processing history and crystallinity over the temperature range 60-110 degrees C. Three additive-free thin films were tested; an undrawn amorphous film, a uniaxially drawn film, and a commercial biaxially drawn Melinex film. A sharp decrease in mechanical properties was observed between 70 and 80 degrees C on the undrawn and uniaxial film consistent with the presence of a glass transition over this temperature range in agreement with literature values for bulk materials.