Deposition of various coatings on surface of engineering components with the aim to improve their performance concerning wear, corrosion, friction, and thermal protection is already a standard practice. In special cases, depositing metallic NiTi shape memory alloy coatings may be a viable alternative for hard ceramic coatings. NiTi coatings offer additional benefits originating from their unique functional thermomechanical properties. However, fabrication of thick NiTi coatings turned out to be difficult. Standard electroplating and laser cladding methods are not suitable for NiTi, the most widely used plasma spray methods tend to produce chemically inhomogeneous coatings that do not transform martensitically, cold sprayed NiTi coatings suffer from poor adhesion to the substrates. In this work, we report on first ever successful fabrication of thick NiTi coatings (100–300 μm) that display functional thermomechanical properties and simultaneously show very good adherence to the substrate. We used high velocity air fuel thermal spray method to fabricate NiTi coatings deposited on mild steel using four different sets of fabrication parameters. Chemical composition, porosity, microstructure, phase transformation and functional thermomechanical properties of the NiTi coatings were evaluated. Although the coatings contain inhomogeneous microstructure, voids, oxide particles, high density of dislocation defects and internal stress, they undergo martensitic transformation upon cooling and/or mechanical loading. As sprayed NiTi coatings need to be annealed to display functional thermomechanical properties. Despite their limited tensile strength, the coatings displayed thermal actuation in 3-point bending tests and shape memory effects in nanoindentation and scratch tests.

This study investigates the plasmonic properties of TiN thin films deposited by pulsed mid-frequency reactive magnetron sputtering combined with RF inductively coupled plasma in a DC magnetic field and electron cyclotron wave resonance (ECWR). The substrate was grounded while the plasma potential was tuned by applying a positive DC bias from 0 to 120 V to the ECWR coil relative to ground. Raising the DC bias increased the plasma potential and thus accelerated ions to energies corresponding to that potential, producing energetic ion bombardment of the grounded substrate. The principal benefit of adding ECWR plasma and a DC bias is an increased degree of ionization in the reactive plasma. Consequently, the resulting denser plasma and enhanced N2 dissociation improve the internal structure of the deposited films even at low substrate temperatures.

This article focuses on the influence of long-term UV radiation exposure on mechanical and structural properties of selected polymeric materials (PLA, ABS, PC, PETG, HIPS) prepared using 3D-print based Fused Filament Fabrication (FFF) method. Existing research in the field of polymers weathering has been focused more on the combined effects so far, moreover on time scales not exceeding units of months. However, it is important to separate individual effects to understand the dynamics of material changes and design strategies to improve material resistance. Our research thus focuses on UV-affected ageing of the selected polymers for time duration exceeding 10 months (7744 consecutive hours, i.e. 322 days), performed in an environmental cell with controlled humidity and temperature. Mechanical properties were evaluated by a locally sensitive nanoindentation method. Surface properties, depth property profiles, and creep were studied as well. Hardness and modulus of elasticity data were obtained for a wide range of samples. Based on our analysis of mechanical properties, the highest UV resistances are characteristic for PLA and PC. On the contrary, noticeable changes of mechanical properties occur in the ABS and HIPS samples (even at greater depths), leading to an embrittlement of the former material. Changes in mechanical properties even in strongly affected samples (PETG) were only evident to depths <10 um. For the selected samples (PLA, ABS, PETG), vibrational spectroscopies (Raman scattering and infrared absorption) were exploited to gain a deeper insight into polymers structural changes. Vibrational spectra supported the results of mechanical properties tests: while PLA revealed no significant changes from the structural viewpoint; ABS and PETG showed differences in characteristic as well as deformation vibrations.

The non-continuous multi-cycle nanoindentation along with scratch and wear tests were performed on super elastic (SE) and shape memory (SM) NiTi alloys in order to observe the behaviour of super elasticity and shape memory effect. A spherical indenter with radius 10 mu m was used in scratch test under three loads (100, 250 and 500 mN) to evaluate critical limits of scratch resistance and in wear test to evaluate material behavior in repetitive scratch under subcritical loads (100 and 250 mN). The study finds that SE shows more elastic recovery after removing the load from the indenter. However, in case of SM the recovery is less pronounced with remaining plastic deformation, indicating that stress induced martensite phase remains in the alloy. Wear test resulted in the pile of the material during multiple ploughing along the track as is observed from the morphology of track profile. The differences between the materials become smaller when the load in the wear test increases, with even the SE showing marked plastic deformation.

Diffuse photons of energy above 0.1 PeV, produced through the interactions between cosmic rays and either interstellar matter or background radiation fields, are powerful tracers of the distribution of cosmic rays in the Galaxy. Furthermore, the measurement of a diffuse photon flux would be an important probe to test models of super-heavy dark matter decaying into gamma-rays. In this work, we search for a diffuse photon flux in the energy range between 50 PeV and 200 PeV using data from the Pierre Auger Observatory. For the first time, we combine the air-shower measurements from a 2 km^2 surface array consisting of 19 water-Cherenkov surface detectors, spaced at 433 m, with the muon measurements from an array of buried scintillators placed in the same area. Using 15 months of data, collected while the array was still under construction, we derive upper limits to the integral photon flux ranging from 13.3 to 13.8 km^-2 sr^-1 yr^-1 above tens of PeV. We extend the Pierre Auger Observatory photon search program towards lower energies, covering more than three decades of cosmic-ray energy. This work lays the foundation for future diffuse photon searches: with the data from the next 10 years of operation of the Observatory, this limit is expected to improve by a factor of ∼20.