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The polypropylene (PP) strips were modified with the industrial gliding arc discharge working in air flow at 50 Hz. The experiments aimed at increased wettability and improved strength of the epoxy adhesive DP190 bond with PP. While working only in dry air, the deterioration of the plasma treatment uniformity was observed at higher treatment speeds than 100 mm/s. At the same time, the tensile strength of the adhesive bond and the atomic concentrations of O and N decreased whereas the water contact angle (WCA) measurement error increased. The fast camera measurements revealed that the PP surface was treated by the direct contact with active plasma filaments. The non-uniformity of the PP surface treatment for increased treatment speed can be explained by taking into account the stochastic character of the filament propagation direction and the characteristic time scales of the process. As an improvement of the gliding arc treatment technology a new geometry utilizing the gas cross flow was proposed with the help of gas dynamic simulations. The addition of argon cross flow led to an improvement of the treatment uniformity and, for the optimized conditions, the measured tensile strength of the adhesive bond to PP was 6.5 times higher than for the untreated PP sample. The treatments with the cross flow of argon mixed with water vapors and volatile organic compounds (VOCs), ethanol and isopropanol, did not increase the tensile strength of the adhesive joint even though the wettability was higher for the mixtures with VOCs. Since the concentration of functional groups measured by X-ray photoelectron spectroscopy was well correlated with the tensile strength of adhesive joints, WCA measurements cannot be used as the only parameter judging the success of the plasma treatment aimed at an improvement of adhesive joint strength.

Small-punch and nano-indentation tests were used for the first time to probe strength of 500 mu m thin Ni50Ti50 shape memory platelets in their hydrogen-free and hydrogen-doped states. Results show excellent reproducibility and suggest that hydrogen penetrates the alloy more efficiently during the cathodic charging at ambient temperatures as compared to heat treatments in a controlled hydrogen atmosphere. Hydrogen content exceeding 100 wtppm results in a retransformation from the B19' martensite to the R lattice and causes a systematic drop of the rupture strength. The retransformation events in thin surface lamellae were documented by the transmission electron microscopy. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Low ductility and brittle deformation behaviors are major drawbacks of currently used commercial hard ceramic-based protective coatings. Recent ab-initio calculations revealed that the coexistence of metallic, boride and carbide bonds in a nanolaminate structure of crystalline W2BC system provides a combination of high hardness together with moderate ductility. The present paper deals with coatings containing W, B and C with different compositions and investigates the effect of the boron to tungsten ratio (B/W) on the structural and mechanical properties of W-B-C coatings prepared by pulsed-DC magnetron sputtering at a moderate temperature. Coatings with low B/W were deposited in a nanocomposite structure, whereas coatings with high B/W ratios were near-amorphous. The structure of the coatings was not a decisive factor in determining their mechanical properties. These were, however, directly correlated with the chemical bonds present. All the coatings exhibited high fracture resistance. These properties together with good adhesion to cemented tungsten carbides make W-B-C coatings promising candidates for the future protective coatings of tools which undergo large deformation in their working cycle.

Polyoxazoline thin coatings were deposited on glass substrates using atmospheric pressure plasma polymerization from 2-ethyl-2-oxazoline vapours. The plasma polymerization was performed in dielectric barrier discharge burning in nitrogen at atmospheric pressure. The thin films stable in aqueous environments were obtained at the deposition with increased substrate temperature, which was changed from 20◦ C to 150◦ C. The thin film deposited samples were highly active against both S. aureus and E. coli strains in general. The chemical composition of polyoxazoline films was studied by FTIR and XPS, the mechanical properties of films were studied by depth sensing indentation technique and by scratch tests. The film surface properties were studied by AFM and by surface energy measurement. After tuning the deposition parameters (i.e., monomer flow rate and substrate temperature), stable films, which resist bacterial biofilm formation and have cell-repellent properties, were achieved. Such antibiofouling polyoxazoline thin films can have many potential biomedical applications. © MDPI AG. All rights reserved., Czech Science FoundationGrant Agency of the Czech Republic [GACR 19-15240S]; Ministry of Defence of the Czech Republic

This research was devoted to studying the influence of the taper angle on the micro-compression of micro-pillars fabricated from near-amorphous and nanocrystalline Mo-B-C coatings. A series of micro-pillars with a taper angle between 4–14° was fabricated by focused ion beam technique. The deformation mechanism was found to be dependent on the taper and, also, on the crystallinity of the coating. In order to obtain correct values of yield strength and Young’s modulus, three empirical models of stress correction were experimentally tested, and the results were compared with nanoindentation measurements. It was shown that the average stress correction model provided comparable results with nanoindentation for the yield strength for taper angles up to ~10°. On the other hand, the average radius or area model gave the most precise results for Young’s modulus if the taper angle was

The current work aimed to characterize the morphology, chemical, and mechanical properties of Pt and PtTi thin films deposited via thermionic vacuum arc (TVA) method on glass and silicon substrates. The deposited thin films were characterized by means of a scanning electron microscope technique (SEM). The quantitative elemental microanalysis was done using energy-dispersive X-ray spectroscopy (EDS). The tribological properties were studied by a ball-on-disc tribometer, and the mechanical properties were measured using nanoindentation tests. The roughness, as well as the micro and nanoscale features, were characterized using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The wettability of the deposited Pt and PtTi thin films was investigated by the surface free energy evaluation (SFE) method. The purpose of our study was to prove the potential applications of Pt-based thin films in fields, such as nanoelectronics, fuel cells, medicine, and materials science.

In this paper the complete optical characterization of an inhomogeneous polymer-like thin film of SiO x C y H z exhibiting a thickness non-uniformity and transition layer at the boundary between the silicon substrate and this film is performed using variable angle spectroscopic ellipsometry. The Campi-Coriasso dispersion model was utilized for describing the spectral dependencies of the optical constants of the SiO x C y H z thin film and transition layer. The multiple-beam interference model was used for expressing inhomogeneity of the SiO x C y H z thin film. The thickness non-uniformity of this film was taken into account by means of the averaging of the elements of the Mueller matrix performed using the thickness distribution for the wedge-shaped non-uniformity. The spectral dependencies of the optical constants of the SiO x C y H z thin film at the upper and lower boundaries together with the spectral dependencies of the optical constants of the transition layer were determined. Furthermore, the thickness values of the SiO x C y H z film and transition layer, profiles of the optical constants of the SiO x C y H z thin film and the rms value of local thicknesses corresponding to its thickness non-uniformity were determined. Thus, all the parameters characterizing this complicated film were determined without any auxiliary methods.

The initial stage of graphene layer deposition on silicon oxide substrate by ethanol decomposition in dual-channel microwave plasma torch at atmospheric pressure was studied in dependence on precursor flow rate and delivered microwave power. Depending on ethanol flow rate and substrate temperature, horizontally or vertically aligned graphene nanosheets with various density could be prepared directly on dielectric substrate. In the regime with high microwave power, above 400 W, mixture of amorphous carbon particles and graphene sheets was deposited on the substrate. Prepared layers were analyzed by scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The microwave plasma diagnostics was carried out using optical emission spectroscopy (OES). The sample analysis showed increasing density of horizontally aligned carbon nanosheets with increasing ethanol flow rate and their delamination and transition into vertically aligned graphene sheets with increasing substrate temperature. The Raman spectroscopy analysis of layers showed presence of D (1345 cm(-1)), G (1585 cm(-1)) and 2D (2685 cm(-1)) peaks with 2D/G ratio of 1.59 and full width at half maximum (FWHM) of 2D peak was 42 cm(-1), corresponding to few layer graphene structure. In case of amorphous nanoparticles deposition, the D* peak at 1210 cm(-1) and D** at 1500 seem-1 was observed in Raman spectra with D/G ratio of 1.19 and Cls XPS spectra of carbon contained 20.4 at.% of spa carbon phase in comparison to 8.3 at.% in case of graphene nanosheets layer. High D/G ratio, up to 3.5, and low intensity 2D band was characteristic for vertically aligned graphene nanosheets layers. The possibility to influence density and size of graphene nanosheets on substrate represents promising alternative for future deposition of graphene on arbitrary substrate. Počáteční fáze nanášení grafenové vrstvy na substrát oxidu křemičitého rozkladem ethanolu v dvoukanálovém mikrovlnném plazmovém hořáku za atmosférického tlaku byl studován v závislosti na průtoku prekurzoru a dodávané mikrovlnné energii. V závislosti na průtoku ethanolu a teplotě substrátu lze přímo na dielektrickém substrátu připravit vodorovně nebo svisle uspořádané grafenové nanosheety s různou hustotou. V režimu s vysokým mikrovlnným výkonem nad 400 W byla na substrát nanesena směs amorfních uhlíkových částic a grafenových listů. Připravené vrstvy byly analyzovány skenovací elektronovou mikroskopií (SEM), Ramanovou spektroskopií a rentgenovou fotoelektronovou spektroskopií (XPS). Diagnostika mikrovlnné plazmy byla prováděna pomocí optické emisní spektroskopie (OES). Analýza vzorku ukázala rostoucí hustotu horizontálně uspořádaných uhlíkových nanosheet se zvyšující se průtokovou rychlostí ethanolu a jejich delaminaci a přechod na svisle zarovnané grafenové desky se zvyšující se teplotou substrátu. Ramanova spektroskopická analýza vrstev ukázala přítomnost píku D (1345 cm (-1)), G (1585 cm (-1)) a 2D (2685 cm (-1)) s poměrem 2D / G 1,59 a plnou šířkou při poloviční maximum (FWHM) 2D píku bylo 42 cm (-1), což odpovídá několika vrstvové grafenové struktuře. V případě ukládání amorfních nanočástic byl v Ramanově spektru pozorován D * pík při 1210 cm (-1) a D ** při 1500 zdán-1 s poměrem D / G 1,19 a Cls XPS spektra uhlíku obsahovala 20,4%. lázeňské uhlíkové fáze ve srovnání s 8,3 at.% v případě vrstvy nanočástic grafenu. Vysoký poměr D / G, až 3,5, a nízkointenzivní 2D pás byl charakteristický pro svisle zarovnané vrstvy nanočástic grafenu. Možnost ovlivnit hustotu a velikost grafenových nanosheetů na substrátu představuje slibnou alternativu pro budoucí depozici grafenu na libovolném substrátu. The initial stage of graphene layer deposition on silicon oxide substrate by ethanol decomposition in dual-channel microwave plasma torch at atmospheric pressure was studied in dependence on precursor flow rate and delivered microwave power. Depending on ethanol flow rate and substrate temperature, horizontally or vertically aligned graphene nanosheets with various density could be prepared directly on dielectric substrate. In the regime with high microwave power, above 400 W, mixture of amorphous carbon particles and graphene sheets was deposited on the substrate. Prepared layers were analyzed by scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The microwave plasma diagnostics was carried out using optical emission spectroscopy (OES). The sample analysis showed increasing density of horizontally aligned carbon nanosheets with increasing ethanol flow rate and their delamination and transition into vertically aligned graphene sheets with increasing substrate temperature. The Raman spectroscopy analysis of layers showed presence of D (1345 cm(-1)), G (1585 cm(-1)) and 2D (2685 cm(-1)) peaks with 2D/G ratio of 1.59 and full width at half maximum (FWHM) of 2D peak was 42 cm(-1), corresponding to few layer graphene structure. In case of amorphous nanoparticles deposition, the D* peak at 1210 cm(-1) and D** at 1500 seem-1 was observed in Raman spectra with D/G ratio of 1.19 and Cls XPS spectra of carbon contained 20.4 at.% of spa carbon phase in comparison to 8.3 at.% in case of graphene nanosheets layer. High D/G ratio, up to 3.5, and low intensity 2D band was characteristic for vertically aligned graphene nanosheets layers. The possibility to influence density and size of graphene nanosheets on substrate represents promising alternative for future deposition of graphene on arbitrary substrate.

Commercial ceramic protective coatings usually exhibit high hardness, but low ductility impairs their performance and application-oriented properties. Accordingly, a state-of-the-art magnetron sputtered W-B-C coating can be a promising coating for the tooling industry due to its hard yet tough characteristics. In the present study, we have employed substrate biasing to enhance the delivered energy to the growing film and have investigated the effect of bias voltage on the structural and mechanical behavior of W-B-C coatings. The investigations revealed that increasing the substrate bias voltage enhanced the re-sputtering of B and C atoms and subsequently varied the chemical composition of the coatings and significantly decreased the growth rate. It also enhanced the crystallinity of the coatings. We demonstrate how the bias voltage led to an unusual transition from a featureless to a columnar microstructure. Furthermore, it was observed that as the substrate bias voltage increased from 0 V to −125 V, the compositional and structural changes resulted in a slight decrease of the hardness, while a further increase in the bias voltage to −200 V enhanced the hardness. This increase was attributed to the suppression of dislocation movement and grain boundary deformation processes by solute segregation and by lattice defects.

With the improvement of depth-sensing instruments nanoindentation has become a standard tool for the study and design of thin film systems, nanocomposites and other nanostructured materials and devices. Mechanical properties, such as elastic modulus and hardness can be measured at scales in the depth range of tens of nanometers. The correct determination of the mechanical properties depends on the proper evaluation of the real contact area. While two standard methods are commonly used, indentations on a reference sample and measurement by atomic force microscopy (AFM), there are many caveats and the issue remains tricky, especially for large depths. In this contribution we present an example where the standard calibration of the tip area function via a reference sample cannot be used for the desired tip and the AFM method must be used instead.

The local mechanical properties of Fe78Al22alloy were studied using nanoindentation techniques. Sharp Berkovich indenter was used to perform load-controlled nanoindentation experiments on the studied sample. Hardness and elastic modulus maps were created on the basis of the indentation tests carried out in different grains. The focus of the work was to study the dependence of mechanical properties on the grain orientation. The results were in good agreement with quantum-mechanical calculations of anisotropic elastic properties of the studied alloy. It was explained that the maximum detected elastic modulus values are likely for grains with [111] crystallographic orientations which we theoretically identified as the hard ones.

Skutterudites are an important class of thermoelectric p- and n-type materials and they have already achieved fair efficiencies for the conversion of heat to electricity. Nevertheless researchers try to further enhance the figure of merit, ZT, by various ways. In this work we study microstructure and mechanical properties of two thermoelectric materials: an industrial n-type (Mm,Sm)yCo4Sb12 skutterudite and an industrial p-type DDyFe3CoSb12 skutterudite, both mixed with 1 wt.% of Ta0.8Zr0.2B. Thin lamellae were prepared from the compacted materials using a focused ion beam. Analytical transmission electron microscopy was used on lamellae to study details of microstructure. A fine dispersion of precipitates was found both at nanograin boundaries and in their interiors. Quasistatic and dynamic nanoindentation tests were carried out on planar polished sections in the range of applied loads from 0.01 to 10 mN. The results were complemented with quantitative modulus mapping of local mechanical properties with 10-nm resolution.

We report on the influence of post-printing curing on the physico-chemical properties of silica-bonded particulate titania photocatalytic layers. Ink consisting of commercial titania nanoparticles and a novel siloxane binder was patterned by inkjet printing. Printed layers were mineralized by three processes: thermal annealing by convection heating in an electric furnace, UV-curing with a high pressure mercury vapour lamp, and atmospheric plasma treatment in a coplanar dielectric barrier discharge. The influence of these processes on the extend of the binder mineralization and resulting physicochemical properties, charge generation and transport as well as photocatalytic activity was investigated. All curing methods proved to be capable to mineralize the binder but atmospheric plasma curing stands out as the fastest one enabling a direct implementation into roll-to-roll fabrication processes.

Preparation of coatings simultaneously exhibiting high hardness and enhanced fracture resistance is a hot topic, as nowadays used ceramic protective coatings show difficulties to cope with increased demands due to their inherent brittleness. Material exhibiting seemingly contradictory combination of mechanical properties like high hardness and moderate ductility enhancing the fracture resistance - was recently predicted by ab initio calculations in the crystalline X2BC system. The presented study is focused on the study of the influence of the C/W ratio on the microstructure, the content of different chemical bonds and the mechanical properties of WBC coatings prepared by magnetron sputtering at moderate temperature.

State-of-the-art protective coatings often suffer from brittleness. Therefore, the coatings are intensively sought which would simultaneously exhibit high hardness and stiffness with moderate ductility and fracture resistance. In this paper, we report on the nanostructure designing of coatings containing metal, boron, and carbon enabling the simultaneous presence of stiff boridic and carbidic bonds together with weaker metallic bonds to provide coatings with these desirable properties. Three designs are presented with different relative amounts of nanocrystalline and amorphous phases, ranging from near-amorphous to prevalently crystalline microstructure. All presented coatings exhibit an unusual combination of high fracture resistance and high hardness that cannot be achieved with state-of-the-art protective coatings. Indentation tests at high loads revealed that no cracks are present at the surface of the investigated coatings while state-of-the-art ceramic protective coatings already exhibit significant cracking. Cracks in the bulk of the presented coating are detected only when the deformation is so severe that the substrate itself fails.

In the present work, SiOxCyHz coatings were prepared in capacitively coupled RF glow discharge from gaseous mixture of trimethylsilyl acetate (TMSAc) monomer and oxygen. Properties of thin solid films prepared using continuous wave (CW) plasma and pulsed wave (PW) plasma were examined, including long–term stability in contact with air and water environments. The presented study proves that it is possible to prepare organosilicon coatings showing properties in a wide range from soft organic polymeric structures to materials similar to SiO2 with Martens hardness of 4 GPa. The content of carbon species in organosilicon structure and water contact angle (WCA) decreased with increasing oxygen ratio from 7.7 % to 75.0 %. The water contact angle of TMSAc-based coatings prepared in CW mode decreased from 95° to 76°. The application of pulsed mode using an oxygen ratio of 50 % and pulse repetition frequencies in the range of 0.33 Hz to 300 Hz led to materials with hydrophobic character (WCA in range of 86°–94°) with increased content of CHx and Si-CH3 structures in comparison to CW mode. This study proves that the aging mechanism significantly depends on deposition parameters. The increase of oxygen ratio, as well as the increase of pulse repetition frequency, led to the higher resistance towards the atmospheric environment. On the other side, organosilicon coatings prepared in CW mode using high oxygen ratios (50–75 %) showed significant delamination after immersion in water. However, the use of PW plasma for the preparation of SiOxCyHz thin films significantly improved the stability of resulting materials under water environment.

Titanium carbide/carbon coatings were deposited by hybrid PVD-PECVD process of titanium sputtering in an atmosphere containing acetylene. Samples were placed above the titanium target centre and above the target racetrack in the same vertical distance to the target to examine the effect of the relative substrate to target position on the properties of the deposited coatings. The different positions of the samples led to significantly different levels of the energy influx onto the growing coating. These differing conditions at the substrate led to altering of the coating's chemical as well as phase composition. Also, the grain size, lattice parameter and the mean grain separation were affected by the energy flux change. Coatings deposited above the racetrack with carbon content ≲ 60% exhibited smaller grains, higher amount of the a-C phase and higher mean grain separation. This microstructure refinement yielded 20–30% higher hardness of the coatings deposited above the target racetrack than corresponding coatings deposited above the target centre. Thus, the sample positioning in the chamber proved to be an important parameter for resulting properties of the deposited coatings.

In the present work, nanocomposite Mo-B-C coatings were deposited on high speed steel and hard metal substrates by magnetron sputtering of three targets. These coatings were subjected to annealing to final temperatures in the range from 500 °C to 1000 °C. It was found that the as deposited Mo-B-C coatings exhibited hardness of ∼20 GPa, nanocomposite microstructure with very fine grains (∼2 nm) and low degree of crystallinity. The X-ray diffraction and transmission electron microscopy together with selective area electron diffraction were used to study the temperature induced changes of the microstructure of the coating and its crystallinity. The annealing process significantly improved the hardness (from ∼20 GPa to ∼30 GPa) and effective elastic modulus (from initial 330 GPa–500 GPa) of coatings while their resistance to fracture was kept sufficiently high.

Nanocomposite coatings consisting of titanium carbide crystallites embedded in amorphous carbon matrix were deposited utilizing direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) of titanium target in argon/acetylene atmosphere. DC driven depositions of coatings with high amount of carbon were accompanied by significant arcing during the deposition. HiPIMS utilization made reliable arc-free deposition of coatings with high carbon content possible. Analyses of the coating structure revealed that utilization of HiPIMS favours carbon incorporation into the TiCx grains rather than to the matrix. HiPIMS deposited coatings exhibited stoichiometry of the TiCx grains closer to unity with grains exhibiting lower lattice parameter and a lower fraction of the a-C matrix. This led to a smaller mean TiCx grain separation by the a-C:H matrix. Also the surface structure of the HiPIMS deposited coatings was much finer. The structure refinement resulted in overall higher hardness of HiPIMS deposited coatings with the hardest coatings reaching the superhard region of > 40 GPa and in 40% increase of H/E ratio and nearly threefold increase of H3/E2 ratio.

Nanocomposite nc-TiC/a-C:H thin films exhibit unique combination of mechanical properties, high hardness, low friction, and wear. Selective doping by weak-carbide forming element can be used in order to specifically design the physical and chemical properties of nc-TiC/a-C:H coatings. In this paper we report on an effect of nickel addition on structure and hardness of the nc-TiC/a-C:H coatings. The effect of Ni alloying on the coating structure under conditions of DCMS and HiPIMS depositions was studied. The coating structure was correlated with the coating hardness. The grain size, the grain carbon vacancy concentration, and the mean grain separation were found to be the key parameters determining the coating hardness. Ni doping proved to have a significant effect on the coating microstructure which resulted in changes of the hardness of the deposited coatings.

Polyoxazolines are a new promising class of polymers for biomedical applications. Antibiofouling polyoxazoline coatings can suppress bacterial colonization of medical devices, which can cause infections to patients. However, the creation of oxazoline-based films using conventional methods is difficult. This study presents a new way to produce plasma polymerized oxazoline-based films with antibiofouling properties and good biocompatibility. The films were created via plasma deposition from 2-methyl-2-oxazoline vapors in nitrogen atmospheric pressure dielectric barrier discharge. Diverse film properties were achieved by increasing the substrate temperature at the deposition. The physical and chemical properties of plasma polymerized polyoxazoline films were studied by SEM, EDX, FTIR, AFM, depth-sensing indentation technique, and surface energy measurement. After tuning of the deposition parameters, films with a capacity to resist bacterial biofilm formation were achieved. Deposited films also promote cell viability.

We combine theoretical and experimental tools to study elastic properties of Fe-Al-Ti superalloys. Focusing on samples with chemical composition Fe 71 Al 22 Ti 7 , we use transmission electron microscopy (TEM) to detect their two-phase superalloy nano-structure (consisting of cuboids embedded into a matrix). The chemical composition of both phases, Fe 66 . 2 Al 23 . 3 Ti 10 . 5 for cuboids and Fe 81 Al 19 (with about 1% or less of Ti) for the matrix, was determined from an Energy-Dispersive X-ray Spectroscopy (EDS) analysis. The phase of cuboids is found to be a rather strongly off-stoichiometric (Fe-rich and Ti-poor) variant of Heusler Fe 2 TiAl intermetallic compound with the L2 1 structure. The phase of the matrix is a solid solution of Al atoms in a ferromagnetic body-centered cubic (bcc) Fe. Quantum-mechanical calculations were employed to obtain an insight into elastic properties of the two phases. Three distributions of chemical species were simulated for the phase of cuboids (A2, B2 and L2 1 ) in order to determine a sublattice preference of the excess Fe atoms. The lowest formation energy was obtained when the excess Fe atoms form a solid solution with the Ti atoms at the Ti-sublattice within the Heusler L2 1 phase (L2 1 variant). Similarly, three configurations of Al atoms in the phase of the matrix with different level of order (A2, B2 and D0 3 ) were simulated. The computed formation energy is the lowest when all the 1st and 2nd nearest-neighbor Al-Al pairs are eliminated (the D0 3 variant). Next, the elastic tensors of all phases were calculated. The maximum Young&rsquo, s modulus is found to increase with increasing chemical order. Further we simulated an anti-phase boundary (APB) in the L2 1 phase of cuboids and observed an elastic softening (as another effect of the APB, we also predict a significant increase of the total magnetic moment by 140% when compared with the APB-free material). Finally, to validate these predicted trends, a nano-scale dynamical mechanical analysis (nanoDMA) was used to probe elasticity of phases. Consistent with the prediction, the cuboids were found stiffer.

The aim of the present work was to study the mechanical properties of thin nanocomposite Mo-B-C coatings consisting of nanocrystalline Mo2BC embedded in amorphous Mo-B-C matrix. Magnetron sputtering of three targets, B4C, C and Mo, was used for coatings preparation. The Mo-B-C coatings were deposited on high speed steel substrates. The fracture resistance of Mo-B-C coatings was studied by both indentation and dynamic impact tests. The impact tests enabled us to predict the load limit causing the coating destruction.

One-step electrolytic method for production of superhydrophobic and oil-reppelent surface on stainless steel using aqueous solution of perfluorooctanoic acid as an electrolyte compared with analogous deposition of superhydrophobic surfaces from ethanolic solutions of myristic and stearic acid. One-step electrolytic method for production of superhydrophobic and oil-reppelent surface on stainless steel using aqueous solution of perfluorooctanoic acid as an electrolyte compared with analogous deposition of superhydrophobic surfaces from ethanolic solutions of myristic and stearic acid. One-step electrolytic method for production of superhydrophobic and oil-reppelent surface on stainless steel using aqueous solution of perfluorooctanoic acid as an electrolyte compared with analogous deposition of superhydrophobic surfaces from ethanolic solutions of myristic and stearic acid. One-step electrolytic method for production of superhydrophobic and oil-repellent surface on stainless steel using aqueous solution of perfluorooctanoic acid as an electrolyte compared with analogous deposition of superhydrophobic surfaces from ethanolic solutions of myristic and stearic acid

A study of a hybrid PVD-PECVD process of sputtering a titanium target in an argon/acetylene gas mixture was performed. This process was used for the deposition of nanocomposite coatings consisting of titanium carbide grains embedded in an amorphous hydrogenated carbon matrix (nc-TiC/a-C:H). The study was performed under industrial conditions employing a large-scale deposition device with a cylindrical sputtering cathode. When the acetylene supply was gradually increased, a discharge voltage drop and total pressure saturation simultaneously occurred at a certain acetylene supply. The hardest coatings were found always to be deposited at the acetylene supply corresponding to these deposition conditions. However, the acetylene supply to detect the voltage drop and pressure saturation was determined to be dependent on the cathode thickness. A fully automatic procedure suitable for the preparation of hard nc-TiC/a-C:H coatings by the hybrid PVD-PECVD process was proposed in this paper. This approach ensured that the optimal deposition setting was consistently found for the deposition process independent of the cathode thickness. The procedure was thoroughly tested, and it was demonstrated to be reliable and robust. Furthermore, the algorithm ensured the deposition of coatings with the same composition and the same high hardness throughout the cathode lifetime.

The effects of thickness non-uniformity on measured optical quantities must be often considered in the optical characterization. The effects of thickness non-uniformity can be taken into account by averaging the Mueller matrices over the distribution of local thicknesses within the measured area. The distribution of local thicknesses can be assumed in a certain form (e.g. the uniform distribution), or it can be derived on the basis of a model assuming a certain shape of thickness non-uniformity. The latter approach is especially useful for the variable-angle spectroscopic ellipsometry since it can take into account dependence on the incidence angle due to the changes in the size of the light spot. This paper presents results of the optical characterization of three polymer-like thin films highly non-uniform in thickness using variable-angle spectroscopic ellipsometry. The shapes of the thickness non-uniform films are determined on the basis of a model assuming local thicknesses given by quadratic polynomials in coordinates along the surfaces of the films. The studied areas on the films were also measured by the imaging spectroscopic reflectometry, which provides a more direct method to determine local thicknesses. The results achieved using the imaging spectroscopic reflectometry and variable-angle spectroscopic ellipsometry were then compared.

The aim of the present work was to prepare SiOxCyHz coatings in capacitively-coupled RF glow discharge from gaseous mixture of trimethylsilyl acetate (TMSAc) monomer and oxygen. The properties of deposited coatings have been investigated using several characterization methods. The presented study proves that properties of TMSAc-based thin films are significantly dependent on the monomer ratio in TMSAc/O2 mixture which varied from 25.0% to 92.3%. Using a low TMSAc ratio (high content of oxygen gas) resulted in organosilicon materials similar to SiO2 in terms of chemical composition and mechanical properties. Increasing the fraction of TMSAc in gaseous mixture led to the formation of more organic polymeric structures enriched with carbon atoms bonded in CHx chains. Values of Martens hardness decreased from 3.97 to 0.76 GPa with increasing TMSAc fraction from 25.0% to 92.3%. The degree of hydrophobicity of prepared coatings evolved in accordance with observed structural changes corresponding to applied monomer ratios. The water contact angle gradually increased from 75.0° to 95.3° with increasing TMSAc fraction. The prepared TMSAc plasma polymers became more hydrophobic with more intensive integration of hydrocarbon species into the surface structure.

A common approach to non-uniformity is to assume that the local thicknesses inside the light spot are distributed according to a certain distribution, such as the uniform distribution or the Wigner semicircle distribution. A model considered in this work uses a different approach in which the local thicknesses are given by a polynomial in the coordinates x and y along the surface of the film. An approach using the Gaussian quadrature is very efficient for including the influence of the non-uniformity on the measured ellipsometric quantities. However, the nodes and weights for the Gaussian quadrature must be calculated numerically if the non-uniformity is parameterized by the second or higher degree polynomial. A method for calculating these nodes and weights which is both efficient and numerically stable is presented. The presented method with a model using a second-degree polynomial is demonstrated on the sample of highly non-uniform polymer-like thin film characterized using variable-angle spectroscopic ellipsometry. The results are compared with those obtained using a model assuming the Wigner semicircle distribution.

Nanostructured C-Ag thin films of 200 nm thickness were successfully synthesized by the Thermionic Vacuum Arc (TVA) method. The influence of different substrates (glass, silicon wafers, and stainless steel) on the microstructure, morphology, and mechanical properties of nanostructured C-Ag thin films was characterized by High-Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and TI 950 (Hysitron) nanoindenter equipped with Berkovich indenter, respectively. The film’s hardness deposited on glass (HC-Ag/Gl = 1.8 GPa) was slightly lower than in the case of the C-Ag film deposited on a silicon substrate (HC-Ag/Si = 2.2 GPa). Also the apparent elastic modulus Eeff was lower for C-Ag/Gl sample (Eeff = 100 GPa) than for C-Ag/Si (Eeff = 170 GPa), while the values for average roughness are Ra=2.9 nm (C-Ag/Si) and Ra=10.6 (C-Ag/Gl). Using the modulus mapping mode, spontaneous and indentation-induced aggregation of the silver nanoparticles was observed for both C-Ag/Gl and C-Ag/Si samples. The nanocomposite C-Ag film exhibited not only higher hardness and effective elastic modulus, but also a higher fracture resistance toughness to the silicon substrate compared to the glass substrate.

Titanium–carbon hard coatings were deposited by sputtering using a rotating cylindrical titanium target in an argon/acetylene gas mixture on cemented tungsten-carbide substrates which were placed on a DC-biasable holder to perform a complex rotation around the central rotating cylindrical Ti cathode. While the optimal deposition process parameters to grow the coating of the highest possible hardness and low friction coefficient were sought, the plasma parameters were monitored and correlated with the properties of the deposited coatings. The Ti/Ar line intensity and the cathode voltage exhibited a sudden drop at the conditions for which the maximal hardness was reached. EDX analyses also showed a sudden drop in the atomic concentration of titanium and a sudden increase in that of carbon at the same moment. The maximal hardness of the coating was always achieved at the conditions that preceded these sudden changes, so this phenomenon was used to set the optimal deposition parameters to produce hard, well-adherent and sufficiently thick titanium–carbon coatings using the industrially attractive concept of a rotating cylindrical magnetron.

This work is aimed at the study of thermal stability of nc-TiC/a-C:H coatings deposited on steel substrates by unbalanced reactive magnetron sputtering of titanium in an acetylene containing atmosphere. The as-deposited coatings show high hardness and elastic modulus together with low wear and low friction coefficients. The coating properties were investigated as a function of annealing temperature using thermal desorption spectroscopy under UHV conditions. The hardness and elastic modulus did not change substantially up to 700 °C compared to the properties of the as-deposited coatings. The most significant changes were observed in case of their fracture toughness, which decreased due to the hydrogen loss from amorphous carbon matrix.

The aim of the present work is to study the nanoindentation induced defects in as-deposited and annealed nanocomposite n-TiC/a-C:H coatings. Furthermore, the resistance of the coatings against indentation induced defect creation was studied using TEM analysis of lamellas prepared using a focused ion beam for both as-deposited and annealed samples.

Several amorphous Mo–B–C coatings with wide range of compositions were subjected to thermal annealing to a final temperature of 1000 °C in UHV conditions. The nature of the induced recrystallization depended mostly on the Mo content in the coating. A higher Mo content resulted in a nanocrystalline Mo2C phase, a lower Mo content in a nanocrystalline Mo2BC phase and Mo content in-between resulted only in a near-amorphous microstructure. In all cases, the hardness and effective elastic modulus increased significantly after annealing up to values of ∼29 GPa and 500 GPa, respectively. The cobalt diffusion from the WC-Co substrates affected the lower parts of coatings forming a MoCoB interface.

This paper presents the results of the optical characterization of inhomogeneous thin films of polymer-like SiO x C y H z and non-stoichiometric silicon nitride SiN x. An efficient method combining variable angle spectroscopic ellipsometry and spectroscopic reflectometry applied at the near-normal incidence based on the multiple-beam interference model is utilized for this optical characterization. The multiple-beam interference model allows us to quickly evaluate the values of ellipsometric parameters and reflectance of the inhomogeneous thin films, which exhibit general profiles of their optical constants. The spectral dependencies of the optical constants of the inhomogeneous SiO x C y H z and SiN x thin films are determined using the Campi–Coriasso dispersion model. The profiles of the optical constants of these films can also be determined. Furthermore, the transition layers at the lower boundaries of the characterized films are also taken into account. Spectral dependencies of the optical constants of these transition layers are also determined using the Campi–Coriasso dispersion model.This paper presents the results of the optical characterization of inhomogeneous thin films of polymer-like SiO x C y H z and non-stoichiometric silicon nitride SiN x. An efficient method combining variable angle spectroscopic ellipsometry and spectroscopic reflectometry applied at the near-normal incidence based on the multiple-beam interference model is utilized for this optical characterization. The multiple-beam interference model allows us to quickly evaluate the values of ellipsometric parameters and reflectance of the inhomogeneous thin films, which exhibit general profiles of their optical constants. The spectral dependencies of the optical constants of the inhomogeneous SiO x C y H z and SiN x thin films are determined using the Campi–Coriasso dispersion model. The profiles of the optical constants of these films can also be determined. Furthermore, the transition layers at the lower boundaries of the characterized films are also taken into account. Spectral dependencies o...

Polymeric surfaces can benefit from functional modifications prior to using them for biological and/or technical applications. Surfaces considered for biocompatibility studies can be modified to gain beneficiary hydrophilic properties. For such modifications, the preparation of highly hydrophilic surfaces by means of plasma polymerization can be a good alternative to classical wet chemistry or plasma activation in simple atomic or molecular gasses. Atmospheric pressure plasma polymerization makes possible rapid, simple, and time-stable hydrophilic surface preparation, regardless of the type and properties of the material whose surface is to be modified. In this work, the surface of polypropylene was coated with a thin nanolayer of plasma-polymer which was prepared from a low-concentration mixture of propane-butane in nitrogen using atmospheric pressure plasma. A deposition time of only 1 second was necessary to achieve satisfactory hydrophilic properties. Highly hydrophilic, stable surfaces were obtained when the deposition time was 10 seconds. The thin layers of the prepared plasma-polymer exhibit highly stable wetting properties, they are smooth, homogeneous, flexible, and have good adhesion to the surface of polypropylene substrates. Moreover, they are constituted from essential elements only (C, H, N, O). This makes the presented modified plasma-polymer surfaces interesting for further studies in biological and/or technical applications.

Skutterudites are an important class of thermoelectric p- and n-type materials and they have already achieved fair efficiencies for the conversion of heat to electricity. Nevertheless researchers try to further enhance the figure of merit, ZT, by various ways. In this work we compare the microstructure and mechanical properties of an industrial p-type DDyFe3CoSb12 skutterudite powder processed by several routes containing various combinations of ball milling, hot pressing, cold pressing and high pressure torsion. Details of the resulting microstructure are studied by means of analytical electron microscopy as well as by means of local mechanical testing.

Microstructure of Cu-2wt.%Co alloy after various heat treatment (and hence with various phase constitution) was studied after equal-channel angular pressing (ECAP) using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) technique in a scanning electron microscope (SEM). We also focused on local mechanical properties measured across the section perpendicular to the ECAP extrusion direction. Starting from the grain size well above 1mm in the Cu-2wt.%Co solid solution, ECAP subsequently reduces grain size down to the submicron level. A comparison with pure Cu shows that the grain size homogenization is shifted towards higher number of ECAP passes. Fine dispersion of precipitates further slows down the grain refinement and grain size homogenization during ECAP processing. Local mechanical properties measured across the section perpendicular to the ECAP extrusion direction reveal systematic inhomogeneities of deformed microstructure caused by local gradients of temperature and pressure and by the processing geometry itself. This should be considered while characterizing the microstructure by a single EBSD measurement on a small selected area.

Multiwalled carbon nanotubes (CNTs) were modified in low pressure capacitively coupled discharges (13.56 and 27.12 MHz) in Ar/NH 3 and oxygen-containing gas mixtures. A direct functionalization by nitrogen groups was not possible but 1–3 percentage of carbon–oxygen bonds increased with the total oxygen content on the expenses of sp 2 C almost independently on the plasma conditions. The plasma modified CNTs were used as fillers for polyurethane (PU) composites prepared by in situ polymerization. The composites were investigated by depth sensing indentation that revealed the existence of surface harder layer caused probably by different polymerization process in the bulk and at the surface that was in a contact with air. The significant improvement of the hardness and elastic modulus was observed when plasma-modified CNTs with high amount of oxygen were added to PU. It also improved the creep resistance of the PU, whereas the ability to recover from a deformation, i.e. anelastic recovery, did not change much.

Nanocomposites like nc-TiC/a-C:H show promising combinations of properties such as high hardness and Young's modulus combined with low friction and wear. These properties can be furthermore tailored to suit particular industrial needs. In this paper, we report on the preparation and analyses of several μm thick and well adherent nc-TiC/a-C:H coatings with different stoichiometry. These coatings were deposited in a relatively low ion bombardment environment using magnetron sputtering of titanium target operated in well-balanced magnetic field configuration on high speed steel and hardmetal substrates. Gaseous hydrocarbon (acetylene) was added to the deposition chamber as source of carbon. Hardness and Young's modulus of 46 GPa and 415 GPa respectively were reached.

At present, local mechanical properties can be measured not only for macroscopic objects but also for nano-objects and thin films with dimensions of only a few tens of nanometers. For these purposes, special indentation devices can be used. In past decades, many special data measurement and processing methods for thin film characterization have been developed. In addition, the method is no longer restricted to materials science but now also has a wide range of applications for biological problems in which the hardness/modulus values are quite different from those in materials science for which the method was originally designed. Data interpretation in the field of metrology is not so straightforward and care is required in dealing with quantitative results, especially if dealing with very soft samples. Therefore, it is necessary to use reference samples that would enable the comparison of different instruments and the validation of the applied methods. In this contribution, we present the results of our effort on preparing and testing thin film–based reference materials prepared using plasma technologies. We describe a deposition procedure that allows us to produce samples with a large range of hardness and modulus values. From these, we choose a very soft but stable sample that is then further tested to verify its suitability as a reference sample. The major issues discussed in this article are the repeatability of the deposition process, time stability, and homogeneity. Copyright © 2012 John Wiley & Sons, Ltd.

The isotopic effect of hydrogen and deuterium on hydrogenation of radiation defects introduced in n-type float zone and Czochralski silicon by irradiation with high-energy alphas was investigated. Silicon diodes were first irradiated with 2.4 MeV alphas to a fluence of 1x1010cm-2and then hydrogen or deuterium was introduced by rf plasma treatment at 250°C. Reactions of hydrogen and deuterium with radiation defects were monitored by deep-level transient spectroscopy during subsequent isochronal annealing at temperatures ranging from 100 to 400°C. Results show that hydrogen rf plasma effectively neutralizes majority of vacancy related radiation defects created by alphas in both materials. In contrast with it, neutralization by deuterium plasma is substantially weaker. Disappearing of vacancy related defect levels due to hydrogen (deuterium) treatment is accompanied by introduction of two dominant deep levels at EC-0.309 eV and EC-0.365 eV. While hydrogenation significantly accelerates annealing of radiation defects especially in Czochralski material, deuteration has weaker effect and gives rise to new defect levels during annealing.

Nanocrystalline titanium carbide embedded in an hydrogenated amorphous carbon matrix (nc-TiC/a-C:H) shows high hardness and Young's modulus together with low wear and low friction coefficient. In this paper, we report on the preparation of well adherent nc-TiC/a-C:H coatings ~ 5 μm thick on stainless steel substrates using a well balanced magnetic field configuration and only very low power RF bias on the substrate. Hardness and Young's modulus of these coatings are 43 GPa and 380 GPa, respectively. The mechanical properties – hardness and Young's modulus – measured from the coating's top reach the values obtained at optimized experiments where the unbalanced magnetic field configuration was used. A simple method of depth profiling suitable for evaluation of mechanical properties of several micrometers thick coatings is developed and employed. The paper reports on the depth profile analyses of the coating hardness, Young's modulus, composition and morphology.

The optical properties and structure of a-C:H films were modified by addition of nitrogen into the CH4/H2 deposition mixture. Three films prepared in capacitively coupled rf discharge were compared: (a) hydrogenated diamond like carbon film with hydrogen content of 34 % and indentation hardness of 21.7 GPa, (b) hard a-C:H:N film with nitrogen content of 13 % and indentation hardness of 18.5 GPa and (c) soft a-C:H:N film with nitrogen content of 10 % and indentation hardness of 6.7 GPa. It is shown how the parametrized density of states model describing dielectric response of electronic interband transitions can be applied to modified a-C:H:N and how it can be combined with correct treatment of transmittance measured in infrared range using additional Gaussian peaks in joint density of phonon states. This analysis resulted in determination of film dielectric function in wide spectral range (0.045-30 eV) and provided also information about the density of states of valence and conduction bands and lattice vibrations.

Model of the DLC band structure that took into account valence to conduction band transitions, pi-to-pi* and sigma-to-sigma*, and valence to extended states transitions sigma-to-xi* was confirmed by using the synchrotron ellipsometry at BESSY II in the range 5–30 eV combined with table-top ellipsometry and spectrophotometry in UV-IR range. The range up to 30 eV covered all the transitions from valence to conduction bands because the maximum energy transition of pi-to-pi* and sigma-to-sigma* were 9.03 and 28.1 eV, respectively. The band gaps of these transitions were 0.75 and 4.74 eV, respectively.

The loading curve dependency and presence of'pop-in' effects were studied for different materials and indentation methods specifically on metals with face-centered cubic (Ni) and tetragonal (Sn) crystalline structures. The nanoindentation experiments were performed on a CSM UNHT (ultra nano hardness tester) instrument using a diamond Berkovich tip and on an atomicforce microscope using a steel indentation cantilever. The dependence of the pop-in creation on the grain orientation (determined using electron backscatter diffraction (EBSD)) was compared with those in the literature and molecular dynamics simulations, using a combination of the embedded atom method and density functional theory (DFT). Due to its computational demands, DFT was used only for validation of the performance of the classical molecular dynamics code.

In order to better understand the effects of the hydrogen incorporation on the defects and the disorder in the undoped nano/microcrystalline SiGe:H, we performed a comparative study on samples deposited under different plasma conditions. With variation of the pressure, we were able to change the structure of SiGe:H films. We have used the combination of the infrared spectroscopy, CPM, PDS and thermal desorption measurements to study the thermal dependence of defect density, disorder, as well as hydrogen concentration. The film mechanical properties were tested by depth sensing indentation technique. The results showing a different hydrogen bonding with the change of deposition conditions are interpreted as a whole by terms of the specific local hydrogen bonding environment, related to different growth mechanism.

Ultrananocrystalline diamond (UNCD) films were deposited directly on polished silicon substrates in microwave discharge (2.45 GHz) combined with rf capacitive plasma (13.56 MHz) ignited at the substrate electrode. The rf discharge induced a dc self-bias accelerating ions towards the growing film during the whole deposition process. The applied microwave and rf powers were 900 W and 35 W, respectively. The gas mixture contained 9.4% of methane in hydrogen at the total pressure of 7.5 kPa. The substrate was either preheated in hydrogen discharge to the deposition temperature of 900 °C or the deposition of intermediate layer started at about 200 °C and reached 900 °C in the 5th minute. The latter procedure resulted in the deposition of coating with the hardness of 70 GPa and very good fracture toughness. The analysis of optical measurement in UV–IR range confirmed the presence of 250 nm thick intermediate layer containing diamond like carbon and SiC materials.

The sample of hydrogenated DLC on c-Si prepared by PECVD technique was investigated by ellipsometry in the NIR-UV range (0.6-6.5 eV), synchrotron ellipsometry in the UV-XUV range (4-20 eV) and reflectometry in NIR-UV range (1.24-6.5 eV). Various dispersion models based on the parametrization of density of states (PDOS) were investigated concerning their application in wide spectral range extending to XUV. In conclusion, the further developed PDOS model demonstrated its applicability to correct the calculation of the dielectric response of hydrogenated DLC material in the wide spectral range. Naturally, it can be used for any other disordered materials and it will, together with the optical measurements extended to XUV, bring important information about their band structure.

The functionalization of multi-walled CNTs in O2/Ar and H2O/Ar low pressure capacitive discharges was studied by XPS and FT-IR. The pristine and functionalized CNTs were used as fillers in polyurethane paints. Successful plasma functionalization was confirmed by changes in atomic composition and chemical shift of XPS atomic signals. The functionalization was indicated also by the shift of IR absorption peaks corresponding to the motion of carbon skeleton, especially the peak at about 1560cm-1. The presence of carbonyl was confirmed by IR absorption peak at 1723cm-1 only for O2/Ar plasma. The plasma functionalized CNTs increased significantly the universal and plastic hardness of the CNTs reinforced polyurethane as compared to the composites with pristine CNTs.

Complete optical characterization of diamond-like carbon (DLC) films non-uniform in thickness is performed using spectroscopic imaging reflectometry (SIR). It is shown that by using this technique it is possible to determine the area distribution (area map) of the local thickness of these films with arbitrary shape of this thickness non-uniformity. Furthermore, it is shown that in principle it is possible to determine the distributions of the refractive index and extinction coefficient of these films simultaneously with the thickness distribution, if a suitable dispersion model of these optical constants is chosen. In this paper the dispersion model of the optical constants of the DLC films based on parameterization of density of electronic states (DOS) is used. The values of the material parameters of this dispersion model are determined too. It is shown that the DLC films studied do not exhibit the area non-uniformity in material parameters and optical constants. The method presented can be used to characterize the non-uniform films consisting of other materials.