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A research is reported on the nanomechanics and tribology of the Arboblend V2 Nature biopolymer (a 100% bio-based material, biodegradable, or resistant depending of application), being a mixture of different biopolymers such as lignin, polylactic acid, cellulose, biopolyamides, and other natural additives. The specimens were made by an industrial-scale injection molding machine. The nanoindentation characterization have unveiled that an increase in processing temperature from 160°C to 170°C produces a rise in hardness and elastic modulus of ∼20%. Tribological characterization against a bearing-steel counterface has shown that for both processing temperatures, the increase of the applied load or the increase of sliding speed will produce an increase of the friction coefficient (µ) and wear. At an applied load of 1 N (contact pressure of 104 MPa) and tracks in a direction perpendicular to the surface textured lines, the lowest µ ∼ 0.148 are for samples made T = 170°C, while for tracks parallel to the textured lines, the lowest µ ∼ 0.059 is obtained for samples made at T = 160°C. Experiments made at different ambient humidity have established that friction coefficient is higher at 0% RH or at 75% RH than at 33% RH. Our results show that the biopolymers Arboblend V2 Nature is a candidate to substitute some popular fossil-based thermoplastics in numerous tribological industrial applications.

High hardness and toughness are generally considered mutually exclusive properties for single-crystal ceramics. Combining experiments and ab initio molecular dynamics (AIMD) atomistic simulations at room temperature, we demonstrate that both the hardness and toughness of single-crystal NaCl-structure VNx/MgO(001) thin films are simultaneously enhanced through the incorporation of anion vacancies. Nanoindentation results show that VN0.8, here considered as representative understoichiometric VNx system, is approximate to 20% harder, as well as more resistant to fracture than stoichiometric VN samples. AIMD modeling of VN and VN0.8 supercells subjected to [001] and [110] elongation reveal that the tensile strengths of the two materials are similar. Nevertheless, while the stoichiometric VN phase cleaves in a brittle manner at tensile yield points, the understoichiometric compound activates transformation-toughening mechanisms that dissipate accumulated stresses. AIMD simulations also show that VN0.8 exhibits an initially greater resistance to both {110} < 1 (1) over bar0 > and {111} < 1 (1) over bar0 > shear deformation than VN. However, for progressively increasing shear strains, the VN0.8 mechanical behavior gradually evolves from harder to more ductile than VN. The transition is mediated by anion vacancies, which facilitate {110} < 1 (1) over bar0 > and {111} < 1 (1) over bar0 > lattice slip by reducing activation shear stresses by as much as 35%. Electronic-structure analyses show that the two-regime hard/tough mechanical response of VN0.8 primarily stems from its intrinsic ability to transfer d electrons between 2nd-neighbor and 4th-neighbor (i.e., across vacancy sites) V-V metallic states. Our work offers a route for electronic-structure design of hard materials in which a plastic mechanical response is triggered with loading. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. Funding Agencies|Swedish Research CouncilSwedish Research Council [201607213]; VINN Excellence Center Functional Nanoscale Materials (FunMat-2) Grant [2016-05156]; Olle Engkvist Foundation; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW-2016-0358]; Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

Bi2S3 is a promising solid lubricant for demanding applications, such as oil extraction, heavy mining, and aerospace components. However, its tribological behavior has not been studied in depth. Burnished Bi2S3 soft coatings were evaluated utilizing reciprocating sliding tests under different levels of relative humidity level, normal load, and sliding speed and the results were benchmarked against MoS2 coatings. In addition, ab initio calculations using density functional theory modeling were employed for studying the interaction between the sulfides and the steel substrates and the effect of water intercalation at an atomic level. It was found that Bi2S3 coatings present excellent environmental adaptability and substrate protection over a wide range of testing conditions, thanks to their characteristic crystal structure.

Bi2S3 is a promising solid lubricant for demanding applications, such as oil extraction, heavy mining, and aerospace components. However, so far its tribological behavior has not been studied in depth. Bi2S3 soft coatings were evaluated utilizing reciprocating sliding tests under different levels of relative humidity level, contact stress, and sliding speed and the results were benchmarked against MoS2 coatings. In addition, ab initio calculations using density functional theory modeling were employed for studying the interaction between the sulfides and the steel substrates and the effect of water intercalation at an atomic level. It was found that Bi2S3 presents excellent environmental adaptability and substrate protection over a wide range of testing conditions, thanks to its characteristic crystal structure.

We deposit CSx thin solid films by reactive direct current magnetron sputtering of a C target in an argon plasma, using carbon disulfide (CS2) as a precursor to film growth. We investigate the influence of the partial pressure of the CS2 vapor introduced into the plasma on the composition, the chemical bonding structure, the structural, and the mechanical properties as determined by x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and nanoindentation for films deposited at 150 and 300 degrees C. The Raman and the XPS results indicate that S atoms are incorporated in mostly sp(2) bonded C network. These results agree with previous ab-initio theoretical findings obtained by modeling of the CSx compound by the Synthetic Growth Concept. The microstructure of the films as well as the results of their Raman characterization and the nano mechanical testing results all point out that with the increasing S content some spa bonding is admixed in the predominantly sp(2) bonded CSx network, leading to typical amorphous structure with short and interlocked graphene-like planes for S contents between 2% and 8%. We conclude that CSx thin solid films deposited by using CS2 as a precursor would be CSx films deposited at low temperature of similar to 150 degrees C and with an S content in the region of 6 at.% may be interesting candidates for applications as hard/elastic protective coatings. Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; Swedish Research Council (VR) through FLAG-ERA JTC 2015 project GRIFONESwedish Research Council [VR 2015-06816, VR 2017-04071]; Aforsk grant [18-266]; VRSwedish Research Council [VR 2016-05362]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]

We studied the microtribological behavior of amorphous and fullerene-like (FL) carbon and carbon-nitride coatings deposited by filtered-cathodic-arc. All films show similar friction coefficients but different wear mechanisms. The FL films exhibit a surface swelling with the formation of a layer that thickens during the test, limiting wear and maintaining a low friction. X-ray photoelectron spectroscopy on worn FL film surfaces show an increase in the sp2-content, indicating that the lubricious layer generated by the wear process is probably the result of re-hybridization due to plasticity induced by localized shear. In contrast, the wear results of the amorphous films, involving tribomechanical and tribochemical surface phenomena, show that the surface layer formed during sliding is a precursor to the onset of wear.

Nanoindentation, in combination with scanning probe microscopy, has been used to measure the hardness and Youngs modulus in the hydride and matrix of a high burn-up neutron-irradiated Zircaloy-2 cl ...

In this work, we present a mechanical and tribological study at the microscale of sol–gel TiO2–CdO films, which are used in photocatalytic applications. The films were deposited as a good-quality polycrystalline material with majority of CdO or CdTiO3 phases depending on their Ti/Cd concentration ratios. Films with the majority of CdTiO3 phase presented the highest hardness and lowest plastic deformation during the indentation tests. The evolution of wear, friction coefficient, and roughness on the films was quantitatively studied by multiple-passes measurements on a depth-sensing instrumented indentation system. These measurements allowed us to observe the films’ wear mechanisms and correlate them with their microstructure and mechanical properties. To compare the crystal structure, mechanical properties and tribological behavior of these films, we also analyzed sol–gel CdO and TiO2 films deposited under similar conditions.

V 0.5 Mo 0.5 N x /MgO(001) alloys with the B1-NaCl structure are grown by ultra-high-vacuum reactive magnetron sputter deposition in 5 mTorr mixed Ar/N 2 atmospheres at temperatures T s between 100 and 900 °C. Alloy films grown at T s ≤ 500 °C are polycrystalline with a strong 002 preferred orientation; layers grown at T s ≥ 700 °C are epitaxial single-crystals. The N/Metal composition ratio x ranges from 1.02 ± 0.05 with T s = 100–500 °C to 0.94 ± 0.05 at 700 °C to 0.64 ± 0.05 at T s = 900 °C. N loss at higher growth temperatures leads to a corresponding decrease in the relaxed lattice parameter a o from 4.212 A with x = 1.02 to 4.175 A at x = 0.94 to 4.120 A with x = 0.64. V 0.5 Mo 0.5 N x nanoindentation hardnesses H and elastic moduli E increase with increasing T s from 17 ± 3 and 323 ± 30 GPa at 100 °C to 26 ± 1 and 370 ± 10 GPa at 900 °C. Both polycrystalline and single-crystal V 0.5 Mo 0.5 N x films exhibit higher toughnesses than that of the parent binary compound VN. V 0.5 Mo 0.5 N x films deposited at higher T s also exhibit enhanced wear resistance. Valence-band x-ray photoelectron spectroscopy analyses reveal an increased volume density of shear-sensitive d-t 2g – d-t 2g metallic states for V 0.5 Mo 0.5 N x compared to VN and the density of these orbitals increases with increasing deposition temperature, i.e., with increasing N-vacancy concentration.

The macro- and microtribological properties of carbon nitride thin films deposited by high power impulse magnetron sputtering at different substrate bias voltages (Vb) were investigated. Vb of -100, -150, -200, and -300 V were used. A Hysitron Triboindenter TI950 and a reciprocating Tribotechnic tribometer with diamond counterparts were used in order to assess the tribological performance of the films at the micro- and macroscale, respectively. Initial Hertzian contact pressures of 2.5 GPa, 3.3 GPa and 3.9 GPa were chosen for the comparative measurements at both scales. At the macroscale, films with higher initial roughness present an increased wear. Debris creation and asperity deformation takes place causing abrasive wear. At the microscale, compression of the surface material occurs. The run-in friction shows similar trends at both scales; an initial decrease and an increase thereafter. Steady-state friction is not reached at the microscale, attributed to the absence of a graphitic tribolayer in the contact. At the macroscale, all films show abrasive wear and debris creation. Here, the changes in friction coefficients are attributed to the debris loss from the contact during the tribotests. The CNx film tested at 2.5 GPa shows a continuous increase of friction, due to the continuous loss of debris from the contact. The other films reach a steady-state friction coefficient, since most of the debris is lost before the end of the tribotests.

Thin films of (Ti0.71Al0.29)B2+1.08 have been deposited by magnetron sputtering. Post-deposition annealing at 1000 degrees C for 1 h results in increased hardness and elastic modulus, from 32 to 37 ...

W-B-C films were deposited on Si(100) substrates held at elevated temperature by reactive sputtering from a W target in Kr/trimethylboron (TMB) plasmas. Quantitative analysis by X-ray photoelectron spectroscopy (XPS) shows that the films are W-rich between ~ 73 and ~ 93 at.% W. The highest metal content is detected in the film deposited with 1 sccm TMB. The C and B concentrations increase with increasing TMB flow to a maximum of ~18 and ~7 at.%, respectively, while the O content remains nearly constant at 2-3 at.%. Chemical bonding structure analysis performed after samples sputter-cleaning reveals C-W and B-W bonding and no detectable W-O bonds. During film growth with 5 sccm TMB and 500 oC or with 10 sccm TMB and 300-600 oC thin film X-ray diffraction shows the formation of cubic 100-oriented WC1-x with a possible solid solution of B. Lower flows and lower growth temperatures favor growth of W and W2C, respectively. Depositions at 700 and 800 oC result in the formation of WSi2 due to a reaction with the substrate. At 900 oC, XPS analysis shows ~96 at.% Si in the film due to Si interdiffusion. Scanning electron microscopy images reveal a fine-grained microstructure for the deposited WC1-x films. Nanoindentation gives hardness values in the range from ~23 to ~31 GPa and reduced elastic moduli between ~220 and 280 GPa in the films deposited at temperatures lower than 600 oC. At higher growth temperatures the hardness decreases by a factor of 3 to 4 following the formation of WSi2 at 700-800 oC and Si-rich surface at 900 oC., 14 pages, 8 figures

It is known that a hierarchical configuration helps to improve adhesion to the substrate and reduce the effects that generate a sharp change in a conventional multilayer coating, like interface stresses. We present a study of the mechanical properties and tribological behavior at the micro and macro scale of WC/WCN/W multilayer coatings deposited by magnetron sputtering, combining soft and hard layers with a hierarchical architecture. Variations in the number of layers and thicknesses, as well as the distribution within the coating are determinant to obtain the adequate mechanical properties in order to reduce the wear rate. It was found that the coating with high hierarchical configuration presented lower wear rates, in comparison to single layer and low hierarchical configuration coatings. (C) 2016 Elsevier Ltd. All rights reserved. Funding Agencies|CONACYT-CDTI [189207]; CONACYT (REDISYT) [254790]; CONACYT [297914/225114, CB-2012-01#179304, 166286]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; SSF frame program FUNCASE Functional Carbides and Advanced Surface Engineering; LIDTRA [123630]

Differences in friction coefficients (mu) of ferroelectric YCrO3, textured and polycrystalline films, and non-ferroelectric Y-Cr-O films are analyzed. The friction coefficient was evaluated by atom ...

Zirconium diboride (ZrB2) exhibits high hardness and high melting point, which is beneficial for applications in for e.g. metal cutting. However, there is limited data on the mechanical properties of ZrB2 films and no data on epitaxial films. In this study, ZrB2(0001) thin films, with thicknesses up to 1.2 μm, have been deposited on Al2O3(0001) substrates by direct current magnetron sputtering from a compound target. X-ray diffraction and transmission electron microscopy show that the films grow epitaxially with two domain types exhibiting different in-plane epitaxial relationships to the substrate. The out-of-plane epitaxial relationship was determined to ZrB2(0001)|Al2O3(0001) and the in-plane relationships of the two domains to ZrB2[100]‖Al2O3[100] and ZrB2[110]‖Al2O3[100]. Mechanical properties of the films, evaluated by nanoindentation, showed that all films exhibit hardness values above 45 GPa, a reduced Young's modulus in the range 350–400 GPa, and a high elastic recovery of 70% at an applied load of 9000 μN. Funding agencies: Swedish Research Council (VR) [621-2010-3921]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Knut and Alice Wallenberg Foundation

A single hydride platelet and the matrix material next to it in a Zircaloy-2 cladding have been targeted for hardness, H, and Young’s modulus, E, measurement using nanoindentation. The results were compared with those obtained in the matrix material far away from the hydride. The results show that hardness and Young’s modulus in the hydride are higher than those of the matrix adjacent to the hydride, which are the same as those of the matrix far away from the hydride.

The micro- and macro-tribological behaviors of a novel hierarchical TaN/Ta coating deposited on Ti6Al4V biomedical alloy by direct current magnetron sputtering were analyzed in the present work. This analysis was associated with the morphological, structural, and mechanical properties, as well as the roughness changes during and after the tribological tests. The wear track of the coating after the macro-tribology tests was evaluated by Raman spectroscopy in order to detect the compounds formed as a result of the tribo-reactions that occurred during the tests. Micro- and macro-tribology behaviors showed a significant wear rate reduction of the hierarchical coating in comparison to the Ti6Al4V substrate. For the case of the micro-tribology tests, this reduction was attributed to the high hardness of the coating (31.4 GPa), however, this hardness caused a considerable increment in the friction coefficient. On the other hand, the macro-tribology performance was associated with the hardness and the ability of the hierarchical architecture to prevent the propagation of cracks. Moreover, the friction coefficient increased considerably at the end of the test, this increment was associated with the tantalum oxides in the wear track detected by Raman spectroscopy.

During the last decades, there has been an increased interest in the use of lignin-based composites following the ideas of developing green materials for fossil-based raw materials substitution. The biopolymer Arboform is a mixture of lignin, plant fibers, and additives, which is nowadays successfully used in many applications. As a thermoplastic, it can be molded and is therefore also called “liquid wood.” In this paper, we report a study comparing the nanomechanical and tribological properties of Arboform (AR), and Aramid-reinforced Arboform (AR-AF) composite biopolymers. The samples were produced in an industrial-scale injection molding machine. Nanoindentation experiments have revealed that, in both series of biopolymer samples, an increase in temperature or a change in the injection direction from 0 deg to 90 deg produces an increase in hardness. On the other hand, Young's modulus is slightly affected by the increase in temperature, and not affected by the injection angle. Tribological characterization has shown that all samples, except the AR-AF injected at 175 °C, present noticeable wear and have a similar friction coefficients μ ∼ 0.44–0.49 at Hertzian contact pressures p0 between 90 and 130 MPa. Interestingly, the reinforced polymer produced at 175 °C shows no wear and low friction of μ ∼ 0.19 at p0 = 90 MPa. Our results show that the reinforced Arboform biopolymers are a good candidate to replace other polymers in many mechanical and tribological applications.

This chapter will discuss the mechanical and tribological stability at the microand nanoscales of oxide films deposited by the sol–gel technique. The importance of tribological studies on sol–gel oxide films and of some works available in the literature will be shown. Particularly, films with applications in photovoltaic and photocatalyst devices compound of Cd2SnO4 and CdO+CdTiO3 films, respectively, and films obtained from their precursor solutions were evaluated by a quantitative novel method for simultaneous in situ measurement of the wear and friction evolution. The results obtained show the microtribological performance C.J. Diliegros-Godines (*) • F.J. Flores-Ruiz CINVESTAV-Unidad Queretaro, Queretaro, Qro, Mexico CNyN-UNAM, Ensenada, BC, Mexico e-mail: janani.diliegros@gmail.com R. Castanedo-Perez • G. Torres-Delgado CINVESTAV-Unidad Queretaro, Queretaro, Qro, Mexico E. Broitman Thin Film Physics Division, Linkoping University, Linkoping, Sweden # Springer International Publishing Switzerland 2016 L. Klein et al. (eds.), Handbook of Sol-Gel Science and Technology, DOI 10.1007/978-3-319-19454-7_115-1 1 of the sol–gel oxides strongly depends on their crystalline phase, microstructure, and synthesis conditions.

Multilayered thin films of Al/Cu/Fe have been prepared by magnetron sputtering and annealed into quasicrystalline and approximant phases on Al2O3 and Si substrates, respectively. The nanomechanical and nanotribological properties, such as hardness, elastic modulus, friction, and toughness, have been measured using a triboindenter and analytical methods. The approximant phase was proved to be slightly harder than the quasicrystalline phase with a hardness of about 15.6 GPa, and with a similar elastic modulus of about 258 GPa. These values however decreased rapidly with an increasing amount of Si in the approximant. The indentation toughness of the approximant

We report a design of photocathode, which combines the good photoemissive properties of lead (Pb) and the advantages of superconducting performance of niobium (Nb) when installed into a superconducting radio-frequency gun. The new configuration is obtained by a coating of Nb thin film grown on a disk of Pb via pulsed laser deposition. The central emitting area of Pb is masked by a shield to avoid the Nb deposition. The nanomechanical properties of the Nb film, obtained through nanoindentation measurements, reveal a hardness of 2.8±0.3 GPa, while the study of the electrical resistivity of the film shows the appearance of the superconducting transitions at 9.3 K and 7.3 K for Nb and Pb, respectively, very close to the bulk material values. Additionally, morphological, structural and contamination studies of Nb thin film expose a very low droplet density on the substrate surface, a small polycrystalline orientation of the films and a low contamination level. These results, together with the acceptable Pb quantum efficiency of 2×10−5 found at 266 nm, demonstrate the potentiality of the new concept photocathode. Funding agencies: Italian National Institute of Nuclear Physics (INFN); Italian MIUR through the Project FIRB Futuro in Ricerca [RBFR12NK5K]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Thermal barrier coatings (TBC) are used in gas turbines to reduce the temperatures in the underlying substrate. There are several mechanisms that may cause the TBC to fail; one of them is cracking ...

Friction is a fundamental phenomenon in tribology involving complex mechanisms between the contacting surfaces. Measurements of friction are often made using devices with substantially larger contact area than dimensions corresponding to microstructural features of the materials. Hence, for multi-phase materials, influence of particular microstructural constituents is not resolved. In the present work, a tribometer with a contact area in the nanoscale range was used to map friction for different types of tool steels with different chemical-and phase composition. Owing to the small tip radius, frictional characteristics of primary carbides and the steel matrix were measured and compared. Depending on chemical composition, a difference was observed where the coefficient of friction was approximately twice higher for the steel possessing highest coefficient of friction, including both carbides and the steel matrix.

Pb thin films were prepared by the nanosecond pulsed laser deposition technique on Si (100) and polycrystalline Nb substrates for photocathode application. As the photoemission performances of a cathode are strongly affected by its surface characteristics, the Pb films were grown at different substrate temperatures with the aim of modifying the morphology and structure of thin films. An evident morphological modification in the deposited films with the formation of spherical grains at higher temperatures has been observed. X-ray diffraction measurements showed that a preferred orientation of Pb (111) normal to the substrate was achieved at 30 °C while the Pb (200) plane became strongly pronounced with the increase in the substrate temperature. Finally, a Pb thin film deposited on Nb substrate at 30 °C and tested as the photocathode showed interesting results for the application of such a device in superconducting radio frequency guns.

A theoretical and experimental study on the growth and properties of a ternary carbon-based material, CS

The surface of a detector grade CVD polycrystalline diamond sample (5 × 5 × 0.05 mm3) was irradiated by an ArF excimer laser (? = 193 nm, ? = 20 ns) to produce graphitic conductive layers. In particular, two sets of four parallel graphitic strip-like contacts, with 1 mm pitch, were created along the whole sample on the top and on the rear surfaces of the sample respectively. The two series of stripes lie normally to each other. Such a grid allows to obtain a segmented all-carbon device capable of giving bi-dimensional information on particle detection processes in nuclear applications. Afterwards, an extensive characterization of the samples was performed: SEM and micro-Raman investigations to study the morphological and structural evolution of the irradiated areas, EDS measurements to individuate any absorption phenomena from environment associated to laser treatment, and nanoindentation mapping to understand how the hard-soft transformation occurred depending on the locally transferred energy. Finally, current-voltage analyses were carried out checking the ohmic behavior of the diamond-graphite contact. By comparing the results of the different characterization analyses, a strong periodicity of the modified surface properties was found, confirming the reliability and reproducibility of the laser-induced graphitization process. The results demonstrate that the laser-writing technique is a good and fast solution to produce graphitic contacts on diamond surface and therefore represents a promising way to fabricate segmented all-carbon devices. © 2016 Elsevier B.V.

Yttrium (Y) thin film was grown by pulsed laser deposition (PLD) on a copper (Cu) polycrystalline substrate. Ex situ morphological and structural characterisations of the circular Y film of 1.2 µm thickness and 3 mm diameter have shown a very low droplet density on the film surface and a crystalline feature with a preferred orientation along the Y (100) plane. Moreover, Y thin film resulted in being very adherent to the Cu substrate and more scratch resistant than Cu bulk. A twin thin film was deposited also on a Cu backflange of a radio-frequency (RF) gun to test the suitability of the metallic thin film as photocathode. It was observed that the Y-coated photocathode was characterised by a quantum efficiency (QE) higher than that of the Cu bulk photocathode even if the presence of space charge effects didn’t allow deriving the absolute maximum value of QE of Y photocathode.

In this paper, the authors report the growth of Pb thin films on both Si and Nb substrates by radio-frequency sputtering technique. Deposited films were characterized and tested to deduce the structure, the morphology, the nanomechanical properties, and also the quantum efficiency. Granular structures and large presence of voids were observed by scanning electron microscopy; moreover, the roughness and grain size of the film surface, investigated by surface probe microscopy, increased with the film thickness. Crystallographic orientation, studied by x-ray diffraction, showed the growth of polycrystalline Pb thin films and the presence of weak diffraction peaks related to penta-lead oxide (Pb5O8). The nanomechanical analysis reveals a film hardness with a value (∼1.5 GPa) well beyond the hardness of Pb bulk (0.04 GPa). Finally, twin Pb thin films deposited on Nb substrates were tested as photocathodes showing its great potentiality to be used in superconducting radio-frequency guns with a quantum efficienc...

Ca-Si-O-N thin films were deposited on commercial soda-lime silicate float glass, silica wafers and sapphire substrates by RF magnetron co-sputtering from Ca and Si targets in an Ar/N-2/O-2 gas mixture. Chemical composition, surface morphology, hardness, reduced elastic modulus and optical properties of the films were investigated using X-ray photoelectron spectroscopy, scanning electron microscopy, nanoindentation, and spectroscopic ellipsometry. It was found that the composition of the films can be controlled by the Ca target power, predominantly, and by the reactive gas flow. Thin films in the Ca-Si-O-N system are composed of N and Ca contents up to 31 eq. % and 60 eq. %, respectively. The films thickness ranges from 600 to 3000 nm and increases with increasing Ca target power. The films surface roughness varied between 2 and 12 nm, and approximately decreases with increasing power of Ca target. The hardness (4-12 GPa) and reduced elastic modulus (65-145 GPa) of the films increase and decrease with the N and Ca contents respectively. The refractive index (1.56-1.82) is primarily dictated by the N content. The properties are compared with findings for bulk glasses in the Ca-Si-(Al)-O-N systems, and it is concluded that Ca-Si-O-N thin films have higher values of hardness, elastic modulus and refractive index than bulk glasses of similar composition. (C) 2017 Elsevier B.V. All rights reserved. Funding Agencies|AForsk Foundation [14-457]; Vinnova [2015-04809]; European Research Council under the European Commission Seventh Framework Programme (FP)/ERC [335383]; Swedish Foundation for Strategic Research (SSF) through the Future Research Leaders 5 Program; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University Faculty Grant SFO Mat LiU [2009 00971]

Nanoindentation with in-situ electrical characterization was used to characterize piezoelectric scandium aluminum nitride (ScxAl1-xN) thin films with Sc contents up to x=0.3. The films were prepare ...

Single crystalline hexagonal wurtzite zinc oxide nanowires were grown on conductive commercial textile fabric as piezoelectric material. Aqueous chemical growth (ACG) method was used for the synthe ...

A novel TiAlCN/CNx multilayer coating, consisting of nine TiAlCN/CNx periods with a top layer 0.5 μm of CNx, was designed to enhance the corrosion resistance of CoCrMo biomedical alloy. The multilayers were deposited by dc and RF reactive magnetron sputtering from Ti0.5Al0.5 and C targets respectively in a N2/Ar plasma. The corrosion resistance and mechanical properties of the multilayer coatings were analyzed and compared to CoCrMo bulk alloy. Ion beam analysis (IBA) and X-ray diffraction tests were used to measure the element composition profiles and crystalline structure of the films. Corrosion resistance was evaluated by means of potentiodynamic polarization measurements using simulated body fluid (SBF) at typical body temperature and the nanomechanical properties of the multilayer evaluated by nanoindentation tests were analyzed and compared to CoCrMo bulk alloy. It was found that the multilayer hardness and the elastic recovery are higher than the substrate of CoCrMo. Furthermore the coated substrate shows a better general corrosion resistance than that of the CoCrMo alloy alone with no observation of pitting corrosion.

The authors study the nanomechanical and microtribological properties of yttrium (Y) thin films deposited by pulsed laser deposition on Cu polycrystalline substrates. Nanoindentation tests reveal that such films have a high hardness of H = 2.3 GPa and a reduced elastic modulus of 71.7 GPa with respect to the Cu substrates. The friction coefficient between a diamond tip and the Y film reaches a steady state value of μ ∼ 0.34, lower than that for the Cu (μ ∼ 0.38). Moreover, nanoscratch experiments show that Y films are more scratch-resistant than the Cu substrates, probably due to their greater hardness, higher elastic recovery, and lower friction coefficient. Their results confirm that the mechanical and tribological properties of the Y films are suitable for designing and fabricating scratch-resistant hybrid photocathodes and can reduce instabilities and unwanted discharges in the cavity of the radio-frequency gun. Furthermore, the low surface roughness and the low work function of the material are important characteristics for a photocathode based on the Y thin film for the production of high-brightness electron beams.

In this work yttrium and lead thin films have been deposited by pulsed laser deposition technique and characterized by ex situ different diagnostic methods. All the films were adherent to the substrates and revealed a polycrystalline structure. Y films were uniform with a very low roughness and droplet density, while Pb thin films were characterized by a grain morphology with a relatively high roughness and droplet density. Such metallic materials are studied because they are proposed as a good alternative to copper and niobium photocathodes which are generally used in radiofrequency and superconducting radiofrequency guns, respectively. The photoemission performances of the photocathodes based on Y and Pb thin films have been also studied and discussed. Funding agencies: Italian National Institute of Nuclear Physics (INFN); Italian Ministry of Research [RBFR12NK5 k]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure with respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate...

There is an increasing demand for glass materials with better mechanical and optical properties for display and electronic applications. This paper describes the deposition of novel thin films of Mg-circle divide-Si-O-N onto float glass substrates. Amorphous thin films in the Mg-Si-O-N system with high nitrogen and magnesium contents were deposited by reactive RF magnetron co-sputtering from Mg and Si targets in Ar/N-2/O-2 gas mixtures. The thin films studied span an unprecedented range of compositions up to 45 at% Mg and 80 at% N out of cations and anions respectively. Thin films in the Mg-Si-O-N system were found to be homogeneous and transparent in the visible region. Mechanical properties like hardness (H) and reduced elastic modulus (Er) show high values, up to 21 GPa and 166 GPa respectively. The refractive index (1.87-2.00) increases with increasing magnesium and nitrogen contents. (C) 2016 Elsevier Ltd. All rights reserved. Funding Agencies|AForsk foundation [14- 457]; European Research Council under the European Communitys Seventh Framework Programme (FP)/ERC grant [335383]; Swedish Foundation for Strategic Research (SSF) through the Future Research Leaders 5 Program; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University Faculty Grant SFO Mat LiU [2009 00971]

We use in-situ heated nanoindentation to investigate the high-temperature nanomechanical properties of epitaxial and textured ZrB2 films deposited by magnetron sputtering. Epitaxial films deposited on 4H-SiC(0001) show a hardness decrease from 47 GPa at room temperature to 33 GPa at 600 °C, while the reduced elastic modulus does not change significantly. High resolution electron microscopy (HRTEM) with selected area electron diffraction of the indented area in a 0001-textured film reveals a retained continuous ZrB2 film and no sign of crystalline phase transformation, despite massive deformation of the Si substrate. HRTEM analysis supports the high elastic recovery of 96% in the films. Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Research Council (VR) [621-2010-3921]

This work reports the fabrication of Nb/Pb structures with an application as photocathode devices. The use of relatively low energy densities for the ablation of Nb with ultrashort pulses favors the reduction of droplets during the growth of the film. However, the use of laser fluences in this ablation regime results in a consequent reduction in the average deposition rate. On the other hand, despite the low deposition rate, the films present a superior adherence to the substrate and an excellent coverage of the irregular substrate surface, avoiding the appearance of voids or discontinuities on the film surface. Moreover, the low energy densities used for the ablation favor the growth of nanocrystalline films with a similar crystalline structure to the bulk material. Therefore, the use of low ablation energy densities with ultrashort pulses for the deposition of the Nb thin films allows the growth of very adherent and nanocrystalline films with adequate properties for the fabrication of Nb/Pb structures to be included in superconducting radiofrequency cavities.

Sol–gel wet-chemical techniques were used to prepare ZnO, Al–ZnO (Al:Zn = 1:10 mol/mol) and Cu–ZnO (Cu:Zn = 1:10 mol/mol) thin films for characterization as functional layers for chemiresistive oxygen sensors. Cu and Al minor components influence the ZnO films' topography and their thermally induced chemical and structural evolution. As prepared (room temperature) films have the structure of layered basic zinc acetate, a lamellar ZnO precursor. Upon annealing at temperatures through 973 K, the films display similar chemical evolution patterns—temperatures above 773 K are needed to completely desorb solvents and decompose precursors. Cu facilitates c-axis orientation of the film as its structure matures, while Al slows its crystallization. Chemiresistive sensors, fabricated by coating thin film functional layers onto interdigitated electrode (IDE) transducers, were evaluated for their responses to oxygen at operating temperatures through 873 K. A ZnO/IDE sensor displays high sensitivity for O2 at an intermediate temperature, 673 K, reflecting an optimal balance between surface O2 coverage and carrier availability. At 1:10 mol/mol Cu:Zn and Al:Zn, the developing ZnO structure cannot accommodate all minor component atoms. Surplus atoms accumulate in independent phases at grain boundaries, contributing to both high base resistances (in N2) and low sensitivity to oxygen.

This work explores the effect of surface modification of stainless steel with a carbon nitride (CNx) film, under sliding wear of the UHMWPE/steel. Wettatibility of CNx coatings is assessed by means of the sessile drop method using two different liquid media. Microhardness and stiffness of CNx coatings are estimated by depth-sensing indentation. The sliding performance of UHMWPE against stainless steel and CNx was evaluated using a pin on disk tribometer. It is demonstrated that CNx surface properties are quite different from those of stainless steel, with a concomitant substantial reduction of the coefficient of friction of UHMWPE/CNx in comparison with the one of UHMWPE/steel under sliding conditions. Even tough imposed sliding conditions do not conduct to wear mass loss in UHMWPE, wear track patterns against steel and CNx are quite different. © 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of 11 th International Congress on Metallurgy & Materials SAM/CONAMET 2011.

The inherent resiliency, hardness and relatively low friction coefficient of the fullerene-like (FL) allotrope of carbon nitride (CNx) thin solid films give them potential in numerous tribological applications. In this work, we study the substitution of N with P to grow FL-CPx to achieve better cross- and inter-linking of the graphene planes, improving thus the material’s mechanical and tribological properties. The CNx and CPx films have been synthesized by DC magnetron sputtering. HRTEM have shown the CPx films exhibit a short range ordered structure with FL characteristics for substrate temperature of 300 °C and for a phosphorus content of 10-15 at.%. These films show better mechanical properties in terms of hardness and resiliency compared to those of the FL-CNx films. The low water adsorption of the films is correlated to the theoretical prediction for low density of dangling bonds in both, CNx and CPx. First-principles calculations based on Density Functional Theory (DFT) were performed to provide additional insight on the structure and bonding in CNx, CPx, and a-C compounds.

Pseudobinary V0.5Mo0.5Nx(111) alloys with the B1-NaCl crystal structure are grown on Al2O3(0001) substrates in an ultra-high-vacuum system by reactive magnetron sputter deposition in mixed Ar/N2 atmospheres at temperatures Ts between 100 and 900 °C. Nitrogen-to-metal, N/(V + Mo), fractions x vary monotonically from 0.9 ± 0.1 with Ts = 100 °C to 0.4 ± 0.1 at Ts = 900 °C. Nitrogen loss at higher growth temperatures leads to a corresponding decrease in the relaxed lattice parameter ao from 4.21 ± 0.01 A at Ts = 300 °C to 4.125 ± 0.005 A with Ts = 900 °C. Scanning electron micrographs of cube-corner nanoindents extending into the substrate show that the films are relatively ductile, exhibiting material pile-up (plastic flow) around the indent edges. Nanoindentation hardnesses H and elastic moduli E, obtained using a calibrated Berkovich tip, of V0.5Mo0.5Nx(111) layers increase with increasing Ts (decreasing x) from 15 ± 1 and 198 ± 5 GPa at 100 °C to 23 ± 2 and 381 ± 11 GPa at 900 °C. These values are lower than the corresponding results obtained for the 001-oriented V0.5Mo0.5Nx films. In addition, film wear resistance increases with increasing Ts, while the coefficient of friction, under 1000 μN loads, is 0.09 ± 0.01 for all layers.Pseudobinary V0.5Mo0.5Nx(111) alloys with the B1-NaCl crystal structure are grown on Al2O3(0001) substrates in an ultra-high-vacuum system by reactive magnetron sputter deposition in mixed Ar/N2 atmospheres at temperatures Ts between 100 and 900 °C. Nitrogen-to-metal, N/(V + Mo), fractions x vary monotonically from 0.9 ± 0.1 with Ts = 100 °C to 0.4 ± 0.1 at Ts = 900 °C. Nitrogen loss at higher growth temperatures leads to a corresponding decrease in the relaxed lattice parameter ao from 4.21 ± 0.01 A at Ts = 300 °C to 4.125 ± 0.005 A with Ts = 900 °C. Scanning electron micrographs of cube-corner nanoindents extending into the substrate show that the films are relatively ductile, exhibiting material pile-up (plastic flow) around the indent edges. Nanoindentation hardnesses H and elastic moduli E, obtained using a calibrated Berkovich tip, of V0.5Mo0.5Nx(111) layers increase with increasing Ts (decreasing x) from 15 ± 1 and 198 ± 5 GPa at 100 °C to 23 ± 2 and 381 ± 11 GPa at 900 °C. These values are lower t...