Physical Vapor Deposition Technology Research Articles

Effect of substrate bias on microstructure and mechanical properties of WC-DLC coatings deposited by HiPIMS

The hardness and friction coefficient of the molding tools are the two key factors in influencing their performance during the cutting process. In this regard deposited by physical vapor deposition (PVD), WC-DLC nanocomposite hard coatings featuring high hardness and low friction coefficient are highly preferred to be used as protective coatings. As a newly developed PVD technology, high power impulse magnetron sputtering (HiPIMS) is quite advantageous in terms of the deposition of hard coatings. Substrate bias voltage exerts significant influences on the discharge characteristic of HiPIMS, plasma energy, chemical composition and the microstructure of the deposited coatings, which subsequently affect the coating's mechanical properties and performance in production. This article aims at investigating the effects of substrate bias on the plasma discharge characteristic of HiPIMS and on the mechanical properties, surface morphology, deposition rate, cross-sectional morphology, element concentration, crystal phase composition and tribological properties of the deposited coatings. The results show that the peak discharge current rises up from 57 A to 76 A with the increase of substrate bias from −40 V to −200 V. By controlling the bias voltage, WC-DLC coatings with different microstructures, mechanical properties and tribological properties have been produced. Meanwhile, the C concentrations of deposited coatings decline and the composed phase of the coating is transformed from hexagonal α-C at low bias voltage to equiaxial β-WC1−x and then hexagonal β-W2C accompanied by the rising bias voltage. The deposited WC-DLC coatings exhibit a decrease in surface roughness from Ra 16.1 nm to Ra 9.2 nm. Crystal phase evolutions also play a part in addition to the biased voltage upon the grain size and the hardness of the coating. It is found that the minimum grain size of 6 nm and the maximum hardness of 40.1 GPa appear at −160 V bias voltage when the coating is composed mainly of equiaxial β-WC1−x phase and mixture of β-WC1−x and β-W2C. The friction coefficient of the WC-DLC coating measured by ball-on-disk test increased correspondingly with the increase of the bias voltage except that the wear rate reaches the lowest at −120 V bias voltage, indicating that the wear rate is related not only to friction coefficient but also to coating hardness.

Tribological studies on self-lubricating (Cr,Al)N+Mo:S coatings at elevated temperature

Due to the high material utilization and the associated resource and energy efficiency, production processes from the field of cold forging of steel are of great importance. At present, environmentally harmful lubricants have to be used to ensure process stability as well as low wear and friction. Due to environmental, economic and legislative aspects, there is an increased research potential to reduce or to completely substitute lubricants. To achieve the goal of lubricant free dry cold forging of steel, physical vapor deposition (PVD) coatings with self-lubricating properties are applied on forming tools. Promising for this application are PVD coatings on the basis of a (Cr,Al)N hard phase with embedded molybdenum and sulfur which simultaneously meet the requirements of high wear resistance and friction reduction. In the presented work, three self-lubricating coatings (Cr,Al)N+Mo:S deposited with varying bias voltage were investigated. The hybrid PVD technology, consisting of direct current and high power pulse magnetron sputtering dcMS/HPPMS, was used for the coating deposition in an industrial coating unit. Two different steels AISI D2 (DIN 1.2379) and AISI M2 (DIN 1.3343) were used as substrate materials. The influences of substrate material and heat treatments at T=250°C were investigated. The samples were analyzed with respect to the universal hardness HU and modulus of indentation EIT using nanoindentation. To determine the interfacial adhesion of the compound coating/substrate, Rockwell indentation and scratch tests were carried out. For the analysis of the tribological behavior, unhardened AISI 5115 (DIN 1.7131) was used as counterpart material. The influence of the elevated temperature on the friction and wear behavior was investigated by Pin-on Disk (PoD) at T=250°C and T=23°C. The wear of the basic bodies as well as the counterparts were analyzed by confocal laserscanning microscopy. The investigations have shown that the high temperature has a significant influence on the friction and wear behavior. The wear rate of the counterparts decreases by up to a factor greater than x=100 compared to the test at T=23°C. Furthermore, the wear rates of the basic body of the uncoated reference specimen increase rapidly at tribological stress at high temperatures. The examined coatings exhibit high wear resistance at elevated temperatures. The contact surface was studied by Raman spectroscopy after the tribological tests. PoD tests have shown, that the applied coatings led to a significantly reduction in friction most likely due to the tribo-chemically induced formation of self-lubricating MoS2 reaction layers.

Metal (Ag/Ti)-Containing Hydrogenated Amorphous Carbon Nanocomposite Films with Enhanced Nanoscratch Resistance: Hybrid PECVD/PVD System and Microstructural Characteristics.

This study aimed to develop hydrogenated amorphous carbon thin films with embedded metallic nanoparticles (a–C:H:Me) of controlled size and concentration. Towards this end, a novel hybrid deposition system is presented that uses a combination of Plasma Enhanced Chemical Vapor Deposition (PECVD) and Physical Vapor Deposition (PVD) technologies. The a–C:H matrix was deposited through the acceleration of carbon ions generated through a radio-frequency (RF) plasma source by cracking methane, whereas metallic nanoparticles were generated and deposited using terminated gas condensation (TGC) technology. The resulting material was a hydrogenated amorphous carbon film with controlled physical properties and evenly dispersed metallic nanoparticles (here Ag or Ti). The physical, chemical, morphological and mechanical characteristics of the films were investigated through X-ray reflectivity (XRR), Raman spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) and nanoscratch testing. The resulting amorphous carbon metal nanocomposite films (a–C:H:Ag and a–C:H:Ti) exhibited enhanced nanoscratch resistance (up to +50%) and low values of friction coefficient (<0.05), properties desirable for protective coatings and/or solid lubricant applications. The ability to form nanocomposite structures with tunable coating performance by potentially controlling the carbon bonding, hydrogen content, and the type/size/percent of metallic nanoparticles opens new avenues for a broad range of applications in which mechanical, physical, biological and/or combinatorial properties are required.

Luminescence from impact- and abrasive-damaged ZnS ceramics

IR windows made of ZnS ceramics serve as protective elements for the thermal imaging systems established on mobile carriers, whereon they suffer from weathering and dust impacts. In this study, the erosion of ZnS ceramics was simulated by the abrasive damaging of polished specimens, and the response of the crystal lattice on the external forcing was investigated by the method of photoluminescence (PL). Impacts of isolated hard particles were modelled with the discrete shocks of a pointed striker, and fractoluminescence (FL) from the damaged spot was detected. The FL evidenced that the impact forcing triggers a two-stage mechanism of damage nucleation in this ductile ceramic. The dislocation motion at the stage of initial deformation followed by the interatomic bonds breakage at the stage of cracking. The PL data showed the higher stability of crystallites in chemically vapor-deposited (CVD) ZnS ceramics as compared with the same compounds obtained by the hot pressing (HP) or physical vapor-deposition (PVD) technologies. The abrasive treatment of ZnS-CVD did not affect significantly the entirety of crystallites because of plasticity of intercrystallite substance, in which the impact-induced tension dissipated. Undamaged crystallites retained their optical properties that is did not exhibit additional absorbance. Thus, the decrease of the transmissive capability under particle impacts occurs predominantly due to light scattering on the newly-formed surface irregularities.

The Influence of Process Parameters on Structure of Ceramic Coatings Deposited by PS-PVD Method

Thermal Barrier Coatings (TBC) is the most advanced system for protection of turbine blades and vanes against high temperature, and oxidation. They are used in most advanced jet engines. In present article the new Plasma Spray Physical Vapour Deposition Technology was used to obtain yttria stabilized zirconia oxide coating with columnar structure. In research the different process parameters were changed. It was observed that powder feed rate had big influence on coating thickness. The large amount of Ar in plasma gasses combined with high powder feed rate resulted in partial evaporation of ceramic powder and splat-type structure. The same effect was observed when the power current was decreased form 2400 to 1600 A as well as pressure was increased to 200 Pa when the powder feed rate was 30 g/min. The obtained results showed that full evaporation of ceramic powder requires very low feed rate of ceramic material (2 g/min), high power current and high He content into plasma.

High temperature oxidation protection of γ-titanium aluminide using (Cr,Al)ON coatings deposited by high-speed physical vapor deposition

In recent years great efforts have been made in the development of γ-TiAl alloys for use in aerospace applications such as turbines, where low densities and high temperature strength are required. However, γ-TiAl alloys show poor oxidation resistance at temperatures T>850°C due to the formation of a non-protective oxide layer consisting of a mixture of TiO2+Al2O3 in air, which could be easily spalled off, resulting in a shortened lifetime of the components. One promising way to overcome this problem is the deposition of an oxidation protective coating with low oxygen permeability at high temperatures. However, the interdiffusion between coating and substrate is still challenging even for advanced oxidation resistant coatings such as MCrAlY (M=Ni or Co) and aluminide. The present work focuses on the (Cr,Al)ON coating system, inspired from its outstanding diffusion barrier properties. Four (Cr,Al)ON coatings with different Cr:Al and N:O ratios were deposited onto γ-TiAl substrate by the innovative High-Speed Physical Vapor Deposition (HS-PVD) technology, which enables the deposition of oxygen-rich coatings in a stable plasma process without target poisoning. Basing on hollow cathode discharge (HCD) and gas flow sputtering (GFS), the HS-PVD made it possible to deposit (Cr,Al)ON coatings at a deposition rate ds/dt>16μm/h. The as-deposited coatings show an X-ray amorphous structure. Subsequently, the transmission electron microscopy (TEM) analysis confirmed the nanocomposite coating structure. The thermal stability and oxidation behavior of the coatings were evaluated by means of differential scanning calorimetry (DSC) and thermogravimetry (TGA) between T=100°C and T=950°C. It was confirmed that the X-ray amorphous structure even remained stable at temperatures up to T=950°C. Moreover, cross-sectional SEM images of the coated samples after the HT-XRD measurements showed neither the formation of oxides at the coating substrate interface nor the interdiffusion of Ti into the coating, indicating a promising performance of the diffusion barrier. The results of the conducted research reveal a high potential of the HS-PVD deposited (Cr,Al)ON coatings for the oxidation protection of γ-TiAl at T>850°C in turbine applications.

Antimicrobial effects and dissolution properties of silver copper mixed layers

Within the last years, research in the areas of hygiene and healthcare has focused on the resurgence of antimicrobial coatings to prevent infections and control their spreading.We used a physical vapor deposition technology to deposit coatings of either silver or copper individually or as mixtures on flexible polymeric substrates. Five combinations of silver and copper coatings were produced with a thickness of 50nm. The respective amounts of silver and copper on the coated surfaces were determined using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX). The antimicrobial characteristics of silver and copper against Escherichia coli K12 (E. coli) were investigated, focusing on the possible synergistic effects of the two metals.The deposited coatings showed homogeneous mixtures of silver and copper clusters. The mixtures of silver and copper as well as pure silver showed antimicrobial properties. In contrast, pure copper did not exhibit antimicrobial effects.The dissolution behavior of copper and silver was determined by incubation of mixed layers in physiological media (synthetic sweat). Copper coatings proofed to be fully dissolvable whereas silver showed lower solubility. With increasing copper content in the mixed coatings, the dissolution of silver increased as well. The observed dissolution behavior was correlated to the results of the antimicrobial activity of the investigated coatings.

Scale‐up of Solid Oxide Fuel Cells with Magnetron Sputtered Electrolyte

AbstractThe possibility of fabricating large‐area solid oxide fuel cells (SOFC) with thin film electrolyte using a commercial physical vapor deposition technology is investigated. Yttria‐stabilized zirconia (YSZ)/gadolinium‐doped ceria (GDC) bilayer electrolyte is successfully deposited on a 10 × 5 cm2 commercial NiO/YSZ anode support by reactive magnetron sputtering. The microstructure of the fuel cells was studied by scanning electron microscopy. Current‐voltage characteristics of fuel cells at a temperature of 750°C and their power stability under electrical load were investigated. Single cells with La0.6Sr0.4Co0.2Fe0.8O3/ Gd0.1Ce0.9O1.95 (LSCF/GDC) cathode had an open cell voltage of 1.14 V and a maximum power density of 490 mW cm−2 at 750 °C using H2/N2 gas mixture as fuel and air as the oxidant. Three‐cell planar SOFC stack using 10 × 5 cm2 anode‐supported unit cells with power density of 450 mW cm−2 at a voltage of 0.7 V per cell has been assembled and tested.

High-rate deposition of thick (Cr,Al)ON coatings by high speed physical vapor deposition

Inspired by diffusion barriers, (Cr,Al)ON coatings are developed as oxidation protection for gamma titanium aluminide alloys (γ-TiAl), offering oxidation resistance for applications at elevated temperatures, such as turbines. In this study, (Cr,Al)N and (Cr,Al)ON coatings were deposited by means of high speed physical vapor deposition (HS-PVD) technology, basing on hollow cathode discharge (HCD) and gas flow sputtering. Using argon as plasma gas and transport medium, the HS-PVD combines the advantages of thermal spraying and physical vapor deposition, which provides very high deposition rates. The objectives of this study were to synthesize thick PVD (Cr,Al)ON coatings and to understand how various process parameters influence coating morphology, deposition rate and phase composition. Keeping other parameters constant, the argon gas flow was varied between QAr=6000sccm and QAr=12,000sccm, different N2:O2 gas flow mixtures from 1:2 to 4:1 were introduced into the coating chamber and the bias voltage was adjusted between UB=−25V and UB=−150V. A special target configuration was applied for synthesizing coatings with different Cr:Al ratios within one coating cycle. The atomic Cr:Al ratio was varied between 25/75 and 75/25. The results showed that thick s>35μm (Cr,Al)ON coatings can be synthesized very efficiently at a deposition rate ds/dt≈20μm/h. Strong influences of argon gas flow and bias voltage on the deposition rate were revealed. Furthermore, stable plasma processes were observed, even at high oxygen flows QO2=600sccm, which would lead to target poisoning in conventional PVD processes. In this way, the HS-PVD technology reveals a high potential for the deposition of high temperature oxidation protective coatings and extends the application range of conventional PVD technology significantly.

Investigation of Ti0.54Al0.46/Ti0.54Al0.46N multilayer films deposited by reactive gas pulsing process by nano-indentation and electron energy-loss spectroscopy

Physical vapour deposition technology is well suited to the deposition of advanced TiAlN-based coatings. Among these thin films, multilayer systems consisting of stacked layers of metallic Ti1−xAlx and nitride Ti1−xAlxN with x around 0.5 are expected to have improved mechanical properties with respect to single nitride layers of the same composition. A set of Ti0.54Al0.46/Ti0.54Al0.46N multilayer films with five different periods Λ (from 4 to 50nm) were deposited using the reactive gas pulsing process (RGPP). This RGPP approach allows the deposition of TiAl-based alloy/nitride multilayer films by radio frequency reactive magnetron sputtering with a controlled pulsing flow rate of the nitrogen reactive gas. The coherent growth of the multilayer coatings, depending on the period, is checked by X-ray diffraction and the mechanical properties are determined by Berkovich nano-indentation and friction experiments. A model to describe the dependence of the indentation modulus M and the hardness HB on the penetration depth h, the period Λ, and the film thickness ef is proposed. The indentation modulus of the multilayer films (M at h=0 and for ef~1900nm) is found to be in the range of 340GPa<M<525GPa≈M(Ti0.54Al0.46N). For a fixed penetration depth, M follows a Hall and Petch evolution as a function of the period (4≤Λ≤50nm). The Berkovich hardness, 25GPa<HB<50GPa, also presents the same kind of evolution, and for Λ<16nm (at h=0), HB>HB (Ti0.54Al0.46N)=33GPa. Hence, a superlattice effect is clearly evidenced. Moreover, for the larger periods, the wear behaviour of these multilayered coatings seems to be dominated by the plastic deformation of the metallic layer. The multilayer coating of period Λ=10nm, which exhibits a diffraction pattern typical of superlattices and favourable mechanical properties, is more precisely investigated. Transmission electron microscopy confirms the main growth of the film along the [111] direction, and the evolution of the bonding of nitrogen in the direction normal to the rough interfaces between Ti0.54Al0.46 and Ti0.54Al0.46N layers is specified by electron energy-loss near-edge spectroscopy. Nitride nano-grains are included in the metallic layer, which attests to the mixing of nitrogen into the layers. The structure of these nano-grains presents a progressive evolution into the layer and gradually acquires a TiN-like structure near the interface. For this Λ=10nm period, the indentation modulus and hardness for different penetration depths are weakly sensitive to the multilayer film thickness.

Electrochemical Behaviour of TiCN and TiAlN Gradient Coatings Prepared by Lateral Rotating Cathode Arc PVD Technology

TiCN and TiAlN gradient coatings were deposited on the AISI 316L stainless steel substrates by lateral rotating cathode arc (LARC) physical vapour deposition (PVD) technology. Corrosion and tribocorrosion behaviour was studied in 3.5 wt. % NaCl solution. The thickness of coatings was about 3 μm. For both coatings the corrosion potential shifted to more positive values as compared to the uncoated substrate. The corrosion current density decreased for TiCN and TiAlN coatings indicating up to 40 folds higher polarization resistance. The coefficient of friction value of TiCN coating is three times lower and durability is six times higher than that of TiAlN coating under the same tribocorrosion conditions.

Science and technology of cuprate-based high temperature superconductor thin films, heterostructures and superlattices—the first 30 years (Review Article)

During the three decades after the discovery of superconductivity at high temperatures in copper oxides, intense research activities generated a tremendous progress in both, mastering the scientific challenges underpinning the understanding of the properties of these chemically and structurally complex materials as well as achieving a mature technology in preparing single phase bulk specimens—including single crystals—and epitaxially grown single crystalline thin films. This review covers in addition to more basic physics oriented developments mainly technological aspects of complex oxide thin film deposition as an enabling technology to explore the physics of these materials. It consists of two parts: after a brief introduction to the materials development prior to the discovery of superconducting copper oxides, a description of the relevant properties of copper oxide superconductors with focus on YBa2Cu3O7−δ is given, followed by the coverage of essentials of complex oxide thin film deposition technology with the copper oxides at its core. Here, the major physical vapor deposition technologies (evaporation and oxide molecular beam technology, sputtering and pulsed laser deposition) are described followed by an overview of substrate requirements to deposit high quality thin films. Opportunities by choosing special substrates with unique properties far beyond the usual mechanical support for a film are introduced with examples aside from usual lattice mismatch induced strain effects. One is the continuous modification of the strain state by poling ferroelectric oxide substrates linked to a piezoelectric effect, the other is the nanoscale tailoring of substrate step-and-terrace structures resulting in a controllable generation of planar defects in complex oxides, thus contributing to the physics of flux-line pinning in cuprate superconductors. In the second part of this review, first some highlights of single layer thin film research are given such as to tailor thin film orientation, generating well defined antiphase boundaries in YBa2Cu3O7−δ thin films as flux-line pinning centers as well as contributions to understand fluctuation conductivity in relation to the pseudogap state. In the last section new developments in high Tc cuprate based heterostructures and superlattices are reviewed with a special focus on the opportunities offered by interface-induced electronic interactions.

Experimental investigations on hot forming of AA6082 using advanced plasma nitrocarburised and CAPVD WC: C coated tools

The use of lubricant for hot stamping process of sheet material can reduce the tendency of adhesion between work-piece and tool significantly and the friction coefficient. However, the post-process of cleaning the formed part and lubricating the tools before each stamping operation can compromise the manufacturing efficiency. It is especially challenging for hot stamping because reducing lubricant could lead to severe adhesion between tool and blank during stamping. Hence, it is desirable to develop an advanced tooling technique suitable for hot stamping processes of aluminium alloys. In this paper, an innovative tooling technology enabling hot and cold forming of aluminium with little lubricant has been developed using plasma thermochemical treatment and Cathodic Arc Physical Vapour Deposition (CAPVD) technologies. The forming performance was validated on a top-hat part stamping test to benchmark the performance of the developed tools at different forming temperature, blank-holding force (BHF) and lubrication state. The results show that WC: C coating prepared by CAPVD adequately reduced the aluminium sticking on the tool surfaces, to the extent that it achieved an 80% lubricant reduction in the hot forming stamping of a top-hat part with a drawing depth of 70mm. The morphology of die showed that aluminium adhesion at the corner area of the die where the contact pressure doubled was still noticeable, while no severe adhesion was observed on the top flat surfaces. A further investigation of tribology on hot and cold stage tribometers was deployed to quantify the friction coefficient and wear resistance of tooling materials which were found correlated to the material’s universal hardness and time-dependent adhesion rate of aluminium.

Identification and assessment of professional competencies for implementation of nanotechnology in engineering education

ABSTRACTThe purpose of this study was to construct the indicators of professional competencies of the nanotechnology-based sputtering system industry based on industry requirements and analyse the core competencies of the industry for promoting the human resource of physical vapour deposition technology. The document analysis, expert interview, and Delphi technique surveys were considered and the survey items with 32 items divided into 7 domains were selected according to consensus opinions of 10 experts by the Delphi survey technique. Through three questionnaire surveys’ analysis, the professional competence scales for the K–S tests showed a good internal consistency. The findings of this study provide guidelines for professional competence for nanotechnology-based sputtering technology by applying surface heat-treatment industry. These guidelines can also reveal the practical competency requirements of nanotechnology-based sputtering technology to deal with any subsequent challenges, future developments, and invisible services for students in a technology institute programme.

Development of the modern vacuum coating technologies

Modern physical vapor deposition and chemical vapor deposition technologies intended for the protection of surfaces of products, in particular, the pyrolytic deposition of chromium carbide coatings using organometallic compounds as precursors, are discussed.

Cylindric high power impulse magnetron sputtering source and its discharge characteristics

High power impulse magnetron sputtering (HiPIMS) is a popular physical vapor deposition (PVD) technology because of the high ionization of the sputtering materials, large coating density, good adhesion, and other favorable properties. However, this technique suffers some disadvantages such as the small deposition rate induced by the high target potential, the metallic droplets produced by the unstable discharge, and different ionizations for different sputtering materials, thereby hampering wider acceptance by the industry. A cylindric HiPIMS source in which the discharge is restricted in the cylinder is described in this paper. By using this source, coatings can be deposited with 100% ions without metallic droplets arising from the unstable discharge, and the unionized sputtered atoms cannot be extracted by the extraction grid with negative potential. Electron oscillation and repetitive sputtering of the unionized atoms occur in the cylinder to enhance collision and ionization. Due to the enlarged discharge area by the cylinder internal surface comparing with the area of the ion outlet (end face of the cylinder), the sputtering ions converge from the inwall to the center of the cylinder target and form an enhanced flow to spray out from the source, which will improve the deposition rate. The structure and discharge characteristics of the novel HiPIMS source are investigated by simulation and experiments. Our results indicate that 8 magnets can provide the reasonable magnetic field and the highest target utilization rate. The distributions of electrons and ions in the target each consist of 8 petals in the optimized magnetic structure, and the highest plasma density happens near the target, which is above 1.31017 m-3. The discharge characteristics confirm that the cylindric sputtering source can be operated under HiPIMS conditions and the evolution of the target currents with target voltage exhibits I-V characteristics typical of HiPIMS. An obvious pre-ionization is observed on the discharge glow and discharge current curves when the extra direct current (DC) is added. The racetrack area is about 60.0% of the target surface. The ion current curves are similar to those of the target currents, but a 40 s delay and about one-tenth current value are observed compared with the target currents. The sputtering is improved by the extra DC, inducing the increased metallic ions and the opposite evolution of gas ions. The results suggest that the cylindric sputtering source can be effectively used to conduct HiPIMS and is a novel way to improve and promote the application of HiPIMS.

Properties, Application and Synthesis Methods of Nano-Molybdenum Powder

Nano molybdenum powder has been applied in many industrial fields in forms of lubricant additives, metallurgical additives, powder sintering additives, and one of raw materials of electrical components, cleaner and smoke suppressor. The processes, mechanisms and prospects of its synthesis methods are comprehensively analysized, including plasma physical vapor deposition technology (PPVD), reduction of MoCl4 vapor, activated reduction technology, electro-explosion of molybdenum wire (Elex process), pulsed wire discharge technology, electron beam irradiating method, hybrid plasma process, vapor phase reduction of MoO3, and microwave plasma chemical vapor deposition (MPCVD), etc.

Development of Ti–C–N coatings with improved tribological behavior and antibacterial properties

In artificial metallic joint implants, the failure is provoked by two effects in most of the cases: mass loss and wear debris removed due to tribological-corrosive effects on the implant alloy, and infections due to the presence of bacteria. In this work, several Ti–C–N corrosion and wear protective coatings were developed by Physical Vapour Deposition technology, and deposited on Ti6Al4V alloy. In order to provide the implant antibacterial properties, an additional silver top coating has been deposited. Tribological behavior was characterized through tribocorrosion and fretting tests. On the other hand, wettability tests were performed to study the grade of hydrophilicity/hydrophobia. Additionally, antibacterial properties were evaluated by means of bacterial adhesion tests. As a result of these characterization studies, the coating with the best performance was selected. The as-coated material includes excellent protection against tribocorrosion and fretting effects (in relation to the uncoated one) and the silver layer has been confirmed to exhibit antibacterial properties.

Synthesis of highly crystalline copper phthalocyanine needles by solvothermal method

As an important organic semiconductor, copper phthalocyanine has been widely used in various photo/electronic devices. Until now, the one-step synthesis of copper phthalocyanine micro/nano-crystals is mainly limited to the high cost physical vapor deposition technology. Herein, for the first time, we proposed a green and low-cost solvothermal method for direct synthesis of highly crystalline copper phthalocyanine needles in nontoxic anhydrous ethanol medium at 190°C. The purification of the as prepared copper phthalocyanine needles just required washing unreacted reactants with ethanol. The structures and morphologies of the copper phthalocyanine needles were characterized by Raman spectroscopy, X-ray powder diffractometor, and scanning electronic microscopy, respectively. Moreover, the thermal and photoelectronic performances were investigated preliminarily.

All inorganic thin film electrochromic device using LiPON as the ion conductor

All inorganic solid-state thin-film electrochromic devices based on lithium ion (Li+) insertion and using lithium phosphorus oxynitride (LiPON) as the ion conductor were fabricated by physical vapor deposition technology. Multilayer architecture consisting of TCO/V2O5/LiPON/LixWO3/TCO was deposited by RF sputtering technology on glass substrate. Electro-optical characterization carried out on complete devices highlighted transmittance changes as large as 40% at 600nm wavelength upon ±1.5V voltage application, with coloring and bleaching time of 30s. Several hundreds of bleaching/coloration cycles have been carried out with almost no performance degradation.The effect of the multilayer architecture was investigated. The results showed interactions between the depositing and the deposited layers, which influences the total amount of injected charges and hence the device performance. In particular, it has been observed a reversibly inserted Li+ charge capacity during LiPON deposition and a charge capacity extraction during deposition in presence of lithiated layers. The described phenomena should be considered in order to achieve the charge balance between the electrodes for optimum device performance.