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Titanium (Ti) and Ti alloys possess extensive applications in the medical field due to their non-toxic, biocompatible, and antibacterial properties. This study investigates the biocompatibility enhancement of a Ti-based alloy, Ti-6Al-4V, through a multi-step process involving cathodic arc ion plating of a TiZrTa thin film and subsequent laser-textured oxidation (LTO). LTO treatment produced a structured microtopography with regular groove patterns, including straight lines (L-s), circles (L-c), and checkboards (L-ch), resulting in surface oxidation and the formation of various oxides on the TiZrTa coating. Microstructure analyses revealed substantial alterations in surface topography induced by laser texturing. Antibacterial assessments against Staphylococcus aureus (S. aureus) showed that the films with LTO treatment did not exhibit significant advantages after 12 or 24 h of coculture because the laser-textured portions consisted of a combination of the film and the substrate, and the antibacterial effect was not obvious. Coatings with LTO treatment significantly improved L-929 mouse fibroblasts cell viability at 48 h, particularly for samples with a 50 μm spacing of straight and circular patterns (L-s and L-c). After two weeks of MG-63 human osteosarcoma cell culture, the viability of all samples reached similar levels. It suggested that the TiZrTa-coated Ti-6Al-4V exhibited good biocompatibility with both cells. This study contributed to the understanding of surface modification techniques for enhancing the biocompatibility of Ti-based alloys in biomedical applications. • A TiZrTa thin film with LTO treatment was applied onto Ti-6Al-4V alloys. • LTO produced regular groove patterns and resulted in superior hydrophilicity. • LTO-treated thin films did not have obvious antibacterial improvement of S. aureus. • LTO-treated thin films improved the cell viability of both L-929 and MG-63 cells. [ABSTRACT FROM AUTHOR]

Transition metal nitride coatings, such as CrN, AlCrN and AlTiN, have excellent mechanical properties such as high strength, hardness, wear resistance and thermal stability. In this study, AlCrN and AlCrBN thin films were deposited by cathodic arc evaporation (CAE) using binary AlCr and ternary AlCrB alloy targets. The adhesion strength of the films to the substrate was effectively improved using composition-gradient interlayers. To study the thermal stabilities, the AlCrN and AlCrBN coatings were annealed at high temperature up to 900 °C, and their oxidation resistance, mechanical properties and thermal stabilities were studied. AlCrN and AlCrBN coated WC-Co samples were tested using pin-on-disk wear test configuration to evaluate the tribological performance. According to experimental results, the AlCrBN is composed of a face-centered cubic B1 (FCC) nanocrystalline structure, which can effectively inhibit the growth of grains, resulting in formation of a compact structure of grain refinement, and hinder the plastic deformation, thus obtaining high hardness and excellent wear resistance. The addition of 0.6 at.% B into the AlCrN decreased the grain size to 8.7 ± 0.8 nm from 13.7 ± 1.1 nm of AlCrN. Due to the addition of B element, the grains of AlCrBN coatings were refined to form a compact structure. Oxygen (O) did not penetrate and oxidize easily along the grain boundaries during annealing at high temperature. In addition, the AlCrBN coatings maintained a certain hardness (27.9–30 GPa) after high temperature oxidation, and the AlCrBN coating after annealing at 900 °C had the lowest wear rate (1.25 × 10−7 mm3/Nm). The AlCrBN coating annealed at high temperature still possessed predominant tribological properties, excellent thermal stability and good adhesion. This study demonstrates the feasibility of improving the life and performance of WC-Co tools by the application of cathodic arc deposited AlCrBN coatings using ternary AlCrB alloy targets. • AlCrBN coatings were deposited using ternary AlCrB alloy targets. • The addition of small fraction of B into the AlCrN decreased the grain size. • The AlCrBN coating had good thermal stability and oxidation resistance. • The AlCrBN coating showed improved wear resistance especially after annealing at 900 °C. [ABSTRACT FROM AUTHOR]

The optical emission spectrometer (OES) is an effective experimental tool for monitoring plasma states and the composition of gases during the growth of silicon thin films by plasma-enhanced chemical vapor deposition. In this paper, hydrogenated amorphous silicon (a-Si) (a-Si:H) and microcrystalline silicon (\mu\c-Si) thin films have been deposited in a parallel-plate radio frequency (RF) plasma reactor using silane and hydrogen gas mixtures. The plasma emission atmosphere was recorded using an OES system during the growth of the Si thin films. The plasma was simultaneously analyzed during the process using an OES method to study the correlation between growth rate and microstructure of the films. In the deposition, the emitted species (\SiH^\ast, \Si^\ast,\ \and\ \H^ \ast) were analyzed. The OES analysis supported a chemisorption-based deposition model of the growth mechanism. The effects of RF power, electron-to-substrate distance, and \H2 dilution of the emission intensities of excited SiH, Si, and H on the growth rate and microstructures of the film were studied. Finally, single-junction a-Si:H and \mu\c-Si solar cells were obtained with initial aperture area efficiencies of 9.71% and 6.36%, respectively. A tandem a-Si/\mu\c-Si cell was also realized with an efficiency of 12.3%. [ABSTRACT FROM PUBLISHER]

Abstract: Metal plasma ion implantation has being successfully developed for improving the electronic and optical properties of semiconductor materials. Prior to deposition, a TiO2 colloidal suspension was synthesized by microwave-induced thermal hydrolysis of the titanium tetrachloride aqueous solution. The TiO2 thin film was optimized to obtain a high-purity crystalline anatase phase by calcinations at 550°C. The TiO2 coating was uniform without aggregation, which provided good photo conversion efficiency. Ag ion implantation into the as-calcined TiO2 thin films was conducted with 1×1015 ~1×1016 ions/cm2 at 40keV. The peak position and intensity of the photoluminescence and UV–Vis absorption spectra are quite sensitive to Ag doping. The optical characterization showed a shift in optical absorption wavelength towards infrared ray side, which was correlated with the structure variation of the Ag+ implanted TiO2. Due to the strong capability of forming compounds between the energetic silver ions and TiO2, the photoluminescence emission and UV–Vis absorption efficiencies were improved. [Copyright &y& Elsevier]

Abstract: Nickel incorporated amorphous hydrogenated carbon (Ni/a:C–H) thin films were deposited onto the Si substrates via biased target ion beam sputtering of nickel combined with reactive ion beam deposition of a:C–H using CH4/Ar gas mixture. The effects of Ni doping and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscopy and nanoindentation. It was found that the Ni content in the films gets increased with increasing target bias voltage, and most of the Ni atoms react with C atoms to form NiC x phases in the Ni/a:C–H films. Moreover, the nickel carbide nanoparticles attain crystallinity even at low deposition temperature and get embedded in the cross-linked carbon matrix. It was found that the presence of Ni3C nanoparticles tends to increase the content of sp2 carbon, thus decreasing the hardness of Ni/a:C–H films as compared with that of a:C–H films. Additionally it was found that the nickel incorporated films do not show any adverse effect on the osteoblast cellular adhesion. Overall, these carbidic nanocrystals initiate direct graphitization and intend to change diamond-like to graphite-like carbon structure in Ni/a:C–H films with promising biocompatibility. [ABSTRACT FROM AUTHOR]

Abstract: Nano-crystalline TiO2 thin films were synthesized by using sol–gel and spin-coating techniques on glass substrates for photo-catalytic applications. Prior to deposition, a TiO2 colloidal suspension was synthesized by microwave-induced thermal hydrolysis of the titanium tetrachloride aqueous solution. In this study, the deposited TiO2 coating with a grain size of 13±2nm was uniform without aggregation. Co ion implantation into the as-calcined TiO2 thin films was conducted with fluences of 1×1015–1×1016 doses/cm2 at 40keV. In addition to the emission of TiO2, the photoluminescence study showed the presence of another Co-related optical center at 405nm in the Co-implanted TiO2 thin films. Due to the strong capability of forming impurity compounds between the energetic cobalt ions and TiO2, the photoluminescence emission and UV–Vis absorption efficiencies were improved. [Copyright &y& Elsevier]

Abstract: Multicomponent coatings based on different metallic and non-metallic elements possess the combined benefit of individual components leading to further improvement of coating properties. In this study, monolayered Ti–Al–N, multilayered Ti–Al–N/TiN, gradient Ti–Al–Si–N, and multilayered Ti–Al–Si–N/TiN coatings were synthesized by using a cathodic-arc evaporation (CAE) system. In addition to Ti, Ti33Al67 and Al88Si12 cathodes were used for the deposition of Ti–Al–N, and Ti–Al–Si–N coatings, respectively. The gradient Ti0.50Al0.43Si0.07N, and multilayered Ti0.50Al0.43Si0.07N/TiN with nanograins separated by disordered grain boundaries possessed lower residual stress (−2.8~−4.8 GPa) than that of monolayered Ti–Al–N (−6.8 GPa) and multilayered Ti–Al–N/TiN coatings (−5.7 GPa). The highest hardness was obtained for the gradient Ti0.50Al0.43Si0.07N (38±2 GPa) with Ti/(Ti+Al+Si) content ratio being 0.5. On the contrary, the multilayered Ti0.50Al0.43Si0.07N/TiN possessed the highest H 3/E ⁎2 ratio of 0.182±0.003 GPa, indicating the best resistance to plastic deformation, among the studied coatings. [Copyright &y& Elsevier]

Abstract: The monolayered TiSiN and multilayered TiSiN/CrN were synthesized by cathodic arc evaporation. The Ti/Si (80/20 at.%) and chromium targets were used as the cathodic materials. With the different I [TiSi]/I [Cr] cathode current ratios of 1.8, 1.0, and 0.55, the multilayered TiSiN/CrN coatings possessed different multilayer periods (Λ) of 8.3 nm, 6.2 nm, and 4.2 nm. From XRD and TEM analyses, both the monolayered TiSiN and multilayered TiSiN/CrN revealed a typical columnar structure and B1-NaCl crystalline, no peaks of crystalline Si3N4 were detected. Among the multilayered TiSiN/CrN coatings, the multilayered coating with Λ =8.3 nm possessed higher hardness of 37±2 GPa, higher elastic modulus of 396±20 GPa and the lower residual stress of −1.60 GPa than the monolayered (Ti0.39Si0.07)N0.54 coating(−7.25 GPa). Due to the higher Cr/(Ti+Cr+Si) atomic ratio, the multilayered TiSiN/CrN with Λ =5.5 nm possessed the lowest friction coefficient. But the lowest of wear rate was obtained by the multilayered TiSiN/CrN with Λ =8.3 nm, because of higher H3/E⁎ 2 ratio of 0.323 GPa. The monolayered TiSiN possessed the highest wear rate of 2.87 μm2/min. Therefore, the mechanical and tribological property can be improved by the design of multilayered coating. [Copyright &y& Elsevier]

Abstract: Chromium carbide and chromium oxide coatings deposited by physical vapor deposition methods have been successfully applied in molding industries for their excellent tribological performances. In addition, nanocomposite coatings have recently attracted interest because of their high hardness, wear resistance, and good thermal and chemical stability. In this study, Cr–C–O/a-C nanocomposite coatings were synthesized by cathodic-arc evaporation with plasma enhanced duct equipment. A pure CO2 reactive gas was introduced to react with chromium to form Cr–C–O/a-C nanocomposite coatings during the deposition process. The atomic content ratio of O/(C+O) increased with increasing CO2 deposition pressure. A nanocomposite structure of coexisting Cr2O3 and Cr7C3 crystallites and amorphous carbon phases was found in the Cr–C–O/a-C coatings. The nanoindentation test revealed the nanocomposite Cr–C–O/a-C coatings with the highest atomic content ratio of O/(C+O) possessed the highest hardness of 23 GPa. [Copyright &y& Elsevier]

Abstract: Ti1−x Si x N coatings were synthesized by cathodic arc evaporation with plasma-enhancing filter duct, using Ti80Si20 alloy target as cathodes. Optical emission study revealed that excitation, ionization and charge transfer reactions of the Ti-Si-N plasma occurred during the Ti1−x Si x N deposition process. The chemical content of Si varied from 3.3 to 6.0at% in Ti1−x Si x N depending on the nitrogen partial pressure of the reaction chamber. All the Ti1−x Si x N coatings displayed a NaCl structure and a preferred (200) orientation parallel to the substrate surface. Among the studied Ti1−x Si x N coatings, the Ti1−x Si x N with 6at.% Si possessed the highest hardness of 45GPa and H 3/E*2 ratio of 0.527GPa, indicating the best resistance to plastic deformation. We found that the structure and mechanical properties of the Ti1−x Si x N films were correlated with the nitrogen pressure and silicon content of the coatings. [Copyright &y& Elsevier]

Abstract: Chromium doped a-C:H (Cr-C:H) films were synthesized by using a cathodic-arc activated deposition (CAAD) process with different bias voltage. Chromium plasma with intensive ion energies catalyzes the decomposition of hydrocarbon gas (C2H2), and induces the formation of hydrogenated DLC films with a mixture of sp2 and sp3 carbon bonds. The deposited carbon films consist of nanocomposite Cr-C:H films on top of a graded chromium nitride interlayer. It has been found that the structural and electrical properties of the films were correlated as a function of bias voltage. The formation of larger cluster of sp2 coordinated carbon atoms under high bias voltage results in a more enhancement of the electrical conductivity. The nature of the heterojunction is confirmed by the spreading resistance characteristics of the Cr-C:H film/CrN/Si junction showing a behavior dependant on the structure changes. [Copyright &y& Elsevier]

Nitrogen-doped Cr&z.sbnd;C:H/N films containing chromium were synthesized by using cathodic-arc activated deposition (CAAD) process. Metal plasma with intensive ion energies catalyzes the decomposition of hydrocarbon gas (C2H2), and results in the deposition of amorphous carbon films. Nitrogen was introduced to form nitrogen-containing Cr&z.sbnd;C:H/N films, which contained a mixture of sp2 and sp3 carbon bonds. The deposited carbon films consist of nano-composite Cr&z.sbnd;C:H/N films on top of a graded chromium nitride interlayer. The wear properties were correlated with the nitrogen doping. Cr&z.sbnd;C:H/N films exhibits steady state friction coefficients lower than 0.11 when deposited at low N2/C2H2 flow rate ratio (<15%). Cr&z.sbnd;C:H/N possesses improved wear properties, resulting from its adhered dense microstructure and the nature of the transferred layer induced by the friction condition between the Cr&z.sbnd;C:H/N coatings and the sliding counterpart. [Copyright &y& Elsevier]

Multi-element material coating systems have received much attention for improving the mechanical performance in industry. However, they are still focused on ternary systems and seldom beyond quaternary ones. High entropy alloy (HEA) bulk material and thin films are systems that are each comprised of at least five principal metal elements in equally matched proportions, and some of them are found possessing much higher strength than traditional alloys. In this study, CrVTiNbZr high entropy alloy and nitrogen contained CrVTiNbZr(N) nitride coatings were synthesized using high ionization cathodic-arc deposition. A chromium-vanadium alloy target, a titanium-niobium alloy target and a pure zirconium target were used for the deposition. By controlling the nitrogen content and cathode current, the CrNbTiVZr(N) coating with gradient or multilayered composition control possessed different microstructures and mechanical properties. The effect of the nitrogen content on the chemical composition, microstructure and mechanical properties of the CrVTiNbZr(N) coatings was investigated. Compact columnar microstructure was obtained for the synthesized CrVTiNbZr(N) coatings. The CrVTiNbZrN coating (HEAN-N165), which was deposited with nitrogen flow rate of 165 standard cubic centimeters per minute (sccm), exhibited slightly blurred columnar and multilayered structures containing CrVN, TiNbN and ZrN. The design of multilayered CrVTiNbZrN coatings showed good adhesion strength. Improvement of adhesion strength was obtained with composition-gradient interlayers. The CrVTiNbZrN coating with nitrogen content higher than 50 at.% possessed the highest hardness (25.2 GPa) and the resistance to plastic deformation H3/E*2 (0.2 GPa) value, and therefore the lowest wear rate was obtained because of high abrasion wear resistance. [ABSTRACT FROM AUTHOR]

Abstract: Graded and multilayered Al x Ti1−x N nanocrystalline coatings were synthesized by using cathodic-arc evaporation (CAE) process. Ti33Al67 and Ti50Al50 alloy cathodes were used for the deposition of Al x Ti1−x N nanocrystalline coatings with different Al/(Ti+Al) ratios. Optical emission spectra of the plasma species including atomic and ionized Ti, atomic Al, excited and ionized nitrogen (N2 and N2 +) revealed that the excitation, ionization and charge transfer reactions of the Al–Ti–N plasma occurred during the Al x Ti1−x N coating process. A preferred (111) orientation was shown in the Al0.67Ti0.33N with high Al/(Ti+Al) atomic content ratio (0.63) and small grain size (29 nm). The graded Al0.67Ti0.33N/TiN possessed the highest hardness of Hv25 g 3850±180. However, the multilayered Al0.67Ti0.33N/TiN coating supported a longer tool life with lower residual stress. It has been found that the wear performance and mechanical properties of the films were correlated with the Al/(Ti+Al) content ratio and multilayered structure. [Copyright &y& Elsevier]

Pure titanium (Ti) and titanium alloys are widely used as artificial implant materials for biomedical applications. The excellent biocompatibility of Ti has been attributed to the presence of a natural or artificial surface layer of titanium dioxide. Zinc oxide and tantalum oxide thin films are recognized due to their outstanding antibacterial properties. In this study, high power impulse magnetron sputtering (HiPIMS) was used for the deposition of tantalum oxide and zinc-doped Ta(Zn)O thin films on Ti with rough and porous surface, which was pretreated by plasma electrolytic oxidation (PEO). Surface morphology, antibacterial property as well as cell biocompatibility were analyzed. The antibacterial effect was studied individually for the Gram-positive and Gram-negative bacteria Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans). The deposited Ta (Zn)O coating was composed of amorphous tantalum oxide and crystalline ZnO. The antibacterial results on the tantalum oxide and Ta(Zn)O coated Ti indicated a significant inhibition of both S. aureus and A. actinomycetemcomitans bacteria when compared with the uncoated Ti samples. The deposited Ta(Zn)O showed the best antibacterial performance. The Ta(Zn)O coated Ti showed lower level of the cell viability in MG-63 cells compared to other groups, indicating that Zn-doped Ta(Zn)O coatings may restrict the cell viability of hard tissue-derived MG-63 cells. However, the biocompatibility tests demonstrated that the tantalum oxide and Ta(Zn)O coatings improved cell attachment and cell growth in human skin fibroblasts. The cytotoxicity was found similar between the Ta2O5 and Ta(Zn)O coated Ti. By adopting a first PEO surface modification and a subsequent HiPIMS coating deposition, we synthetized amorphous tantalum oxide and Ta(Zn)O coatings that improved titanium surface properties and morphologies, making them a good surface treatment for titanium-based implants. [ABSTRACT FROM AUTHOR]

Abstract: Falling film microreactors, which provide very high specific interfacial area, have become a promising solution to the fast and strongly exothermic/endothermic gas–liquid reaction systems. A computational fluid dynamic simulation of the two-phase flow for a falling film microreactor is presented using the volume of fluid (VOF) model. The hydrodynamic characteristics, from both 2-D and 3-D simulations, including liquid film thickness, velocity, pressure and shear stress profiles, are analyzed. 2-D simulation is adopted for the study of the relationship of liquid flow rate and film thickness, as well as the effects of gas flow rate, surface tension, liquid viscosity and pressure difference on the liquid flow rate. 3-D simulation is necessary to provide the comprehensive flow profiles. Although the system is in the laminar flow regime, the liquid film features a wavy structure and the velocity profiles are complex. [Copyright &y& Elsevier]