This article reviews the present state of the art in the field of flexible antibacterial coatings which efficiently kill bacteria on their surfaces. Coatings are formed using a reactive magnetron ...sputtering. The effect of the elemental composition and structure of the coating on its antibacterial and mechanical properties is explained. The properties of Cr-Cu-O, Al-Cu-N, and Zr-Cu-N antibacterial coatings are used as examples and described in detail. The efficiency of killing of bacteria was tested for the
bacterium. The principle of the formation of thick, flexible antibacterial coatings which are resistant to cracking under bending is explained. It is shown that magnetron sputtering enables production of robust, several-micrometer thick, flexible antibacterial coatings for long-term use. The antibacterial coatings produced by magnetron sputtering present huge potential for many applications.
Our investigation was concentrated on two basic challenges in the field of hard protective coatings prepared by magnetron sputtering: (1) Toughness and resistance to cracking (TRC) and (2) Flexible ...Hard Coatings with high thermal stability (TS). While results of investigation of TRC were already comprehensively published in a chapter of the book Thin Films and Coatings, Toughening and Toughness Characterization 1, results of the investigation of TS have not been comprehensively published yet. These results are described in detail in this new article. The choice and the presentation of the material in this article reflect the interests and perspectives of the principal author.
The paper reports on the enhanced hardness and thermal stability of nanocomposite coatings, and on the formation of the X-ray amorphous coatings with thermal stability and oxidation resistance above 1000 °C and of flexible hard coatings. Reported results can be used in the development of the flexible ceramic coatings, in the surface strengthening of brittle materials, and in the prevention of (i) cracking of the functional coatings and (ii) the crack formation on the surface of bent materials. It is shown that the energy delivered into the flexible hard coatings during their growth plays a key role in their formation. Special attention is devoted to formation of coatings with unique, fully reproducible properties and to new technology based on highly non-equilibrium processes at the atomic level. Special attention is also devoted to the speed of cooling of hard nanocoatings and to its effect on their thermal stability at high temperatures reaching up to 2000 °C. The key role of interdisciplinary insights in the development of new advanced hard coatings is also discussed. In conclusion trends in the next development of new advanced hard nanocoatings are indicated.
•Nanoscale features give unique properties to coatings.•The energy delivered into the growing coatings is a key parameter affecting their properties.•Speed of cooling of deposited coatings determines their thermal stability.•Resistance to cracking depends on the H/E⁎ ratio.•Interdisciplinary insights will be important in the development of new nanocoatings.
Hydrophobic materials capable of withstanding harsh conditions are required for various applications. Here, we show that oxides and nitrides of various low‐electronegativity metals are hydrophobic ...hard ceramics. We attribute their hydrophobicity to low Lewis acidity of the low‐electronegativity cations implying a low ability of the cations on the surface to form coordinate bonds with water oxygen anions. Furthermore, we observe a systematically stronger hydrophobic behavior of nitrides compared with the corresponding oxides, which we attribute to nitrogen being a poorer Lewis base than oxygen due to a reduced number of lone pairs of electrons, implying a lower ability of nitrogen anions on the surface to form hydrogen bonds with water hydrogen cations. Most of the oxides and nitrides investigated exhibit high values of hardness. Therefore, oxides and nitrides of low‐electronegativity metals should find application as hydrophobic materials in harsh conditions.
The article reports on the investigation of mechanical properties of Si-rich (Zr, Si) alloy films deposited by magnetron sputtering. The main aim of this investigation is to develop flexible hard ...(Zr, Si) alloy films with enhanced resistance to cracking. The (Zr, Si) films were formed by a pulsed dual magnetron discharge. Mechanical properties and elemental composition of sputtered (Zr, Si) films were tuned by a negative substrate bias Us, i.e. by the energy Ebi delivered to the growing film by bombarding ions. It was found that using of pulsed dual magnetron discharge makes it possible to deposit flexible hard (Zr, Si) alloy films with high values of hardness H ≈ 20 GPa, ratio H/E⁎ > 0.1, elastic recovery We > 60%, compressive macrostress (σ < 0) and dense, voids-free microstructure. These alloy films contain the same amount of Zr and Si in at.% and exhibit strongly enhanced resistance to cracking.
•Substitution of one Me in the (Me1, Me2) alloy by metalloid removes its brittleness.•Hard ZrSix alloy films with x ≈ 1 are resistant to cracking.•The ZrSix films with x ≈ 1 exhibit a low electrical resistivity of 2∙10−4 Ωcm.•The ZrSix films were sputtered by pulsed dual magnetron.
•Superhard Ti coatings were deposited by a new sputtering technology.•The technology is based on an atomic-level strongly nonequilibrium process.•Superhard Ti coatings were formed from melted ...Ti.•Superhard Ti coatings with H/E* ≥ 0.1 are flexible and resist cracking.•Soft Ti coatings with H/E* < 0.1 are brittle and easily crack.
The letter reports on the surface hardening of bulk soft metal materials by protective coatings made of the same metal as bulk but with up to 6 times higher hardness than that of the bulk material. This surface hardening is demonstrated by covering of the Ti substrate with a low hardness Hbulk ≈ 5 GPa by a 1200 nm thick Ti coating with a high hardness Hcoating ≈ 30 GPa. The protective hard Ti coatings were sputtered by a new sputtering technology based on extremely high pressures (≥1000 GPa), high temperatures exceeding the melting temperature Tm of the coating material and extremely high cooling rate of the created coating (≥1010 K/s). The principle of this technology realized at an atomic level is described in detail.
The article reports on the contamination of Ag thin films sputtered from a pure Ag target in Ar and Ne gas by the RF magnetron by gas atoms contained in residual gas atmosphere in the deposition ...chamber at different values of the base pressure. The amount of O atoms generated at different values of base pressure is compared with the amount of Ag atoms sputtered at different deposition rates of Ag film. This comparison reveals a great problem in the formation of pure metallic films at low deposition rates and high values of the base pressure. No pure Ag films can be deposited at low in deposition chambers evacuated with diffusion or root pumps to the base pressures lower than 1 mPa only.
The manuscript describes the plasma composition of RF magnetron discharges during silver sputtering and the question of contamination of layers by residual gas. The problem of film contamination is closely connected with the vacuum level and is very often incorrectly neglected by many authors dealing with sputtering processes.
We have carried out a systematic study of the influence of Ne, Ar and Kr working gases on both plasma and film properties of RF magnetron sputtering of silver. The magnetron plasma was characterised ...by optical emission spectroscopy (OES) and mass spectrometry. Silver thin film morphology was examined by SEM and AFM. We studied influence of magnetron power and working gas pressure on the plasma composition. The magnetron power was varied from 25 to 100W. The ambient pressure was changed from 0.5Pa to 3Pa. Both mass and OES spectra revealed presence of highly excited plasma in the substrate vicinity for all sputtering gases. The increasing OES signal intensities of Ag and Ag+ with increasing RF power and gas pressure were observed. However, in Ar discharge there was no Ag+ signal detected by OES at lower pressures of 0.5Pa and 1Pa. Similar profiles of the energy distributions of the ions with a maximum located around 19eV were obtained in Ar and Kr discharges at pressure of 3Pa while a maximum at 28eV was measured in Ne discharge. Ag2+ and AgX+ radicals, where X is atom of particular inert-working gas, were observed in the mass spectra. Silver thin film deposited in Ne gas revealed lower roughness than the films deposited in the other gases.
► Silver thin film was prepared by magnetron sputtering in Ne, Ar and Kr discharges. ► Plasma properties were characterised by mass and optical emission spectroscopy. ► Ag+ ions exhibited higher energy in Ne discharge. ► Silver film roughness was improved in Ne gas discharge.
Formation and number of molecules, radicals, and ions in ECR acetylene/argon discharge is studied as functions of gas flow rate, supplied power, and partial pressure of acetylene. The spectra ...obtained by neutral mass spectrometry (NMS) exhibit the presence of atomic hydrogen and H2 molecules. The quantity of acetylene ions is rather high in the range of power up to 350 W, but it drops down with increasing power. At higher powers, the change to C2H+ ion takes place and its quantity grows with increasing power. The dependence of the number of C2+, C2H+, C2H2+ on the electron energy is judged by appearance potential mass spectrometry in the energy range 0–100 eV. The obtained findings are useful for the technology of industrial preparation of DLC thin films.
We present plasma study of microwave ECR discharge in acetylene for processes of DLC film synthesis. The process of hydrogen loss from the acetylene molecule is study by neutral mass spectroscopy. For discharge powers up to 350 W acetylene molecules are significantly present. Formation of C2H2+ and C2H+ ions in discharge above 350 W of power is discover by appearance potential mass spectrometry.
We focus our attention on the study of the initial stage of the silver growth. The silver layers were deposited by RF magnetron sputtering in pure argon or its mixture with nitrogen. The initial ...stage of the nucleation and the layer growth was studied by means of the optical and electrical monitoring, which are based on a principle of in-situ spectral ellipsometry. The measured data were fitted to a mathematical model. The nano-granular character of the grown layer is revealed by resonant features in the extinction coefficient spectra in visible spectral range. Thus, the mode of the layer growth (Volmer–Weber or Stranski–Krastanov) was clearly distinguished in the monitored data. The microstructure of the completed layer was further analyzed by X-ray diffraction (XRD) and atomic force microscopy (AFM). In this work, we show that the growth mode of the silver can be controlled by the deposition condition. We also present a method for preparation of an ultra-thin, continuous and smooth silver layer. The nucleation process is significantly influenced by presence of the nitrogen in the sputtering gas.
► Silver layer growth was monitored by in-situ spectroscopic ellipsometry. ► The growth mode was indicated by a presence of surface plasmon resonance peak. ► Addition of nitrogen in the sputtering gas influences the silver growth mode. ► We report a preparation of the ultra-thin, smooth and continuous silver layer.
In this work, we focus on study of the formation and behavior of molecules, radicals, and ions in ECR discharge in a mixture of argon and methane. Discharge properties are studied at various ...conditions; total gas flow (0–50 sccm), absorbed microwave power (0–900 W) and the partial pressure of methane (0–1.2 Pa). Neutral mass spectrometry does not reveal the presence of radical CH5 commonly described in literature. Spectra show the presence of atomic hydrogen H and especially H2 molecules. The number of CH4+ and CH3+ species shows that the amount of CH4+ in areas power up to 350 W is high, but with further increase of the power their amount decreases. With the increasing power the CH3+ ions are more intensively generated. The obtained data helps optimize process conditions for the fabrication of diamond and DLC thin films.
In this work, we focus on mass spectrometry studies of the formation and behavior of molecules, radicals, and ions in ECR discharge in a mixture of argon and methane. The obtained data can help with determination and optimization of process conditions for the preparation and manufacturing of diamond and DLC thin films.
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