ИССЛЕДОВАНИЕ ТОНКИХ ПОКРЫТИЙ В СИСТЕМЕ Si–B–C–N, ПОЛУЧЕННЫХ С ПОМОЩЬЮ МАГНЕТРОННОГО РАСПЫЛЕНИЯ МИШЕНЕЙ SiBC

Amorphous thin-film Si–B–C–(N) coatings are fabricated by magnetron sputtering of sintered Si–B–C targets. The coating structure is investigated using X-ray phase analysis, scanning and transmission electron microscopy, scanning probe microscopy, glow-discharge optical emission spectroscopy, and Raman spectroscopy. Mechanical and tribological properties of coatings are determined using nanoindentation, scratch testing, and pin-on-disc testing. The oxidation resistance of coatings is investigated in a temperature range of 1200–1600 °C. It is established that coatings of the optimal composition possess hardness of 20 GPa, elasticity modulus of 210 GPa, elastic recovery of 53 %, friction coefficient of 0,6 against cemented carbide ball, and oxidation resistance above 1200 °C due to the formation of the SiO2-based protective film on their surface. Coatings deposited by sputtering the target of the Si70B25C composition in Ar + 15%N2 medium showed oxidation resistance both under long-term heating at t = 1200 °C for 12 h and short-term heating at temperatures of 1400, 1500, and 1600 °C.Методом магнетронного распыления спеченных мишеней Si–B–C получены аморфные тонкопленочные покрытия Si–B–С–(N). Структура покрытий исследована с применением рентгенофазового анализа, растровой и просвечивающей электронной микроскопии, сканирующей зондовой микроскопии, оптической эмиссионной спектроскопии тлеющего разряда и спектроскопии комбинационного рассеяния света. Механические и трибологические свойства покрытий определены с помощью методов наноиндентирования, скратч-тестирования и трибологических испытаний. Исследована жаростойкость покрытий в диапазоне температур 1200–1600 °С. Установлено, что покрытия оптимального состава обладают твердостью 20 ГПа, модулем упругости 210 ГПа, упругим восстановлением 53 %, коэффициентом трения 0,6 в паре с твердосплавным шариком, а также жаростойкостью выше 1200 °С, что обусловлено формированием на их поверхности защитной пленки на основе SiO2. Покрытия, осажденные из мишени состава Si70B25C5 в среде Ar+15%N2, помимо высокой жаростойкости при t = 1200 °С и выдержке в течение 12 ч показали стойкость к кратковременным тепловым нагрузкам при температурах 1400, 1500 и 1600 °С

Different concepts for creating antibacterial yet biocompatible surfaces: Adding bactericidal element, grafting therapeutic agent through COOH plasma polymer and their combination

Antibacterial coatings have become a rapidly developing field of research, strongly stimulated by the increasing urgency of identifying alternatives to the traditional administration of antibiotics. Such coatings can be deposited onto implants and other medical devices and prevent the inflammations caused by hospital-acquired infections. Nevertheless, the design of antibacterial yet biocompatible and bioactive surfaces is a challenge that biological community has faced for many years but the "materials of dream" have not yet been developed. In this work, the biocompatible yet antibacterial multi-layered films were prepared by a combination of magnetron sputtering (TiCaPCON film), ion implantation (Ag-doped TiCaPCON film), plasma polymerization (COOH layer), and the final immobilization of gentamicin (GM) and heparin (Hepa) molecules. The layer chemistry was thoroughly investigated by means of FTIR and X-ray photoelectron spectroscopies. It was found that the immobilization of therapeutic components occurs throughout the entire thickness of the plasma-deposited COOH layer. The influence of each type of bactericide (Ag+ ions, GM, and Hepa) on antibacterial activity and cell proliferation was analyzed. Our films were cytocompatible and demonstrated superior bactericidal efficiency toward antibioticresistant bacterial E. coli K261 strain. Increased toxicity while using the combination of Ag nanoparticles and COOH plasma polymer is discussed

Antibacterial TaC-(Fe,Cr,Mo,Ni)-(Ag/Cu) Composite Coatings with High Wear and Corrosion Resistance in Artificial Seawater

The synergistic effect of simultaneous mechanical wear, chemical/electrochemical corrosion (tribocorrosion) and microbial attack poses a serious threat to marine and coastal infrastructure. To address this important problem, we have developed composite coatings consisting of TaC (25–35 at.%) and a corrosion-resistant α-Fe(Cr,Ni,Mo)-based metal matrix, as well as bactericidal elements (Cu, Ag). Coatings 50–75 μm thick were obtained by electrospark deposition in vacuum. The coatings possess high hardness (up to 10 GPa) and resistance to cyclic dynamic loads compared with the stainless steel (SS) substrate. Tribocorrosion experiments showed that the decrease in the corrosion potential associated with the removal of a passivating film from the surface during friction was 2–2.5 times smaller for the Ag-containing coating than for the other tested materials. The material passivation rates were also different: almost instantaneous passivation of the Ag- and Cu-doped coatings, and slow passivation for several minutes of the Ag/Cu-free coating and SS. The Ag-containing coating shows the lowest friction coefficient (0.2–0.25) and a minimal wear rate (1.6 × 10−6 mm3/Nm) in artificial seawater. The Ag-doped coating also exhibits the most positive value of corrosion potential and the lowest current density. After exposure in seawater for 20 days, only the Ag-doped coating showed no signs of pitting corrosion. All the studied materials have a pronounced bactericidal effect against Bacillus cereus Arc30 bacteria. The resulting coatings can be used to protect steel products from tribocorrosion and fouling in seawater

Antibacterial TaC-(Fe,Cr,Mo,Ni)-(Ag/Cu) Composite Coatings with High Wear and Corrosion Resistance in Artificial Seawater

The synergistic effect of simultaneous mechanical wear, chemical/electrochemical corrosion (tribocorrosion) and microbial attack poses a serious threat to marine and coastal infrastructure. To address this important problem, we have developed composite coatings consisting of TaC (25–35 at.%) and a corrosion-resistant α-Fe(Cr,Ni,Mo)-based metal matrix, as well as bactericidal elements (Cu, Ag). Coatings 50–75 μm thick were obtained by electrospark deposition in vacuum. The coatings possess high hardness (up to 10 GPa) and resistance to cyclic dynamic loads compared with the stainless steel (SS) substrate. Tribocorrosion experiments showed that the decrease in the corrosion potential associated with the removal of a passivating film from the surface during friction was 2–2.5 times smaller for the Ag-containing coating than for the other tested materials. The material passivation rates were also different: almost instantaneous passivation of the Ag- and Cu-doped coatings, and slow passivation for several minutes of the Ag/Cu-free coating and SS. The Ag-containing coating shows the lowest friction coefficient (0.2–0.25) and a minimal wear rate (1.6 × 10−6 mm3/Nm) in artificial seawater. The Ag-doped coating also exhibits the most positive value of corrosion potential and the lowest current density. After exposure in seawater for 20 days, only the Ag-doped coating showed no signs of pitting corrosion. All the studied materials have a pronounced bactericidal effect against Bacillus cereus Arc30 bacteria. The resulting coatings can be used to protect steel products from tribocorrosion and fouling in seawater

Effect of Boron and Oxygen on the Structure and Properties of Protective Decorative Cr–Al–Ti–N Coatings Deposited by Closed Field Unbalanced Magnetron Sputtering (CFUBMS)

Boron and oxygen-doped Cr–Al–Ti–N coatings were deposited by closed field unbalanced magnetron sputtering (CFUBMS) of TiB target manufactured by self-propagating high-temperature synthesis, and Ti, Cr, and Al targets. To evaluate the influence of doping elements, as-deposited coatings were studied by glow discharge optical emission spectroscopy (GDOES), SEM, XRD, and optical profilometry. Mechanical properties were measured by nanoindentation and tribological, abrasive and electrochemical testing. The introduction of boron suppresses columnar growth and leads to structural refinement and a decrease of coating’s surface roughness. The addition of 2.3 at.% boron results in the highest mechanical properties: hardness H = 15 GPa, stable friction coefficient f = 0.65, and specific wear Vw = 7.5 × 10−6 mm3N−1m−1. To make the coating more visually appealing, oxygen was introduced in the chamber near the end of the deposition cycle. Upper Cr–Al–Ti–B–O–N layers were studied in terms of their composition and coloration, and the developed two-layer decorative coatings were deposited on cast metallic art pieces

Influence of TiC Addition on Corrosion and Tribocorrosion Resistance of Cr₂Ti-NiAl Electrospark Coatings

Marine and coastal infrastructures usually suffer from synergetic effect of corrosion and wear known as tribocorrosion, which imposes strict requirements on the structural materials used. To overcome this problem, novel composite wear- and corrosion-resistant xTiC-Fe-CrTiNiAl coatings with different TiC content were successfully developed. The coatings were obtained by the original technology of electrospark deposition in a vacuum using xTiC-Cr2Ti-NiAl (x = 0, 25, 50, 75%) electrodes. The structure and morphology of the coatings were studied in detail by XRD, SEM, and TEM. The effect of TiC content on the tribocorrosion behavior of the coatings was estimated using tribological and electrochemical (under stationary and wear conditions) experiments, as well as impact testing, in artificial seawater. The TiC-free Fe-Cr2Ti-NiAl coating revealed a defective inhomogeneous structure with transverse and longitudinal cracks. Introduction of TiC allowed us to obtain coatings with a dense structure without visible defects and with uniformly distributed carbide grains. The TiC-containing coatings were characterized by a hardness and elastic modulus of up to 10.3 and 158 GPa, respectively. Formation of a composite structure with a heavily alloyed corrosion-resistant matrix based on α-(Fe,Cr) solid solution and uniformly distributed TiC grains led to a significant increase in resistance to stationary corrosion and tribocorrosion in artificial seawater. The best 75TiC-Fe-CrTiNiAl coating demonstrated the lowest corrosion current density values both under stationary (0.03 μA/cm2) and friction conditions (0.8 μA/cm2), and was characterized by both a 2-2.5 times lower wear rate (4 × 10−6 mm3/Nm) compared to AISI 420S steel and 25TiC-Fe-CrTiNiAl and a high fracture toughness

Comparative investigation of oxidation resistance and thermal stability of nanostructured Ti–B–N and Ti–Si–B–N coatings

Nanostructured Ti–B–N and Ti–Si–B–N coatings were deposited on silicon substrate by ion implantation assisted magnetron sputtering technique. To evaluate the oxidation resistance and thermal stability the coatings were annealed on air and in vacuum at 700–900°C. As-deposited and thermal-treated coatings were investigated by transmission electron microscope, selected area electron and x-ray diffraction, atomic force microscopy, Raman and glow discharge optical emission spectroscopy. Nanoindentaion tests were also performed. Obtained results show that Si alloying significantly improves the thermal stability of Ti–B–N coatings and increases their oxidation resistance up to 900°C. It was shown that formation of protective amorphous SiO2 top-layer on the coating surface plays important role in the increasing of the oxidation resistance

Structural analysis and atomic simulation of Ag/BN nanoparticle hybrids obtained by Ag ion implantation

The present paper describes fabrication of Ag/BN nanoparticle hybrids by means of Ag ion implantation into the hollow BN nanoparticles (BNNPs) with a petal-like surface. The structural transformations occurring during Ag ion implantation into BNNPs are studied by low- and high-resolution transmission electron microscopy (TEM), high angle annular dark field scanning TEM (HAADF-STEM) paired with energy-dispersive X-ray (EDX) spectroscopy mapping. The experimental results are theoretically verified in the framework of the classical molecular dynamics (MD) method. Our results have demonstrated that by changing Ag ion energy in the range of 2-20 kV it is possible to selectively fabricate Ag/BNNP nanohybrids with crystalline or amorphous BNNP structures and various Ag NPs distributions over the BNNP thicknesses. © 2016 Elsevier Ltd