Nanocomposite Si3N4/PEEK 708 coatings were successfully fabricated on the Ti-6Al-4V alloy substrate by electrophoretic deposition (EPD) and post-EPD heat treatment. The addition of chitosan polyelectrolyte into ethanolic-based suspensions enabled the cathodic co-deposition of ceramic and polymeric particles. Zeta potential measurements allowed the elaboration of stable suspensions. The selection of the optimal EPD voltage and time enabled uniform coatings to be obtained. Heating above the PEEK melting point and cooling with a furnace or in water resulted in the formation of dense coatings with semi-crystalline or amorphous polymer structures, respectively. Both coatings with a thickness in the range of 90–105 µm had good adhesion and scratch resistance to the substrates, despite the presence of relatively high degrees of open porosity. The coatings improved the tribological properties of the titanium alloy. However, a strong relationship between the polymeric matrix structure and wear resistance was observed. Semi-crystalline coatings proved to be significantly more wear resistant than amorphous ones.
Materials based on Ni-Co-Fe alloys, due to their excellent magnetic properties, attract great attention in nanotechnology, especially as candidates for high-density magnetic recording media and other applications from spintronic to consumer electronics. In this study, Ni-Co-Fe nanocrystalline coatings were electrodeposited from citrate-sulfate baths with the Ni2+:Co2+:Fe2+ ion concentration ratios equal to 15:1:1, 15:2:1, and 15:4:1. The effect of the composition of the bath on the morphology, microstructure, chemical composition, microhardness, and magnetic properties of the coatings was examined. Scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffractometry (XRD), and energy dispersive X-ray spectroscopy (EDS) were used to study surface morphology, microstructure, chemical, and phase composition. Isothermal cross-sections of the Ni-Co-Fe ternary equilibrium system for the temperature of 50 °C and 600 °C were generated using the FactSage package. Magnetic properties were analyzed by a superconducting quantum interference device magnetometer (SQUID). All the coatings were composed of a single phase being face-centered cubic (fcc) solid solution. They were characterized by a smooth surface with globular morphology and a nanocrystalline structure of grain diameter below 30 nm. It was determined that Ni-Co-Fe coatings exhibit high hardness above 4.2 GPa. The measurements of hysteresis loops showed a significant value of magnetization saturation and small coercivity. The microstructure and properties of the obtained nanocrystalline coatings are interesting in terms of their future use in micromechanical devices (MEMS).
The present study explores the possibilities of fabricating a graphite/polyetheretherketone (PEEK) composite coating on a Ti-6Al-4V titanium alloy through duplex treatment consisting of electrophoretic deposition (EPD) and heat treatment. It has been found that the electrophoretic co-deposition of graphite and PEEK microparticles can be performed from environmentally-friendly pure ethanolic suspensions. Zeta potential measurements and a study of the interaction between both particle types with the use of transmission electron microscopy allowed potential mechanisms of particle co-deposition to be indicated. Microstructure characterization was performed on macro-, micro- and nanoscale using visible light microscopy, X-ray diffractometry and electron microscopy. This allowed the coating homogeneity and distribution of graphite particles in the polymer matrix to be described. Graphite particles in the form of graphene nanosheet packages were relatively evenly distributed in the coating matrix and oriented parallel to the coating surface. The heat-treated coatings showed high scratch resistance and no adhesive type destruction was observed, but they were highly susceptible to deformation. The corrosion measurements were performed with use of electrochemical techniques like open circuit potential and linear sweep voltamperometry. The coated alloy indicated better electrochemical corrosion resistance compared with the uncoated alloy. This work showed the high versatility of the electrophoretic co-deposition of graphite and PEEK particles, which combined with post-EPD heat treatment allows composite coatings to be fabricated with controlled distribution of graphite particles.
The aim of the presented investigations was to deposit the thin films La1−xSrxFeO3 (x = 0, 0.1, 0.2) on (100) Si substrate by using the Pulsed Laser Deposition (PLD) method. Structure was exanimated by using XRD, SEM, AFM, TEM and XPS methods. The catalytic properties were analyzed in 4 ppm acetone atmosphere. The doping of Sr thin films La1−xSrxFeO3 (x = 0, 0.1, 0.2) resulted in a decrease in the size of the crystallites, the volume of the elemental cell and change in the grain morphology. In the LaFeO3 and La0.9Sr0.1FeO3, clusters around which small grains grow are visible in the structure, while in the layer La0.8Sr0.2FeO3, the visible grains are elongated. The TEM analysis has shown that the obtained thin films had a thickness in the range 150–170 nm with triangular or flat column ends. The experiment performed in the presence of gases allowed us to conclude that the surfaces (101/020) in the triangle-shaped columns and the plane (121/200) faces in flat columns were exposed to gases. The best properties in the presence of CH3COCH3 gas were noted for LaFeO3 thin film with triangle columns ending with orientation (101/020).