Micromechanical and Tribological Properties of Nanostructured Carbonitride Coatings Deposited by PVD Technique

Nanostructured smart coatings (NSC) based on the TiAlSi-CN composite structure elements were deposited using reactive high-power physical vapor deposition (PVD) technique. The advanced modular deposition system included up to 8 high-power magnetron sputtering devices (MSD) allowing operate them simultaneously and exceed power density of 120 W/cm2 within each device erosion zone. The novel designed NSC on bearing steel 100Cr6 substrates demonstrated enhanced mechanical and tribological properties comparably with bearing steel ones required for multifunctional high-tech applications. The deposited NSC containing TiAlSi-CN nanoparticles strengthened by elemental additives Cr and Nb exhibited microhardness as high as 2500 HV values in comparison with 750 HV of 100Cr6 steel substrates. Load-displacement curves obey Meyer’s power-law surprisingly well because power-trendline fitted ones by R-squared value of 0.9999 for all the film-samples. Tribological properties were measured under dry friction conditions between the bearing steel ball of Ø 6 mm and the film-samples’ flat surface. Coefficient of friction (CoF) ranges between 0.22-0.56 depending on a sample and load. Tribotracks worn under the friction indenter were too shallow to evaluate them by Mitutoyo profilometer SJ-500. Therefore, the wear rate was estimated as ball wear of the friction indenter.

Smart coating with dual-pH sensitive, inhibitor-loaded nanofibers for corrosion protection

Smart coatings that provide corrosion protection on demand have received a lot of recent attention. In the present study, nanofibers containing a corrosion inhibitor were prepared by a coaxial electrospinning technique, which addresses the limitations of inhibitor-loaded microcapsules or nanocontainers. The as-prepared nanofibers have a core-shell structure with Ce(NO3)3 and the chitosan/polyacrylic acid polyelectrolyte coacervate as the core and shell materials, respectively. UV-vis spectroscopic analysis confirms that the nanofibers are pH-sensitive and able to release the enclosed Ce(NO3)3 at both low and high pH conditions, which are spontaneously generated during corrosion at local anodes and cathodes, respectively. A coating system consisting of such nanofibers within a polyvinyl butyral coating matrix exhibits improved corrosion protection of an AA2024-T3 substrate. Moreover, the embedded Ce(NO3)3-loaded nanofibers can persistently release Ce(NO3)3 to impede corrosion of AA2024-T3 when the artificially damaged coating sample is exposed to NaCl solution.

Nanostructured TiAlSi-CN:Me/a-CN:Si3N4 Composite Coatings Deposited by Advanced PVD Technique

Nanostructured smart coatings (NSC) based on the TiAlSi-CN composite structure elements were deposited using advanced reactive physical vapor deposition (PVD) method. The novel NSC on steel substrates demonstrated enhanced wear and corrosion resistance required for multifunctional high-tech applications. The deposited NSC containing TiAlSi-CN nanoparticles strengthened by Cr, Nb and Hf additives exhibited a coefficient of friction (CoF) less than 0.2 and wear rate as low as 10E-8 mm3/Nm. In addition, some self-healing properties were observed preventing denitrification of the core carbon-nitride (CN) layer due to specific tribochemical reactions of Al and Si constituents. Thus, the chemical composition and tentative nano-structure of the NSC can be described by a stoichiometric formula TiAlSi-CN:Me/a-CxNy:Si3N4, where Me=Cr, Nb or Hf.

Self-Healing Performance of Smart Polymeric Coatings Modified with Tung Oil and Linalyl Acetate

This work focuses on the synthesis and characterization of polymeric smart self-healing coatings. A comparison of structural, thermal, and self-healing properties of two different polymeric coatings comprising distinct self-healing agents (tung oil and linalyl acetate) is studied to elucidate the role of self-healing agents in corrosion protection. Towards this direction, urea-formaldehyde microcapsules (UFMCs) loaded with tung oil (TMMCs) and linalyl acetate (LMMCs) were synthesized using the in-situ polymerization method. The synthesis of both LMMCs and TMMCs under identical experimental conditions (900 rpm, 55 °C) has resulted in a similar average particle size range (63–125 µm). The polymeric smart self-healing coatings were developed by reinforcing a polymeric matrix separately with a fixed amount of LMMCs (3 wt.% and 5 wt.%), and TMMCs (3 wt.% and 5 wt.%) referred to as LMCOATs and TMCOATs, respectively. The development of smart coatings (LMCOATs and TMCOATs) contributes to achieving decent thermal stability up to 450 °C. Electrochemical impedance spectroscopy (EIS) analysis indicates that the corrosion resistance of smart coatings increases with increasing concentration of the microcapsules (TMMCs, LMMCs) in the epoxy matrix reaching ~1 GΩ. As a comparison, LMCOATs containing 5 wt.% LMMCs demonstrate the best stability in the barrier properties than other developed coatings and can be considered for many potential applications.

Chitosan-based smart hybrid materials: a physico-chemical perspective

An overview of the properties of chitosan-based materials: polyelectrolyte complexes, gels, chitosan-surfactant complexes, smart coatings, organic–inorganic hybrids.