Forming of Composite Cutting Layer on Tool Steel by Heat Treatment of CVD Coatings

СVD chromium coatings are evaporated on steel substrate from chrome-organic compounds. For crystallization with forming of nano-particles of chromium carbides, subsequent heating (annealing) of tool steel with hybrid coatings is carrying out. Significant increase of micro-hardness of the coating up to 27000 MPa is observed due to the dispersion strengthening. Optimal annealing parameters (temperature and duration) are determined, which maximally strengthen the coatings and increase their adhesion to the steel substrate.

Hybrid Sol-Gel Coatings Doped with Non-Toxic Corrosion Inhibitors for Corrosion Protection on AZ61 Magnesium Alloy

Physiological human fluid is a natural corrosive environment and can lead to serious corrosion and mechanical damages to light Mg–Al alloys used in prosthetics for biomedical applications. In this work, organic–inorganic hybrid coatings doped with various environmentally friendly and non-toxic corrosion inhibitors have been prepared by the sol-gel process for the corrosion protection of AZ61 magnesium alloys. Effectiveness has been evaluated by pH measurements, optical microscopy, and SEM during a standard corrosion test in a Hanks’ Balanced Salt Solution. The results showed that the addition of an inhibitor to the sol-gel coating can improve significantly the corrosion performance, being an excellent barrier for the L-cysteine-doped hybrid sol-gel films. The incorporation of TiO2 nanoparticles, 2-Aminopyridine and quinine organic molecules slowed down the corrosion rate of the Mg–Al alloy. Graphene oxide seemed to have the same response to corrosion as the hybrid sol-gel coating without inhibitors.

Effect of Modified Silica Materials on Polyvinyl Chloride (PVC) Substrates to Obtain Transparent and Hydrophobic Hybrid Coatings

In this research, we report a simple and inexpensive way to prepare transparent and hydrophobic hybrid coatings through deposition of different silica materials on polyvinyl chloride (PVC) substrates. The silica materials were prepared using an acid-catalyzed sol–gel method at room temperature (25 ± 2 °C), using alkoxysilanes: tetraethoxysilane (TEOS), as the silica source, and ethoxydimethylvinylsilane (DMVES), triethoxyoctylsilane (OTES), and trimethoxyhexadecylsilane (HDTMES), as modifier agents. The obtained materials were characterized (either as powders or as thin films) by Fourier-transform infrared spectroscopy (FTIR), UV/Vis spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and water contact-angle measurements. UV/Vis spectra showed that the PVC substrate coated with the silica material containing TEOS/DMVES/OTES had a transmittance of about 90% in the wavelength range of 650–780 nm. The water contact angles increased from 83° for uncoated PVC substrate to ~94° for PVC substrates coated with the sol–gel silica materials. These PVC films with hybrid silica coatings can be used as the materials for outdoor applications, such as energy-generating solar panel window blinds or PVC clear Windmaster outdoor blinds.

The effect of the thickness on structural, optical limiting, and dielectric properties of hybrid coatings rhodamine B dye films on an epoxy polymeric substrate for display applications

Various thickness of Rhodamine B (RhB) laser dye was deposited on epoxy polymeric as a new dielectric organic substrate by spin coating method for the first time. This study focused on the newly considered RhB dye on an epoxy substrate for wide-scale applications. The thickness effect on structural, optical, and dielectric properties of the hybrid coating films was performed. The XRD patterns of the films indicated a large hump amorphous design and lack of Bragg peak intensity associated with the RhB laser dye, due to amorphous film concentration. From UV-Visible spectroscopy, the optical absorption edge shifts to the higher wavelengths direction (redshift) with the variation in RhB dye thicknesses. It was found that the energy band gap decreased when the RhB dye film thickness changed. The refractive index is an important parameter influencing the optical component design. Their values vary according to each relationship that extremely useful the films in optical devices. Laser power attenuation sensitivity of pure epoxy polymeric substrate and its coating films shows that under reducing the thicknesses of RhB dye, the laser power intensity effect increases. Several dielectric parameters are extracted from the series and parallel capacitance measurements. The present results offer new material films for luminescent energy solar concentrator applications.

Hybrid Zinc-Based Multilayer Systems with Improved Protective Ability against Localized Corrosion Incorporating Polymer-Modified ZnO or CuO Particles

Localized corrosion and biofouling cause very serious problems in the marine industries, often related to financial losses and environmental accidents. Aiming to minimize the abovementioned, two types of hybrid Zn-based protective coatings have been composed. They consist of a very thin underlayer of polymer-modified ZnO or CuO nanoparticles and toplayer of galvanic zinc with a thickness of ~14 µm. In order to stabilize the suspensions of CuO or ZnO, respectively, a cationic polyelectrolyte polyethylenimine (PEI) is used. The polymer-modified nanoparticles are electrodeposited on the steel (cathode) surface at very low cathodic current density and following pH values: 1/CuO at pH 9.0, aiming to minimize the effect of aggregation in the suspension and dissolution of the CuO nanoparticles; 2/ZnO at pH 7.5 due to the dissolution of ZnO. Thereafter, ordinary zinc coating is electrodeposited on the CuO or ZnO coated low-carbon steel substrate from a zinc electrolyte at pH 4.5–5.0. The two-step approach described herein can be used for the preparation of hybrid coatings where preservation of particles functionality is required. The distribution of the nanoparticles on the steel surface and morphology of the hybrid coatings are studied by scanning electron microscopy. The thickness of the coatings is evaluated by a straight optical microscope and cross-sections. The protective properties of both systems are investigated in a model corrosive medium of 5% NaCl solution by application of potentiodynamic polarization (PDP) curves, open circuit potential (OCP), cyclic voltammetry (CVA), and polarization resistance (Rp) measurements. The results obtained allow us to conclude that both hybrid coatings with embedded polymer-modified CuO or ZnO nanoparticles ensure enhanced corrosion resistance and protective ability compared to the ordinary zinc.