INFLUENCE OF PLASMA-ELECTROLYTIC OXIDATION PROCESS TECHNOLOGICAL PARAMETERS OF ALUMINUM ON COATING GROWTH RATE

There has been carried out an analysis of methods of oxide covering formation productivity increasing during plasma electrolytic oxidation of aluminum in electrolyte. There has been developed a technology of blank manufacturing and part strengthening by plasma electrolytic oxidation in the electrolyte, as well as the workbench has been modernized. There has been studied the process of oxidoceramic coating synthesis for the D16T aluminum deformed alloy of during plasma electrolytic oxidation in the electrolyte for different process parameters. It is established that the growth rate of oxidoceramic coating can be significantly increased by electrolyte component concentration involved in aluminum oxidation and rational choice of process electrical parameters. Hydrogen peroxide addition leads to obtained oxoceramic coating thickness increasing due to O, O2, OH, OH– concentration increasing in the electrolyte. It is established that the optimal concentration of H2O2 ranges from 5 g/l to 7 g/l. A further increase of peroxide concentration leads to a decrease in peroxide effect on oxoceramic coating growth rate on the D16T aluminum deformed alloy due to pH changes of the electrolyte and the deterioration of the oxide coating.

Formation of phosphonate coatings for improved chemical stability of upconverting nanoparticles under physiological conditions

The protection of phosphonate coatings against the dissolution of upconverting nanoparticles under physiological conditions was significantly improved by increasing the coating-synthesis temperature to 80 °C.

Synthesis of Tin Oxide Thin Layer by Doping Aluminum, Fluorine, and Indium Using Sol-Gel Spin Coating Technique

The synthesis of tin oxide thin films with doping aluminum, fluorine, and indium (SnO2: Al + F + In) by sol-gel spin coating technique has been successfully carried out. This synthesis aims to determine the quality of the thin film formed by adding doping aluminum, fluorine, and indium. The basic material used is SnCl2.2H2O, while the doping material used is AlCl3, NH4F, and InCl3.4H2O. The comparison of the basic ingredients and doping mixture of aluminum, fluorine and indium (SnO2: Al+F +In) used were 100: 0%, 95: 5%, 90: 10%, 85: 15%, 80: 20% and 75: 25%. The synthesis uses a glass substrate with size (10 x 10 x 3) mm. Coating synthesis includes substrate preparation, sol-gel making, film making, and sample heating. The layers that are made consist of 1 to 4 layers. The results showed that the layer formed had a high degree of transparency along with the increasing concentration of the doping material percentage. The higher the doping concentrations of aluminum, fluorine, and indium, the higher the transparency of the resulting layer. Besides, the greater the number of layers, the lower the transparency level of the layers

Low Weight Hollow Microspheres of Iron with Thin Dielectric Coating: Synthesis and Microwave Permeability

Spray pyrolysis of an aqueous solution of iron nitrate, proceeded with reduction of the product in hydrogen, gave iron powder with micron-sized hollow particles. Coating these iron particles with SiO2 through tetraethyl orthosilicate hydrolysis prevented interparticle electrical contacts and suppressed DC percolation. This material shows a high ferromagnetic resonance frequency of 18 GHz, low permittivity, and weighs 20% less than common carbonyl iron. Potential microwave applications are for inductors and electromagnetic interference shielding designs.

Controlling the Structural, Mechanical and Frictional Properties of MoSx Coatings by High-Power Impulse Magnetron Sputtering

Tribology, as the science and technology of interacting surfaces, typically relies on liquid lubricants which reduce friction and wear. For environmentally friendly tribological purposes and applications requiring a liquid-free performance, solid lubricants, such as MoS2 coatings, play an essential role. It is crucial to understand the interplay between the parameters of the coating synthesis and the characteristics of the coating. The impact of the deposition parameters on the structural, mechanical and frictional properties of MoSx thin films, which are synthesized by high-power impulse magnetron sputtering, are studied. The morphology, topography and stoichiometry (2.02 < x < 2.22) of the films are controlled by, in particular, the bias-voltage and heating power applied during the sputtering process. In combination with a low pulse frequency the hardness and elastic stiffness of the MoSx films are enhanced up to 2 and 90 GPa, respectively. This enhancement is assigned to a shortening of the Mo-S bonding lengths and a strengthening in the interatomic coupling as well as to a formation of small-sized crystallites at the surface. The friction coefficient reduces to µ = 0.10 for films with an initial (100) orientation and the mean roughness of the MoSx films decreases below 15 nm by shortening the cathode pulses.

Surface Hardening of Machine Parts Using Nitriding and TiN Coating Deposition in Glow Discharge

Surface hardening of machine parts substantially improves their performance. The best results are obtained when combined hardening consists of surface nitriding and subsequent deposition of hard coatings. The nitriding of machine parts immersed in the plasma of glow coatings have been studied, and the study results are presented. Titanium atoms for coating synthesis are obtained via titanium evaporation in a hollow molybdenum anode of the discharge. Stable evaporation of titanium occurs only when the power density of electrons heating the liquid titanium does not exceed ~500 W/cm2. To start evaporation, it is only necessary to reduce the gas pressure to 0.02 Pa. To stop evaporation, it is enough to increase the gas pressure to 0.1 Pa. Fast argon and nitrogen atoms used for cleaning the machine parts, heating them, and bombarding the growing coating are obtained using a grid composed of plane-parallel plates under high negative voltage and immersed in plasma.