FEATURES OF APPLICATION OF GAS-THERMAL AND PLASMA METHODS FOR OBTAINING FUNCTIONAL COATINGS

The article provides recommendations for the modes and parameters of gas-thermal and plasma coating technologies in relation to flat friction pairs subject to uneven operational loads

Increasing the wear resistance of the pump-controlled hydraulic drive units

Due to the lack of 63.5 mm balloons in Ukraine in the first layout of Hop-900 hydraulic transmission sample, the balls of the PBG company (Precision Ball and Gauge Co., England) were used. However, the trials of hydraulic transmission showed increased wear and cracks on the surface of the balls. Goal. The purpose of the work is to increase the wear resistance of the units of a pump-controlled hydraulic drive. Methodology. The coating on the TICRN ball was carried out at the Bu-Lat-3T installation. The coating modes were chosen using a methodology for mathematical planning of an experiment by evaluating microhardness of molded coating and the material use factor. Metallographic studies of the structure of the materials studied and sprayed coatings were performed on the digestive and non-digestive grinds on the MIM-8M microscope. The phase composition of the spray coatings was determined on a Don-1.5 diffractometer in monochromatic CUKα radiation. Results. Following the wear resistance of all investigated materials showed the largest wear resistance of the balls with ion-plasma coating on the surface. Originality. The tests of the samples of radial ball-piston hydraulic transmission of GOP-900 type allowed to conclude that their reliability and further improvement is largely due to the reliability of the piston ball, to which there are high requirements for wear resistance, minimum volume of force and temperature deformation. Practical value. Taking into account the negative experience of using imported steel balls from chrome steel, positive experience of using balloons from Steel SH-15CG, mastered by the production of OJSC HARP, and at the same time, the need to increase the heat resistance and wear resistance of balls should be considered as promising research when using beads from powder, rapid steels of type P6M5F3-MP, ceramic balls having high strength properties.

Effect of Sterilization (Autoclave) on Wear of Tungsten-Carbide Burs Coated With Diamond Particles With Different Thicknesses

Background: Extending the lifespan and improving the physical properties of dental burs as the most extensivly used instruments have been the subject of several studies. One of the proposed methods is using surface coatings for the burs. Since the dental instruments are reused, they require sterilization. One of the possible causes of the damage to dental burs is autoclaving process. This study aimed to investigate sterilization (autoclave) effect on wear of diamond coated tungsten-carbide burs with different thicknesses. Methods: In this in vitro study, 40 tungsten-carbide dental burs (IQ DENT, Poznan, Poland) were selected, out of which 20 burs were coated with 1.5-μm-like diamond particles, and 20 burs were coated with 3.5-μm by PVD method using Swin Plasma Coating Machine. Then, the burs were randomly divided into four groups (n=10) as follow: G1: 1.5 μm thickness coated burs without sterilization; G2: 3.5 μm thickness coated burs without sterilization; G3: 1.5 μm coated with sterilization; and G4: 3.5μm thickness coated burs with sterilization. Their weights were measured before wear test.Wear test was performed and then they were re-weighted. Data were analyzed using SPSS software (version 21) as well as Two-way ANOVA and Tukey HSD supplementary tests (α=0.05). Results: Mean and standard deviation of the burs weights without sterilization in the control groups were 7.31±2.63 and 7.96±1.61 mg, respectively; and mean and standard deviation of the burs weights in the sterilization groups were 7.06±0.98 and 7.12±1.11 mg, respectively. The study results showed that "sterilization application" and "thickness of coated layer" were the main factors and their intraction had no statistically significant difference (P=0.589). Conclusions: The sterilization process had no effect on wear of diamond coated tungsten-carbide burs with different thicknesses.

Modeling of protective plasma spray ceramic coating made of clad powder mixture

To solve the problem of increasing the adhesive-cohesive strength of plasma multifunctional coatings used to protect parts of power and mechanical engineering equipment components from wear and corrosion, a ceramic coating of the “Al2O3 - Ni” system, obtained from a powder mixture based on corundum clad with nickel, is proposed for use and studied. The coating was applied by high-energy plasma powder deposition (on the “Thermoplasma-50” installation) to the intermetallic sublayer of the “Ni-Co-Cr-Al-Y” system. The aim of this work was to study the micro structure and phase composition of the powder mixture of oxide ceramics clad with a refractory metal component (nickel), as well as the plasma coating formed from this powder material. According to the results of the research, it was found that the powder mixture clad with nickel has a multiphase composition (Ni+l-Al2O3+r-Al2O3), a spherical morphology of particles. From this powder material, a coating with a phase composition (Ni+L -Al2O3+J ’-L J u Ll) is formed, characterized by a layered microstructure with a columnar structure of oxide grains and nickel interlayers. The coating has high hardness and adhesive-cohesive strength, low coefficient of friction and is recommended for protection against wear of energy and mechanical engineering parts.

Influence of argon ion irradiation dose on the formation of the surface layers composition and changing mechanical properties of ion-plasma coated carbon steel

The effect of argon ion irradiation with an energy of 40 keV in the dose range of 1016 - 1018 ion/cm2 on the formation of the surface layers composition, changes in the morphology and mechanical properties (microhardness, and wear resistance) of carbon steel AISI 1020 with a deposited ion-plasma coating Ni80Cr20 was studied. It is shown that irradiation with doses greater than 1017 ion/cm2 leads to the formation of a layer consisting of nickel, chromium and iron. The most optimal treatment mode for improving wear resistance is irradiation with a dose of 5.1017 ion/cm2.

THE GAIN IN SHIEDLING EFFECTIVENESS ACHIEVED BY SUPERPOSITION OF STAINLES-STEEL PLASMA COATED WOVEN FABRICS

Electromagnetic shielding based on textile fabrics is important in applications for ensuring proper work of electronic equipment and for protection of human’s health. Fibre-based materials include a good capability for a precise design of the physical and electric properties of the EM shields. There are two main methods to impart electroconductive properties to textile fabrics: insertion of conductive yarns into the fabric structure and coating with conductive layers. In our approach, both methods were applied: cotton woven fabrics with conductive yarns of stainless steel and silver, were coated by magnetron sputtering with stainless steel layers. Electromagnetic shielding effectiveness (EMSE) was determined by Transversal-Electric- Magnetic (TEM) cell measurement system, according to standard ASTM ES-07. Moreover, EMSE was determined for the superposition of the manufactured textile shields. The stainless-steel plasma coating improves EMSE with 20 dB in case of the fabrics with stainless steel yarns and with 15-17 dB in case of the fabrics with silver yarns, in the frequency range of 0.1-1000 MHz. By superposition of the plasma coated shields, the gain in EMSE achieved was of 6 dB for the fabrics with stainless steel yarns and of 5-8 dB for the fabrics with silver yarns, on the same frequency range. EMSE has significant higher values in case of the superposed shields with silver yarns and stainless-steel coating for the frequency domain of 100-1000 MHz, due to the higher thickness and the significant contribution of the multiple reflection term.

STRENGTHENING OF PIPE TOOLS FOR COLD ROLLER ROLLING OF CORROSION-RESISTANT PIPES BY APPLICATION OF AMORPHOUS ALLOYS

In the production of pipes from corrosion-resistant steels on pipe rolling plants, the current problem is the low stability of the pipe tool. Therefore, the creation of high-performance and durable tools is associated primarily with the production and processing of materials that could withstand harsh working conditions. The technology of heat hardening of the pipe tool for cold roller rolling of corrosion-resistant pipes (rollers and support laths of HPTR mills) from 4Х5МФ1С steel which excludes the third holiday and uses drawing of a covering from powders of amorphous alloys 100…150 µm thick is offered in the work. As a result of the offered technology durability, wear resistance, and also hardness to HV0.1 950–1050 (in comparison with HV 587–690 on existing technology of heat treatment in factory conditions) increases. A wide range of studies of the structure of the coating and industrial tests of rollers and support bars. It is shown that gas-plasma coating of amorphous alloy based on Fe–Si–B system increases the hardness of the tool surface by 1.3–1.6 times and their stability by ~ 30…50%.

Experimental industrial ion-plasma plants MESh-50 and MAP-R for applying protective coatings on transport and power gas turbine components

The paper considers selected features of the protective ion-plasma coating deposition onto large-sized gas turbine components using vacuum-arc method by means of the MESh-50 and MAP-R pilot plants. The units have been developed based on the long-term operating experience of MAP-1 (MAP-1M) serial production. These plants are widely used in Russian and international aircraft-building complexes enabling all basic ion-plasma technological processes using standard cathodes made of nickel, cobalt, aluminum alloys and pure metals (Cu, Ti, Cr, Zr, etc.). The increased dimensions of the deposition chamber and the simultaneous use of several evaporators with pipe cathodes 180 mm in diameter and 540 mm high make it possible to apply coatings to large-sized components of gas turbine engines and plants, including such complex parts as “blisk” and “blink”.

Ultrathin fibre coatings on nanofibrous nonwovens by plasma enhanced chemical vapor deposition

For the generation of tailor-made polymer coatings on nanofibrous nonwovens plasma enhanced chemical vapor (PECVD) is a promising process, even for complex geometries. The plasma coatings can greatly improve their suitability for biomedical applications by optimising biocompatibility to the local needs, especially for cardiovascular disease treatments. Therein, wound healing and endothelialisation are important steps which are connected by a complex interaction. The monomers allylamine and hexamethyldisiloxane, as well as different process conditions were studied for the coating of nanofibrous thermoplastic silicone polycarbonate polyurethane (TSPCU) nonwovens. Aim of this study was to investigate the feasibility of plasma polymer coating under preservation of the nanofibrous morphological structure. Beside characterization of the nonwoven, biological evaluation with endothelial and fibroblast cells was performed. The prepared nonwoven samples support the feasibility of plasma coating under preservation of the nanofibrous structure. Also, different effects of the surfaces in contact with fibroblasts and endothelial cells could be observed.