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Titanium dioxide (TiO2) coatings, renowned for their photocatalytic properties, are of significant interest for environmental and industrial applications. This study investigates the deposition of black titanium oxide (BTO)- containing coatings using the atmospheric plasma spraying (APS) process, employing an argon-hydrogen plasma mixture. The influence of hydrogen flow rate, spray distance, and powder feed rate on the structure and mechanical properties of the resulting coatings was examined. Deposited coatings were examined in terms of their structure, thickness porosity and specific surface area. Examination of the mechanical properties included hardness test and Young's modulus measurement. Presence of partially sintered fine droplets was revealed by SEM observations and mechanism of their formation was discussed. The examination of mechanical properties showed that within the examined parameters, spray distance has the greatest impact on Young's modulus, hardness and porosity of the coatings, while the powder feed rate affects coatings thickness. [ABSTRACT FROM AUTHOR]

The paper presents new results of manufacturing coatings by magnetron sputtering to improve the functional properties of joint endoprostheses. The antibacterial properties of Ti-Cu and Ta-Cu coatings deposited by DC multi-magnetron sputtering on Ti6Al4V alloy substrates subjected of gas-abrasive treatment have been investigated. The roughness of the substrate was measured by optical profilometry. The coating hardness and elastic modulus were estimated by nanoindentation methods; the adhesion characteristics were assessed by Rockwell test. Scanning electron microscopy with energy-dispersive X-ray analysis verified the application of coatings with 25 at.% Cu, at thicknesses of 2 μm and 10 μm to roughened Ti6Al4V alloy. All coatings demonstrated sufficient adhesion, whereas Ta-Cu coatings generally revealed higher hardness, while the elastic modulus decreased with increasing coating thickness. Staphylococcus aureus strains were used for in vitro study of the antibacterial properties of Ti-Cu and Ta-Cu coatings. The largest zones of inhibition of bacteria S. aureus 23 mm were observed for 10 µm Ta-Cu coating thickness. The release dynamics of Cu ions from Ta-Cu and Ti-Cu coatings into physiological solution analyzed over seven days via inductively coupled plasma mass spectrometry, matched the inhibition zone growth. The Ti-Cu and Ta-Cu coatings of 2 µm thickness provided weaker antibacterial effect. The optimal parameters of magnetron sputtering of antibacterial Ti-Cu and Ta-Cu coatings on Ti6Al4 alloy substrates were selected. These findings support the potential of these coatings in developing endoprosthesis implants with enhanced antimicrobial and wear-resistant properties [ABSTRACT FROM AUTHOR]

Atmospheric plasma spraying (APS) allows deposition of ceramic coatings on metallic substrate, significantly increasing the wear resistance of the component. Coating's microstructure and consequently its properties, depend on heat treatment of the feedstock particles. This property can be controlled by process parameters, especially electric power and spray distance. On the other hand, some plasma torches allow introducing another variable, an injection mode, which could be realized in external or in internal way. In the presented research, wear resistance of Al2O3+13 wt.% TiO2 coatings deposited under various values of spray distance and different injection modes were examined using ASTM G-99 procedure. The impact of spraying parameters on the coating's microstructure was established and connected to the functional properties of the manufactured deposits. Observed differences indicated influence of injection mode and spray distance value. Coatings deposited with internal feedstock injection exhibit lower porosity and slightly higher hardness than these made with external injection mode. In terms of wear resistance for both spray distance the wear factor was lower for internal injection system. Obtained results confirmed assumed thesis, that internal injection mode improves heat treatment and consequently ameliorate wear performance of plasma sprayed alumina-titania coatings. [ABSTRACT FROM AUTHOR]

Cermet coatings are one of the best surface protection of machine elements against wear. On the other hand, the most universal and economically justified method of applying such coatings is high velocity oxy-fuel (HVOF) spraying. This method makes it possible to produce coatings characterized by compact structure, low porosity and very good adhesion to the substrate. All these fundamental properties contribute to the high wear resistance of these coatings. However, carrying out full wear tests (e.g. ball-on-disc) is time-consuming, especially when it is necessary to select the proper feedstock material and carefully selected process parameters. The aim of the following researches was to statistically investigate the possibility of replacing long-term wear resistance tests with estimation of this performance on the basis of determining the fundamental mechanical properties of the coatings. Three types of coating materials were selected: WC-12Co, WC-10Co-4Cr and WC-20Cr3C2-7Ni, which were deposited on AZ31 magnesium alloy substrates from three different spray distances: 320, 360 and 400 mm. On the basis of the tests carried out and using cluster analysis techniques (the Ward and k-means methods), the relative similarity between the obtained coatings was determined. The applied methodology allowed to select from the analyzed cermet coatings such samples that were characterized by improved resistance to abrasive wear. The obtained results of the analyzes were also referred to the results of tests of resistance to abrasive wear. [ABSTRACT FROM AUTHOR]

The manuscript analyzes the impact of the HVOF (high-velocity oxygen fuel) coating spraying technology on a substrate made of a light and high-specific-strength magnesium casting alloy from the AZ31 series. Among others, the following were examined: the influence of the spraying distance of coatings using commercial cermet powders (WC–Co, WC–Co–Cr, and WC–Cr3C2–Ni) on their resistance to erosive wear. It is worth emphasizing the energy savings resulting from the possibility of spraying on the surfaces of existing machine parts to protect or regenerate them. Energy savings result from the possibility of recycling the substrate material (AZ31), as well as from extending the functionality of an existing element without the need to dispose of it and the energy-intensive production of a new component. Tests have shown that the best resistance to the destructive effects of erodent in the form of hard corundum particles is characterized by a WC–Co–Cr coating sprayed at a distance of 320 mm. [ABSTRACT FROM AUTHOR]

This article describes spark plasma sintering of ceramics based on silicon carbide with nanoadditives, as follows: MnOnano 5.5 wt. % + Al2O3nano 2.0 wt. % + SiCnm (37–57 wt. %) + SiCµm (31–51 wt. %) + SiO2µm 4.5 wt. %. Sintering was carried out at 2000 °C. The diffraction pattern of the analyzed sample showed the presence of silicon carbide with a hexagonal crystal lattice. Residual amounts of rhombohedral SiC, α-Fe, and a solid solution of silicon in iron were also found. The method of thermogravimetric analysis established the change in mass, heat flow, temperature of the samples, and the change in the partial pressures of gases during the experiment. Samples obtained by SPS show a higher density of the material at the level of 3.3 g/cm3, average mechanical strength of 454 MPa, and microhardness of 35 GPa, compared with samples obtained by liquid-phase sintering. The SPS method also made it possible to obtain materials with a higher density (by 8%) and practically no significant crystal growth compared to samples obtained by liquid phase sintering. The results of the study facilitate the achievement of a combination of new approaches to the design of compositions and the technology of manufacturing SiC ceramics, which significantly expands their areas of application. [ABSTRACT FROM AUTHOR]

Cermet coatings provide protection against an aggressive operating environment of machine and device elements, such as corrosion, wear or high-temperature conditions. Currently, WC-based cermet coatings are frequently used in different industry branches. In this work, conventional WC-based powders (WC-Co and WC-Co-Cr) were sprayed with high velocity oxy fuel (HVOF) onto AZ31 magnesium alloy with different spray distances (320 and 400 mm). The research aimed to investigate the effect of the spray distance on the microstructure of the coatings, phase composition and electrochemical corrosion resistance. Results revealed that a higher spray distance results in greater porosity, 1.9% and 2.3% for 320 mm and 2.8% and 3.1% for 400 mm in the case of WC-Co and WC-Co-Cr coatings, respectively. Also, an impact on coatings microhardness was observed, c.a. 1300 HV0.3 for shorter spray distances, whereas for longer ones it was less than 1100 HV0.3. The corrosion resistance estimated in potentiodynamic polarization measurements was the best for WC-Co-Cr coating deposited from the shorter spray distance, corrosion current density was equal to 2:9 μA·cm-2 and polarization resistance was equal to 8424 Ω·cm2. [ABSTRACT FROM AUTHOR]

The paper presents the computational studies of microstructure- and topography- related features of suspension plasma sprayed (SPS) coatings of yttria-stabilized zirconia (YSZ). The study mainly covers the porosity assessment, provided by ImageJ software analysis. The influence of boundary conditions, defined by: (i) circularity and (ii) size limits, on the computed values of porosity is also investigated. Additionally, the digital topography evaluation is performed: confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) operating in Shape from Shading (SFS) mode measure surface roughness of deposited coatings. Computed values of porosity and roughness are referred to the variables of the spraying process, which influence the morphology of coatings and determines the possible fields of their applications.