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The paper presents a one-dimensional model of heat conduction in a couple consisting of a cylinder made of a sliding plastic material, TG15, and a cuboid made of alloy AW 6061 coated with a hard anodic coating, where the couple is heated with the heat generated during friction. TG15 is a composite material based on polytetrafluoroethylene (PTFE) with a 15% graphite filler, used for piston rings in oil-free air-compressors. Measurement of temperature in the friction zone is extremely important for the understanding and analysis of the phenomena occurring therein. It is practically impossible to introduce a temperature sensor in such a place. Therefore, the interaction taking place in such a couple was modelled using numerical methods. In order to simplify and accelerate the calculations, a one-dimensional model and constant thermophysical parameters of the materials participating in friction were adopted. To solve the proposed model, the finite difference method was used (FDM). The resultant system of equations was solved by means of an explicit scheme.

In the present paper, a model of wear mechanism of Al203/WS2 with polyether ether ketone (PEEK)IBG plastic has been presented. An amorphous Al203 oxide layer with a tungsten disulfide modifier has been characterized by the Scanning Electron Microscope equipped with an Energy Dispensive Spectrometer (SEM/EDS) and XRD analysis. The addition of WS2 to the acid bath reduces the friction coefficient of the Al203/WS2-PEEKi BG friction pair. The technology applied to receive the Al203/WS2 layer, with appropriately selected conditions, allows us to obtain a tribological layer that enables the delivery of WS2 solid lubricant during friction. [ABSTRACT FROM AUTHOR]

Al2O3/IF-WS2 nanocomposite coating was prepared in a two-step process. The Al2O3 nano-fibers are the matrix of the composite and the nanoparticles of WS2 with fullerene-like structure (IF-WS2) are the dispersed phase material, which can improve the mechanical and tribological properties of the nanocomposite. Detailed structural analysis of the nanocomposites was performed using scanning electron microscopy (SEM) and X-ray diffraction. These analyses show that the IF nanoparticles are entrapped in the microporous surface-film of the alumina matrix. The structure and mechanical properties of the nanosized Al2O3/IF-WS2 nanocomposite film was analyzed. This analysis demonstrates that the hardness and composition of the film exhibits graded functional material characteristics, suggesting possible tribological applications. [ABSTRACT FROM AUTHOR]

The paper presents a new method of obtaining aluminium oxide composite layers formed by means of hard anodizing in an electrolyte composed of water solution of acids and graphite. The produced layers subject to tests and their results, such as the influence of process parameters on the properties of composite layers, are presented. A possibility of incorporating graphite particles into an anodic oxide layer structure has been demonstrated. The thickness and microhardness of the obtained layers and AI2O3 layers fabricated in identical conditions have been compared. [ABSTRACT FROM AUTHOR]

The article presents the effect of anodizing parameters of the EN AW-5251 aluminum alloy on the thickness and roughness of Al 2 O 3 layers as well as their wettability and tribological properties in a sliding combination with the T7W material. The input variables were the current density of 1, 2, 3 A/dm 2 and the electrolyte temperature of 283, 293, 303 K. The tribological tests were performed on the T-17 tester in reciprocating motion, in conditions of technically dry friction. The tests were carried out on a 15 km road with a constant average slip speed of 0.2 m/s and a constant unit pressure of 1 MPa. The measurement of the wettability of the layers was performed using the sitting drop method, determining the contact angles on the basis of which the surface free energy was calculated. The profilographometric measurements were made. The analysis of the test results showed that the anodizing parameters significantly affect the thickness of the Al 2 O 3 layers. The performed correlation analysis also showed a significant relationship between the roughness parameters and the wettability of the surface of the layers, which affects the ability to create and maintain a sliding film, which in turn translates into sliding resistance and wear of the T7W material. The analysis of friction and wear tests showed that the layer with hydrophobic properties produced at a current density of 1 A/dm 2 in an electrolyte at a temperature of 283 K is the most favorable for sliding associations with T7W material.

The article presents the effect of the thermo-chemical treatment of Al 2 O 3 layers on their nanostructure, surface morphology, chemical composition as well as their micromechanical and sclerometric properties. Oxide layers were produced on EN AW-5251 aluminium alloy (AlMg 2 ) by the method of direct current anodizing in a three-component electrolyte. The thermo-chemical treatment was carried out in distilled water and aqueous solutions of Na 2 SO 4 ·10H 2 O and Na 2 Cr 2 O 7 ·2H 2 O. It was shown that the thermo-chemical treatment process changes the morphology of the surface of the layers (the formation of a sub-layer from the Na 2 SO 4 ·10H 2 O and Na 2 Cr 2 O 7 ·2H 2 O solutions), which directly increases the thickness of the layers by 0.37 and 1.77 µm, respectively. The thermo-chemical treatment in water also resulted in the formation of a 0.63 µm thick sub-layer. The micromechanical tests indicated a rise in the surface microhardness of the layers in the case of their thermo-chemical treatment in water and the Na 2 SO 4 ·10H 2 O solution and a decrease in the case of the layers modified in the Na 2 Cr 2 O 7 ·2H 2 O solution. The highest microhardness (7.1 GPa) was exhibited by the layer modified in the Na 2 SO 4 ·10H 2 O solution. Scratch tests demonstrated that the thermo-chemically treated layers had better adhesive properties than the reference layer. The best scratch resistance was exhibited by the layer after thermo-chemical treatment in the Na 2 SO 4 ·10H 2 O solution (the highest values, practically for all the critical loads) which, together with its low roughness and high load capacity, predispose it to sliding contacts.

The paper presents the influence of the surface anodizing parameters of the aluminum alloy EN AW-5251 on the physicochemical properties of the oxide layers produced on it. Micrographs of the surface of the oxide layers were taken using a scanning electron microscope (SEM). The chemical composition of cross-sections from the oxide layers was studied using energy dispersive spectroscopy (EDS). The phase structure of the Al₂O₃ layers was determined by the pattern method using X-ray diffractometry (XRD). The nanomorphology of the oxide layers were analyzed based on microscopic photographs using the ImageJ 1.50i program. The energetic state of the layers was based on the surface-free energy (SFE), calculated from measurements of contact angles using the Owens-Wendt method. The highest surface-free energy value (49.12 mJ/m²) was recorded for the sample produced at 293 K, 3 A/dm², in 60 min. The lowest surface-free energy value (31.36 mJ/m²) was recorded for the sample produced at 283 K, 1 A/dm², in 20 min (the only hydrophobic layer). The highest average value nanopore area (2358.7 nm²) was recorded for the sample produced at 303 K, 4 A/dm², in 45 min. The lowest average value nanopore area (183 nm²) was recorded for the sample produced at 313 K, 1 A/dm², in 20 min.

It has been reported that the size and shape of the pores depend on the structure of the base metal, the type of electrolyte, and the conditions of the anodizing process. The paper presents thin Al 2 O 3 oxide layer formed under hard anodizing conditions on a plate made of EN AW-5251 aluminum alloy. The oxidation of the ceramic layer was carried out for 40-80 minutes in a three-component SAS electrolyte (aqueous solution of acids: sulphuric 33 ml/l, adipic 67 g/l, and oxalic 30 g/l) at a temperature of 293-313 K, and the current density was 200-400 A/m 2 . Presented images were taken by a scanning microscope. A computer analysis of the binary images of layers showed different shapes of pores. The structure of ceramic Al 2 O 3 layers is one of the main factors determining mechanical properties. The resistance to wear of specimen-oxide coating layer depends on porosity, morphology, and roughness of the ceramic layer surface. A 3D oxide coating model, based on the computer analysis of images from a scanning electron microscope (Philips XL 30 ESEM/EDAX), was proposed.