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.
1 January 2016 in International Journal of Surface Science and Engineering
This paper presents methods of modifying the anode surface layers of Al2O3 by introducing carbon to their microstructure. Composite coatings were prepared using two different methods. In the first, coatings were formed by means of oxidation under constant current conditions. Anodic oxidation of aluminium was conducted in a multicomponent electrolyte with the addition of organic acids and graphite. The second method was based on the formation of oxide coatings in an electrolyte without the addition of graphite or heat treatment of the layers of succinic acid. The obtained coatings were tested using SEM, TEM, and GDOES (glow discharge optical emission spectrometry) and their tribological and stereometric properties were measured. The study demonstrated the beneficial effects of the methods when used to improve the tribological properties of sliding couples.
Nanotechnology is currently a very promising field of materials science. One of the most recent directions of research in this field is the nanotechnology of the upper layers for applications in engineering kinematic systems. The paper presents the influence of the production parameters of Al2O3 oxide layers on an EN AW-5251 aluminum alloy substrate on the nanostructure, nanomorphology of these layers, and their energy condition. The energy level was determined on the basis of Surface-Free Energy (SFE), determined from wettability (contact) angle measurements using the Owens-Wendt method. Using systematic scanning, the geometric structure of the surface (SGS) was determined for the produced layers. By means of a scanning electron microscope (SEM), the surface morphology and structure, and the chemical composition of the layers (EDS) were analyzed. Computer analysis of the surface nanoporosity was performed by means of the ImageJ 1.50i program. It was noted in the investigations that the oxide layer production parameters induce changes in the surface free energy of the layers. Changes in the nanomorphology of the upper layers were also observed, depending on the anodizing parameters.
In the present paper, a model of wear mechanism of Al2O3/WS2 with polyether ether ketone (PEEK)/BG plastic has been presented. An amorphous Al2O3 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 Al2O3/WS2-PEEK/BG friction pair. The technology applied to receive the Al2O3/WS2 layer, with appropriately selected conditions, allows us to obtain a tribological layer that enables the delivery of WS2 solid lubricant during friction.
1 October 2012 in Chemical and Process Engineering: New Frontiers
The paper presents the properties of surface oxide layers with an increased content of carbon for tribological applications. The composite surface oxide layers were produced using a two-step technology through hard anodising of the surface of an aluminium alloy, followed by thermochemical treatment of anodic oxide coatings. The surface oxide layers were subjected to tribological tests in an oil-less sliding couple with T5W plastic. The presented test results confirm the usefulness of the proposed modifications of surface oxide layers for the purpose of enhancing the operational durability of oil-less sliding couples in a reciprocating motion.