This paper presents the results of corrosion and tribological analysis of pure and nanocomposite zinc coatings. Coatings were electroplated using commercially available products—zinc acidic bath and a nanoparticle carrying plating additive. Electrochemical measurements were carried out to compare the anticorrosion performance of coatings. An investigation into the influence of nanoparticles on the mechanical properties was performed. The zinc nanocomposite coating exhibited better wear resistance and higher hardness than the plain zinc coating. The application of confocal laser scanning microscopy (CLSM) allowed the detailed description of friction/wear marks. The electrochemical studies revealed that the introduction of nanoparticles into the coating did not compromise its protective properties—a similar resistance of plain and nanocomposite coatings to corrosion was obtained.

The paper presents the results of in vitro studies of fretting and fretting corrosion processes of Ti6Al4V implant alloy in the environment of natural saliva and self-made mucin-based artificial saliva solutions. The study was performed on a specially designed fretting pin-on-disc tester, which was combined with a set used for electrochemical research. The open circuit potential measurements and potentiodynamic method were used for corrosion tests. The worn surfaces were subjected to microscopic observations and an evaluation of wear. Results were interpreted using the dissipated energy and third-body approaches. The X-ray diffraction analysis showed that titanium oxides constitute over 80% of the friction products. Special attention was paid to the role of saliva and its substitutes, which in certain cases can lead to the intensification of fretting wear. On the basis of the received results, a new phenomenological model of fretting corrosion processes was proposed. This model involves the formation of an abrasive paste that is a combination of metal oxides and the organic components of saliva.

The paper presents the results of research of the fretting process of 316 austenitic stainless steel in the environment of natural saliva and mucin-based saliva preparations. The aim of the work was the evaluation of synthetic saliva preparations on biomaterial wear during fretting and fretting-corrosion. The fretting process, in the oscillatory micro-movements conditions, occurs in the joints of removable dentures, especially during the chewing phase. Fretting usually leads to the intensification of fatigue damage processes of materials. Experimental research, through rheological, fretting, fretting-corrosion, and microscopic analysis were performed. Tests indicate that natural saliva and saliva preparations are similar in terms of viscoelastic properties. The statistically significant proposed saliva solutions reduced the material wear in comparison to dry sliding, which is important in the case of people with saliva secretion problem. The addition of xanthan gum to the artificial saliva composition improved rheological characteristics, but on the other hand, led to an increase of secondary wear. It was confirmed by the volumetric wear of the samples and evaluation of energy dissipated during friction. Fretting-corrosion processes were explained by a mechanism related to crevice corrosion supported by friction.

The synovial fluid is responsible for adequately lubricating, moisturizing, and nutritional human joints. This liquid should have appropriate viscoelastic properties and ensure a low coefficient of friction in biotribological systems. Many artificial synovial fluid preparations used in viscosupplementation treatments are based on hyaluronic acid. This work aimed to evaluate the influence of molecular weight on the functional properties of solutions based on hyaluronic acid. 1% solutions based on hyaluronic acid with five different molecular weights from 50,000 Da to 2 MDa were made. Rheological (viscosity, viscoelasticity), tribological (coefficient of friction, wear assessment), and wettability tests were carried out. Significant differences were observed in the rheological tests, where the viscosity strictly depends on the molecular weight of the hyaluronic acid. It has been shown that the molecular weight of HA has little effect on the coefficient of friction. On the other hand, the differences in the tribological wear are much more significant. The molecular weight of biopolymers is one of the essential parameters in developing new artificial synovial fluids. Using a higher molecular weight of hyaluronic acid increases viscosity and wettability, resulting in less tribological wear.

Synovial joints are a basic part of the human body. Lack of proper lubrication of joints can lead to significant wear of their surfaces. The tribological and rheological properties of artificial synovial fluid solutions based on hyaluronic acid were studied. It was found that the concentration of selected hyaluronic acid solutions significantly affects the investigated parameters. The most promising results were obtained for 8 wt% hyaluronic acid solution, which showed the highest viscosity and wettability, and the lowest wear.