Zinc oxide nanoparticles, especially those with a high aspect ratio (i. e., nanorods and nanowires), are of great interest for many applications as they are piezoelectric, photocatalytic and antimicrobial. In the present study, a plasma flight-thru synthesis method was developed that allows controlling the particle size and shape of the zinc oxide nanoparticles. In a direct current thermal plasma reactor operated at atmospheric pressure, zinc powder injected into the plasma jet was molten, vaporized and oxidized, which allowed growing zinc oxide nanoparticles. The particle spectrum ranged from small nanospheres to nanorods, nanowires and multipodic nanoparticles such as tetrapods. The influence of the oxygen rate and the plasma power (correlated to the discharge current) on the particle morphology was studied, and the feasibility of the nanowire-like particles as piezoelectric sensor material was investigated. Piezoelectric test sensors, equipped with the plasma-synthesized zinc oxide nanowires, successfully responded to mechanical stimulation after poling.

In this study, tungsten disulfide–zinc (WS₂-Zn) composite films were generated on polyether ether ketone (PEEK) disks by an atmospheric pressure plasma jet (APPJ) equipped with a shrouding attachment. The friction and wear properties of the WS₂-Zn coatings were intensively investigated by using a rotational ball-on-disk setup under dry sliding and ambient room conditions. In order to gain more information about the lubrication mechanism, the coating areas as deposited and the worn areas (i.e., in the wear track) were analyzed with a scanning electron microscope (SEM) with regard to their chemical composition in depth by energy-dispersive X-ray spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) was conducted to obtain precise chemical information from the surface. The results indicated that WS₂-Zn coatings significantly improved the tribological properties, exhibiting a coefficient of friction (COF) of <0.2. However, the tribological performance of the coatings is strongly dependent on the plasma process settings (i.e., plasma current, dwell time of the powder particles in the plasma jet), which were tuned to reduce the oxidation by-products of WS₂ to a minimum. The COF values achieved of the dry lubricant films were significantly reduced in contrast to the uncoated PEEK by a factor of four.

In order to increase the resistance of the polyamide 11 (PA 11) surface to sliding wear, the economical low-temperature atmospheric pressure plasma deposition (APP D) technique was used to produce innovative thick Zn/MoS2/graphite/Zn coatings with self-dry-lubrication and self-healing functions [1]. The specific problem was concern on structure characterization in nano- and atomic scale of these effects. The self-dry-lubrication was possible thanks to the possible breaking of weak van der Waals’ bonds both in graphite and MoS2 structures. The effect was described as a result of the shifting of atomic layers in both MoS2 and graphite layers within the same phase and at their boundaries while the self-healing effect occurred in the form of closing micro-cracks in the structure of the coatings and rebuilding van der Waals’ atomic bonds.

High-performance polymers (PEEK, PA11) are vital in lightweight engineering but limited by friction and wear. This review analyzes self-lubricating and self-healing MoS2 and WS2 coatings deposited via atmospheric pressure plasma jet (APPJ). By integrating recent literature with the authors’ previous studies [25,26], the paper evaluates coating design, microstructure, and tribology on polymer substrates. While lamellar sliding ensures low friction, WS2 offers stability in humidity, and MoS2 provides adaptive self-healing via crack filling. The review concludes that optimized coatings significantly enhance durability and provide guidelines for designing high-performance, multifunctional polymer surfaces.