International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Tribological properties of functional surfaces are a key factor influencing the durability, reliability and efficiency of mechanical systems. One of the progressive approaches to surface modification is laser surface microtexturing, which allows for the precise creation of controlled microstructures capable of modifying contact conditions and lubricant retention at tribological interfaces. This article focuses on the application of laser-induced surface microtexturing to improve the tribological performance of hard nanocomposite coatings nACRo³ and nACRo⁴. The experimental part of the research is dedicated to the preparation of microtextures on the substrate surface using a pulsed laser system, followed by the deposition of nanocomposite coatings nACRo³ and nACRo⁴. The created microstructures are characterized in terms of their geometry, distribution and influence on the contact properties of the coated surfaces. The wettability of the microtextured surfaces was evaluated based on the measurement of the contact angle. Optimizing surface microtexture is an effective way to increase wettability and potentially improve lubrication conditions during technological processes of forming or tribological loading of materials.
Keywords: laser surface texturing, tribology, nanocomposite coating, wettability, contact angle, PVD coating, tool steel, die casting

The paper presents the results of research aimed at determining surface wettability. The research was focused on microtexturing by low-energy laser irradiation of the surface of molded parts using innovative engraved surface treatment methods (LBT and EBT) to ensure a smooth distribution of the separation agent on the surface of high-pressure Al castings. The basic material was Uddeholm Dievar, which is used to make molds. PVD coatings were applied to the base material. The effect of laser texturing surfaces on the contact angle size was determined. Contact angle was evaluated on the base material, on PVD coatings without surface treatment and with the use of two types of separating agents.

It has been established that in the study of a solid surface by atomic force microscopy, the hydrophobic interaction is more advantageous due to a decrease in the interaction forces between the probe and the liquid adsorbed on the surface under study. Despite the fact that silicon is a hydrophobic material, it has been shown that the material acquires hydrophilic properties in air, as a result of which the use of carbon-modified probes has been proposed. An approach to experimental statistical modeling is proposed, based on the experiment planning method, which shows that with a scanning speed of 12 μm / s, a scanning step of up to 82 nm and a delay time before scanning of 6 ms, the interaction force between the probe and the adsorbed liquid reaches minimum values. As a result of the research, it was found that with a decrease in the scanning speed, a scanning step and an increase in the delay time of the probe before measurement, the interaction between the probe and the liquid membrane is hydrophobic. It is shown that by changing the initial parameters, it is possible to control the hydrophobic interaction between the probe and the liquid. It has been established that increased air humidity leads to hydrophilic interaction. This is due to the increase in the thickness of the adsorbed liquid layer on the surface under study.

Physical surface properties including surface roughness, topography, morphology, and wettability could influence the implant material behavior, bio-response, bacterial contamination and contact with other bio-active surfaces or fluids. This work investigates microand nanoscale roughness parameters and surface morphology of PVD deposited (Ti,Al,V)N/TiO₂ coating using optical microscopy, white light interferometry (WLI), contact profilometer and scanning electron (SEM) microscopy. Results indicated that vacuum oxidized surface possessed medium roughness values, anisotropy in surface texture and irregular morphology. The vacuum oxidation of the nitride maintained the oxide with nano-crystal size and showed pores at the interface between the layers. The effect of prolonged exposure to Ringer-Braun solution droplet on the modified crystalline structure of the oxide was also explained.