The modern coating market is dominated by acrylic, polyurethane, and polyester polymer resins produced from unsustainable fossil resources. Herein, we propose the preparation of resins from biobased components to produce functional and solvent-free wood coatings with enhanced performance properties. Acrylated rapeseed, linseed, and grapeseed oils were prepared via a one-step synthesis and used as a basis for the control of resin viscosity and fatty acid content. A combination of vegetable oil acrylates was used as a matrix and the biobased monomer propoxylated glycerol triacrylate (GPT) was selected to tailor the properties of the UV crosslinked network. During polymerization, the GPT monomer induced a two-phase microstructure as indicated by an SEM analysis. The possibility of generating a tailored microstructure in the final material was examined in this study. The addition of GPT increased the storage modulus by up to five-fold, crosslink density by up to two-fold at 20 °C, and glass transition temperature by up to 10.2 °C. Pull-off adhesion tests showed a strength of 1.21 MPa. In addition, the photo-oxidation effect on samples, i.e., aging, was assessed with microhardness, sliding friction, and optical microscopy. Coatings showed a microhardness value up to 250 MPa, while a coefficient of friction (μ) was in the range of 0.21 to 0.88.
In this article, the fabrication, characterization, tribological performance, and micromechanical properties of nanostructured smart coatings (NSC) based on the multilayered alternating carbonitride/nitride bilayer {TiMe-CN/TiAlSi-N}n system are discussed. The symbol “Me” denotes refractory metals Hf or Nb, and the index “n” shows the number of superlattice periods. The NSC samples were deposited onto bearing steel (100Cr6) substrates using a reactive high-power physical vapor deposition (PVD) technique that can be scaled up for industrial use. The deposited multilayered NSC contained crystalline nanometer-scale TiMe-CN/TiAlSi-N nanoparticles strengthened by Hf or Nb additives, which increased surface microhardness up to 3000 HV. The measured steady-state friction coefficient (CoF) was within the 0.2–0.4 range, and a specific wear rate lower than 2 × 10−6 mm3/Nm was observed in the dry friction regime. The impact of NSC substrate hardness and NSC coating thickness on microhardness measurement values was investigated. A thicker coating provided a higher integrated (coating + substrate) microhardness value at a lower indentation test force (<0.3 N). As the indentation test force increased, the obtained microhardness values decreased faster for the coatings deposited on a softer substrate. The surface roughness impact on wear properties for specific NSC coatings was observed.
Ceramic Nanostructured Superlattice Coatings (NSC) have broad applicability to improve the parts’ and assemblies’ tribological and mechanical properties for the needs of the automotive and aerospace industries. Improving the material properties using nanocoatings for such a widely used material as, for example, bearing steel 100Cr6 makes it possible to improve the service life of machine parts. In this paper, the correlation dependence between tribological and mechanical properties of the NSC and its surface texture are considered to determine how much surface texture will affect the tribological performance of the coated workpieces, as well as the measuring and evaluation procedure of the nanocoatings, are presented. Three different NSC described by a general empirical formula {TiMe1Me2-CN/TiAlSi-N}n and based on the modified carbonitride/nitride non-stoichiometric chemical composition were created, and their tribological and mechanical properties measured and analyzed in the context with surface texture. NSC deposited by the advanced PVD (Physical vapor deposition) technique demonstrated significantly higher wear resistance (up to 28 times), reasonably lower friction coefficient (CoF) (up to 4 times), and significantly higher hardness of the coated workpieces (up to 7 times) versus substrate material. A strong correlation between the steady-state dry sliding friction, CoF, and the amplitude and functional surface texture parameters of tribo-track were observed. The first results of the initiated research regarding the correlation analysis of the tribological and mechanical properties, on the one hand, and surface texture, on the other hand, of the NSC are reported here.
This article discusses the micromechanical properties and true microhardness determination of nanostructured tribological coatings (NTCs) based on a multilayered alternating nitride/carbonitride bilayer substructure for transition metals. The constituent nitride/carbonitride bilayers in the superlattice structure of the NTC were alloyed with refractory metals, denoted as Me = Me1 or Me2= Cr, Hf, Nb, W, and Zr. The resulting NTC coatings were deposited onto 100Cr6 steel substrates using an advanced physical vapor deposition (PVD) technique, referred to here as high-power ion-plasma magnetron sputtering (HiPIPMS). The comprising crystalline nanometer-scale TiAlSiMe1-N/TiMe2-CN nanoparticles strengthened by Me additives significantly increased the NTC microhardness to over 3200 HV. The primary focus of this research was to determine the true microhardness of the NTC film samples. The apparent microhardness (Ha) of the film/substrate system for various NTC samples was measured during microindentation testing using the Vickers method. Nine NTC samples were tested, each generating a corresponding microindentation dataset containing between 430 and 640 imprints, depending on the specific NTC sample. These datasets were analyzed using three distinct empirical approaches: (i) the inverse power-law model (IPL-Model), (ii) the sigmoid-like decay model (SLD-Model), and (iii) the error function model (ERF-Model). The observed solid correlation between the proposed models and experiments suggests that the true microhardness estimates (Hf) obtained through the empirical mathematical modeling approach are reliable.
This study investigates the nanomechanical and tribological behavior of multilayered nitride/carbonitride nanostructured superlattice type coatings (NTCs) composed of alternating TiAlSiNb-N and TiCr-CN sublayers, deposited via high-power ion-plasma magnetron sputtering (HiPIPMS) technique. Reinforced with refractory elements Cr and Nb, the NTC samples exhibit high nanohardness (39–59 GPa), low friction, and excellent wear resistance. A novel analytical approach was introduced to extract stress–strain field (SSF) gradients and divergences from nanoindentation data, revealing alternating strain-hardening and strain-softening cycles beneath the incrementally loaded indenter. The discovered oscillatory behavior, consistent across all samples under the investigation, suggests a general deformation mechanism in thin films under incremental loading. Fourier analysis of the SSF gradient oscillatory pattern revealed a variety of characteristic dominant wavelengths within the length-scale interval (0.84–8.10) nm, indicating multi-scale nanomechanical responses. Additionally, the NTC samples display an anisotropic coating morphology exhibited as unidirectional undulating surface roughness waves, potentially attributed to atomic shadowing, strain-induced instabilities, and limited adatom diffusion. These findings deepen our understanding of nanoscale deformation in advanced PVD coatings and underscore the utility of SSF analysis for probing thin-film mechanics.
28 November 2020 in Powder Metallurgy and Metal Ceramics