A comparison of different measurement methods of mechanical properties of Al thin films

The paper compares two different methods for testing of metallic thin films: microcompression test and nanoindentation. Microcompression test is one possibility how to perform mechanical tests on a very small scale. This method requires preparation of a small cylindrical specimen (micropillar) of micrometric size by FIB and execution of a compression test using nanoindenter device equipped with a flat diamond punch. Stressstrain curves of the thin films were obtained from such tests. Nanoindentation tests were then conducted to compare the results on the same films. Two different metal thin films - AlCuW, AlCuSi with thickness 2 mu m and grain size 3.8 mu m in average were prepared by PVD method. In this paper, we announce the results of measurements, a comparison of the results obtained by each method and identify advantages and limitations of the methods

DYNAMIC IMPACT WEAR AND IMPACT RESISTANCE OF W-B-C COATINGS

Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings’ impact lifetime

Measurement of Mechanical Properties of Composite Materials

The aim of the present work was the study of mechani- cal properties of MWCNT/PU. Four types of coatings were compared. Two different concentrations of MWCNTs com- mercially functionalized with COOH group were prepared and studied. These composites showed improved mechanical properties compared to PU, and the modified nanotubes proved to be much better fillers than the unmodified MWCNTs due to stronger filler-to-matrix attachment. Be- cause the modified nanotubes seem to be much more conven- ient composite filler, the first experiments with nanotube modification have been carried out. Modification using induc- tively coupled discharge in argon and oxygen mixture was successful and the mechanical properties of the composite were increased at the same level as in case of the commer- cially COOH functionalized MWCNT fillers.V práci byly studovány mechanické vlastnosti vrstev MWCNT/PU a porovnávány čtyry různé typy jejich nanášení. Práce byla zaměřená zejména na studium vlivu funkcionalizace uhlíkových nanotrubek v plazmatu na mechanické vlastnosti výsledného kompozitu. Rovněž se zabývalo modelováním viskoelastických a viskoplastických vlastností kompozitů MWCNT/PU

Comparison of plasma-polymerized thin films deposited from 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline: I film properties

Poly(2-oxazoline) is a promising new class of polymeric materials due to their antibiofouling properties and good biocompatibility. Poly(2-oxazoline) coatings can be deposited on different substrates via plasma polymerization, which can be more advantageous than other coating methods. The aim of this study is to deposit poly(2-oxazoline) coatings using a surface dielectric barrier discharge burning in nitrogen at atmospheric pressure using 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline vapours as monomers and compare the film properties. For the comparison, the antibacterial and cytocompatibility tests were peformed according to ISO norms. The antibacterial tests showed that all the deposited films were highly active against Staphylococcus aureus and Escherichia coli bacteria. The chemical composition of the films was studied using FTIR and XPS, and the film surface’s properties were studied using AFM and surface energy measurement. The cytocompatibility tests showed good cytocompatibility of all the deposited films. However, the films deposited from 2-methyl-2-oxazoline exhibit better cytocompatibility. This difference can be explained by the different chemical compositions and surface morphologies of the films deposited from different monomers.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (DKRVO RP/CPS/2022/005, RP/CPS/2022/001, RP/CPS/2022/002); Ministerstvo Obrany České Republiky, MOČRMinistry of Defence of the Czech Republi

Atmospheric pressure plasma polymerized 2-ethyl-2-oxazoline based thin films for biomedical purposes

Polyoxazoline thin coatings were deposited on glass substrates using atmospheric pressure plasma polymerization from 2-ethyl-2-oxazoline vapours. The plasma polymerization was performed in dielectric barrier discharge burning in nitrogen at atmospheric pressure. The thin films stable in aqueous environments were obtained at the deposition with increased substrate temperature, which was changed from 20◦ C to 150◦ C. The thin film deposited samples were highly active against both S. aureus and E. coli strains in general. The chemical composition of polyoxazoline films was studied by FTIR and XPS, the mechanical properties of films were studied by depth sensing indentation technique and by scratch tests. The film surface properties were studied by AFM and by surface energy measurement. After tuning the deposition parameters (i.e., monomer flow rate and substrate temperature), stable films, which resist bacterial biofilm formation and have cell-repellent properties, were achieved. Such antibiofouling polyoxazoline thin films can have many potential biomedical applications. © MDPI AG. All rights reserved.Czech Science FoundationGrant Agency of the Czech Republic [GACR 19-15240S]; Ministry of Defence of the Czech Republi

Optical characterization of inhomogeneity of polymer-like thin films arising in the initial phase of plasma-enhanced chemical vapor deposition

In this study, an optical investigation in a wide spectral range of polymer-like (SiOxCyHz) thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) is presented. The primary focus is on assessing the homogeneity of the grown films. Within the PECVD, it is possible to alter the properties of the deposited material by continually adjusting deposition process parameters and hence allow for the growth of inhomogeneous layers. However, as shown in this study, the growth of homogeneous layers could be similarly challenging. This challenge is especially pronounced at the beginning of the deposition process, where it is necessary to consider the influence of the substrate among other factors, as even slight variations in the deposition conditions can lead to the formation of inhomogeneous layers. Several series of polymer-like thin films were deposited onto silicon substrates with the goal of producing homogeneous layers, i.e. all deposition parameters were held constant. These samples were optically characterized with a special interest in homogeneity, especially at the beginning of the growth. It was found that initial inhomogeneous growth is always present. The thickness of the initial inhomogeneous part was found to be surprisingly large

On the study of the mechanical properties of Mo-B-C coatings

Mo2BC thin films show a favourable combination of high stiffness, hardness and elastic modulus together with moderate ductility. In this study we focused on the comparison of mechanical properties of Mo-B-C thin films with different structures (nanocrystalline or amorphous). The thin films were deposited on steel, hard metal and silicon substrates using DC magnetron sputtering. The mechanical properties of Mo-B-C films were studied using indentation techniques under both quasistatic and dynamic conditions using a wide range of loads from 50 μN up to 1 N. The results showed that even amorphous Mo-B-C thin films had high hardness of 19.5 ± 0.5 GPa and elastic modulus of 276 ± 5 GPa. Their hardness is comparable with the common amorphous diamond-like carbon coatings. Moreover, their fracture toughness is significantly higher. The results of mechanical tests were correlated with microstructure observations carried out using scanning and transmission electron microscopy. The images of the deformed area under the residual indentation imprints showed no cracking even after high loads or after indentation with sharp cube corner indenter