Beáta Ballóková

Surface analysis of polymeric substrates used for inkjet printing technology

Purpose – This paper aims to find an optimal surface treatment of commonly used polymeric substrates for achieve the high adhesion of printed structures. For this reason, the investigation of substrates surfaces from different perspectives is presented in this paper. Design/methodology/approach – The contact angle measurements as well as the roughness measurements were realised for the analysis of surface properties of investigated substrates. The impact of applied chemical agents for surface treatment onto the wettability is analysed for polyimide, polyethylene terephthalate and polyethylene naphthalene substrates. Findings – The results prove the correlation among wettability, surface energy and work of adhesion with respect to the theoretical background. The surface treatment of polymeric substrates by chemical agents, such as acetone, toluene, ethanol, isopropyl and fluor silane polymer, has a significant impact onto the wettability of substrates which affects the final deposition process of nanoinks....

Creep behaviour of MoSi2–SiC and MoSi2–HfO2

Abstract Creep resistance of two MoSi 2 -based materials containing SiC and HfO 2 particles, respectively, in ambient atmosphere was studied in the temperature range 1100–1400°C under a load of 100 MPa. The microstructure and its response to high-temperature load were investigated by TEM using the thin foil technique. Comparison of the creep resistance of both materials at each particular testing temperature shows that the performance of MoSi 2 –HfO 2 is about one order of magnitude better than the other one.

Surface integrity of Mg-based nanocomposite produced by Abrasive Water Jet Machining (AWJM)

ABSTRACT This paper investigates the influence of jet traverse speed on the surface integrity of 0.66 wt% Al2O3 nanoparticle reinforced metal matrix composite (MMC) generated by Abrasive Water Jet Machining (AWJM). Surface morphology, surface topography, and surface roughness (SR) of the AWJ surface were analyzed. The machined surfaces of the nanocomposites were examined by laser confocal microscope and field emission scanning electron microscope (FESEM). Microhardness and elasticity modulus measurement by nanoindentation testing were also performed across thickness of the samples to see depth of the zone, affected by AWJ cutting. The result reveals that extent of grooving by abrasive particle and irregularity in AWJ machined surface increases as the traverse speed increased. Similarly, the rise in value of surface roughness parameters with traverse speed was also seen. In addition, nanoindentation testing represents the lower hardness and elastic modulus due to softening occurs in AWJ surface.

Investigation of nano-inks’ behaviour on flexible and rigid substrates under various conditions

Purpose This paper aims to find the optimal deposition conditions for achieving the homogenous structure of the silver layers onto three types of polymeric substrates as well as on the rigid substrates. For this reason, the detailed investigation of the silver-based layers deposited at different technological conditions by microscopic methods is presented in this paper. Design/methodology/approach The special test pattern has been designed and deposited at different substrate temperatures by using two types of generally available silver-based nano-inks. Cross-sections and 3D profiles of the deposited silver layers have been profoundly analysed by using the optical profiler Sensofar S Neox on the generally used polymeric (PI, PET and PEN) and rigid substrates (951 and 9K7 LTCC, glass and alumina). Findings The results prove the strong correlation between the substrate temperature during the deposition process and the final shape of the created structure which has the a direct impact on the layers’ homogeneity. The results also prove the theory of the coffee ring effect creation in the inkjet printing technology. Originality/value The main benefit of this paper lies in the possibility of the homogeneity achievement of the deposited silver-based layers on the several polymeric and rigid substrates by managing the temperature during the deposition. The paper also offers the comparative study of nano-inks’ behaviour on several polymeric and rigid substrates.

Observation of Anisotropy of Creep Fracture Using Small Punch Test for Al-Al4C3 System Produced by Equal Channel Angular Pressing

Abstract The anisotropy of the creep properties and fracture using small punch tests for the Al-Al4C3 system produced by ECAP were analysed in this work. Small punch creep tests under constant force were performed at the temperature of 623 K. It was shown that the fracture results, i.e. time to fracture and deflection at fracture were different in specimens with different orientation with respect to the axis of ECAP deformation. Fracture surface analysis of the tested small punch specimens was conducted. Fractures have transcrystalline ductile character. The fracture dimples are equiaxial as well as elongated in the dependence on strain direction. Fracture dimples are of two categories, the small ones sized from 0.1 to 0.5 μm and large ones ranging from 3 to 6 μm.

High Temperature Properties of the MoSi2 and MoSi2 SiC Nonocomposites

High temperature properties of the monolithic MoSi2 and MoSi2 composite reinforced by nano-SiC particles were studied. The materials were prepared via powder metallurgy using high temperature controlled reaction sintering (CRS). Creep testing in four-point bending and in compression was performed in order to determine high temperature properties of the experimental materials. Comparison of the materials showed that incorporating of nano SiC particles into the MbSi2 matrix resulted in improvement of creep resistance for temperatures up to 1473 K for applied stress from 50 to 100 MPa. Creep stress exponent (n) of the composite, measured after compressive creep testing, was 1.27 (1273 K) and 3 (1473 K), respectively. Microstructure and its response to high temperature loading were investigated by TEM using the thin foil technique. Based on the presented parameters of creep kinetics and transmission electron microscope analyses probable mechanism of creep deformation was determined.

Creep Testing of MoSi2 - Bases Composites

The creep resistance of MoSi2 composite materials in ambient atmosphere has been studied in the temperature range 1273 1673 Κ under a load of 100 MPa. The material MoSi2 containing 10 vol% nanometersized SiC particles had the optimum microstructure. Creep tests of the investigated composite materials confirmed their relatively good creep resistance. Creep parameters changed with temperature differently in each material. The highest creep resistance, at temperature 1273 K, had the material MoSi2-10% nanometer-sized SiC particles. At the temperature interval 1473 1673 K, the materials MoSi2 10 vol.% SiC particles and MoSi2 10 vol.% Si3N4 particles were the most resistant. K e y w o r d s : composite material, microstructure, creep behaviour

The Analyse of Nanocomposite Thin Coatings Using Specimens Prepared by Focused Ion Beam Milling

The microstructure of physical vapour deposition (PVD) coatings deposited by duplex technology was investigated by Dual Beam FIB/SEM system (focused ion beam / scanning electron microscope), which allows one to examine cross sections of specimens from their surface down to the substrate. Examined were PVD coatings of nanocomposite type: duplex AlXN3 (X=Cr) and duplex nACRo3, deposited by LARC and CERC technologies. Duplex coating is a modern technology, which combines plasma nitriding and PVD coating in one cycle. The FIB analysis can be widely used in the field of study of basic materials and technological applications as it is based on highly focused ion beam which enables accurate machining of the investigated specimens and flexible processing at a micro/nanometric level. Cross sections of specimens obtained by FIB-SEMs document the arrangement of individual deposited nanomultilayers within the nanocomposite coatings and their EDS analysis in specific locations.

Fracture Analysis and Mechanical Properties of Magnesium Based Composites

Mechanical properties and microstructure and fracture analysis of a magnesium alloys based composite series with different volume fraction of alumina dispersoid nanoparticles were studied. The initial states of the composites were further treated by severe plastic deformation (SPD) using equal channel angular pressing (ECAP) in order to achieve microstructures with very fine grains of matrix. Microstructure parameters, in particular the matrix grain size, average size of the dispersed particles and their distribution, were observed using optical microscopy. The average grain sizes of MMCs decreased evidently with the increase of the weight percentage of Al2O3 particles additions and ECAP passes. The heat deformation process of such materials, besides the formation of incorporated Al2O3 particles, also leads to the creation of intermetallic compound Mg17Al12. Fracture surfaces after tensile tests at room and elevated temperature were studied by SEM. The fracture of studying materials were characterized as the ductile fracture due to the existence of a large number of dimples.In summary, it has been shown that mechanical properties are affected by lattice, physical parameters of phases within the composite systems. They are also affected by microstructure and substructure, which depend on the technology of compaction and densification.

Micromechanisms of Fracture of Magnesium Based Composite After Superplastic Deformation

Abstract The micromechanisms of fracture of AZ61 + 1 wt. % Al2O3 composite in the zone of superplastic deformation was analysed and quantified in this work. The specimens were tested at temperature of 200°C at different strain rates. Changing the strain rate, from 1x10-2 s-1 to 1x10-4 s-1, a significant growth of ductility was observed. At maximum value of superplasticity the fracture was transcrystalline ductile with dimples of two size categories. Based on the statistical analysis of fracture micromechanisms at the elevated temperature and strain rates of 10-0- 1x10-4 s-1 hyperbolic dependency was depicted according to Gurland - Plateau theory.