A 2D CELLULAR AUTOMATON MODEL OF LIQUID ABSORPTION INTO PAPER FIBERS WITH HYDROPHOBIC TREATMENT

In this work, the issue of applying water or a homogeneous aqueous suspension with a uniform size of (nano)particles (e.g., ink) to the surface of SBSK (southern bleached softwood kraft) paper with randomly arranged local hydrophobic treatment is investigated and then simulated. Based on the two investigated models, various simulation approaches were compared, an own simulation model was created, and its validity was subsequently demonstrated on the experiments performed

Effect of the composition of hybrid sands on the change in thermal expansion

In the foundry industry, silica sands are the most commonly used type of sands for the production of sand foundry moulds using various types of binders. Their greatest disadvantage is their significant volume changes at elevated temperatures, which are associated with the formation of many foundry defects from stress, such as veining, and thus have a direct influence on the final quality of the casting. In the case of non-silica sands and synthetic sands, the volume stability is more pronounced, but this is accompanied by a higher purchase price. Therefore, a combination of silica sand and synthetic sand CERABEADS is considered in order to influence and reduce the thermal expansion. The hybrid mixtures of sands, and their most suitable ratios, were evaluated in detail using sieve analysis, log W and cumulative curve of granularity. It was found that the addition of 50% CERABEADS achieves a 32.2% reduction in dilatation but may increase the risk of higher stresses. The measurements showed a significant effect of the granulometric composition of the sand on the resulting thermal expansion, where the choice of grain size and sorting can achieve a significant reduction in dilatation with a small addition of CERABEADS.Web of Science1517art. no. 618

Influence of structure development on performance of copper composites processed via intensive plastic deformation

Designing a composite, possibly strengthened by a dispersion of (fine) oxides, is a favorable way to improve the mechanical characteristics of Cu while maintaining its advantageous electric conductivity. The aim of this study was to perform mechanical alloying of a Cu powder with a powder of Al2O3 oxide, seal the powder mixture into evacuated Cu tubular containers, i.e., cans, and apply gradual direct consolidation via rotary swaging at elevated temperatures, as well as at room temperature (final passes) to find the most convenient way to produce the designed Al2O3 particle-strengthened Cu composite. The composites swaged with the total swaging degree of 1.83 to consolidated rods with a diameter of 10 mm were subjected to measurements of electroconductivity, investigations of mechanical behavior via compression testing, and detailed microstructure observa tions. The results revealed that the applied swaging degree was sufficient to fully consolidate the canned powders, even at moderate and ambient temperatures. In other words, the final structures, featuring ultra-fine grains, did not exhibit voids or remnants of unconsolidated powder particles. The swaged composites featured favorable plasticity regardless of the selected processing route. The flow stress curves exhibited the establishment of steady states with increasing strain, regardless of the applied strain rate. The electroconductivity of the composite swaged at elevated temperatures, featuring homogeneous distribution of strengthening oxide particles and the average grain size of 1.8 µm2, reaching 80% IACS (International Annealed Copper Standard).Web of Science1613art. no. 478

Effect of strain path on severely deformed aluminium

The twist channel angular pressing (TCAP) technology was recently developed in accordance to the contemporary trend of increasing the efficiency of severe plastic deformation technologies. This study was aimed to analyse structural changes, particularly grain sizes and orientations and textures, in commercial purity aluminium after a single pass TCAP and to put the structure in connection with the strain path. For comparison, another sample processed by two passes equal channel angular pressing (ECAP), Bc route, was analysed. Three independent shear planes affecting the material during a single pass TCAP caused the grains to refine down to the average size of 5.8 µm. The sample after a TCAP pass also exhibited highly developed subgrains. The textures of the samples exhibited differences in preferential orientations and their intensities.Web of Science18028328

Characterising correlations between electric conductivity and structural features in rotary swaged Al/Cu laminated conductors

This study aims to characterize the correlations between electric characteristics and selected structural features of newly designed Al/Cu laminated conductors manufactured via room temperature rotary swaging. After swaging, the laminates with diameters of 15 mm were subjected to two different post-process annealing treatments. Structure analyses performed to evaluate the effects of thermomechanical processing were performed via scanning and transmission electron microscopies. Electric conductivity and resistivity of the laminates were experimentally measured and numerically simulated using models designed according to the real conditions. The results showed that the electric resistivity was affected by the grain size, bimodal grains' distribution (where observed), the presence of twins, and, last but not least, dislocation density. Among the influencing factors were the area fractions of Al and Cu at the cross-sections of the of the laminated conductors, too. The results revealed that fabrication of the laminate via the technology of rotary swaging introduced more advantageous combinations of electric and mechanical properties than fabrication by conventional manufacturing techniques. The lowest specific electric resistivity of 20.6 omega m x 10(-9) was measured for the laminated conductor subjected to the post-process annealing treatment at 350 degrees C, which imparted significant structure restoration (confirmed by the presence of fine, equiaxed, randomly oriented grains).Web of Science153art. no. 100

Synthesis of an Al/Al2O3 composite by severe plastic deformation

The influence of severe plastic deformation on fabrication of an aluminum/alumina composite made from pre-sintered Al powders was evaluated. Spherical powder particles with diameters up to 45 μm were pre-compacted using cold isostatic pressing (CIP), subsequently vacuum sintered for 60 min at 500 °C, and subjected to processing using either 4 passes of swaging or 1 or 10 revolutions of high pressure torsion (HPT). For all the samples we calculated average strain and measured microhardness. Results showed an increase in microhardness with an increase of the imposed strain. However, the microhardness values and uniformity were also influenced by possible residual porosity. The smallest and most uniform grain size was achieved for the samples processed by HPT, especially after 10 revolutions (average diameter of 0.22 μm). Residual porosity was completely eliminated only after 10 HPT revolutions. Texture evaluations showed 〈111〉 fiber texture development after swaging, while grain orientations after HPT were more random.Web of Science64624123

Evolution of macroscopic elastic moduli of martensitic polycrystalline NiTi and NiTiCu shape memory alloys with pseudoplastic straining

Elastic constants of polycrystalline NiTi and NiTiCu shape memory alloys in the martensite phase were determined by resonant ultrasound spectroscopy; the evolution of these constants was studied with subsequent applications of compressive loads inducing reorientation of martensitic variants. While the initial thermally -induced martensite exhibited only weak elastic anisotropy resulting from the underlying crystallographic texture of the parent phase, the materials with oriented martensitic microstructures exhibited strong elastic anisotropy with Young's moduli in different directions differing by several tens of GPa-s. A qualitative difference in behaviors was observed between the monoclinic B19' martensite in the NiTi alloy and the orthorhombic B19 martensite in the NiTiCu alloy.Web of Science12315614