Jaroslaw Borc

This work reports an experimental study of the micromechanical properties of the Co₇₀Fe₃Mn_3.5Mo_1.5Si₁₁B₁₁ (at. %) amorphous alloy. All experiments were performed at room temperature on the unannealed sample in order to avoid the influence of thermally induced structural relaxation. X-ray diffraction confirmed the amorphous structure. Using nanoindentation tests, we determined key mechanical characteristics under a 20 mN load, including hardness, elastic and plastic deformation parameters, creep ratio, and other micromechanical properties. Scratch testing was performed under both static (20 mN) and dynamic (0.3–100 mN) regimes. We analyzed variations in penetration depth and residual depth during scratch testing. Surface morphology analysis after scratch testing confirmed no macroscopic crack formation or delamination. The friction coefficient behavior indicates sensitivity to localized contact loading and is consistent with localized deformation processes within the sample. A pronounced time-dependent deformation (C_IT ~ 4.7%) under localized contact loading was also observed. The data were analyzed considering the structural state of the sample’s amorphous matrix and existing theories of plastic deformation mechanisms in amorphous systems. The ratio of elastic to plastic deformation, along with time-dependent deformation (creep), enables specification of the mechanical response of the investigated amorphous ribbon under localized microcontact loading. The obtained results provide qualitative insight into the deformation characteristics of unannealed amorphous ribbons.

In this work, an experimental study of the micromechanical properties of the Co70Fe3Mn3.5Mo1.5Si11B11 (at. %) amorphous alloy is reported. All experiments were performed at room temperature on the unannealed sample in order to avoid the influence of thermally induced structural relaxation. The amorphous structure was confirmed by X-ray diffraction. Using nanoindentation tests, key mechanical characteristics were determined under a 20 mN load, including hardness, parameters of elastic and plastic deformation, creep ratio, and other micromechanical properties. Scratch testing was performed under both static (20 mN) and dynamic (0.3–100 mN) regimes. Variations in penetration depth and recovery depth during scratch testing were analyzed. Surface morphology analysis after scratch testing confirmed the absence of macroscopic crack formation or delamination. The behaviour of the friction coefficient indicates sensitivity to localized contact loading and is consistent with localized deformation processes within the sample. A pronounced time-dependent deformation (CIT ~ 4.6%) under localized contact loading was also observed. The obtained data were analyzed taking into account the structural state of the amorphous matrix of the sample as well as existing theories concerning the mechanisms of plastic deformation in amorphous systems. The ratio between the elastic and plastic deformation components, along with the presence of time-dependent deformation (creep), makes it possible to specify the nature of the mechanical response of the investigated amorphous ribbon under localized microcontact loading. The obtained results provide qualitative insight into the deformation characteristics of unannealed amorphous ribbons.

Results of an investigation of the effect of surface tilt in range of 0 degrees-6 degrees on nanoindentation measurements under Berkovich indenter at different loads made on copper and glass surfaces are presented and discussed. It was found that: (1) measured hardness increases for tilt angle theta > 3 degrees and this increase is about 12% at theta = 6 degrees for both samples at all applied loads, (2) the overestimation in hardness is due to the increase of projected contact area A with the tilt angle theta, but the theoretical contact area A described by the traditional analytical area function leads to lower change in the hardness than the experimental one up to about 5% may be attributed to the horizontal deflection of the stem holding the indenter, and (3) indentation modulus E is more sensitive to the tilt for glass than copper and the sensitivity in the values of E at a given tilt angle theta increases with decreasing indention load.

The load carrying capacity (contact pressures) of hybrid (metal-polymer) plain bearings is calculated in the article according to the author's research method, considering the differences of the Young's modules of the bushing made of polymeric materials. Studies have been conducted for metal-polymer bearings with a bushing of two types of polymer composites: epoxy based antifriction composite materials DIAMANT Moglice (DIAMANT Metallplastic GmbH) and DK6 (PT) (fillers - graphite, MoS2, Zr). The elastic constants of composite materials, in particular the Young's modulus, have a noticeable effect on the contact pressures in metal-polymer bearings. The Young's modulus is significantly different in these composite materials. In accordance with this factor, the influence of load, bushing diameter and radial clearance on the maximum contact pressures was studied. Quantitative and qualitative regularities of maximum contact pressures from the accepted factors of influence: Young's modulus, loading, bushing diameter, radial clearance, type of bushing material are established. The obtained results are compared with the results obtained by known conventional calculating methods of contact pressures

In the presented work the influence of different 3MgO·4SiO₂·H₂O (talc) contents in polypropylene samples on the structure, hardness, elasticity, and friction of the surface layer was investigated. The talc content ranged from 0 to 25 wt.%, and all the samples were obtained in the same conditions by the injection molding process. The analysis of the microstructure was performed by X-ray diffraction. Changes in the hardness and elasticity were determined for three different depths (300, 800, and 4000 nm) using an ultra nano tester. For the purpose of the examination of the friction properties of the obtained compounds, a nano-scratch tester was applied. Increasing the talc content caused growth in the indentation modulus and hardness values. Simultaneously, an effect of decreasing hardness and elastic modulus with increasing indentation depth was observed. The smallest effect size was observed for 25 wt.% talc content, which might suggest that talc addition increased the homogeneity of the observed composites. Scratch tests showed increasing scratch resistance along with increasing talc content for both constant and progressive loads. The growth in talc concentration led to a decrease in the degree of the polypropylene (PP) crystallinity of the surface layer. The exfoliation process occurred in PP composites.

The aim of study was to investigate the influence of kaolin on the physical properties and utility of film produced from native starch. The work involved measurements of strength, structure, and thermal properties. The films were prepared by the casting method. Composite films with 0%, 5%, 10%, and 15% kaolin additives were examined. Measurements of mechanical properties were carried out using the uniaxial tensile test, the nanoindentation test, and nanoscratching. Surface properties were examined by atomic force microscopy and contact angle measurements. Structure was determined by the X-ray diffraction method, and thermal properties were determined by differential scanning calorimetry. A significant influence of kaolin on the strength parameters and thermal and barrier properties of composite films was found. An increase in kaolin content reduced the tensile strength, Young’s modulus, and Poisson’s ratio. Structural analysis showed a partial intercalation and the layered arrangement of kaolin particles. Kaolin additives increased the barrier properties of water vapor in composite films of about 9%. Biopolymer modification by nanoclay reduced the thermal stability of composite films by 7% and could accelerate the biodegradation process. Increasing the concentration of kaolin in the biopolymer matrix led to heightened surface roughness (approximately 64%) and wettability of the surfaces of the film composites of 58%.

The results of Raman spectroscopy and electrical measurements of 40 keV boron-ion-implanted polymethylmethacrylate with ion doses from 6.25 × 1014 to 5.0 × 1016 ions/cm2 are reported for the first time. The Raman spectra recorded in the 400–3800 cm−1 range, showing the formation of new carbon–carbon bands for the as-implanted samples at higher ion doses (>1016 ions/cm2), are found to be an additional support for carbonization processes earlier revealed by slow positrons. The current–voltage dependences at 360 K testify also that the as-implanted samples examined with higher fluences (3.75 × 1016 and 5.0 × 1016 ions/cm2) have created a very thin conductive layer or conductive joints due to carbonization.