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1

Effects of Third-generation LED LCU on Nanomechanical Properties of Orthodontic Adhesives

100%

Bilgic F., Altan H., Akinci Sözer Ö., Arslanoglu Z., Kale E., Özarslan S.

Acta Physica Polonica A

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2017

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vol. 132

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issue 3

697-701

EN

The aim of this study was to compare the hardness and elastic modulus of orthodontic adhesives cured with different light-curing units, based on light-emitting diodes. Standardized samples of orthodontic adhesives, Transbond™ XT, Opal® Bond™ and Light Bond™ were prepared in cylinder blocks and cured for three seconds with Valo Ortho LED (Ultradent Products, South Jordan, Utah) and Valo LED High-Power Mode. After grinding and polishing, specimens were stored in distilled water at 37°C for one day. Specimens were investigated using nanoindenter. Employment of Valo Ortho unit has resulted in significantly higher elastic modules for Transbond™ XT (p=0.041). The highest nanohardness and elastic modules were measured for Transbond™ XT cured with Valo Ortho (9.47 GPa; 81.85 GPa, respectively) and lowest for Opal® Bond™ for both Valo Ortho (0.44 GPa; 14.52 GPa, respectively) and Valo High-Power groups (0.44 GPa; 11.84 GPa, respectively).

2

Structure and Physicomechanical Properties of Nanostructured (TiHfZrNbVTa)N Coatings after Implantation of High Fluences of N⁺ (10¹⁸ cm¯²)

100%

Pogrebnjak A., Bondar O., Borba S., Piotrowska K., Boiko O.

Acta Physica Polonica A

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2017

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vol. 132

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issue 2

217-221

EN

New classes of high-entropy alloys, which consist of at least 5 main elements with atomic concentrations 5-35 at.%, are under great interest in modern material science. It is also very important to explore the limits of resistance of high-entropy alloy nitrides to implantation by high-energy atoms. Structure and properties of nanostructured multicomponent (TiHfZrNbVTa)N coatings were investigated before and after ion implantation. We used the Rutherford backscattering, scanning electron microscopy with energy dispersive X-ray spectroscopy, high resolution transmission electron microscopy and scanning transmission electron microscopy with local microanalysis, X-ray diffraction and nanoindentation for investigations. Due to the high-fluence ion implantation (N⁺, the fluence was 10¹⁸ cm¯²) a multiphase structure was formed in the surface layer of the coating. This structure consisted of amorphous, nanocrystalline and initial nanostructured phases with small sizes of nanograins. Two phases were formed in the depth of the coating: fcc and hcp (with a small volume fraction). Nitrogen concentration reached 90 at.% near the surface and decreased with the depth. Nanohardness of the as-deposited coatings varied from 27 to 34 GPa depending on the deposition conditions. However, hardness decreased to a value of 12 GPa of the depth of the projected range after ion implantation and increased to 23 GPa for deeper layers.

3

Microhardness and the Young Modulus of Thin, MBE-Grown, (Sn,Mn)Te Layers Containing up to 8% of Mn

76%

Adamiak S., Zięba M., Minikayev R., Reszka A., Taliashvili B., Szuszkiewicz W.

Acta Physica Polonica A

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2017

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vol. 132

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issue 2

347-350

EN

The thin layers of (Sn,Mn)Te solid solution were grown by molecular beam epitaxy onto (111)-oriented BaF₂ substrates and characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectrometry, and X-ray diffraction methods. The epitaxial character of the growth was confirmed. All the layers exhibited a regular (fcc) structure of the rock-salt type and were (111)-oriented, their thickness was close to about 1 μm. The layers contained up to 8% of Mn. The microhardness and the Young modulus values were determined by the nanoindentation measurements. The Berkovich type of the intender was applied, the maximum applied load was equal to 1 mN. The results of measurements demonstrated a lack of the composition dependence of the Young modulus value. A slight increase of the microhardness value with an increasing Mn content in the (Sn,Mn)Te solid solution was observed.

4

Nanomechanical Comparison of Commonly Used Dental Crown Cements to a Newly Developed One

76%

Kale E., Arslanoğlu Z., Altan H., Bılgıç F., Tuzlali M., Köroğlu A., Özarslan S.

Acta Physica Polonica A

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2017

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vol. 132

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issue 3

954-958

EN

The main goal of nanoindentation tests is to obtain elastic modulus and hardness of the specimen material from load-displacement measurements. With this study, it was aimed to establish a quantitative relationship between the nanomechanical properties of commonly used dental cements in comparison to a newly developed crown cement and to predict its performance potential. Nanomechanical properties of polycarboxylate cement (PCC), glass-ionomer cement (GIC), dual-cure self-adhesive cement (SAC) and a newly developed glass-carbomer cement (GCC) were investigated by nanoindentation tests. All samples were fabricated according to their respective manufacturer's instructions. Available damage on the surface due to manipulation was removed by grinding with 1200, 2400 and 4000 grit sandpaper, and then polishing on 6, 3, and 1 μm diamond-lap-wheel was performed. Nano-mechanical measurements were done using nanoindenter machine with resolution less than 1 nN and displacement resolution of 0.04 nm. Berkovich diamond indenter tip was used for the nanoindentation tests. For each indentation, a set of nanoindentation tests at least on 6 different locations per specimen surface were performed to obtain more representative mean results. Indentation test load-displacement curves were analysed using Oliver-Pharr method, and one-way ANOVA or Kruskal-Wallis test, following Kolmogorov-Smirnov and Shapiro-Wilk, was used to compare the results. Nanohardness (H_{nano}) values were 0.52± 0.25, 0.45± 0.18, 1.03± 0.82 and 0.43± 0.18 GPa for GIC, GCC, PCC, and SAC, respectively. Reduced elastic modulus (E_{r}) values were 9.51± 6.17, 11.77± 5.04, 27.37± 20.61, 10.33± 5.08 GPa for GIC, GCC, PCC, and SAC, respectively. There was no statistical difference between the tested materials. PCC was the hardest, and GIC was the least hard material, whereas the newly developed GCC was the second, in terms of H_{nano}, before SAC. PCC also had the highest E_{r} mean, compared to the other dental crown cements, suggesting lower elastic properties. SAC was more elastic than GCC and less elastic than GIC. GCC had the second highest E_{r}, standing closer to SAC and GIC. Within the limitations of the current study, it can be concluded that the newly developed glass-carbomer cement is comparable to the other tested commonly used dental crown cements, regarding H_{nano} and E_{r}.

5

Impact of Impulse Shot Peening Parameters on Properties of Stainless Steel Surface

64%

Wiertel M., Zaleski K., Gorgol M., Skoczylas A., Zaleski R.

Acta Physica Polonica A

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2017

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vol. 132

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issue 5

1611-1615

EN

Shot peening was applied to austenitic stainless steel 1.4541 (EN). The surface treatment was performed at various impact energies E, impact densities j and ball diameters D. This resulted in improved microhardness, which increases monotonically with the increase of E, j and 1/D. However, its changes with E and j achieve saturation at about 400 HV0.1. On the contrary, no saturation is observed in the investigated range for 1/D. In the un-shot peened 1.4541 (EN) steel, the lifetime component of low intensity was found with use of positron annihilation lifetime spectroscopy (PALS). It corresponds to positron annihilation from delocalized state of positrons in bulk. In the shot peened samples the bulk component is no longer observed. Instead, two types of defects can be identified: vacancy-like defects coupled with edge dislocations and vacancies or their small clusters (consisting 3÷5 vacancies). The results of PALS and hardness testing do not correspond very well, especially in the case of the samples shot peened with balls of varying diameters. The most probable reason for this are different depth profiles of both methods. It seems that the defects, which are responsible for the increase of static microhardness above 400 HV0.1 are located mostly below the surface layer penetrated by positrons.

6

Mechanical Properties of the Stellite 6 Cobalt Alloy Implanted with Nitrogen Ions

64%

Budzyński P., Kamiński M., Wiertel M., Pyszniak K., Droździel A.

Acta Physica Polonica A

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2017

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vol. 132

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issue 2

203-205

EN

The effect of nitrogen ion implantation on Stellite 6 cobalt alloy was investigated. In this research, cobalt alloy was implanted with 65 keV nitrogen ions at the fluence of (1÷10)×10¹⁶ N⁺/cm². The distribution of implanted nitrogen ions and vacancies produced by them was calculated using the SRIM program. The surface morphology was examined and the elemental analysis was performed using scanning electron microscopy, energy dispersive X-ray spectroscopy and grazing incidence X-ray diffraction. The wear tests were conducted with the use of the pin-on-disc method. The results demonstrate that implantation with nitrogen ions significantly reduces the friction factor and wear. The friction coefficient of the implanted sample at the fluence of 1×10¹⁷ N⁺/cm² increased to the values characteristic of an unimplanted sample after 5000 measurement cycles. The depth of the worn trace was about 2.0 μm. This implies that the thickness of the layer modified by the implantation process is ≈2.0 μm and exceeds the initial range of the implanted ions by an order of magnitude. This is referred to as a long-range implantation effect. The investigations have shown that the long-range effect is caused by movement of not only implanted nitrogen atoms but also carbon dopant atoms towards the friction zone. Diffusion of carbon atoms has been documented here for the first time. Furthermore, the increased content of oxygen atoms on the track bottom indicates a dominant oxidative wear of the Stellite samples after nitrogen implantation with the energy 65 keV and the fluences of 5×10¹⁶ and 10¹⁷ N⁺/cm².

7

Mechanical and Tribological Behaviour of Chopped E-Glass Fiber-Reinforced Epoxy Composite Materials

64%

Ozsoy N., Ozsoy M., Mimaroglu A.

Acta Physica Polonica A

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2017

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vol. 132

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issue 3

852-856

EN

Chopped E-glass fiber-reinforced epoxy composites (10%, 30% and 50%) were fabricated and their mechanical and tribological behaviour was investigated. Three-point bending tests were performed according to the ASTMD790 and tensile tests were performed according to the ASTMD638 standards. Impact tests and hardness measurements of the composites were also carried out. Wear behaviour of composites was studied using pin on disc wear testing device. The design of experiments approach, using Taguchi method, was employed to analyze the results. Signal-to-noise ratio and analysis of variance were used to determine the influence of parameters on the wear rate and coefficient of friction.

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Effects of Third-generation LED LCU on Nanomechanical Properties of Orthodontic Adhesives

Structure and Physicomechanical Properties of Nanostructured (TiHfZrNbVTa)N Coatings after Implantation of High Fluences of N⁺ (10¹⁸ cm¯²)

Microhardness and the Young Modulus of Thin, MBE-Grown, (Sn,Mn)Te Layers Containing up to 8% of Mn

Nanomechanical Comparison of Commonly Used Dental Crown Cements to a Newly Developed One

Impact of Impulse Shot Peening Parameters on Properties of Stainless Steel Surface

Mechanical Properties of the Stellite 6 Cobalt Alloy Implanted with Nitrogen Ions

Mechanical and Tribological Behaviour of Chopped E-Glass Fiber-Reinforced Epoxy Composite Materials