Temat: 81.20.Wk - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Optimization of Effects of Pocket Tool Path Strategies and Cutting Parameters on Surface Quality
Autorzy:: Etyemez, A.
Tematy:: 81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1186800.pdf Link otwiera się w nowym oknie
Opis:: In this study, surface roughness and cutting forces were investigated experimentally in milling of Al 7075 material by DLC coated end-mill cutting tools. Effect of tool path, feed and cutting depths on surface roughness and cutting forces was examined. Taguchi technique was used for optimization of the milling process. Also, a variance analysis (ANOVA) was used for determination of effect of each parameter on the obtained results. In conclusion, the relationship between the dependent and the independent variables was modelled with regression analysis. Optimal machinability of Al 7075 material by DLC coated end-mill was determined in this study.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Mechanical Activation of Deposited Brown Coal Fly Ash in Stirred Media Mill
Autorzy:: Molnár, Z.
Kristály, F.
Mucsi, G.
Tematy:: 81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1375549.pdf Link otwiera się w nowym oknie
Opis:: Present paper deals with the mechanical activation of deposited brown coal fly ash in a high energy density mill. The mechanical activation was carried out in a laboratory scale stirred media mill using various rotor circumferential speed (5 and 7 m/s), and different grinding time (from 1 min up to 180 min). The consumed energy was measured during the grinding process. Furthermore, particle size distribution and specific surface area were determined using laser particle size analyzer. The structural changes were detected by Fourier transform infrared spectroscopy. Additionally, transformation in mineralogical phases was measured by X-ray diffraction, as well as particle morphology and crystal defects were determined by transmission electron microscopy. As a result of the investigation, relationship between the technological parameters of the grinding and the properties of the ground material was created. It was found that there is a certain mechanochemical effect on the crystal structure of fly ash components in the stirred media mill, as it was revealed by X-ray diffraction and transmission electron microscopy. The most efficient grinding parameters were determined.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Geopolymerisation of Mechanically Activated Lignite and Brown Coal Fly Ash
Autorzy:: Mucsi, G.
Molnár, Z.
Kumar, S.
Tematy:: 81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1375557.pdf Link otwiera się w nowym oknie
Opis:: Geopolymers have been synthesized from mechanically activated lignite and brown coal fly ash. Mechanical activation of fly ash has been carried out using laboratory ball mill. To determine the structural changes in both, the fly ash and the resulted geopolymer, Fourier transform infrared spectroscopy measurements were performed. Isothermal conduction calorimetry method was applied to study the geopolymerisation reactions in mechanically non-activated (raw) and activated fly ash samples. The isothermal conduction calorimetry results showed similar peak intensity for mechanically activated (5-30 min) fly ash samples. However, the intensity of peak for 120 min milled brown coal fly ash was the highest. The compressive strength of the specimen was found to be dependent on the grinding residence time as well as composition/type of fly ash.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Investigation of CNC Turning Parameters by Using a Vortex Tube Cooling System
Autorzy:: Yüksel, S.
Onat, A.
Tematy:: 81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1400564.pdf Link otwiera się w nowym oknie
Opis:: Controlling the heat, generated during the cutting process, is an important factor in improving the quality of the product and performance of the machining. A vortex tube was employed to evaluate the effects of cooling on the turning parameters. Various cutting parameters (100 m/min, 250 m/min and 400 m/min) together with various cooling temperatures (-4°C, 8°C and 20°C) were considered to find surface roughness, cutting force and cutting temperature. Response surface methodology was used to optimize the experimental parameters. The best attainable surface roughness value was found to be 0.77 μm Ra, under the conditions of 0.15 mm/rev feed, 400 m/min cutting speed, -4°C (with vortex tube) cutting temperature and 1.2 mm tool edge radius. Cutting forces were not affected by the temperature changes. The difference was negligible and as small as 1%. The minimum cutting temperature was 74.17°C, which was obtained under the machining conditions of 0.25 mm feed, 250 m/min cutting speed -4°C (with vortex tube) cutting temperature and 0.8 mm tool edge radius.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Mechanochemical Preparation and Magnetic Properties of Fe₃O₄/ZnS Nanocomposite
Autorzy:: Bujňáková, Z.
Zorkovská, A.
Kováč, J.
Tematy:: 81.07.Bc
81.20.Ev
81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1032141.pdf Link otwiera się w nowym oknie
Opis:: Powder nanocomposite of Fe₃O₄/ZnS was prepared by mechanochemical synthesis in a planetary ball mill. In this reaction natural magnetite mineral Fe₃O₄ was used, together with zinc acetate (CH₃COO)₂Zn·2H₂O and sodium sulfide Na₂S·9H₂O, as precursors for the zinc sulfide ZnS. X-ray diffraction revealed that the sample is composed of small nanocrystalline particles, containing Fe₃O₄ and ZnS. The non-milled magnetite showed distinctive Verwey transition at around 120 K, this becomes suppressed after milling, as a consequence of structural disorder and presence of defects. Moreover, the reduction of saturation magnetization from 91 A m²/kg to 69.2 A m²/kg was observed, as a consequence of the milling process. The magnetization of the Fe₃O₄/ZnS nanocomposite was the lowest (34.5 A m²/kg), due to the milling and to the decreased weight fraction of the ferrimagnetic component. Nevertheless, the Fe₃O₄/ZnS sample demonstrates ferrimagnetic behavior as well, and its structure is less perturbed by milling, the Verwey transition, although less impressive, but is preserved.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Characterization of Machined Surface by EDM for $Al//B_4C_{p}$ Composite Material
Autorzy:: Kasman, S.
Feray Guleryuz, L.
Ozan, S.
Ipek, R.
Tematy:: 81.05.Ni
81.20.Ev
81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399698.pdf Link otwiera się w nowym oknie
Opis:: In this study, electrical discharge machining process was performed to investigate the machinability of $Al//B_4C_p$ metal matrix composites manufactured by powder metallurgy. For this, an experimental layout was conducted by using full factorial design. In the analysis, there are three parameters of which one is at three levels and the remaining are two levels. Totally, 48 experiments were carried out. The surface roughness $(R_{a})$ was increased with increasing the current (C), pulse-on-time $(T_{on})$, pulse-off-time $(T_{off})$ and amount of particle (PR).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Mechanochemically Synthesized CuFeSe₂ Nanoparticles and Their Properties
Autorzy:: Dutková, E.
Škorvánek, I.
Sayagués, M.
Zorkovská, A.
Kováč, J.
Baláž, P.
Tematy:: 81.05.Hd
81.07.Wx
81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1032137.pdf Link otwiera się w nowym oknie
Opis:: The mechanochemical synthesis of nanocrystalline CuFeSe₂ particles prepared by high-energy milling in a planetary mill in an argon atmosphere from copper, iron, and selenium for 60 min is reported for the first time. The CuFeSe₂ nanoparticles crystallize in tetragonal structure with mean crystallite size of about 32±1 nm. High resolution transmission electron microscopy measurements confirmed the presence of agglomerates which are formed by small nanocrystalline domains (5-40 nm). The magnetic data revealed that paramagnetic CuFeSe₂ nanoparticles coexist with a small amount of ferromagnetic impurities at room temperature. The magnetic transition towards a weak ferromagnetic or ferrimagnetic behavior occurs in CuFeSe₂ at approximately 79 K. The band gap of the CuFeSe₂ particles is 0.95 eV which is wider than the band gap in bulk materials (0.16 eV), which could be in many aspects of application more beneficial.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Effects of cutting parameters on delamination during drilling of Polyphthalamide (PPA) Matrix Composite Material with 30% Glass Fiber Reinforcement
Autorzy:: Ficici, F.
Ayparcasi, Z.
Tematy:: 81.05.Qk
81.05.Lg
81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1194139.pdf Link otwiera się w nowym oknie
Opis:: The drilling of glass fiber reinforced plastics (GFRP) often results in damage around the drilled hole. The drilling of such composite material may generate delamination of drilled holes on workpiece. The aim of this research is to investigate the influence of the drilling parameters, such as cutting speed, feed rate and differences in cutting materials on delamination produced while drilling GFRP composite. The experimental results indicate that the feed rate is the most significant factor, followed by spindle speed and cutting tool material. The best results were obtained at lower feed rates and higher spindle speeds when using Carbide drill.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Mechanochemistry of Solids: New Prospects for Extractive Metallurgy, Materials Science and Medicine
Autorzy:: Baláž, P.
Baláž, M.
Achimovičová, M.
Bujňáková, Z.
Dutková, E.
Tematy:: 81.05.Dz
81.20.Wk
81.07.Bc; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1375090.pdf Link otwiera się w nowym oknie
Opis:: In this review paper recent advances in chalcogene mechanochemistry are described. Three selected areas are being covered, i.e. metallurgy, materials science, and medicine. In extractive metallurgy, the processing of copper arsenic mineral enargite ($Cu_3AsS_4$) with the aim of its dearsenification and subsequent preparation of a new anticancer drug ($Na_3AsS_4$) and of copper in nanocrystalline state ( ≈ 20 nm) illustrate the non-traditional prospect of ore treatment. In material science, the new nanocrystalline semiconductors were synthesized mechanochemically, e.g. selenides of zinc and lead (ZnSe, PbSe) and bismuth sulphide ($Bi_2S_3$). Metal and chalcogene were applied as reaction precursors. In some cases, the amino acids (cystine, cysteine) were applied as sulphur precursor, in order to provide reactive sites on synthesized solid (PbS) for bioconjugation and to prevent agglomeration. The concept of nanomilling is described as a way to prepare effective substances for cancer treatment in medicine. In vitro activity of realgar ($As_4S_4$) as an example is described. In all three areas the focus is aimed also on industrial applications where suitable large-scale mills are described. The described examples represent the contemporary aim of mechanochemists - to prepare substances with the desired properties in a reproducible way under easy-operating, environmentally friendly and essentially waste-free conditions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Mechanochemically Synthesized Nanocrystalline $Sb_2S_3$ Particles
Autorzy:: Dutková, E.
Sayagués, M.
Real, C.
Zorkovská, A.
Baláž, P.
Šatka, A.
Kováč, J.
Ficeriová, J.
Tematy:: 81.05.Hd
81.07.Bc
81.20.Wk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1375343.pdf Link otwiera się w nowym oknie
Opis:: Nanocrystalline $Sb_2S_3$ particles have been synthesized from Sb and S powders by high-energy milling in a planetary mill using argon protective atmosphere. X-ray diffraction, particle size analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electron diffraction, high resolution transmission electron microscopy, UV-VIS, and differential scanning calorimetry methods for characterization of the prepared particles were applied. The powder X-ray diffraction pattern shows that $Sb_2S_3$ nanocrystals belong to the orthorhombic phase with calculated crystallite size of about 36 nm. The nanocrystalline $Sb_2S_3$ particles are constituted by randomly distributed crystalline nanodomains (20 nm) and then these particles are forming aggregates. The monomodal distribution of $Sb_2S_3$ particles with the average hydrodynamic parameter 210 nm was obtained. The quantification of energy dispersive X-ray spectroscopy analysis peaks give an atomic ratio of 2:3 for Sb:S. The optical band gap determined from the absorption spectrum is 4.9 eV, indicating a considerable blue shift relative to the bulk $Sb_2S_3$. Differential scanning calorimetry curves exhibit a broad exothermic peak between 200 and 300°C, suggesting recovery processes. This interpretation is supported by X-ray diffraction measurements that indicate a 23-fold increase of the crystallite size to about 827 nm as a consequence of application of high temperature process. The controlled mechanochemical synthesis of $Sb_2S_3$ nanoparticles at ambient temperature and atmospheric pressure remains a great challenge.
Dostawca treści:: Biblioteka Nauki

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