Papers by Keyword: Milling Time

Abstract: Al₂O₃-TiO₂-graphite nanocomposite can be used as alternative material for coating application. Fine composite coating particles is commonly produced by milling in a high energy ball milling. This study focused on evaluate the effects on the structural, microstructural and physical properties of Al₂O₃-TiO₂-graphite nanocomposite. The alumina, titania and graphite powder were milled in a planetary ball mill at 2, 4, 8 and 10 h and 200, 250 and 300 rpm. The composite particles was compacted for green density determination. The phase analysis and microstructure of nanocomposite were characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Increasing milling time and milling speed contributes to a small solubility between Al₂O₃ and TiO₂. Increasing milling time and speed decreased the Al₂O₃ crystallite and internal strain increased as a result of continuous impact on the powder and repeated collision between powder and the wall container. Higher milling time and speed produce finer and flaky shape of Al₂O₃-TiO₂-graphite particles which then affects the green density of the composite.

Abstract: The optimization of the Copper ions (Cu ions) adsorption from aqueous solution for inclusion in prolonged the milling time of the extracted iron oxides from waste mill scales has been investigated. Different milling times were used to reduce the size of the raw mill scale which are 24, 48 and 72 h. The three adsorbents were characterized using XRD, FESEM and VSM. Adsorbents that milled for 72 hours gave pure magnetite from the XRD results. FESEM images revealed that prolonged the milling time might reduced the particle sizes. Magnetic hysteresis revealed that all the samples having ferromagnetic behavior. Batch adsorption experiment had been carried out with the three adsorbents and as the results, adsorbents that milled with 72 hours shown highest removal of Cu ions with 95% removal efficiency.

Abstract: In this study, the mechanical disc milling of coal fly ash (CFA) produced by ESKOM thermal station in South Africa has been investigated. The present work covers the effects of milling time on the characteristics such as crystal phases, particle sizes, morphology and physiology of the powder. The produced nanoparticle powders were characterized by SEM-EDX, XRD, and XRF. The milling time was carried out at (t=0, 20, 40, and 60 minutes) at a constant milling speed of 940 rpm. The results showed that mean area of the particles of the particle sizes increased from 75 µm size to approximately 200 nm which revealed that there was 62.5 % increase in the number of particle size as a result of the disintegration of the area of particle sizes. The crystal phases detected by the XRD in CFA are hexagonal, orthorhombic, rhombohedral and anorthic. XRD analysis showed that the most dominant minerals in coal fly ash are Quartz (SiO₂), Mullite (Al_2.32Si_0.68O_4.84), Sillimanite (Al₂(SiO₄)O, Calcite high (CaCO₃), Hematite (Fe₂O₃), Microcline (KAlSi₃O₈). It was also revealed by EDX that the main elemental compositions present in CFA are silicon, aluminium, calcium, iron, titanium and magnesium. It was established in the study that the duration of the milling affects volume, surface area, particle size, pore size distributions, as well as the microstructure

Abstract: Al₂O₃/Ni nanocomposite powder was obtained by high-energy mechanical milling starting from a mixture of Al₂O₃ and Ni commercially powders. The Al₂O₃+15%vol. Ni mixture was homogenized for 15 minutes in the Turbula-type blender and then was milled in a planetary ball mill (Fritsch, Pulverisette 4) under argon atmosphere up to 120 min. Several milling times were used: 10, 30, 60, 90 and 120 minutes respectively. The evolution of the powders during milling and the stability of the composite phases were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). The SEM and OM images show a high level of homogenization of the Ni and Al₂O₃ phases for milling times larger than 90 minutes. The X-ray studies indicate no mixing between the two phases. The crystallite grain size is decreasing with the milling time.

Abstract: In the present study high energy ball milling was utilized to produce aluminum (Al-6061) matrix nanocomposite powders reinforced with nanosilicon carbide (SiC) particles. The starting materials containing different percentages (1,3 or 5 wt.%) of nanoSiC particles (25-50 nm) and Al (38-63 μm) were co-milled for different times (16, 20, 24 h) to achieve nanocomposite powders. The crystal size of powders were evaluated by quantitative XRD analysis. Laser particle size analysis was used to evaluate the size of powders during milling. The microstructure of powders and their microhardness values were evaluated by Scanning Electron Microscopy (SEM) and a microhardness tester respectively. The results indicated that the crystal size of the matrix alloy decreased by milling time. The increased SiC content up to 3% resulted in increased microhardness of the powders. However, further increase of SiC to 5% resulted in decreased microhardness due to agglomeration. It was concluded that the maximum microhardness together with a uniform distribution of SiC particles within the matrix alloy was obtained after 20 h milling of powder mixture containing 3% of SiC nanoparticles.

Abstract: Currently, thermal energy generation through coal combustion produces ash particles which cause serious environmental problems and which are known as Fly Ash (FA). FA main components are oxides of silicon, aluminum, iron, calcium and magnesium in addition, toxic metals such as arsenic and cobalt. The use of fly ash as a cement replacement material increases long term strength and durability of concrete. In this work, samples were prepared by replacing cement by ground fly ash in 10, 20 and 30% by weight. The characterization of raw materials and microstructure was obtained by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The final results showed that the grinding process significantly improves the mechanical properties of all samples when compared replacing a mortar made with cement by ground fly ash and the reference samples without added fly ash. The beneficial effect of the ground fly ash can increase the use of this product in precast concrete industry.

Abstract: In this study, Zingiber officinale (ginger) rhizome nanoparticles were prepared using a planetary ball milling process and the effect of prolong milling time up to 8 hours on the physical and antioxidant properties has been investigated. The particle size was successfully reduced to 222.3nm after 4 hours of milling process but agglomerated nanoparticles were observed for sample that was continuously milled. Sample milled for 4 hours showed higher Total Phenolic Content (TPC) (356.06 mgGAE/g extract) as well as Total Flavonoid Content (TFC) whereas lowest value shown by sample milled for 8 hours. The inhibition of DPPH reached up to 60% for all tested nanostructured ginger except very low percent of inhibitory shown by sample milled for 6 hours. The IC50 concentration for DPPH inhibition was 800ppm for sample milled for 2 hours, 400ppm for 4 hours and1000ppm for sample milled for 8 hours. However sample milled for 8 hours showed significantly (p<0.05) greater Ferric Reducing Antioxidant Power (FRAP) among other tested samples.

Abstract: This paper report the effect of milling time on the structural properties of TiO₂ nanopowder prepared from sol-gel milling process. The synthesized TiO₂ nanopowders have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR). XRD result reveals that the TiO₂ nanopowder in anatase phase is detected. The morphology of the TiO₂ nanopowder change obviously with the increase of the milling time. Further, FTIR results found the sharp peaks of Ti-O-Ti and Ti-O bonding at below 600 cm^-1 for all TiO₂ nanopowder.

Abstract: The polycrystalline Yttrium Iron Garnet (YIG) powder with the chemical formula Y3Fe5O12 has been synthesized by using High Energy Ball Milling technique. The effect of various preparation parameters on the crystallinity, morphology and complex permeability of YIG, which includes milling time and annealing temperature were studied respectively by using XRD, SEM and Impedance Material Analyzer. The frequency dependence of complex permeability namely real permeability, µ’ and magnetic loss, µ’’ were measured at room temperature for samples sintered from 600°C to 1400°C, in the frequency range 10 MHz to 1 GHz. The results showed that milling time plays a role in determining the crystallinity of the milled powder where higher milling time results in better crystallinity due to high reactivity of the particles. From complex permeability measurement, it was observed that the initial permeability and magnetic loss increased with increasing grain size. The permeability values increased with annealing temperature and the absolute values of permeability decreased after attaining the natural resonance frequency of the material.

Abstract: The Fe₃Al-TiB₂-Al₂O₃ composite has been prepared by self-propagating high-temperature synthesis (SHS) from FeTiO₃-B₂O₃-Al system. The standard Gibbs energy minimization method was used to calculate the equilibrium compositions of the reacting species. The reactions were carried out in a SHS reactor under static argon gas at the pressure of 0.5 MPa. The effects of Al molar ratio of 4, 4.33 and 5 mole on the results product were investigated. The composition and microstructure of SHS products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The optimum result of Fe3Al intermetallics phase was obtained when using 4.33 mole of Al.