Papers by Keyword: Ball Milling

Abstract: The aim of this work is to synthesis nanoparticles from bamboo charcoal and identify the majority elements of the nanoparticles. The bamboo charcoal is made by pyrolysis process. The charcoal was manually pulverized before being sieved through a filter with a mesh size of 200. The synthesis of the nanoparticle was conducted by using a top-down approach of ball milling process. The charcoal powder that had passed through the filter and the milling balls of steel were then poured into a vial of glass. In the vial, the milling operation was carried out. The vial had a diameter of 71 mm and a length of 119 mm, while the ball's diameter was 0.25 inches. To have the balls collide and reduce the size of the charcoal particles, the vial was rotated. 5 million cycles at 500 revolutions per minutes were performed on the shaker machine. The empty space in the vial was one third of vial volume for the movement of the milling balls. The ball milling process was separated into two conditions, namely dry and wet. For the wet procedure, the particles are filtered to separate the particles based on their size. The particle morphology, size, and elements in the particle produced by the process were examined using a scanning electron microscope (SEM) and an Energy Dispersive X-ray (EDX). The results showed that the size of the particles of the dry procedure is un-uniform in the range of about 300 nm to 600 nm with irregular shape. The dominant element is carbon. The wet procedure produced a more uniform size in the range of 100 nm to 200 nm with also irregular shape. The most dominant element is also carbon.

Abstract: The extraction of ilmenite minerals using the sulfate route is one of the commercial methods for producing titanium dioxide (TiO₂) materials. The sulfate process requires a high concentration of sulfuric acid to achieve high extraction yield of titanium. However, this process also results in the generation of high amounts of sulfuric acid waste. Modifying ilmenite minerals is thought to be one of approaches in reducing the consumption of highly concentrated sulfuric acid. In the current study, we investigated the effect of the ilmenite-to-water mass ratio (ITWR) on the wet-ball milling process to enhance the dissolution of titanium from the ilmenite mineral. The results revealed that increasing the water amount from 10 to 70% wt has decreased the particle size from 167.60 to 0.55 μm and increased the titanium yield from 479.36 to 1228.89 ppm. On the basis of investigation, it was shown there is a significant relationship between the ilmenite-to-water mass ratio and titanium dissolution, highlighting the importance of an optimal ratio for achieving maximum dissolving yield. The obtained TiO₂ nanoparticles provide the average crystallite size of 4.16 nm, with rutile and anatase phase, and spherical morphology.

Abstract: Ceramic/ metal functionally graded materials (FGMs) have been promising to sustain coating structures working under super high temperature as well as high temperature gradient conditions. Compositional gradients in the FGMs can be engineered according to functional performance requirements. This study aims to fabricate Al₂O₃/ZrO₂/SUS304 hybrid FGMs with continuous compositional gradient manners using a combination of centrifugal slurry methods and spark plasma sintering (SPS). The compositional gradients in the FGMs were investigated on microstructures with elemental distributions and hardness on the cross sections of the FGMs. It was demonstrated that the compositions of ZrO₂ and SUS304 continuously varied in the FGMs, while Al₂O₃ resided only on ZrO₂-rich sides, which can effectively enhance the fracture toughness of the ZrO₂-rich layer. Ball milling treatments can make the Al₂O₃ layer more formed in the ZrO₂-rich layer. With increasing the amount of Al₂O₃, the Al₂O₃ layer resided closer to the top of the ZrO₂ surfaces in the FGMs subject to ball milling treatments, which can prevent the crack propagation from the ZrO₂ top surfaces.

Abstract: Ceramic-metal functionally graded materials (FGMs) are advantageous to two dissimilar materials joined directly together, which includes smoothing of thermal stress distributions, minimization or elimination of stress concentrations and singularities at the interface corners and increase in bonding strength. In this study, ZrO₂/ 304 stainless steel (SUS304) FGMs with continuous gradient manners, not stepwise manners, were fabricated by a combination of centrifugal slurry methods and spark plasma sintering (SPS). The size and surface smoothness of the powders of SUS304 highly affected formation of compositional gradient patterns in the FGMs. Effects of ball milling time and ball sizes on such conditions of the powders as well as compositional gradients in the FGMs were investigated by microstructure observations with element analysis and hardness probing on the cross sections of the FGMs.

Abstract: The production of nanocomposite tungsten carbide buttons was studied. Using the mechanically induced solid-state mixing technique, the nanopowders were mixed with Cobalt (Co) and Zirconium Oxide (ZrO₂). During the consolidation and manufacturing process, the nanocrystalline characteristics of the nanocomposite were improved by replacing Co with ZrO₂-2 mol% yttria (YO₃), and the average grain size was reduced to 23-49µm. With the advent of fast sintering techniques and the synthesis of nanocomposites from the consolidation of nanocomposite powders, full dense buttons with outstanding properties were produced. These buttons have a very high nano hardness value (24.41GPa) and a low Young's modulus (E) value (332.02 GPa).

Abstract: Recently much interest has been attracted in replacing heavy metals with light metals such as aluminum to reduce weight to improve fuel efficiency of automobiles. However, weight reduction by light metals often leads to decrease in strength, which causes problems in terms of safety and sustainability. This study aims to produce carbon nanotube (CNT) reinforced aluminum (Al) matrix composites with high performance using a combination of spark plasma sintering (SPS) and hot rolling techniques. Dry ball milling and SPS followed by hot rolling were conducted to uniformly disperse CNT in Al matrix. The microstructures of the composites including dispersibility of CNT were observed using a scanning electron microscope (SEM) and transmission electron microscope (TEM). Anisotropic mechanical behavior was investigated through Vickers hardness and tensile tests. The experimental results demonstrated that the post-sintering hot rolling can highly enhance the tensile strength of the composites.

Abstract: Nitrides of ‘2:17’ - type based on rare earth metals and iron are of interest as promising magnetic materials for the development of high-energy permanent magnets. The magnetic properties and phase composition of the starting compound Sm_1.8Er_0.2Fe₁₇, nitride Sm_1.8Er_0.2Fe₁₇N_2.1 and its crushed powders have been investigated. The magnetic measurements of the samples were studied in magnetic fields up to 70 kOe at room temperature. It was found that the introduction of nitrogen atoms into the crystal lattice of the substituted composition (Sm,Er)₂Fe₁₇ in combination with the effect of high-energy milling of nitride leads to an increase in the saturation magnetization (σ_S) and coercive force (H_C).

Abstract: This paper study the effect of structural behaviour and electrical properties in cubic NaZn13-type La (FeSi)₁₃ compounds annealed at different high temperatures from 1000oC to 1200oC. The Raman spectroscopy measurement revealed a different level of coexistence of La (FeSi)₁₃-type phase and α-Fe in 1000oC, 1100oC and 1200oC annealed samples. The different level coexistence of the phases suggested that the samples show a significant phase change with different annealing temperature methods. This finding has also supported by impedance analyzer measurement, where the pattern shows that the 1000oC and 1100oC samples have similar behaviour waveform pattern compared to the 1200oC, which has different behaviour. Besides, the impedance pattern clearly shows that the propagation of the signal for the 1000oC and 1100oC before it arrives in the conductor state (R=0.00) has high resistive values compared to 1200oC annealed samples. Further investigation on the electrical properties was done with the conductivity and tan delta measurements. The results show that 1200oC annealed sample have a high value of conductivity (S=18μ S/m) compares with 1100oC (S= 0.1μ S/m) and 1000oC (S=4.89n S/m). The tan delta measurements found that samples annealed at 1200oC temperature has low value of resistivity (tan ɗ = 0.117) compares with 1100oC (tan ɗ = 0.335) and 1000oC (tan ɗ = 0.482) respectively.

Abstract: In this work, the effect of different annealing treatments on the phase transition, structural behaviour and thermal analysis of MnCoGe alloys has been analysed. The changes in the transition temperatures have been studied by Simultaneous Thermal Analysis (STA). The results show that the structural transition temperature (T_str) depends on the annealing treatment of the samples preparation. However, under the same heat treatment no significant change is observed on the curie temperature (T_c). The thermal analysis reveals endothermic peak which corresponds to the structural phase transition of the compounds. The microstructural evolution has been monitored using in-situ X-ray diffraction which made known this compound produce three type of structures which are hexagonal, orthorhombic and mix structure (hexagonal and orthorhombic).

Abstract: Since the discovery of magnetocaloric effect (MCE), numbers of method in producing magnetocaloric materials has been studied. Among those methods, ball milling has been shown as a very versatile technique with several advantages compared to other preparation methods. In this work, the effect of ball milling preparation technique on the phase structural behaviour and electrical properties of MnCoGe alloys has been analysed. The changes in the structural behaviour have been studied by X-ray powder diffraction (XRD) and Raman Spectroscopy. The results suggest that the samples show significant structural changes with different method of ball milling running time. This finding has also been supported by electrical properties where the measurement found that the frequency also plays important role in the structure changes. The absolute impedance value,|Z| (Ω) suggest that structure start to change at initial frequency structure of hexagonal at point 3.22 Ω and 44.1 MHz region. The permittivity and dielectric loss (tan delta) graph that corresponds to a frequency (Hz) up to 100 kHz shown that the 2-hours milling time MnCoGe compound has the lowest permittivity value which make it had lower energy and required more frequency to react.