Papers by Keyword: Ball Milling

Abstract: In this paper, a theoretical model based on multi-gene genetic programming (MGGP) approach has been applied to predict the structural and magnetic properties in nanocrystalline Fe–Ni powders prepared by mechanical alloying (MA) using a planetary ball mill. The MGGP model was used to correlate the input parameters (milling speed, chemical composition, and milling time), to output parameters (crystallite size and coercivity) of nanocrystalline Fe–Ni powders. The model obtained was tested with additional data to demonstrate its performance and prediction ability. The MGGP model is a robust and efficient method to find an accurate mathematical relationship between input and output data. A sensitivity analysis study was applied to determine the most influential milling parameters on the crystallite size and coercivity.

Abstract: The objective of this research is to study the effect of water content on particle characterization and agglomeration of bamboo charcoal resulted from ball milling process. The characterization is determined by the particle size and the morphology of the particle. The milling was performed in cylinder vial of stainless steel. The element of milling is steel balls. The dimension of the cylinder vial was 120 mm length and 1-inch diameter, while the ball diameter was 5/32 inch. The charcoal resulted from pyrolysis was milled manually then strained with a filter size of 200 meshes. The particles passing the strainer were washed in water and then dried to obtain 25%, 28%, 32% and 35% water content. Then they were put together with the milling balls into cylinder vial. There were four vials with a water content of 25%, 28%, 32% and 35% respectively for milling process. Every vial contained 11 grams of bamboo charcoal and approximately 299 grams of steel balls. It represents 1/3 of vial volume for charcoal, 1/3 of vial volume for ball and 1/3 of vial volume for empty space. Two type tests were conducted. The first test was to run the milling machine at 700 rpm for 2 million cycles and the second test was to run the milling machine at 1000 rpm for 3 million cycles. Particulate characterization was done by a particle size analyzer (PSA), a scanning electron microscope (SEM) with energy dispersive X-Ray (EDX). The results showed that the water content does not have any influenced to the particle size. For the both test the particle sizes are in the range of 100 nm or less to more than 1 μm. However, the second test produces smaller particles and a higher number of smaller particles due to higher impact energy and longer milling time. The two tests inform that agglomeration does not happen by having wet milling. The dominant element of the bamboo charcoal is carbon with more than 90% in number.

Abstract: Metal matrix composites attain a significant position in Industrial, defense, structural and automobile applications. To amplify that strategy there is a need to find out the conditional behavior of the composites and enhancing the properties will be mandatory. The present work mainly investigates on the effect of processing parameters like densification rates, sintering temperature, reinforcement content on the microstructure, mechanical properties of the Al7175/B4C composite material fabricated by mechanical milling and powder metallurgy techniques. Results show there is a grain size reduction and refinement in the composite material through ball milling operations and along with that increasing B4C content in the composite powders make milling conditions very effective. Increasing the sintering temperature results in a consistent grain growth along with that porosity level decreases up to a limit and then attain a steady state, the strength of the composites increases with compaction pressures but reinforcements content effects the strength of the material by losing its ductility making it brittle.

Abstract: This paper is devoted to fabrication of alumina reinforced EP648 matrix composite material, using selective laser melting. of two-phase composite powder, prepared by ball milling of metal and ceramic powders. Five 10x10x5 mm bulk specimens were successfully manufactured using different process parameters. The obtained MMC specimens were characterized by scanning electron microscopy.

Abstract: In this work, PVDF/BaTiO₃ nanocomposites consisting of polyvinylidene fluoride (PVDF) as matrix and BaTiO₃ (BT) as fillers were prepared by ball milling and hot-pressing process. It is known that nanofillers content and frequency affect the effective dielectric permittivity of the nanocomposites materials. Therefore, a developed model based on deep neural network (DNN) was used to study the effect of the input parameters on the dielectric permittivity of the nanocomposites. The volume fraction (vol%) of BT and frequency of alternating current (AC) were selected as the input parameters and the effective dielectric permittivity as the output response. The results show that the developed DNN model was able to predict the effective dielectric permittivity of PVDF/BT nanocomposites with a correlation coefficient (R) of 0.997. Thus, our study confirmed the accuracy and efficiency of the developed DNN model for predicting the relative dielectric permittivity of PVDF/BT nanocomposites.

Abstract: Carbon nanotube (CNT) has been one of promising candidates as a reinforcement in metal matrix composites (MMCs) for its variety of excellent properties such as lightweight, high strength etc. It is necessary to disperse CNT to the level of each one in order to lead to efficiently reflect the excellent essential physical properties of CNT in the composites. This research investigates fabrication processes linked with dry ball milling and cold pressing followed by sintering to uniformly disperse CNT in aluminum (Al) matrix. It was found that dispersibility of CNT were improved with increasing ball milling time based on observation of morphology of mixed powders and the composites using SEM. Vickers hardness and tensile strength of CNT/ Al composites increased with increasing ball milling time up to 24 hours, while they were constant or decreased because of increase of voids in case of longer than 24 hours of ball milling time.

Abstract: Influence of the rate at which energy is applied to aluminum powder during its ball milling is investigated. Rolling granulation is a main process due to which treated particles achieve their unique morphology and microstructure. Drastic temperature rise at rapid ball milling leads to increase in plasticity and local melting of treated powder particles that result in their adherence to the surfaces of milling balls and mill cylinder walls. Mass of aluminum powder adhered to the ball surface is proportional to the total surface area of all balls loaded in mill.

Abstract: Fe-10wt% La (OH)₃ composite powders have been fabricated by ball milling, under argon atmosphere for milling periods of 0, 5 and 10 h, respectively. Changes in structural, morphological, thermal and magnetic properties of the powders during mechanical alloying and during subsequent annealing have been examined by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). XRD results: showed the formation of new phases (Fe and LaFeO3 perovskite) created through the ball milling. The results showed that the crystalline size of ball milled powders decreased with increasing the milling time. In fact, after 10 h of ball milling, La (OH)₃ changes from nanostructure in amorphous structure. The magnetic measurements display a distinct saturation magnetization and coercivity.

Abstract: The main purpose of this work was to determine the effect of the powder composition on the microstructure and properties of iron-based sinters used as a matrix in diamond tools. The Fe-Cu-Ni sinters obtained from a mixture of ground powders were used for experiments. The influence of manufacturing process parameters on the microstructure and mechanical properties of sinters was investigated. Sintering was performed using hot-pressing technique in a graphite mould. The investigations of obtained sinters included: density, hardness, static tensile test, X-ray diffraction analysis, microstructure and fracture surface observations. The obtained results indicate that the produced sinters have good plasticity and relatively high hardness.

Abstract: Cermet is an important new engineering material that not only maintains the excellent properties of ceramic materials, but also has the advantages of metal materials. In this paper, the encapsulated alumina-aluminum composite powder was prepared by ball milling and characterized, which laid a foundation for the development of high properties cermet materials. Through the analysis of experimental results, the conclusions are shown when the ball milling time is greater than 3 h, the alumina particles are more evenly distributed around the aluminum powder. the ball milling for 6 h may have reached a limit of the mixing uniformity of the two powder, so the ball milling is determined 6 h as the better ball milling time. Under the ball milling condition of 50 r/min, the distribution of alumina particles around the aluminum powder is more uniform around the aluminum powder than the ball mill under 75 r/min, the ball milling speed is preferably 50 r/min. As the content of aluminum powder increases, the distribution of alumina in aluminum powder is large and uniform, and there is a small amount of pinning. It provides a package-like composite for the preparation of cermet with a wrapped structure and the thermal conduction mechanism of the controlled cermet.