Effects Of Ball Milling Conditions Research Articles

Effect of ball milling conditions on the microstructure for alumina-based ceramic with nano-silica additives

Abstract Alumina-based ceramics, known for their excellent high-temperature stability and tensile strength, are utilized across various sectors like metallurgy, aerospace, and chemicals as thermal insulators and reinforcements. The mechanochemical method, which involves mechanical actions like stirring and grinding to induce chemical reactions without solvents, offers a green, time-efficient approach with minimal pollution. This technique is pivotal for nanomaterials preparation. This study successfully crafts nano-silica-enhanced alumina-based ceramics via mechanochemical methods. The impact of mechanochemical processes on ceramic properties is assessed through particle size, N2 adsorption, and various microscopic analyses.

Effect of Ball Milling Conditions on the Microstructure and Dehydrogenation Behavior of TiH2 Powder

This study investigated the effects of revolution speed and ball size in planetary milling on the microstructure and dehydrogenation behavior of TiH2 powder. The particle size analysis showed that the large particles present in the raw powder were effectively refined as the revolution speed increased, and when milled at 500 rpm, the median particle size was 1.47 m. Milling with a mixture of balls of two or three sizes was more effective in refining the raw powder than milling with balls of a single size. A mixture of 3-mm and 5-mm-diameter balls was the optimal condition for particle refinement, and the measured median particle size was 0.71 m. The dependence of particle size on revolution speed and ball size was explained by changes in input energy and the number of contact points of the balls. In the milled powder, the endothermic peak measured using differential thermal analysis was observed at a relatively low temperature. This finding was interpreted as the activation of a dehydrogenation reaction, mainly due to the increase in the specific surface area and the concentration of lattice defects.

Azilsartan-nicotinamide cocrystal: Preparation, characterization and in vitro / vivo evaluation

Azilsartan (AZL) is an angiotensin II receptor antagonist, which is mainly used for the treatment of hypertension. AZL has the advantages of high selectivity, hypotensive effect, protection of cardiovascular and cerebrovascular diseases. In order to improve the water solubility of AZL and its bioavailability, AZL -nicotinamide (NA) cocrystal was prepared by mechanical ball milling, and the effect of ball milling conditions on cocrystal preparation were studied. AZL-NA cocrystal was identified and characterized by powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy and Fourier transform infrared spectrometry. The results showed that AZL-NA cocrystal with the molar ratio of 1:2 was successfully prepared. And the optimum ball milling condition was milling speed of 300 rpm, milling time of 50 min, the solvent was ethanol/acetonitrile (1:1, v/v), and the solvent dosage (η) was 0.8 μL/mg. The results of solubility tests showed that the solubility of AZL in the cocrystal was 3.39 times higher than the pure drug at 24 h. And the results of vitro dissolution tests showed that the cumulative dissolution of AZL in 2 h was about 10%. While distilled water, pH 1.2 and pH 4.5 acid or buffered solutions and pH 6.8 buffer phosphate salt solution was used as the dissolution medium, the cumulative dissolution of AZL in cocrystal reached 50%, 35%, 55% and 90%, respectively, showing obvious improvement of dissolution. In addition, the accelerated stability tests showed that the AZL-NA cocrystal had good chemical stability. And the pharmacokinetic results showed that AZL-NA cocrystal could significantly improve the bioavailability of AZL.

The influence of pre-fibrillation via planetary ball milling on the extraction and properties of chitin nanofibers

A planetary ball milling was applied as a pretreatment of chitin powder to prepare precursors for chitin nanofiber (ChNF) production. The study aims to examine the effects of ball milling conditions (dry milling, and wet milling in neutral and acidic aqueous medium) on the degree of pre-fibrillation of the ChNF precursors and the characteristics of the resulting nanofibers. The results showed that no fibrous-morphology ChNFs were obtained using dry ball milling followed by high-pressure homogenization (HPH), but fibrous-morphology ChNFs were successfully prepared using wet ball milling as a pretreatment. Ball milling in a mildly acidic aqueous medium was found to most effectively pre-fibrillate chitin, thus facilitating fibrillation in the subsequent HPH treatment to generate the finest ChNFs with an average diameter of around 12 nm and the narrowest size distribution. The resultant chitin products from wet milling pretreatment exhibited much higher crystallinity and thermal stability than those from dry milling. The results suggest that pre-fibrillation of chitin via ball milling in this study plays a crucial role in the successful procuration of the ChNFs in a subsequent mechanical disintegration process, while wet ball milling, especially under mildly acidic conditions, is a promising green approach to produce efficient precursors for ChNF production.

Effect of ball milling conditions on microstructure and lithium storage properties of LiNi0.5Mn1.5O4 as cathode for lithium-ion batteries

In this work, the precursors of LiMn1.5Ni0.5O4 (LNM) are respectively synthesized by dry and wet ball-milling. Under wet ball-milling, the problem of sticky residue in dry ball-milling is effectively resolved, the three raw materials form homogeneous slurry and mix well in micrometers level. LNM-w12 sample synthesized by using precursor added 12 mL milling medium gains the atomic composition closed to the theoretical value, ordered crystal structure and the highest lithium diffusion coefficient. At 0.1 C rate, LNM-w12 delivers the capacity of 136 mAh g−1 at the first cycle, and 133 mAh g−1 at the 100th cycle. Moreover, LNM-w12 delivers the initial capacity of 97 mAh g−1 at 10 C rate, and remains 78% after 1000 cycles. The great rate capability of LNM-w12 can be attributed to the well-formed crystal structure, ordered and stable surface structure, which is conducive to the diffusion of lithium ions and prevents the dissolution of the material at high voltage.

Densification and microstructural evolution of yttria transparent ceramics: The effect of ball milling conditions

Abstract Ho:Y2O3 ceramics were prepared by using solid-state reaction method with commercial oxide powders. The effect of ball milling condition, specifically slurry concentration (CS), on densification, microstructure evolution and transmittance of the Ho:Y2O3 ceramics was studied. Ho:Y2O3 powders were ball milled with slurry concentrations of 33.2–17.4 vol%. The samples were vacuum sintered between 1400 and 1850 °C. Over the CS range of 33.2–18.4 vol%, decreasing slurry concentration improved the densification, normal grain growth and optical transmittance of the Ho:Y2O3 ceramics. The 18.4 vol% Ho:Y2O3 powders showed the lowest agglomeration and highest densification rate, from which the ceramics prepared have the best transmittance. The grain growth exponents of the Ho:Y2O3 ceramics during final-stage of sintering were also studied.

Effects of Ball Milling Conditions on Breakage Response of Baban Tsauni (Nigeria) Lead-Gold Ore.

The effects of ball milling conditions on breakage response of Baban Tsauni (Nigeria) lead-gold ore was examined in this research work. The three factors considered were, the grinding media mass to ore sample mass ratio, the grinding time and the ball mill speed. The breakage response measured in terms of cumulative per cent mass passing the liberation size increased with increase in media mass to sample mass ratio and reached optimum at a ratio of 10:1. The response per unit time decreased as the grinding time was increased gradually from 2minutes to 10minutes, thereby indicating that long grinding circuits were poor in performance. The optimum ball milling speed of the ore was found to be 82.9% of the critical mill speed. This work established a rational approach in the choice of grinding speed. The effects of the three parameters on generation of fines were less pronounced.

Effect of ball-milling conditions on microstructure during production of Fe–20Mn–6Si–9Cr shape memory alloy powders by mechanical alloying

Phase transitions associated with Fe–20 wt% Mn–6 wt% Si–9 wt% Cr alloy during mechanical alloying and after subsequent annealing of that are studied experimentally. The conventional powder metallurgy route was used in preparing the sample. The milling time ranged from 5 to 20 h. Changes in microstructure as a function of milling time were investigated by using X-ray diffraction analysis, differential scanning calorimeter, and scanning electron microscopy. The grain sizes of powder milled are determined. The critical temperatures associated with the transformations are found to change with increasing ball-milling time.

Formation of Core-Shell Structure in BaTiO3Grains

To understand the formation of core-shell structure in BaTiO₃ (BT) grains in multilayer ceramic capacitors, specimens were prepared with BT powders mixed with Y and Mg, and their microstructures were investigated with scanning electron microscopy, x-ray diffractometry, and transmission electron microscopy. Microstructural investigation showed that Y dissolved easily in BT lattice to a certain depth inside of the grain, whereas Mg tended to stay at grain boundaries rather than become incorporated into BT. It was considered that in case of Y and Mg addition in a proper ratio, Y could play a dominant role in the formation of shell leading to a slight dissolution of Mg in the shell. Next, the effects of ball-milling conditions on the core-shell formation were studied. As the ball-milling time increased, the milled powders did not show a significant change in size distribution but rather an increase of residual strain, which was attributed to the milling damage. The increase in milling damage facilitated the shell formation, leading to the increased shell portion in the core-shell grain.

Effects of ball-milling conditions and additives on the hydrogen sorption properties of Mg + 5 wt% Cr2O3 mixtures

Effects of particle size of Cr2O3 catalyst on the hydrogen absorption/desorption kinetics of Mg + 5 wt% Cr2O3 mixtures have been studied. To explain the effect of particle size of Cr2O3 and also to yield information about the role of Cr2O3 during the sorption process, the kinetics data have been analyzed using Avrami–Erofeev rate equations. The activation energies and diffusion coefficients of these mixtures are in the ranges of 50.6–63.2 kJ/mol and 1.2.10−11 to 8.9.10−10 cm2/s, respectively. The addition of nano-oxides led to an increase of the diffusion coefficient of hydrogen by one order of magnitude.

Effects of ball-milling conditions on dehydrogenation of Mg(NH 2) 2–MgH 2

The dependence of chemical reaction between Mg(NH 2) 2 and MgH 2 on the ball-milling conditions has been investigated. While the decomposition of the component Mg(NH 2) 2 resulted in gaseous products consisting mainly of ammonia, the mixtures of Mg(NH 2) 2–MgH 2 prepared by ball-milling released H 2 at temperatures as low as 65 °C. In addition, the increase in ball-milling time can effectively suppress the ammonia evolution during the thermal treatment. The conversion of the amide and hydride to imide-like structure was demonstrated by FTIR and XRD characterization. A total amount of 4.8 wt.% of H 2 could be released from the investigated system.

Effect of ball milling conditions on the microstructure and the transformation behavior of Ti−Ni and Ti−Ni−Cu shape memory alloy powders

Ti−50Ni and Ti−40Ni−10Cu (at.%) shape memory alloy poweders have been fabricated by the ball milling method. Their alloying behaviour and transformation behaviour were investigated by means of optical microscopy, electron microscopy, X-ray diffractometry and differential scanning calorimetry. As-milled Ti−Ni powders fabricated with a milling time of less than 20 hrs were a mixture of pure elemental Ti and Ni, and therefore we were unable to obtain alloy powders because the combustion reaction between Ti and Ni occurred during heat treatment. Since those fabricated with a milling time of more than 20 hrs were a mixture of Ti-rich and Ni-rich Ti−Ni solid solution, it was possible to obtain alloy powders without a combustion reaction during heat treatment. Clear exothermic and endothermic peaks appeared in the cooling and heating curves, respectively, in DSC curves of 20 hr and 30 hr milled Ti−Ni powders. On the other hand, in DSC curves of 1 hr, 10 hrs, 50 hrs and 100 hrs, the thermal peaks were almost discernible. The optimum ball milling time for fabricating Ti−Ni alloy powders was 30 hrs. Ti−40Ni−10Cu alloy powders were fabricated successfully by the optimum ball milling conditions deduced from Ti−50Ni alloy powders.

Ball Milling Conditions of a Very Small Amount of Large Particles in Silicon Nitride Powder

The effect of ball milling conditions on pulverization of the very small amount of large particles in silicon nitride powder was examined. In this paper, the wet sieve analysis and X-ray sedimentation method were used to measure the content of large particles in the ground powder which influence important properties of sintered ceramics such as fracture strength. As a result, it was made clear that the wet sieve analysis would be a reliable method to measure the content of just a few large particles in the ground powder. By applying this analysis to the ball-mill grinding of silicon nitride powder, it was found that the processing conditions required to grind the large particles were different from those to obtain high specific surface area as well as small average size of particles. This is because the impact force exerted onto the particles by the media balls is more effective on grinding large particles.