Effect Of Grinding Time Research Articles

Parameter Optimization in the Synthesis of BZT Ceramics to Achieve Good Dielectric Properties

The powder synthesis of barium zirconate titanate (BZT) (BaZrTiO3) from the mechanochemical activation of BaCO3, ZrO2, and TiO2 was studied. The grinding effect, by using a planetary ball milling, on the crystallization temperature of BZT powders was analyzed. X-ray diffractometry, differential thermal analysis, thermogravimetric analysis, and scanning electronic microscopy (SEM) were used as characterization methods. The crystallization behavior of powders activated by high-energy grinding and the effect of grinding time on the BZT crystallization were analyzed. After grinding by 4 h, the BaZr(0.05)Ti(0.95)O3 sample was almost fully crystallized at . The results of dielectric and ferroelectric properties show that high-energy ball milling is a practical and promising way to prepare BZT ceramics.

Effect of Grinding Time on the Texture and Physical Properties of Sesame Seeds

Effect of Grinding Time on the Texture and Physical Properties of Sesame Seeds

Flexural and Morphological Properties of Poly(Methyl Methacrylate)/ Hydroxyapatite Composites: Effects of Planetary Ball Mill Grinding Time

Poly(methyl methacrylate) (PMMA)/hydroxyapatite (HA) composites have potential applications in bone cement, prosthesis, and dental implant. In this study, PMMA containing 5 wt% of HA is prepared using polymerization followed by compression molding. PMMA and HA powder are ground using planetary ball milling. The grinding time takes from 30 to 120 min. The effects of the grinding time and particle size of the PMMA/HA powder on the flexural properties and morphology of the composites are investigated. The structure patterns of PMMA/5HA are characterized using X-Ray diffraction (XRD). No new phase is observed in the XRD pattern with the different sizes of PMMA/HA powder. This indicates that planetary milling solely reduces the size of PMMA/ HA powder. However, it does not modify the structure of PMMA and HA. A reduction of ~40% in the particle diameter is observed in both PMMA and PMMA/5HA powder after subjected to planetary milling for 60 min. For the planetary ball mill-ground PMMA/HA powder, the flexural modulus of the respective PMMA composites is slightly increased. Planetary milling can increase the volume of fine particles in the composites specimens, which results in a more homogeneous distribution of HA and a reduction of void contents in PMMA matrix. The reduction in void content is observed on the fractured surface of PMMA composites through field emission scanning electron microscopy.

Preparation of potassium acetate intercalated metakaolinite

Abstract Potassium acetate was intercalated into metakaolinite by grinding. The effect of grinding time, potassium acetate content and heat was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TG–DSC) and transmission electron microscopy (TEM). Thermal analysis revealed that the melting temperature of potassium acetate in the intercalated complexes slightly increased, suggesting that the potassium acetate was present in the interlayer space of metakaolinite. TEM showed that metakaolinite was delaminated after intercalation of potassium acetate. The intensity of the characteristic reflections of metakaolinite decreased during heating, increasing grinding times and potassium acetate content.

Effect of Grinding Media Shapes on Breakage Parameters

AbstractIn the present study, the effect of grinding media shape on breakage parameters was investigated. Balls and cylpebs were used as the grinding media. It was observed that the grinding of quartz obeyed first‐order breakage kinetics in the case of balls and cylpebs. Higher breakage rates were noted with cylpebs than with balls. Furthermore, it was found that the primary breakage distribution function is dependent on the feed size (i.e., non‐normalizable), but independent of the grinding media shape. The effect of grinding time on the product size distribution has also been investigated. Following four and ten minute grindings, cylpebs produced a relatively finer product compared to balls.

Processing and dielectric properties of Bi-doped Sr(Ti0.95Zr0.05)O3 ceramics

Abstract This paper investigates Bi-doped Sr(Ti0.95Zr0.05)O3 ceramics prepared by solid state method. Both the effect of grinding time on particle size distribution of ceramic powders and the effect of sintering temperature on microstructure and dielectric properties of ceramics are studied. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). Apparent density measurements and their dielectric properties are established at room temperature. XRD analysis shows that the ceramics kept cubic perovskite structure with the grain size about 1–2 μm observed by SEM image. The relative density of the obtained materials reaches higher than 94% and they exhibit properties as follows: dielectric constant ɛr > 500 and dielectric loss tanδ 10 kV/mm.

Preparation of Drug Nanoparticles by Co-grinding with Cyclodextrin: Formation Mechanism and Factors Affecting Nanoparticle Formation

The aim of this study was to investigate the factors affecting the formation of pranlukast nanoparticle prepared by co-grinding with beta-cyclodextrin (beta-CD) and to elucidate the mechanism of nanoparticle formation. The effects of grinding time, moisture content and CD content on the nanoparticle formation were evaluated by means of UV quantitative determination and particle size analysis. High-resolution scanning electron microscopy (HRSEM) was employed to observe drug nanoparticles in the ground mixture. Nanoparticle recovery was higher than 95% for 2 : 1 molecular mixtures of beta-CD : pranlukast which had been ground for 10 min with moisture levels between 10 and 15%. While that of the 1 : 2 ground mixture prepared at 8% moisture level was only 57%. Nanoparticle recovery from beta-CD : pranlukast 2 : 1 mixture ground for 1 min was 2.5%, while that of the 10 min ground mixture was as high as 95%. HRSEM demonstrated that primary drug nanoparticles having a particle size around 50 nm were observed in the ground mixture. The grinding time, the moisture content, and the CD content had significant influences on the formation of drug nanoparticles. The CD matrix may form and stabilize primary particles by its interaction with the particle surface through water molecules. Primary nanoparticles existed in the ground mixture as 50 nm drug nanocrystallites.

Quantification of low levels of amorphous content in sucrose by hyperDSC

A method was developed for the quantification of low levels of amorphous content in sucrose with hyperDSC. The method was based on the fact that the change of specific heat at the glass transition is linearly proportional to the amorphous content. It was found out that as annealing time increased, the glass transition temperature moved to a higher temperature and the change of specific heat increased. Δ C p for annealed totally amorphous sucrose was 0.761 ± 0.012 J g −1 °C −1. Synthetic mixtures with various proportions of crystalline and amorphous sucrose were prepared. The following linear regression between Δ C p and amorphous content was obtained: Δ C p = 0.0075 x − 0.00484 ( R = 0.999). The limit of detection (LOD) and the limit of quantification (LOQ) values were 0.062 and 0.207%, respectively. The effect of grinding time on the amorphous content of crystalline sucrose was studied and a correlation between grinding time and amorphous content of sucrose was found. It was also found that the amorphous content could only attain a value of about 80–90% by grinding in the way used in this study.

Effects of high-energy ball milling on the morphology and the field emission property of multi-walled carbon nanotubes

The effects of grinding time in a vibration mill on the morphology and the field emission property of multi-walled carbon nanotubes (MWNTs) were studied using XRD, Raman spectra and high-resolution transmission electron microscopy (HRTEM). The results show that the closed ends of MWNTs are partly broken when ground for 4 h. The number of broken ends increases with grinding time. The field emission measurement results indicate that the presence of Fe particles can improve the field emission property of ground MWNTs.

Grinding-induced equimolar complex formation between thiourea and ethenzamide.

We prepared and characterized a grinding-induced equimolar complex of thiourea with ethenzamide. When thiourea and ethenzamide were co-ground at a molar ratio of 3 : 1, new powder X-ray diffraction (PXRD) peaks were observed in addition to PXRD peaks of thiourea crystals. The optimum stoichiometry of the new structure was confirmed as 1 : 1 mol/mol. Effect of grinding time on the thiourea-ethenzamide equimolar complex formation was investigated by using PXRD, differential scanning calorimetry and Fourier transform infrared spectroscopy. The equimolar crystal structure was confirmed by X-ray diffraction measurements of the single crystal which was recrystallized from ethanol. It was found that the intermolecular hydrogen bond formations between thiourea and ethenzamide molecules contributed to the equimolar complex formation. The complex formation was not observed in the cases where benzamide, salicylamide or 3-ethoxybenzamide was co-ground with thiourea. 2-Alcoxyl benzamide structures should be required for the grinding-induced equimolar complex formation with thiourea.

Investigation of the direct hydrometallurgical processing of mechanically activated low-grade wolframite concentrate

Experimental laboratory work on leaching of low-grade wolframite concentrate has shown that the dissolution of tungsten with a high extraction (90%) can only be reached after mechanical treatment of the studied wolframite concentrate, following oxidative leaching at 170°C in an autoclave in the presence of oxygen partial pressure of 10 bar. The effects of grinding time, temperature, sodium hydroxide concentration and oxygen partial pressure on the oxidation rate as well as the kinetics of the leaching process have been determined.

タンタル電解コンデンサ用原料粉体の調製と評価

A method for the preparation of the powder of tantalum capacitor was investigated. The fine grinding of tantalum powder with binder in a dry phase was conducted in the particle composition equipment.The effect of grinding time on the particle size distribution, angle of repose, tap density and the frequency response of impedance of the powder in the particle composition equipment was investigated.It was found that the DC resistance of the conducted powder is closely related to the angle of repose and tap density.

Investigation of the direct hydrometallurgical processing of mechanically activated complex sulphide ore, Akarem area, Egypt

Experimental laboratory work on leaching complex sulphide ore has shown that the dissolution of nickel, copper and cobalt with a high extraction rate can only be reached after mechanical treatment of the ores, following oxidative leaching at 110°C, in an autoclave with an oxygen partial pressure of 10 bar. The effects of grinding time, temperature, initial acid concentration and oxygen partial pressure on the oxidation process rate have been determined.

Mechanical decarbonylation of coal

Desorption, oxidation and mechanically activated decarbonylation of coal were examined as possible sources of carbon monoxide emitted from coal during the grinding process. The effects of grinding time, temperature, coal pretreatment and coal rank on CO emission as well as adsorptive capacity of coal for carbon monoxide were investigated for 12 coal samples. Mechanical decarbonylation of coal was found to be the most probable source of CO evolved from coal in milling under inert conditions. During milling under oxygen, however, some of the CO emission originates from coal oxidation.

媒体撹はん型ミルにおけるチタニアの超微粉砕同時表面処理による超微粒子化過程

Ultra-fine grinding of titania accompanied by simultaneous surface treatment was conducted in a laboratory-scale media agitating mill. The grinding solvent was n-decane, and stearic acid was added to the solvent as the surfactant. Zirconia beads of 0.6mm diameter were used as the grinding media. The effect of grinding time on the characteristics of titania commimuted in the media agitating mill was investigated. The measured characteristics were true density, specific surface area, particle size distribution, crystallite size, crystal lattice distortion and morphology of the comminuted titania. The amount of contamination of the comminuted titania from the grinding media, rotator and mill wall was also measured.Titania became flaky by surface attrition during the initial stage of grinding. Subsequently, the flaky particles were ground into ultra-fine particles. The comminuted titania had low crystal lattice distortion in the order of 10-4 and a small crystallite size of less than 200A after 5 hours of grinding. The true density of the comminuted titania was almost the same as that of intact titania. There was almost no increase in the background intensity in the XRD profile, and the lattice constant of the comminuted titania was kept constant.

Studies on the Densification Process of Kaolin Bodies

Densification processes and microstructural changes of kaolin bodies during firing were examined and their co-relations were discussed.From the results of the firing shrinkage, bulk density and apparent porosity measurements, following results were obtained. Degree of densification increased with the temperature. The longer the grinding time of the kaolin, the lower the densification of the bodies when fired at 1000°C. However, when fired at temperatures higher than 1100°C, the effect of grinding time on the densification of kaolin resulted inversely.Shrinkage behaviours were also examined kinematically, and the following results were inferred. The kaolin body shrank at about 500°C, 900°C and 1100°C. Shrinkage occurred at about 900°C might be due to the diffusion sintering process of metakaolin grains. Shrinkage occurred at slightly lower temperatures than 1100°C might be attributed to the viscous flow mechanism and partly diffusion process in the spinel intermediate phase.Microstructural changes of the fired bodies were also examined by means of X-ray diffraction, polarizing microscope and scanning electron microscope. Further, it was shown that the densification processes and accompanied phenomena of the fired bodies were clearly explained by these microstructural observations.

Low-Temperature Grinding Technique for Infrared Analysis of Propellants and Binders in Potassium Bromide Disks

A low-temperature grinding technique for the potassium bromide pressed-disk method was developed to obtain quantitative infrared spectra of propellants and propellant binders. The effects of grinding time and temperature on the intensities of infrared absorption bands were determined. The technique was applied to the study of the thermal degradation of a polyurethane propellant.

Evaluation of a new method for the preparation of homogeneous mycelial suspensions.

Guidry, D. J. (Louisiana State University, New Orleans) and G. H. Trelles. Evaluation of a new method for the preparation of homogeneous mycelial suspensions. J. Bacteriol. 83:53-60. 1962.-An all-glass tissue homogenizer (providing both conical and cylindrical grinding surfaces) was employed in the preparation of homogeneous mycelial suspensions. Pellets of mycelium from constant shake liquid culture were submitted to grinding for various periods of time. The effect of grinding time on optical density of the homogenate, hyphal fragment size, and viability of the fungus was determined. A grinding time of 4 min was found to yield suspensions of mycelium in which 89% of the hyphal fragments contained four or less than four cells. Optical density was used as the basis for both preparation of standard samples of inoculum and measurement of growth. Preparation of a light transmittance curve facilitates the preparation of suspensions of any desired concentration. Although plate colony counts on samples from the same flask showed satisfactory agreement, there was appreciable variation in counts on samples from different flasks. The variation in growth from flasks receiving equal samples of inoculum was also determined. Results indicate that, at concentrations of mycelium equal to an optical density of 0.301, a difference of 15% or more in the optical density of two samples (10 flasks per sample) can be accepted as significant. Some of the factors influencing variation in viability of inoculum as well as variation in flask growth have been determined. Ways in which experimental errors can be kept to a minimum are discussed.