Vibratory Ball Mill Research Articles

Mechanochemistry of Lignin. Part IX. Mechanochemical conversions of .ALPHA.-(2-methoxyphenoxy)-.BETA.-hydroxypropiosyringone.

Mechanical treatment of either syringaldehyde (1) or acetosyringone (2) with CBM (ceramic ball mill) gave no reaction product, but the treatments with both a VBM (vibration ball mill), and a laboratory refiner produced 3, 5-dimethoxy-p-benzoquinone (3) As a model compound with β-O-4 linkage, α-(2-methoxyphenoxy)-β-hydroxypropiosyringone (4) was therefore synthesized and treated mechanically to find out the reaction products. Differently from the cases of syringaldehyde (1) and acetosyringone (2), the treatments of a larger molecule of compound (4) with CBM, VBM, and a laboratory refiner produced 3.5-dimethoxy-p-benzoquinone (3) and others. By the mechanical treatments of compound (4) in the aqueous media, Daikin-type of radical splitting reactions of Car-Cα and Cα-Cβ bonds occurred to give firstly compounds (3), (10), and (11), secondly compounds (12) and (13).

Ｔｉ／Ａｌ ＨＩＰ焼結体の組織と性質に及ぼすミリング条件の影響

Ti and Al powder mixtures with nine compositions(Ti-10at.%Al-90at.%Al) were milled with milling balls of various sizes(2.0-19.1mm) by a vibratory ball mill and were sintered by HIP (Hot Isostatic Pressing). The microstructure and material properties of the sintered compacts were investigated by optical microscopy, SEM. TEM, X-ray diffraction, microhardness measurement, electrical resistivity mesaurement and modified small punch(MSP) test. It was found that the microstructure and the material properties of the sintered compacts were strongly dependent on the milling ball size, milling time and the starting powder composition. A nearly single phase intermetallic compound with more refined structure and higher MSP energy and strength was formed on longer milling time. The sintered compact with the starting composition of Ti-50at.%Al showed the highest MSP strength and energy, which can be related to the well refined microstructure with ultrafine dispersoids of Ti.Al in TiAl matrix.

The effect of milling condition on the formation of nanostructures: Synthesis of vanadium carbides

The mechanical alloying process (MA), has been successfully used to synthesize a number of commercially important alloys and composites. High-energy ball-milling is generally used to mechanically alloy metallic powder and develop microstructural changes to enhance structure dependent properties. Mechanical alloying is usually carried on in commercially available milling devices as: vibratory ball mills or planetary mills. These ball mills, designed mainly for pulverization of ceramics, have very limited control of the milling process. It can be noticed that in commercial ball mills the maximum milling condition has been selected to reduce the milling time. Available adjustment of the milling energies is limited to a narrow range. There are certain disadvantages to that near fixed characteristic in studying of the effect of milling condition on the formation of nanostructures. None of the commercially available devices was designed with the specific needs of the MA process in mind. In this work ball milling was performed using a locally designed ball mill with precise control of milling parameters. The effect of milling intensity on the formation of nanostructures and, in consequence, of V{sub 2}C and VC intermetallics, is described in this paper.

ＳｉＣ粒子／７０７５アルミニウム合金複合材料の超塑性変形特性

An aluminum alloy composite (MA7075+10SiC alloy) has been developed to show high strain rate superplasticity in tension and compression test. Fibers of 7075-0.3 mass%Zr alloy made by a metal cutting chatter technique were mixed with SiC particles by using vibrational ball mill, compacted in nitrogen atmosphere, and then pre-strained at 793K. After the pre-straining, SiC particulates are distributed uniformly within matrix, and a fine grain structure, with average grain size of about 0.8μm is developed. In a strain rate range of 5×10-1 to 1×10s-1 at 793K, the MA7075+10SiC specimen can be compressed to about 0.65 strain without surface cracking under very low flow stress level. The observed m value is larger than 0.3. In tensile test of the MA7075+10SiC specimens warm rolled after the pre-straining, maximum elongation of about 315% is obtained at an initial strain rate of 5 s-1 at 793K. The very fine grain (or subgrain) structure of the composite material is considered to be reason of superplasticity in such a high strain rate range.

Preparation of Nanocrystalline NbN and (Nb, Al)N Powders by Mechanical Alloying under Nitrogen Atmosphere

Elemental niobium powder and Nb 50 Al 50 elemental powder mixture were milled in a vibrational ball mill, Spex 8000, under nitrogen atmosphere, and the structures of milled powders and their sintered materials were examined by means of X-ray analysis, SEM and HRTEM observations. The niobium powder absorbed 50 at% of nitrogen during milling. Several types of nitrides were formed during milling, i.e., γ-Nb 4 N 3 (FCT), δ-NbN (FCC) and δ'-NbN (hexagonal) with increasing nitrogen content. The mean grain size of these nitrides were about 5 nm

メカニカルアロイング合成Ｔｉ系金属間化合物に与える窒素の影響

Mechanical alloying of Ti-base intermetallic compound (Ti -C- 20mass%Ni, Ti -30mass%Al, Ti -26mass%Si) was performed using a vibrational ball mill in Ar or N2 under diminished pressure. The effect of nitrogen on the mechanical alloyed Ti-base intermetallic compound was studied by X-ray diffraction, EPMA and DSC.Results from X-ray diffraction, EPMA and DSC suggested that the synthesis of TiN was carried out in N2 atomosphere under diminished pressure and tended to retard the MA reaction. And the heat treatment of powder, which was mechanical alloyed in Ar under diminished pressure, at 1173K for 1.8ksec in N2 flow made the needle-like shape of the crystals.

ＭＡによるＮｉ３３Ｚｒ６７混合粉末の非晶質化におよぼすミリング条件の影響

Effect of milling mode (the ratio of milling period to pause one) on amorphization of mixed Ni33Zr67 powders by mechanical alloying(MA) was examined using high-speed vibratory ball mill. Three modes were determined by measuring temperatures on inner wall of vessel during MA with Chromel-Constantan(CRC) thermocouple, that is, mode A(the maximum temperature reached at 370 K), mode B(the maximum one 423 K) and continuity(continuous milling. 480 K after 150 ks of milling). The amorphization rate of the specimen by the mode A milling was slower than that by the continuous one, judging from the results of X-ray diffractometry and differential scanning calorimetry. Also, the thermal stability of the amorphous phase obtained was higher in this order: continuity, mode B and mode A.

Studies in additive grinding of minerals

The effects of solid and liquid additives on a dry grinding process were studied at four additive concentrations and two grinding times, using a laboratory vibration ball mill with calcite as the feed material, under selected milling conditions. Among the additives used, the fatty acids are the most effective followed by alcohols, other organic solvents and inorganic salts. The experimental results show that the fineness of the product increases to a maximum and then decreases with an increase in additive concentration. Statistical correlations show that the increase in surface tension and dipole moment and also decrease in viscosity and density of the liquid additives can enhance the grinding process. Based on experimental results and correlations, it is concluded that the physico-chemical properties of the additive influence the cohesive interactions among the particles and in turn the breakage mechanisms for a better grinding environment.

Mechanochemical effects for some Al2O3 powders of dry grinding

Three kinds of Al2O3 powders, i.e. two kinds of low-soda Al2O3 with average particle sizes of 3.9 and 0.6 μm and an electrofused Al2O3 with an average particle size of 21.8 μm, were ground for up to 300 h in a dry vibration ball mill. Variations in particle-size distribution, specific surface area, crystallite size, lattice strain, effective temperature factor and lattice constant were examined against milling time. The mechanism of grinding was found to differ between low-soda Al2O3 and electrofused Al2O3. The mechanochemical effects on these Al2O3 powders occurred in the order decrease of crystallite size → increase of effective temperature factor → increase of lattice strain. The length of the a-axis was clearly increased by a prolonged grinding. The difference in the ground state of three specimens was attributed to differences in the physical state of particles originating from the preparation methods, and also to particle size.

Effects of Fluid Viscosity on Ball Movement and the Initial Rate of Wet Grinding of a Vibration Ball Mill.

Effects of Fluid Viscosity on Ball Movement and the Initial Rate of Wet Grinding of a Vibration Ball Mill.

Reduction of haematite with carbon by room temperature ball milling

The solid state reduction of haematite ( α-Fe 2O 3) to mainly nanocrystalline wüstite by room temperature dry ball milling of haematite and carbon, in an inert atmosphere, is described. In addition to wüstite, a smaller amount of nanocrystalline magnetite is also formed, possibly by a disproportionation reaction of wüstite. The reaction is completed in about 70 h in a Spex vibratory ball mill. Haematite alone is converted by dry milling for 70 h into nanocrystalline magnetite with an average crystallite size of 10 nm as shown by X-ray diffraction and Mössbauer spectroscopy.

Production of amorphous titanium aluminide powder by vibratory ball milling

Production of amorphous titanium aluminide powder by vibratory ball milling

Effects of mechanical activation of inorganic gels on their thermal behavior. 1. Crystallization process of titania gels

The influence of mechanical pretreatment on the crystallization from amorphous titania hydrogel to anatase was studied. The temperature of crystallization, T crys, determined by the DTA exothermic peak, decreased by 18 and 44 K on grinding for 3 hr by the rotation and vibration ball-mill, respectively. Preliminary ordering of anatase in ground gels was detected by Raman spectroscopy and selected area electron diffractometry, before any X-ray diffraction peak appeared. It is suspected that the decrease in T crys by mechanical activation is attributed to the above precursory ordering. By applying mechanical stress, the sudden weight loss was observed at T crys. This suggests that a small amount of hydroxyl groups and NH + 4 may block the long-range ordering of TiO 6 structural units.

Early and late mechanical alloying stages of the Pd-Si system

Four Pd-Si compositions (Pd/Si=2.5/1; 3/1; 4/1 and 5/1) were mechanically alloyed by a ball-milling technique. X-ray diffraction and fluorescence analysis were used to monitor the mechanical alloying (MA) process which was carried out in planetary and vibratory ball mills. The first step of the milling process consists in a very fine fragmentation of the silicon particles into the palladium matrix. After this early stage of milling, formation of the intermetallic line compound Pd3Si can occur for the 2.5/1, 3/1 and 4/1 composition depending on the milling conditions and/or milling apparatus adopted: i.e. on the conditions of energy transfer experimentally realized. Subsequent milling indicates that amorphization probably occurs starting from the previously formed Pd3Si compound. Long milling times, up to 56 h, promote a demixing process towards the parent elements for the 2.5/1 and 4/1 compositions. Thermal treatments of the long-term milled samples confirm the final products obtained from the near room-temperature solid state reaction induced by MA. For the Pd5Si composition the conditions for Pd3Si formation and subsequent amorphization were never reached.

Influence of milling atmosphere on amorphization of chromium and Cr-Cu powders by ball milling

Elemental chromium and Cr-Cu powder mixtures were milled in a vibrational ball mill under air-, nitrogen- and oxygen-containing argon atmospheres. Structural changes during milling and the thermal stabilities of the milled powders were examined by means of X-ray analysis, transmission electron microscopy and differential scanning calorimetry. The amounts of the gaseous elements absorbed by the powder particles during milling were also determined from the pressure reduction in the vial. It was found that large amounts of nitrogen were absorbed during milling in argon-air and argon-nitrogen atmospheres, resulting in significant grain refinement and subsequent amorphization of chromium and Cr 70Cu 30 powders. On annealing, crystallization of the amorphized powders occurred accompanied by the formation of a stable Cr 2N phase. Amorphization did not occur in either the chromium or the Cr-Cu powders when milled in a pure argon or Ar-O 2 atmosphere. A thermodynamic explanation for the grain refinement and the amorphization was proposed.

金属粉末の振動ボールミリングのモデルシミュレーション

The motion of each milling ball during vibratory ball milling of metal powders was simulated by a computer using one-. two- and three-dimensional models of a vibratory ball mill. In these models, the consumpton of impact energy of the balls by the micro-compaction of metal powder particles during impact was assumed to be equivalent to the energy loss by an imaginary viscosity given to the balls and mill container. As a result of the simulation by using the three models, it was found that the motion of the milling balls is strongly dependent on the ball charge fraction. With an increase in the ball charge, the impact frequency increased, while an average of impact velocity normal to each contact surface decreased.

The effect of grinding media on the breakage rate in a planetary ball mill

Grinding experiments on the sieved-size fraction of silica sand in a planetary ball mill were carried out. It was confirmed that the breakage of a relatively fine size fraction by large balls in the mill can be described by the first-order law, but the law breaks down when the ball size is too small. The reasons for this abnormal breakage were experimentally investigated and the relationship between the ball size and the critical size of material was given in this paper. For the normal breakage, the specific rate of breakage of materials was described by the equation S 1 = ax i a Q(z), where Q(z) is the probability function ranging from 1 to 0, which has been used by Austin in a tumbling ball mill. In this equation, S has a maximum value, and the particle size of the maximum can be related to the ball size by x m = 0.05 d B, that is, a 20:1 ball diameter/particle size ratio gives the optimum condition for the planetary milling. This optimum condition is the same as that in a stirred ball mill, but different from tumbling ball milling and vibration ball milling. Finally, the effect of the diameter and the density of balls on the breakage was expressed by the form a = k 3(ρ B/ d B 0.35).

ＭＡによる（Ｃｒ０．７Ｆｅ０．３）‐Ｎ系のアモルファス化とその原子構造観察

Cr and Fe elemental powders at 7:3 atomic propotion were milled in a vibrational ball mill under N2 gas atmosphere. The concentration of N atoms in the Cr0.7Fe0.3-N powders increased with increasing MA time and approached to about 15at%N after 320 hours of milling. The amorphization was observed by X-ray diffraction and DSC measurements.RDF(r) shows that the 2nd nearest neighbor atoms in BCC crystal preferentially moved out of their positions during the amorphization process and the 1st nearest neighbor distance between metal atoms increases with increasing the milling time. The nearest coordination number around a metal atom within about 3.3 A decreases from 14 to 12.5 atoms while the amorphization proceeds. These results definitely tell us that the octahedral unit in a BCC structure is destroyed and is transformed into the tetrahedral unit during the amorphization process. An increase in the metal-metal distance of the 1st nearest neighbor with increasing nitrogen content can be interpreted by the penetration of a nitrogen atom into a polyhedron formed by metal atoms.

ＹＢａＣｕ系複合酸化物製造プロセスにおける液中混合粉砕が製品の超伝導特性に及ぼす影響

The effects of wet milling of YBaCu oxide in ethanol and in n-hexane with a vibration ball mill on the superconducting properties of calcined powders and sintered pellets have been examined with a focus on first-stage milling before calcination in the preparation process. As a result, it was found that there is an optimum range of milling time in both cases.In the wet milling in n-hexane, it was confirmed that the prolonged milling causes agglomeration of particles as in dry grinding, which is considered to be one of the reasons for the degradation of the superconductivity of calcined powder.On the other hand, the elementary analysis by EPMA of the treated powder by wet milling in ethanol showed that the change in degree of mixing of each element agreed well with the tendency of variation in the superconducting props of the calcined powder and sintered pellet.

サーメット合金へのＭＡ処理の影響

Mechanical alloying of Titanium, Molybdenum, Nickel and graphite powders was performed using a vibrational ball-mill. Mechanical alloying process of cermet powder was studied by X-ray diffraction, electron probe micro analysis (EPMA) and scanning electron microscopy.Results from X-ray diffraction and EPMA suggested the synthesis of TiC was carried out for about 50 hours and the addition of Ni assisted this synthesis. The difference of mechanical alloying atmosphere had an effect on particle size of TiC after sintered. Mechanical alloyed Ti-C-20mass%Ni-10mass%Mo was able to sinter at low temperature and had a minute structure.