Papers by Keyword: Attrition Milling

Abstract: In this study the effect of attrition ball milling on cellulose particle size distribution was studied. The effect of moisture content of cellulose and grinding time were examined and grinding was carried out at room temperature and under cryogenic conditions, as well. The grinds obtained were studied with electron microscope, and the characteristic dimensions of ground particles were determined using image processing software. Results revealed that effective size decrease of cellulose particles was achieved at low moisture content at room temperature, while under cryogenic conditions high moisture content was necessary, i.e. frozen moisture enhances grinding efficiency in the latter case.

Abstract: Effect of attrition milling and subsequent ultrasonification of CNT on dispersion in ethanol was investigated. An attempt was also made to disperse the CNT in Mg alloy matrix by solid state friction stirring process for fabrication of metal matrix composite. Attrition milling was performed at a rotation speed of 700rpm for various times up to 6 hour. After 2 hours of milling, amorphous trace was observed in X-ray diffraction pattern. Attrition milling and subsequent ultrasonification enhanced dispersion of CNT in ethanol. Mg alloy matrix composite dispersed with the CNT was successfully fabricated by friction stirring process. The CNT-dispersed composite was analyzed by optical microscopy and Vickers hardness.

Abstract: Oxygen-ion conductors based on strontium-and magnesium-doped lanthanum gallate have been proposed to be used as solid electrolyte in solid oxide fuel cells operating at intermediate temperatures (500-700 °C), due to their high ionic conductivity and stability over a wide range of oxygen partial pressures. In this work, the effect of attrition milling on phase composition of powder and consolidated specimens prepared by solid state synthesis has been investigated. The results show that both the attrition milling and the calcination temperature play a major role in the phase composition. Powders with negligible amount of secondary phases were obtained after two steps of calcination at high temperature followed by attrition milling.

Abstract: Visible photoluminescence was generated in standard soda-lime-silica glass powder, mechanically milled in a high-energy attrition mill. The broad emission band maximum shows a linear dependence on the exciting wavelength, suggesting the possibility to tune the PL emission. The photoluminescence was attributed to defect generation related to unsatisfied chemical bonds due to the high surface area. Raman scattering and ultraviolet-visible optical reflectance measurements corroborate this assertion. Transmission electron microscopy measurements indicate that the powder is composed by nanocrystallites with about 10-20 nanometers immersed in an amorphous media.

Abstract: The reaction-sintered alumina ceramics with low firing shrinkage were prepared from Al/Al2O3 powder mixture by attrition milling and the effect of milling characteristics of raw powders on reaction sintering was investigated. Powder mixtures of flaky shape Al with coarse alumina was much more effectively comminuted by the attrition milling than the mixtures of globular shape Al with coarse alumina powders. Furthermore the coarse alumina was much more useful in pulverizing and grinding the ductile Al particles than fine alumina. After attrition milling and isopressing at 400MPa, the Al/Al2O3 specimen was oxidized at 1200°C for 8 hours followed by sintering at 1550°C for 3 hours. Because mixed powder of coarse alumina with flaky Al was much more effectively comminuted than the globular Al, sintered body of more than 97% theoretical density was achieved, but low contents of Al leads to relatively higher shrinkage of about 8%. As the coarse alumina particles are much more useful in cutting and reducing the ductile Al particles, the use of the coarse alumina powder was much more effective in reaction-sintering.

Abstract: Cordierite has been synthesized by heating mixtures of kyanite and talc, using kyanite powders of two different sizes. The reaction is studied by thermogravimetric and differential thermal analysis. Phase changes are followed by X-Ray diffraction of samples fired between 750 °C and 1400 °C. The evolution of the reaction starts with the dehydration of talc at approximately 880 °C. The kyanite decomposes at approximately 1140 °C. The first traces of α-cordierite appear at around 1200 °C. The influence of the kyanite particle size on the kinetics and microstructure is analyzed.