Basic Study for Developing The Efficient Production Method of Fine Uniform Particles

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The final purpose of this study is to develop the effective production process of fine uniform particles that are suitable for micro-blast-machining. In the present study, the atomization by ultra-rapid spinning of small flat disk was proposed as suitable melt atomization method for the purpose and the validity is investigated through the simulation experiment.The prototype atomizer of ultra-rapid spinning of small flat disk was fabricated, the water atomization test was performed. The atomization pattern transited to fine-ligament type or turbulent film type in the range of high spinning velocity. Owing to the transition the atomizer showed good atomization performance in higher flow rate than the upper limit of atomization which was estimated from previous empirical correlation. The mean diameter of particles and the mean pitch of ligaments were almost agreed with previous empirical correlations and decreased with the increase of spinning velocity.Employing several test liquid, the experimental investigations were performed with changing the properties of liquid, the disk diameter, the spinning velocity and the liquid flow rate. The empirical correlations were obtained for the transition condition of atomization pattern and the pitch of ligament which was concerning directly to the particle diameter. Simple empirical correlation for the range of ligament type atomization was also presented.Based on these results, we projected the atomization test of liquid metal but failed. Aiming to reveal the reasons, the breakup behavior of liquid metal jet into water was observed in detail. The atmospheric condition of jet was controlled electrically. It was supported that the oxidation of metal surface prevent breakup of liquid metal jet and the control of atmospheric condition should play very important role in the melt metal atomization