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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 17    No. 5    October 2007

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Influence of melt superheat on breakup process of close-coupled gas atomization
OUYANG Hong-wu(欧阳鸿武), CHEN Xin(陈 欣), HUANG Bai-yun(黄伯云)

State Key Laboratory of Powder Metallurgy,Central South University, Changsha 410083, China

Abstract: In close-coupled gas atomization(CCGA), the influences of melt superheat on breakup process are fundamental to obtain desired or finer powder. Based on a series of Cu atomization experiment under different superheating conditions, the influences of melt superheat on breakup process were studied. Experimental results indicate that as the melt superheat is increased to 150, 200, 250 and 300 K, the mean particle size (D50) decreases consequently to 34.9, 32.3, 30.9 and 19.7 μm. Theoretical analysis reveals that the primary breakup and secondary breakup processes are close coupled, and the melt superheat radically influences the melt properties, and plays a crucial role on governing the filming process of primary breakup and the atomization modes of secondary breakup. There exists a strong nonlinear decrease of contact angle of melt to nozzle orifice wall when the superheat is increased from 250 K to 300 K, leading to a marked fall of the film thickness formed in primary breakup, and D50 of copper powders is therefore sharply reduced. However, the log-normal distribution feature of particle size has not been substantially improved.

 

Key words: gas atomization; superheat; close-coupled nozzle; powder; particle size

ISSN 1672-7029
CN 43-1423/U

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