Characterization of Metallic Spray with Flow Impingement

• Main Authors: Pin-Jen Chen, 陳品任
• Other Authors: Muh-Rong Wang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/88306034722254868655

碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 93 === 　This research program investigates the characteristics of molten spray jet under impinging conditions, including the normal impingement on the substrate and side impingement by a cross jet. The material of the molten spray jet is eutectic alloy Sn63Pb37 and is firstly melted in the crucible. The melt is then injected by an internal mixing atomizer to become a spray jet. The particle size of the metal powders is measured with Malvern RT-sizer. Experiments of the impingement of the molten spray jet on the substrate show that the particle size of the metal powder increases from 3.13μm to 12.87μm when the height of the substrate ring is 0 cm as the separation distance from the exit of the atomizer to the substrate increasing from 20 cm to 40 cm. It implies that the size of the metal powder can be controlled by adjusting the position of the substrate. It’s more important that the ultra-fine metal powder can be produced by this particular design. Similarly, the particle size of the metal powder increases from 3.79μm to 10.43μm when the substrate designed with a ring of 1.5 cm height is placed at 20cm to 40cm from the atomizer. This result has not been reported in the literature using the conventional atomizers. Moreover, the production rate of metal powder increases from 52% to 81% with the separation distance from the outlet of the atomizer to the substrate increasing from 20 cm to 40 cm. On the other hand, the production of spray forming material decreases from 48% to 19% as the substrate is placed at 20 cm to 40 cm from the atomizer. It is concluded that this process can be used to produce the fine metal powders as well as the spray forming materials. Experiments of the spray with side impingement show that the size of metal powder decreases from 14.11μm to 12.94μm under an impinging pressure of 2 bar. The size of metal powder increases from 14.11μm to 16.41μm when the pressure of side impinging flow is 8 bar. This implies that the droplets within the spray jet experience the coalescence and the breakup processes during the impingement of the side flow. Hence re-distribution of the droplets can be controlled by adjusting the impingement of the side flow.