Abstract Hot gas atomization in spray forming has been used for the first time to improve the quality of spray-formed tubular deposits. This technique reduces gas consumption and produces smaller droplets than cold gas atomization. The flight velocity and cooling rate of the atomized droplets increase with increasing gas temperature. These features can further influence the quality of the spray-formed deposits. Until now, spray-formed tubes have not been used on industrial scale due to insufficient deposit quality in terms of porosity and bonding to the substrate. Using a close-coupled atomizer (CCA), qualitative improvements of the as-sprayed deposits have been previously studied. In the present study, a comparative investigation is done to find the influence of hot gas atomization on the spray forming of the bearing steel AISI 52100 (100Cr6) using a close-coupled atomizer. The spray-formed deposit with hot gas atomization (gas temperature about 300 °C) shows lower deposit surface temperature and smaller grain size in comparison to the deposit produced under cold gas atomization condition due to smaller droplet diameter and higher cooling rate of the droplets. Moreover, the as-sprayed deposits under hot gas atomization show a higher relative density at a lower deposit surface temperature, which extends the process window for the flexible production of spray-formed tubes.

中文翻译：

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热气雾化对使用紧密耦合雾化器 (CCA) 的钢管喷雾成形的影响

摘要 喷射成形中的热气雾化首次被用于提高喷射成形管状沉积物的质量。与冷气雾化相比，该技术可减少气体消耗并产生更小的液滴。雾化液滴的飞行速度和冷却速度随着气体温度的升高而增加。这些特征会进一步影响喷涂形成的沉积物的质量。到目前为止，由于在孔隙率和与基材的结合方面的沉积质量不足，喷涂成型的管尚未在工业规模上使用。使用紧密耦合雾化器 (CCA)，先前已经研究了喷涂沉积物的质量改进。在目前的研究中，进行了对比研究，以发现热气雾化对轴承钢 AISI 52100 (100Cr6) 使用紧密耦合雾化器的喷雾成形的影响。与冷气雾化条件下产生的沉积物相比，由于液滴直径更小和液滴冷却速度更快，热气雾化（气体温度约 300°C）喷雾形成的沉积物显示出更低的沉积物表面温度和更小的晶粒尺寸。此外，热气雾化下的喷涂沉积物在较低的沉积表面温度下显示出较高的相对密度，这扩展了喷涂成型管的灵活生产的工艺窗口。与冷气雾化条件下产生的沉积物相比，由于液滴直径更小和液滴冷却速度更快，热气雾化（气体温度约 300°C）喷雾形成的沉积物显示出更低的沉积物表面温度和更小的晶粒尺寸。此外，热气雾化下的喷涂沉积物在较低的沉积表面温度下显示出较高的相对密度，这扩展了喷涂成型管的灵活生产的工艺窗口。与冷气雾化条件下产生的沉积物相比，由于液滴直径更小和液滴冷却速度更快，热气雾化（气体温度约 300°C）喷雾形成的沉积物显示出更低的沉积物表面温度和更小的晶粒尺寸。此外，热气雾化下的喷涂沉积物在较低的沉积表面温度下显示出较高的相对密度，这扩展了喷涂成型管的灵活生产的工艺窗口。