| Summary: | Gas atomization (GA) is the main method to produce metal powders for additive manufacturing (AM) because of its low cost and high efficiency. However, the liquid breakup behaviors in high-speed gas flow during GA remains unclear, especially the primary breakup in the near field and the secondary breakup in the far field. Great difficulty exists in in-situ observation of the interactions between high-speed gas and high-temperature molten metal because of the limitations of the enclosed environment. Here, we built a new GA simulation system with a close-coupled atomizer utilizing liquids with low melting temperature, such as water, glycerin, etc. We use a high-speed camera to capture the evolution of liquid behaviors at various parameters. We first reveal that four primary breakup modes and four secondary breakup modes exist in the GA process, and these breakup modes significantly influence the particle size distribution (PSD) and the defects of the powder. Besides, the breakup modes are clarified by the dimensionless analysis. This manuscript provides an effective experimental platform to understand the breakup behaviors of the liquid jet in GA and suggests the optimal breakup mode for powder production.
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