Sequential Solidification of Metal Powder by a Scanning Microwave Applicator

Area of Science:

• Materials Science
• Additive Manufacturing
• Microwave Engineering

Background:

• Traditional additive manufacturing (AM) methods like laser-based systems face limitations in speed and cost.
• Localized Microwave Heating (LMH) has previously shown potential for incremental metal powder solidification.
• A continuous, lateral scanning approach for LMH in AM has not been fully explored.

Purpose of the Study:

• To investigate the fundamental feasibility of continuous, lateral metal powder solidification using localized microwave heating (LMH).
• To evaluate LMH as a potential alternative for additive manufacturing (AM) and 3D printing (3DP) of metal parts.
• To compare the properties of LMH-processed metal parts with those produced by conventional laser-based AM systems.

Main Methods:

• Utilizing a scanning, all-solid-state microwave applicator for localized microwave heating (LMH).
• Implementing a continuous lateral scanning process, layer by layer, analogous to laser scanning in powder beds.
• Conducting experiments on bronze powder with controlled scanning rates (~1 mm³/s) and microwave power (~0.25 kW).
• Mechanically confining the solidified layers to dimensions of approximately 1-4 mm thickness and 2-4 mm width.

Main Results:

• Achieved LMH solidification in bronze powder at scanning rates of ~1 mm³/s using ~0.25-kW microwave power.
• Produced imperfect solid bars (~20×4×5 mm³) with rough surfaces, demonstrating successful lateral solidification.
• Successfully demonstrated the joining of solidified metal parts in an L-shape configuration.
• Experimental solidified products exhibited hardness and density properties comparable to laser-based AM products.

Conclusions:

• The continuous lateral LMH scanning concept shows fundamental feasibility for metal powder solidification in AM.
• LMH offers a potential solid-state alternative for additive manufacturing of metal parts.
• Further research is needed to optimize the process and overcome limitations such as surface roughness and mechanical confinement.