<p>The nitridation of melted silicon powder in a suspended state represents a promising method for continuously synthesizing high-quality Si₃N₄ powders. Enhancing this method's efficiency and product quality hinges on effectively inhibiting the coalescence of silicon agglomerates post-melting, thereby preserving the suspended state and promoting Si–N interface integrity. This study introduces a pre-nitriding step at 1350°C, which forms a protective Si₃N₄ layer on silicon particle surfaces. This layer acts as a barrier, maintaining particle separation even after melting, ensuring stable gas–solid and gas–liquid interfaces during subsequent nitridation. Thermogravimetric analysis was utilized to investigate the process of pre-nitriding, melting and subsequent nitridation. By acting as an isolation layer, the Si₃N₄ layer inhibits melted Si particles from flowing and coalescing to maintain the gas–solid and gas–liquid interfaces. By pre-nitriding Si powder (D50 = 5.2 µm) and subsequently heating to 1450°C at 20°C/min, complete nitride was achieved in under 200 s, with a maximum conversion rate of 3.1%/s—a thousandfold increase compared to solid silicon nitriding at 1350°C. The nitriding products consist of submicron Si₃N₄ grains, with an α-phase Si₃N₄ content exceeding 80%. This breakthrough enables continuous, energy-efficient, high-yield synthesis of submicron α-Si₃N₄ powder via nitridation of micron-sized silicon powders under atmospheric nitrogen.</p>