Continuous electron beam melting technology of silicon powder by prefabricating a molten silicon pool

- We achieved continuous electron beam melting of silicon powder by prefabricating a molten silicon pool for the first time.
- The characteristic of electron beam melting of silicon powder was revealed.
- The feasibility of continuous silicon powder melting was analyzed in basic theory of convective heat transfer.
- The most appropriate powder feeding rate was determined by considering various factors in this experiment.
- Compared with the melting of silicon block, this continuous powder feeding process was confirmed to be more cost saving.

We successfully achieved the continuous melting of silicon powder in a vacuum electron beam melting system. The characteristic of electron beam melting of silicon powder was revealed by comparing the three different approaches to prefabricate the molten silicon pool. The application of silicon block can be regarded as the most efficient method to prefabricate a stable molten silicon pool. Afterward, the silicon powder was added into the molten silicon pool at different rates by a spiral silicon powder feeding device. Finally, all of the silicon powder was melted completely. Although the P removal efficiency decreases with increasing powder feeding rate during the powder feeding process, an appropriate increase in the powder feeding rate is not only beneficial to improve the melting efficiency of silicon powder but also conductive to the improvement in uniformity of the obtained silicon ingot. Therefore, the powder feeding rate of 10 g/min was the best option in this study. Compared with the melting of silicon block, which has been wildly applied, this continuous powder feeding process can be beneficial to saving smelting time and the total cost.