Investigation of the melting behavior of laser-melted lunar regolith simulant for in-situ construction

Additive manufacturing of lunar regolith is one of the most promising methods for lunar surface construction. In order to obtain excellent formability of lunar regolith, the interaction between laser and lunar regolith has to be studied in detail. In this research, the in-situ melting behaviour of lunar regolith simulant was observed using a high-speed camera under a large-spot and low-power laser beam in the vacuum environment. The effects on melting depth and melting rate, contact angle, micro-morphology and composition of samples were studied systematically. The results showed that the melting depth of the lunar regolith simulant was directly proportional to the laser power and irradiation time. Meanwhile, the higher the titanium (Ti) content of the lunar regolith simulant, the higher the light absorption and deeper the melting. Lunar regolith simulant with smaller particle was favourable for fast melting rates, whereas lunar regolith simulant with large particle produced deep melting depths. The wettability of the melt was the highest on the basalt substrate, followed by Ti and alumina substrates. These findings provide theoretical basis for the lunar surface construction in the future.