Pool nucleate boiling of water on sintered surface by laser type metal 3D printing

Abstract

An experimental study is currently being carried out to reveal the effects of the laser power for sintering on the cavity formation of a sintered test piece, and on the pool saturation boiling of deionized water under atmospheric pressure. The test piece is made of maraging steel, and sintered at 40W and 320W laser power by use of a laser type metal 3D printer. The existence of the cavities which become boiling nucleate on the sintered surface is examined in detail by use of an electric microscope. Boiling phenomena on the sintered surface are photographed by use of a high-speed video camera, and analyzed on a monitor. As a result, cavities were confirmed on streaks of doubly sintered seams on the surface when using the 40W laser. Regarding boiling on the surface of 40W condition, the number of active cavities increases with rising wall superheat, and the surface filled with growing bubbles. In 320W condition, on the other hand, no bubble region was observed on the surface, even in the range of high wall superheat, higher than in the case of 40W, due to melting. The optimal laser power may exist in the sintering process for active boiling cavities. The results include boiling curves and performance for latent heat transport, or apparent heat transfer coefficient per cavity.

Keywords

• pool boiling
• nucleate boiling
• water
• metal 3d printing
• sintered surface