Fabricated Li filled heat pipes that operate in air up to 1400C. Heat pipes approximately 14” long, 1” in diameter. Constructed with tri-layer (SiC/C/W) of outside layer of CVD SiC deposited on graphite and inside layer of CVD W deposited on graphite.
Heat pipe operating in air with gas flame next to simple SiC tube. Photo shows the extreme thermo conductivity and heat uniformity of the heat pipe compared to the SiC tube. SiC heat pipe and SiC tube positioned through holes in brick furnace chamber. Gas flame impinges on tubes from under brick.
Cross section of end of heat pipe Li fill tube. Simplified fabrication steps:
1. CVD W on inside of two graphite tubes
2. Join tubes by electron beam welding of W
3. Attach W fill tube
4. Out gas W/graphite tubes at 1500C in vacuum
5. Fill W tube with Li and seal fill tube
6. Cover fill tube with graphite & cement
7. CVD SiC on outer surface