Fig. 4. The volume of the liquid agent inside and outside the crack is represented (1=100% healing agent). Oriented against gravity (a), no liquid flowed to the crack; toward gravity (b), the crack was filled.
ing alloy solidifies in the crack, welding it shut (Fig. 3).
Judging Hollow Reinforcements Computational fluid dynamic (CFD) modeling was applied
to aid in predicting the temperature necessary to induce healing and the types of cracks that could be healed in cast- ings with liquid healing agents. The analysis has shown that
Fig. 5. Simulation for a 0.25-mm crack oriented against gravity showed the liquid healing agent could partially fill the crack (a) or solidify and partially seal the crack (b).
cracks of certain sizes and orientation can be filled from a reservoir of healing liquid within castings. For the hollow micro-tube system, two different metalcasting
alloys were used: a matrix solder of 99.3% Sn-0.7% Cu with a melting point of 439F (226C) and a healing agent of 58% Bi-42% Sn (eutectic) with a melting point of 280F (138C). To investigate the types of cracks that can be healed, different crack diameters
28 Metal Casting Design anD PurChasing
July/august 2011
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