Titanium Casting Procedure Using Thermal Expansion Inhibited Investment: Part 1. Castability and Dimensional Change

We tried to cast the pure titanium with the experimental thermal expansion inhibited investment which has less expansion. In this study, we investigated the effects of the concentration of colloidal silica included into the mixing liquid for castability and fitness of casting. The results were as follows. 1. Using the mixing liquids including any concentration of colloidal silica, it was easy to dig out the castings and to remove the fired investment from castings. 2. There were few blowholes in castings. 3. On the surface roughness of castings, there was little difference between using the thermal expansion inhibited investment and using the investments on the market. 4. Using the liquid which included 10% colloidal silica for mixing, the castings shrank. But the increase in concentration of colloidal silica included in the mixing liquid for the investment caused the expansion of castings. This result shows that it is possible to compensate the casting shrinkage by using the experimental thermal expansion inhibited investment.