Abstract
Thermal expansion of 18 casting alloys and of 3 commercially available phosphate-bonded investments under various conditions of the mixing liquid (distilled water, 20% aqueous glycerol solution, or the special liquid delivered with the powder) and mixing time (30, 45, or 60s) was measured using a differential dilatometer. The total thermal expansion of alloys from room to solidus temperature was calculated using Gruneisen's formula.
For investments with an acceptable low setting expansion, Platorit mixed with the glycerol solution at the mixing time of 60s showed the heighest thermal expansion of 1.31±0.02%.
None of the investments hed sufficient thermal expansion to compensate for the thermal shrinkage of the alloys.
