Thermal expansion coefficient of titanium casting

A reliable measurement of the thermal expansion coefficient (alpha) value is required to achieve a positive thermal mismatch between metal and porcelain for porcelain-fused to metal crowns. Heating rate and specimen conditions may significantly influence the alpha value and the effects of these factors were studied. Commercially pure cast titanium rods, 'as cast' and sandblasted, were heated at various conditions. According to this study, the discrepancy of alpha values between heating and cooling conditions was insignificant when the heating (cooling) rate was reduced to 1 degrees C min(-1). It was revealed that alpha values obtained from 1 degrees C min(-1) cooling rates should be utilized. Dental porcelain with an alpha value lower than 8.5 x 10(-6) degrees C will be suitable for titanium-ceramic applications.