[The sintering process of fired dental metal-ceramic alloys]

The manufacture of fixed prostheses by means of the porcelain-fused-to-metal technique is done by sintering a ceramic powder onto the metal frame work. During this process the ceramic is condensed due to fusion of the powder, accompanied by a loss of volume of the whole material. In this study the sintering process of the dental ceramic VMK 68 was investigated by means of scanning electron microscopy and determination of density. The results showed, that the sintering takes place between 680 degrees C and 950 degrees C, while the density increases from 1.56 g/cm3 to 2.54 g/cm3. The volume shrinkage amounts to 36%. Thermomechanical analyses confirmed that the starting temperature of the sintering process depends on the heating rate. The investigations showed that the instructions for use, given by the manufacturer, represent optimal conditions.