This is quoted for ceramic frits and is derived from the graph produced by a dilatometer. The line (representing increasing thermal expansion) climbs steeply as temperature increases. When the transition point is reached an inflection (direction change) in the curve occurs, after this the expansion increases more rapidly until the material reaches the softening point. That point is the peak of the curve, after that the line drops off vertically and melting proceeds.
This is equal to the sintering point in the HMA test.
Dialometric chart produced by a dilatometer. The curve represents the increase in thermal expansion that occurs as a glass is heated. Changes in the direction of the curve are interpreted as the transformation (or transition) temperature, set point and softening point (often quoted on frit data sheets). When the thermal expansion of a material is quoted as one number (on a data sheet), it is derived from this chart. Since the chart is almost never a straight line one can appreciate that the number is only an approximation of the thermal expansion profile of the material.
Value in degrees: e.g. 560C
Glass Transition Temperature at answers.com
Glass Transition Temperature at Wikipedia
|Tests||Co-efficient of Linear Expansion|
|Tests||Frit Softening Point|
|Tests||Heating Microscope Analysis|
|Tests||Heating Microscope Analysis for Frits|
Frits are used in ceramic glazes for a wide range of reasons. They are man-made materials of controlled chemistry with many advantages or raw materials.
Test conducted primarily on materials use to make bodies or glazes.