How to Measure the CTE of Quartz

When heated, matter has a tendency to expand. This expansion is described by the coefficient of thermal expansion (CTE), which is the ratio of the degree of expansion to the degree of temperature change. The coefficient of thermal expansion has industrial applications, since it determines how appropriate a given material is for a particular temperature exposure. Every system for measuring the CTE combines an ability to measure the change in length with the change in temperature of the material. Do not attempt this laboratory technique without the help of the appropriate professional to avoid hurting yourself or damaging the lab equipment.

Things You'll Need

• Silica dilatometer

Instructions

1. Position the quartz specimen in the furnace of your dilatometer.

2. Ignite the furnace to gradually increase the temperature of the quartz. The dilatometer will take measurements of the expansion of the quartz for each temperature point, using the displacement of the silica within the dilatometer to calculate the quartz expansion.

3. Use the data from your dilatometer, along with a graphing program such as Microsoft Excel, to create a graph of the temperature of the quartz on your x-axis, versus the expansion of the quartz on the y-axis.

4. Use your graphing program to calculate the slope of the curve formed by your points in step 3. This step is equal to the coefficient of thermal expansion.

References

• "Handbook of Workability and Process Design"; George Ellwood Dieter; Howard A. Kuhn; S. Lee Semiatin; 2003;
• University of Bolton: Coefficient of Thermal Expansion