Question: What is the Coefficient of thermal expansion or CTE for silicone at different temperatures compared with other steel or aluminum for a 10 inches long example part?
Answer: Thermal expansion is a change in volume or size of something in response to a change in temperature. The molecular interactions in most materials increase with the increase of temperature causing expansion in the material. Thermal expansion is a direct function of the material and silicones expand significantly greater than other materials like metals for the same change in temperature.
Thermal expansion is usually expressed in one of two ways either volumetric expansion or more commonly linear expansion expressed as a coefficient. For example silicone may expand linearly 5.9E-4 to 7.9E-4 in/in-C compared to aluminum at 23.0E-6 in/in-C or steel at 10.8E-6 in/in-C. So for the sake of comparison, a temperature change from 65 degrees to 150 degrees Fahrenheit for a 10 inches long piece would translate to an expansion for a given material of approximately:
Silicone: 0.279” – 0.374”
The silicone can expand 34X the aluminum and 73X the steel which for higher temperature applications may be worth noting. Many silicone manufacturers do not include thermal expansion rates on their data sheets but will usually provide them by request.