What is Negative Thermal Expansion?
|Thermal expansion refers to a material’s natural increase in size with increasing temperature. While all other metals in the world expand with increasing temperature, ALLVAR Alloys are designed to shrink with increasing temperature. These alloys exhibit a negative coefficient of thermal expansion.
This revolutionary property can compensate for the expansion or contraction of other materials in the world’s most demanding thermal stability applications.
Negative Thermal Expansion alloys can be used as compensating elements or metering structures to passively athermalize optics or as washers or spacers to maintain a constant-force load across a wide temperature range.
|The pictures show a 12" rod of ALLVAR Alloy vs. the same size Aluminum at room temperature, 100°C, and -196°C. At elevated temperatures, the ALLVAR alloy shrinks while aluminum expands. When cooled, the opposite occurs.|
How does ALLVAR compare to other alloys being used?
|Property||Units||ALLVAR Alloy||Invar||304 Stainless Steel||6061 Aluminum||Titanium 64|
|CTE Range @20°C||(ppm/°C)||-30||1.6 to 6||17.3||23.6||9|
|Max Operating Temperature||(°C)||100||200||870||120||540|
|Thermal Conductivity||(W/m·K)||6.2 - 8.7||10.15||16.2||180||6.6|
Do you offer alloys at temperatures higher than 100 degrees C?
Yes. We have received an SBIR to further develop alloys that can withstand higher temperature ranges. If you are interested in a higher temperature alloy, please contact us with more details on your application and desired temperature ranges so we can further the conversation.