Negative Thermal Expansion

Home
/
/

What is Negative Thermal Expansion?

Negative Thermal Expansion proven by comparing ALLVAR's Negative Strain to other materials

Thermal expansion refers to a material’s natural increase in size with increasing temperature. While all other metals in the world expand alongside increasing temperature, ALLVAR Alloys are designed to shrink with increasing temperature. This shrinking while heating is known as a negative thermal expansion (Negative CTE).

This revolutionary property can compensate for the expansion or contraction of other materials in the world’s most demanding thermal stability applications. Spaceborne telescopes, high performance optical assemblies, and the secure transport of petrochemicals are a few of the applications that require enhanced stability and performance when operating under extreme shifting thermal environments. 

Negative CTE alloys can be used as compensating elements or metering structures to passively athermalize optics or create ultra stable struts for telescopes. Outside of its optics applications, negative CTE enabled washers or spacers can be used to maintain a constant-force load across a wide temperature range.

Contact Us Today to Revolutionize Your Thermal Performance

Have an application in mind? Please let us know if you have any questions.

How do Negative CTE ALLVAR Alloys compare to other alloys?

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
Yield Stress
(MPa)
405
276
215
55
828
UTS
(MPa)
800
448
505
124
895
Elastic Modulus
(GPa)
75
141
193
68.9
113.8
Density
(g/cc)
5.08
8.1
8.0
2.7
4.42
Thermal Conductivity
(W/m·K)
8.88
10.15
16.2
180
6.6

Meet the challenge of athermalization with the endless possibilities of ALLVAR.

Optical Tolerancing  The CTE of the material used in an optical housing can add to an optics overall error budget. Gain some wiggle room with ALLVAR. ALLVAR Alloys can be used as a spacer to hone in on a specific desired CTE allowing you to shift that error budget to optical tolerancing. 

SWaP-C Challenges Need to create a smaller or lighter optic that still performs across a wide range of temperatures? Unlike current athermalization solutions, ALLVAR Alloys negative thermal expansion allows housings to be smaller, lighter, and athermal. 

Maintaining performance at temperature Is your system performing well at ambient temperature, but not across its full operating temperature range? Get that performance under control with ALLVAR Alloys. ALLVAR Alloys are designed to keep systems from bolted joints to large metering structures performing at their best, regardless of temperature. 

Component CTE Mismatch Do individual components of your assembly consist of materials with different thermal expansion properties? ALLVAR Alloys compensate for this mismatch with their unique thermal expansion they grow while other materials shrink. 

CTE Control Add a new tool to your design toolbox. ALLVAR Alloy 30 enables designers to create a specific tailored CTE value by combining negative thermal expansion ALLVAR Alloys with positive thermal expansion materials to hone in on a desired CTE target. 

Cryogenics  Maintaining tight bolts is tough in cryogenic systems due to thermal mismatch. ALLVAR Alloy 30 washers were created to combat this specific problem. Ensure your fastened assemblies are consistently tight from ambient to cryogenic temperatures. 

Narrow safety margins Achieving safety margins in bolted joints is a tough challenge when specific (or tight) margins have to be maintained across a wide range of temperatures. ALLVAR Alloys negative thermal expansion washers can help maintain pre-load with narrow safety margins across a wide range of temperatures. 

Reliability Thermal expansion mismatches can be the root cause of a wide range of issues, from fastener slip and fatigue to outright failure. Fastener or bolt slip is caused by a loose bolt that doesn’t have enough clamp force to hold a joint together. ALLVAR Alloy washers can help prevent loss of clamp force and prevent fastener slips through its near-zero thermal expansion properties. Another issue that can arise is fastener fatigue, where components fatigue as they repeatedly become more and less stressed through thermal cycles. ALLVAR Alloys help counter this issue by keeping consistent stress across temperatures. Get control of your thermal expansion mismatches for more reliable performance with ALLVAR Alloys.

Vibration While vibration can cause the loosening of bolts on its own, the effect can be worsened by differential thermal expansion of components. ALLVAR Alloys can lessen these effects by creating a constant clamping force and maintaining a tight joint. 

Contact Us Today to Revolutionize Your Thermal Performance

Have an application in mind? Please let us know if you have any questions.

Do you offer Negative CTE alloys at temperatures higher than 100 degrees C?

Yes. Additional alloys that can withstand higher temperature ranges were developed as part of a NASA SBIR grant. If you are interested in a higher temperature capable alloy, please contact us with more details on your application and desired temperature ranges so we can find the best athermalization solution for you.

Where can I learn more about your alloys?

You can start by visiting our FAQ page and our video library for demonstrations and discussions.  Our News page also has information about our work to develop negative thermal expansion enabled technologies like ultra-stable struts, athermal optics, and constant-force load washers. You can also contact us for more information.

You can also find more information on ALLVAR Alloy 30’s matweb.com page or read published SPIE proceedings on SPIE’s Digital Library.

Negative CTE Related Posts

Learn more about the work being done towards negative CTE alloys and their applications in the ALLVAR blog series.

Contact Us Today to Revolutionize Your Thermal Performance

Have an application in mind? Please let us know if you have any questions.

Subscribe to our newsletter