Graphite & Graphene Sheet Thermal Links

Pyrolytic Graphite Links (PGL™) & Multilayered Graphene Composite Links (GCL™)

Technology Applications, Inc provides Pyrolytic Graphite Links (PGL™), and Graphene Composite Thermal Links (GCL™).

While they offer high thermal performance, all forms of pyrolytic graphite/graphene sheet straps are far more fragile than metallic or graphite fiber straps, and not ideal for certain applications requiring large scale range of motion, flexibility on all axes, or operating temperatures <60K. As a result---just as is the case in any other thermal strap program--it is critical that customers provide a comprehensive list of their requirements and description of the operational environment, in order to ensure PGL™ or GCL™ is a workable solution.

Pictured (right): PGL™ built by TAI (November 2014). 

Ultra-High Conductance Straps: 1,500 - 1,900 W/(m-K)

What sets these straps apart from our GFTS^® products, and other thermal straps in the industry? Simply put: they offer the highest thermal performance available in the market.

In place of our space-qualified GraFlex fiber bundles (GraFlex I & II), or our GraFlex III woven fiber sheet material, we utilize pyrolytic graphite sheets, or multilayered, high conductance graphene composite (97% graphene). These materials provide a material thermal conductance of 1,500 - 1,900 W/(m-K); though graphene composite may one day offer even higher thermal performance than the current 1,500 W/(m-K) available in the industry (as the technology improves). While both multilayered GCL™ and PGL™ offer extremely high thermal performance, our unique, proprietary PGS material provides nearly 2,000 W/(m-K), and offers superior thermal performance to any graphite fiber or graphene strap.  

 It should be noted that we do not provide single layer graphene straps, as there are no (actual) single layer graphene sheet thermal straps available in the world (just a multilayered composite). While single layer graphene sheet can achieve conductance in excess of 3,000 W/(m-K)---and could theoretically achieve well over 5,000 W/(m-K))---there is a catch: single layer sheets are only 0.35 nm thick. This makes single layer graphene entirely impractical--if not impossible--to use in a thermal strap application (as this would require stacking millions of sheets to make your typical strap). 

While these straps do not have years of space qualification and flight heritage (like our copper and graphite fiber thermal straps), they are a unique strap product, offering a particular set of benefits which may make them ideal in volume-restricted applications (such as electronics boxes).

Pictured (top): Graphene Thermal Link (GCL™) made with carbon composite end fittings (April 2017). Pictured (right): First generation PGL™ with inverted aluminum fittings (August 2013).

 

Important Limitations To Consider

First and foremost: don't confuse "single layer graphene," with "multilayered graphene composite," or be deceived by claims regarding the durability of pyrolytic graphite and multilayered graphene composite sheets/films/foils. While (theoretically), graphene sheets should be extremely strong ("as strong as diamond," as material manufacturers often claim), the reality is that pyrolytic graphite and graphene is delicate, fragile, and susceptible to tearing. Not only can these straps be easily torn if flexed on the lateral axis, but repeated flexing or movement on ANY axis can cause localized creasing, damage, and eventual tearing of sheets (even after as little as 10 cycles; depending on length of strap, range of motion, and other factors). This limits carbon film/foil/sheet straps to niche applications requiring no load bearing, nor large range of motion requirements.