Call: 708-425-9080
Common Cryogenic Materials: G-10 & G-11

G-10 and G-11 are glass fabric/epoxy industrial laminates. G-10 (and G-11) is often used as a generic term, however G-10, G-10-FR4, G-11, G-10CR, G-11CR are all different variants of epoxy laminates and are defined in the National Electrical Manufacturing Association (NEMA) Specification “LI 1 Industrial Laminating Thermosetting Products” and in MIL-I-24768. The NEMA glass fabric/epoxy industrial laminates were not originally developed for use in cryogenic applications. Instead they were developed to provide high mechanical strength and good electrical insulation properties at room temperature for such applications as printed circuit boards and structural supports in electromechanical assemblies.
The G-10, G-11, and G-10-FR4 (fire retardant version of G-10) grades can all meet NEMA specifications while varying in fabric style, epoxy formulation, and manufacturing procedures. This leads to a variability in low temperature mechanical and thermal properties that is not always acceptable in cryogenic design applications. The G-10CR and G-11CR grades were specifically developed to reduce this variability in properties and to make them more suitable for cryogenic applications. However the standard grades are often used in non-critical applications.
G-10CR and G-11CR are both fabricated from the same glass fabric of silane-finished E glass with an interlacing thread count of 43 +/-3 per inch in the warp (length) direction and 32+/-2 per inch in the in the fill (width) direction. (Ref. 1) (In a fabric, the warp direction is the long direction or the direction along the roll while the fill direction is the direction across the roll). The glass fabric is impregnated and cured in a non-brominated epoxy resin. G-11CR was formulated to have improved long term properties in a radiation environment. The differences in thread count in the warp and fill directions result in different physical properties in these directions.
As mentioned above, the term G-10 is often used interchangeably to mean G-10CR, etc. For the next paragraph of general statements we are going to do the same.
G-10 is widely used as a thermal insulating material in structural supports in cryogenics applications. G-10 tube is vacuum-tight to air and nitrogen gas and vacuum-tight epoxy joints to stainless steel are possible. (Ref. 2) It is used to make low heat leak necks of dewars. In terms of vacuum compatibility, G-10 compares reasonably well with other plastics. It is relatively inexpensive and relatively strong. The glass cloth gives G-10 a thermal contraction which is well matched to that of stainless steel.
Locating material property data at cryogenic temperatures is, of course, a key to utilizing G-10CR and G-11CR in cryogenic design. The National Institute of Standards and Technology (NIST) maintains an online database for material properties of materials common to cryogenic applications. Properties for G-10CR are available from this database; unfortunately, properties of G-11CR are not. A great paper resource (if you can find it as it’s out of print) is “LNG Materials & Fluids, A User’s Manual of Property Data in Graphic Format,” a 1977 publication that contains data on G-10CR. Most cryogenic texts (Ref. 2, for example) contain data on “G-10”. Reference 1 contains information on the material properties of G-11CR. If any of our readers have a source for G-11CR property data at cryogenic temperatures we would be interested.
Conclusions
Utilizing the correct specifications and properties of materials in cryogenic design is one more way that Meyer Tool strives to Reduce Project Risk to ensure our customers achieve the lowest total cost of ownership.
References
The G-10, G-11, and G-10-FR4 (fire retardant version of G-10) grades can all meet NEMA specifications while varying in fabric style, epoxy formulation, and manufacturing procedures. This leads to a variability in low temperature mechanical and thermal properties that is not always acceptable in cryogenic design applications. The G-10CR and G-11CR grades were specifically developed to reduce this variability in properties and to make them more suitable for cryogenic applications. However the standard grades are often used in non-critical applications.
G-10CR and G-11CR are both fabricated from the same glass fabric of silane-finished E glass with an interlacing thread count of 43 +/-3 per inch in the warp (length) direction and 32+/-2 per inch in the in the fill (width) direction. (Ref. 1) (In a fabric, the warp direction is the long direction or the direction along the roll while the fill direction is the direction across the roll). The glass fabric is impregnated and cured in a non-brominated epoxy resin. G-11CR was formulated to have improved long term properties in a radiation environment. The differences in thread count in the warp and fill directions result in different physical properties in these directions.
As mentioned above, the term G-10 is often used interchangeably to mean G-10CR, etc. For the next paragraph of general statements we are going to do the same.
G-10 is widely used as a thermal insulating material in structural supports in cryogenics applications. G-10 tube is vacuum-tight to air and nitrogen gas and vacuum-tight epoxy joints to stainless steel are possible. (Ref. 2) It is used to make low heat leak necks of dewars. In terms of vacuum compatibility, G-10 compares reasonably well with other plastics. It is relatively inexpensive and relatively strong. The glass cloth gives G-10 a thermal contraction which is well matched to that of stainless steel.
Locating material property data at cryogenic temperatures is, of course, a key to utilizing G-10CR and G-11CR in cryogenic design. The National Institute of Standards and Technology (NIST) maintains an online database for material properties of materials common to cryogenic applications. Properties for G-10CR are available from this database; unfortunately, properties of G-11CR are not. A great paper resource (if you can find it as it’s out of print) is “LNG Materials & Fluids, A User’s Manual of Property Data in Graphic Format,” a 1977 publication that contains data on G-10CR. Most cryogenic texts (Ref. 2, for example) contain data on “G-10”. Reference 1 contains information on the material properties of G-11CR. If any of our readers have a source for G-11CR property data at cryogenic temperatures we would be interested.
Conclusions
- Cryogenic engineers should be careful when specifying glass fabric/epoxy industrial laminates for critical structural applications. The cryogenic material properties of NEMA G-10 and G-10FRP and G-11 grades can vary widely while still meeting the NEMA specification.
- The G-10CR and G-11CR grades have been specifically developed to address this issue of uniform material properties at cryogenic temperatures.
- NIST maintains an online database that includes the cryogenic material properties of G-10CR. Data for cryogenic material properties of G-11CR are not as readily available.
Utilizing the correct specifications and properties of materials in cryogenic design is one more way that Meyer Tool strives to Reduce Project Risk to ensure our customers achieve the lowest total cost of ownership.
References
- Mechanical, Electrical and Thermal Characterization of G-10CR and G-11CR Glass Cloth Epoxy Laminates Between Room Temperature and 4K, M.B. Kasen, G.R. MacDonald, D.H. Beekman Jr. and R.E. Schramm, Adv. Cryogenic Eng. 26, 235 (1980).
- Handbook of Cryogenic Engineering, Weisend II, John, Taylor & Francis, 1998.
- LNG Material & Fluids, A User’s Manual of Property Data in Graphical Format, National Bureau of Standards, 1977.