Properties of materials—I application of adhesives

Ashworth, T.; Rechowicz, M.

doi:10.1016/0011-2275(68)90005-2

Cited by 7 publications

(1 citation statement)

References 4 publications

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“…In the latter, the role of the varnish was to provide good thermal contact with the helium exchange gas in the cryostat. GE-7031 is a polyvinyl phenolic varnish that has been commonly used for decades in various cryogenic applications as an adhesive or sample coating, owing to its good thermal conductivity and mechanical strength at quite low temperatures (Wheatley et al, 1956;Phillips, 1959;Ashworth & Rechowicz, 1968;McTaggart & Slack, 1969;Cude & Finegold, 1971;Heessels, 1971;Stephens, 1975;Jayasuriya et al, 1982;Tsatis, 1987). However, we report here that measurements for the sample embedded in GE-7031 varnish showed an unexpected symmetry-lowering phase transition at $50 K and yielded anomalous lattice constants below $150 K.…”

Section: Introductionmentioning

confidence: 99%

A cautionary tale on the use of GE-7031 varnish: low-temperature thermal expansion studies of ScF₃

2013

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GE-7031 varnish, a commonly used low-temperature adhesive and electrical insulator owing to its high thermal conductivity and mechanical strength at low temperatures, was used as a sample matrix for low-temperature powder X-ray diffraction measurements of the negative thermal expansion (NTE) material ScF 3 . When ScF 3 powder was mixed with GE-7031 varnish, an unexpected cubic to rhombohedral phase transition in the ScF 3 sample was observed at $50 K, and it exhibited smaller low-temperature unit-cell volumes than samples without the varnish matrix. Experimental observations and quantitative estimates suggest that these anomalies are the result of stress induced by a thermal expansion mismatch between the varnish matrix (large positive coefficient of thermal expansion, CTE) and ScF 3 (quite large negative CTE). The use of GE-7031 varnish as a sample matrix for low-temperature measurements should be approached with caution if a large thermal expansion mismatch is expected.

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