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Review : Thermal contact problems at cryogenic temperature
Open accessAbstract
This paper addresses technical problems of thermal contact conductance or resistance which inevitably occurs in most cryogenic engineering systems. The main focus of this paper is to examine what kind of physical factors primarily influences the thermal contact resistance and to suggest how it can be minimized. It is a good practical rule that the contact surface must have sub-micron roughness level with no oxide layer and be thinly covered by indium, gold, or Apiezon-N grease for securing sufficient direct contact area. The higher contact pressure, the lower the thermal contact resistance. The general description of this technique has been widely perceived and reasonable engineering results have been achieved in most applications. However, the detailed view of employing these techniques and their relative efficacies to reduce thermal contact resistances need to be thoroughly reviewed. We should consider specific thermal contact conditions, examine the engineering requirements, and execute each method with precautions to fulfil their maximum potentials.
Overview
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Written from the paper’s full text.
TL;DR
This review summarizes practical factors controlling thermal contact resistance in cryogenic systems and recommends surface preparation, contact pressure, and interstitial materials to minimize it. It emphasizes that true contact area can be only about 1–2% of the apparent area, so careful assembly is critical for conduction-cooled superconducting devices.
Key findings
- True contact area inside the apparent contact region can be only about 1–2% [1]; without interstitial material, micro-asperities cause large temperature jumps at the interface.
- Nominal thermal contact resistance per unit area can be relatively high, between 10⁻³ and 10⁻⁴ m²K/W, equivalent to 1 K/W and 0.1 K/W respectively for a 10 cm² contact area.
- As contact pressure increases from 0.6 to 15 MPa, thermal contact resistance decreases linearly according to reference [2]; higher contact pressure generally lowers resistance.
- Recommended practice: contact surfaces should have sub-micron roughness, no oxide layer, and be thinly covered by indium, gold, or Apiezon-N grease. Indium and gold have room-temperature thermal conductivities of 86 W/m·K and 317 W/m·K, respectively; optimum interstitial thickness is approximately twice the surface roughness [17].
- Thermal contact resistance decreases as temperature goes down, unlike bulk copper which shows maximum thermal conductivity around 20 K.
Methods
- Review paper focused on practical and experimental results, not theoretical phonon dynamics; it examines fundamental aspects of thermal contact between two solid surfaces and ways to improve thermal contact resistance.
- It describes multiple experimental apparatuses for measuring thermal contact resistance: room-temperature measurement under high contact pressure up to 15 MPa by hydraulic jack; sample arrangement between 4 K and 300 K with active thermal platform; liquid nitrogen setup between 85 K and 300 K; horizontally exerted contact force under symmetric situation; indium/sapphire measurement below 5 K; and an in-situ force measurement component.
- Main analysis is a qualitative synthesis and compilation of numerous thermal contact resistance measurements, presented in Fig. 4 as thermal conductance, limited to metal contacts of copper in the temperature range higher than 4 K. Factors considered include oxide layer, contact pressure, surface roughness, interstitial material, cooling temperature, amount of filled interstitial material, and filling before or after pressing.
Limitations
- The paper states that theoretical consideration of phonon dynamics is beyond its scope.
- The paper states that measurement data are widely scattered due to different preparation protocols and diverse techniques, and some experimental data lack specific physical descriptions, so values should be referred to only as nominal representative ones.
- The paper states that most cryogenic experiments did not measure actual contact pressure; compressing force is usually estimated by screw torque at room temperature assembly, with uncertainty due to thermal contraction and possible change of tightening force.
- Evident from the text: this is a review without new primary experiments, and its quantitative focus is limited to copper metal contacts above 4 K.
Model-written summary. Check it against the paper before relying on it.
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Claims the paper makes
0 of 14 cited sources checked · 0 supported · 0 flagged
- Findingreasoning
The nominal value of thermal contact resistance per unit area can be relatively high between 10^-3 and 10^-4 m2 K/W in situations where heat flow is negligible.
“The nominal value of thermal contact resistance per unit area can be relatively high in these situations between 10 -3 and 10 -4 m 2 K/W.”
Quote in the paperNot a substantial claim - Findingcitation
As the contact pressure increases from 0.6 to 15 MPa, the thermal contact resistance decreases linearly.
“As the contact pressure increases from 0.6 to 15 MPa, the thermal contact resistance decreases linearly according to the reference [2].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [2]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Findingown data
Thermal contact resistance decreases as temperature goes down.
“Thermal contact resistance decreases as temperature goes down as shown in Fig. 4.”
Quote in the paperSubstantial claim - Findingcitation
The surface roughness value in the range below 3 micro-meter also influences the sensitivity of thermal contact resistance upon contact pressure.
“The surface roughness value in the range below 3 micro-meter also influences the sensitivity of thermal contact resistance upon contact pressure [2].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [2]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Findingcitation
The optimum thickness of the interstitial material is approximately twice of the surface roughness to ensure complete covering of the micro-asperities.
“The optimum thickness of the interstitial material is approximately twice of the surface roughness [17] to ensure complete covering of the micro-asperities.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [17]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Interpretationreasoning
In cryogenic applications where the cooling target is conductively cooled in a vacuum insulation environment, thermal contact resistance can be a serious problem if proper precautions are not made.
“In various cryogenic applications where the cooling target is conductively cooled at vacuum insulation environment, thermal contact resistance can be a serious problem if proper precautions are not made.”
Quote in the paperSubstantial claim - Premisenone given
In the case of copper, sub-micron roughness value can be readily achievable with lapping or polishing.
“In case of copper, sub-micron roughness value can be readily achievable with lapping or polishing.”
Quote in the paperSubstantial claim - Premisecitation
Unless the copper surface is heated in an oxygen environment, the oxide layer having much less than 1 micrometer thickness does not contribute significant thermal contact resistance.
“Unless the copper surface is heated at oxygen environment, the oxide layer having much less than 1 micro meter thickness [7,8] does not contribute significant thermal contact resistance.”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [7]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites [8]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Interpretationreasoning
The boundary between two dissimilar materials can be considered as a barrier to reflect thermal wave to create additional thermal resistance.
“The boundary can be considered as a barrier to reflect thermal wave to create additional thermal resistance.”
Quote in the paperNot a substantial claim - Interpretationnone given
Poor thermal contact with a non-negligible self-heating effect is the main source of cryogenic thermometry error.
“Poor thermal contact with non-negligible self-heating effect is the main source of cryogenic thermometry error.”
Quote in the paperNot a substantial claim - Interpretationreasoning
The contact gap filled with another thermally conductive solid or liquid material decreases the thermal contact resistance.
“Fig. 1 (c) illustrates that the contact gap is filled with another thermal conductive solid or liquid material to decrease the thermal contact resistance.”
Quote in the paperNot a substantial claim - Interpretationreasoning
Atomic bonding through welding, diffusion bonding, soldering, and plating would give rise to the best surface contact condition for heat transfer.
“This fact confirms that the atomic bonding through welding, diffusion bonding, soldering, and plating would give rise to the best surface contact condition for heat transfer although some techniques are not permitted in a specific application due to severe physical and thermal conditions for the preparation.”
Quote in the paperSubstantial claim - Interpretationreasoning
Small roughness would induce better thermal contact because of the large true contact area.
“Considering the magnified view of the two contacted surfaces, we can deduce the small roughness would induce better thermal contact because of the large true contact area.”
Quote in the paperSubstantial claim - Interpretationreasoning
The temperature jump at the contact can be diminished if the two surfaces are forced to deform by external contact pressure and the true contact area is substantially increased.
“The temperature jump at the contact can be diminished if the two surfaces are forced to deform by external contact pressure and the true contact area is substantially increased as shown in Fig. 1 (b).”
Quote in the paperNot a substantial claim - Interpretationreasoning
Surface roughness basically determines true contact area before any contact pressure is exerted.
“The surface roughness basically determines true contact area before any contact pressure is exerted.”
Quote in the paperSubstantial claim - Interpretationnone given
The contact pressure on the surface with certain smoothness invokes elastic or plastic deformation of the original micro-asperities of the surfaces.
“The contact pressure on the surface with certain smoothness invokes elastic or plastic deformation of the original micro-asperities of the surfaces.”
Quote in the paperSubstantial claim - Premisecitation
In a magnified view of two mated solid surfaces, the true contact area inside the apparent contact region can be only about 1-2%.
“Although two mated surfaces look geometrically matched, the true contact area inside the apparent contact region can be only about 1-2 % [1].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [1]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Interpretationreasoning
In a given geometric contact area of the surface, the actual true contact area depends on the smoothness of surface and the contact pressure.
“In a given geometric contact area of the surface, the actual true contact area depends on the smoothness of surface and the contact pressure.”
Quote in the paperSubstantial claim - Interpretationreasoning
The potential cooling capacity of a cryocooler is diminished because of poor thermal bridging technique.
“The potential cooling capacity of a cryocooler is simply diminished because of poor thermal bridging technique.”
Quote in the paperSubstantial claim - Premisenone given
The oxide layer of copper is typically composed of CuO or Cu2O depending on how the surface is prepared.
“The oxide layer of copper is typically composed of CuO or Cu 2 O depending on how the surface is prepared.”
Quote in the paperNot a substantial claim - Interpretationreasoning
The micro-scale asperities cause relatively large temperature jump at the interface where no interstitial material exists, such as in a vacuum condition.
“The micro-scale asperities comprised of small peaks and valleys cause relatively large temperature jump at the interface where no interstitial material exists such as in a vacuum condition.”
Quote in the paperSubstantial claim - Study design and conductreasoning
Most experiments have been carried out without measuring the actual contact pressure in cryogenic experiments.
“Most experiments have been carried out without measuring the actual contact pressure in the cryogenic experiments.”
Quote in the paperSubstantial claim - Interpretationreasoning
Even for the same specific thermal contact resistance value, a significant temperature jump can occur if the amount of heat across the contact surfaces increases.
“Even for the same specific thermal contact resistance value, however, a significant temperature jump can occur and cause a problem if the amount of heat across the contact surfaces increases.”
Quote in the paperSubstantial claim - Interpretationreasoning
The thermal contact problem is further alleviated if an appropriate interstitial material is interposed in the space between two solids.
“The thermal contact problem is further alleviated if an appropriate interstitial material is interposed in the space between two solids.”
Quote in the paperNot a substantial claim - Interpretationreasoning
This problem becomes worse if the interstitial material is composed of polymer such as grease or epoxy.
“This problem becomes worse if the interstitial material is composed of polymer such as grease or epoxy.”
Quote in the paperNot a substantial claim - Interpretationnone given
Since the contacted surfaces of solids always exist like a grain boundary, the thermal conduction mechanism governing thermal contact resistance is easily affected by boundary scattering.
“Since the contacted surfaces of solids, however, always exist like a grain boundary, thermal conduction mechanism of governing thermal contact resistance is easily affected by the boundary scattering.”
Quote in the paperNot a substantial claim - Interpretationreasoning
The sensitivity of thermal contact resistance to contact pressure depends on the contact material, its hardness, and its yield strength because the amount of deformed area is different for different material properties.
“The sensitivity surely depends on the contact material, its hardness, and its yield strength because the amount of deformed area is different for different material properties.”
Quote in the paperNot a substantial claim - Interpretationcitation
The phenomenon of showing no peak in thermal contact resistance is similar to the behavior of nanowire where thermal conductivity decreases monotonically with temperature.
“The phenomenon of showing no peak in thermal contact resistance is similar to the behavior of nanowire where thermal conductivity decreases monotonically with temperature [16].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [16]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Interpretationreasoning
The void problem can get worse if the temperature is lowered and the thermal contraction of the filler material exceeds that of the mating solids.
“This problem can get worse if the temperature is lowered and the thermal contraction of the filler material exceeds that of the mating solids.”
Quote in the paperSubstantial claim - Interpretationreasoning
Extra interstitial material may cause extra thermal resistance because of its smaller thermal conductivity than that of copper.
“It is indicated, however, that the extra interstitial material may cause extra thermal resistance because of its smaller thermal conductivity than that of copper.”
Quote in the paperSubstantial claim - Premisenone given
The assembled structure at room temperature experiences thermal contraction when it is cooled down to cryogenic temperature.
“The assembled structure at room temperature experiences thermal contraction when it is cooled-down to cryogenic temperature.”
Quote in the paperSubstantial claim - Interpretationreasoning
In compression between two surfaces without melting, malleability and contact pressure are important parameters to determine the final result of interstitial material because it is spread by force and has to fill the gap as a solid phase.
“Malleability and contact pressure are important parameters to determine the final result of interstitial material because it is spread by force and has to fill the gap as a solid phase.”
Quote in the paperNot a substantial claim - Premisereasoning
In most cryogenic applications, soft solids are frequently chosen for interstitial materials.
“In most cryogenic applications, therefore, soft solids are frequently chosen for interstitial materials.”
Quote in the paperNot a substantial claim - Premisecitation
There are three practical methods to apply metallic interstitial materials on the bare contact surfaces.
“There are three practical methods to apply metallic interstitial materials on the bare contact surfaces [18].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [18]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Interpretationreasoning
The interstitial material with its own thermal conductivity contributes extra thermal contact conductance which is better than the dry contact condition.
“The interstitial material with its own thermal conductivity contributes extra thermal contact conductance which is better than the dry contact condition.”
Quote in the paperSubstantial claim - Interpretationnone given
When a liquid filler is solidified, undesirable void space may occur to negate its filling effect.
“When it is solidified, however, undesirable void space may occur to negate its filling effect.”
Quote in the paperSubstantial claim - Interpretationreasoning
The initially filled void by grease or epoxy at room temperature may recreate an empty pocket at cryogenic temperature.
“The initially filled void by grease or epoxy at room temperature may recreate an empty pocket at cryogenic temperature.”
Quote in the paperSubstantial claim
- Probably not a substantial claim. 44
- It may state two separate claims as one. 22
- The quote only partly states this claim. 1
Probably not a substantial claim. The paper’s conclusions may not depend on it.
FindingreasoningThe measurement data are widely scattered due to different preparation protocols as well as diverse techniques applied.
“It is interesting that the measurement data are widely scattered due to different preparation protocols as well as diverse techniques applied.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
Findingnone givenWith a thermal resistance of 1 K/W, only 1 K temperature difference occurs with 1 W of heat flow.
“In the case of 1 K/W, only 1 K temperature difference occurs with 1 W of heat flow.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
PremisecitationIn anodized aluminum, the oxide layer of the surface must be thoroughly removed before assembly for thermal contact because the anodized surface has thermal conductivity of merely 1 W/m.K as an approximate value.
“In the case of anodized aluminum, however, the oxide layer of the surface must be thoroughly removed before assembly for thermal contact because the anodized surface has thermal conductivity of merely 1 W/m .K as an approximate value [9].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [9]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim.
InterpretationreasoningWhen two solid surfaces meet, thermal or electrical contact resistance inevitably occurs due to surface irregularity.
“When two solid surfaces meet for contact, the thermal or electrical contact resistance inevitably occur due to this surface condition.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenThe fundamental mechanism of thermal contact resistance is phonon scattering when two dissimilar materials meet.
“Fundamental mechanism of thermal contact resistance is phonon scattering when two dissimilar materials meet each other.”
Quote in the paperNot a substantial claimProbably not a substantial claim. It may be too vague to check against evidence. It may state two separate claims as one.
Interpretationown dataThe data can present the essential characteristics of thermal contact resistance and suggest a practical way to overcome thermal contact problems in general.
“Nevertheless, the data can present the essential characteristics of thermal contact resistance and suggest a practical way to overcome thermal contact problems in general.”
Quote in the paperNot a substantial claim- Rests on an assumption: The thermal contact resistance data compiled from different studies are comparable enough to reveal general trends despite different preparation protocols and missing physical descriptions.
Probably not a substantial claim. The paper may give no reason why it holds.
Interpretationnone givenThe complex physical situation makes theoretical prediction of thermal contact resistance particularly difficult and inaccurate.
“The complex physical situation makes the theoretical prediction of thermal contact resistance, particularly difficult and inaccurate.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
Study design and conductreasoningSome experimental data are obtained without specific physical descriptions in detail, so the values should only be referred to as nominal representative ones.
“Since some experimental data are obtained without specific physical descriptions in detail, we should only refer these values as nominal representative ones.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
Interpretationnone givenIn conduction-cooled superconducting devices, the temperature jump in imperfect contacts between metals creates additional entropy generation associated with finite temperature-difference heat transfer and increases the cooling load to a cryogenic refrigeration system.
“In the case of conduction cooling mode for a superconducting device, the temperature jump in imperfect contacts between metals creates additional entropy generation that is associated with finite temperature-difference heat transfer and results in the increased cooling load to a cryogenic refrigeration system.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
Interpretationnone givenIn general, the inherent properties of materials, the existence of an oxide layer, the temperature, and the contact pressure are main influencing components to the thermal contact result.
“In general, the inherent properties of materials, the existence of oxide layer, the temperature, and the contact pressure are main influencing components to the thermal contact result.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
InterpretationreasoningExperimental assessment is necessary and more useful for practical applications than theoretical prediction of thermal contact resistance.
“Experimental assessment is, therefore, necessary and more useful for practical applications.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
PremisecitationThe softer material gets inherently more benefit of surface finish treatment, but its effect is more noticeable with contact pressure in association with easier plastic deformation.
“It is clear that the softer material gets inherently more benefit of surface finish treatment, but its effect is more noticeable with contact pressure in association with easier plastic deformation [2].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [2]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
It may state two separate claims as one.
Interpretationnone givenThe physical factors resulting in a much smaller true contact area than the apparently projected area are the roughness of the surface, poor filling of the interstitial material in the gap, and inadequate contact pressure.
“The physical factors of resulting in much smaller true contact area than the apparently projected area are the roughness of the surface, the poor filling of the interstitial material in the gap, if any, and the inadequate contact pressure.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
Interpretationnone givenIf the heat flow across the contact surfaces is negligible, the thermal contact problem does not draw much attention.
“If the heat flow across the contact surfaces is negligible, thermal contact problem does not draw much attention.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
InterpretationreasoningPoor filling of the interstitial material is attributed to insufficient initial amount, but thermal contraction of too much filled interstitial material can also cause poor filling due to thermal contraction mismatch during cooling.
“The poor filling is attributed to insufficient initial amount of the interstitial material, but the thermal contraction of too much filled interstitial material can also cause such a problem due to thermal contraction mismatch during cooling.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenInsufficient thermal bridging design may result in an unnecessarily large cryogenic cooling system.
“The insufficient thermal bridging design may also result in unnecessarily large cryogenic cooling system.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
Study design and conductnone givenThe compressing force is usually estimated by the screw-torque at room temperature assembly.
“The compressing force is usually estimated by the screw-torque at room temperature assembly.”
Quote in the paperNot a substantial claimProbably not a substantial claim.
InterpretationreasoningThe acceptable value of thermal contact resistance depends on the specific application.
“The requirement of the acceptable value of thermal contact resistance depends on the specific application.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
PremisecitationTheoretical analyses and prediction of the true contact area upon the exerted force or pressure have been extensively done by numerous researchers.
“Theoretical analyses and prediction of the true contact area upon the exerted force or pressure have been extensively done by numerous researchers [12,13].”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [12]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites [13]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenAn inadvertent assembly procedure can create a large temperature difference between two contact surfaces, requiring excessively long cool-down from room temperature to cryogenic temperature before normal operation can start.
“The inadvertent assembly procedure sometimes may create large temperature difference between two contact surfaces which shall require excessively long cool-down time from room temperature to cryogenic temperature before its normal operation can start.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
Interpretationnone givenTemperature sensor readings can be erroneous unless the sensors are properly mounted as suggested by the manufacturer's guide.
“The temperature reading can be erroneous unless they are properly mounted as suggested by the manufacturer's guide.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
Study design and conductreasoningSince the contact pressure of the sample at cryogenic temperature is usually created by mechanical screws rather than a hydraulic jack, the exact value of the contact pressure is uncertain due to thermal contraction and possible change of tightening force of the screw.
“Since the contact pressure of the sample at cryogenic temperature is usually created by mechanical screws rather than a hydraulic jack like the room-temperature set-up, the exact value of the contact pressure is uncertain due to thermal contraction and possible change of tightening force of screw.”
Quote in the paperSubstantial claimProbably not a substantial claim.
InterpretationreasoningIncluding an in-situ force measurement component enhances the accuracy of the contact resistance associated with the pressure.
“It is, therefore, recommended to include an in-situ force measurement component as shown in Fig. 3 (f) to enhance the accuracy of the contact resistance associated with the pressure.”
Quote in the paperSubstantial claimIt may state two separate claims as one.
InterpretationreasoningWith a thermal resistance of 1 W/K and 10 W of heat, a phenomenological 10 K temperature difference can occur, which is detrimental for conduction cooling of a superconducting magnet by a cryocooler cold head.
“In this situation, the same thermal resistance of 1 W/K may bring a trouble for conduction cooling of superconducting magnet by creating phenomenological 10 K temperature difference.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Premisenone givenCopper is the most commonly used thermal bridge material for LTS and HTS magnets of conduction-cooling systems.
“Although pure aluminum is often used, copper is the most commonly used thermal bridge material for LTS and HTS magnets of conduction-cooling systems.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds. It may state two separate claims as one. The quote only partly states this claim.
Interpretationnone givenThe essential physical factors to be considered for determining thermal contact resistance values are oxide layer, contact pressure, surface roughness, interstitial material, cooling temperature, amount of filled interstitial material, and filling of interstitial material before or after pressing.
“The followings are essential physical factors to be considered and investigated for further research to determine thermal contact resistance values of the surfaces.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenAn order of 10 W of heat can also be generated by AC loss during a fast ramping process of a magnet.
“Such an amount of heat can be also generated by AC loss during a fast ramping process of magnet.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenThe selection of the interstitial material is as important as the two contact surface preparations.
“The selection of this interstitial material is as important as the two contact surface preparations.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Premisenone givenCryocon grease is supposed to lower the thermal contact resistance by containing copper powder.
“Cryocon grease is supposed to lower the thermal contact resistance by containing copper powder.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenPure indium or gold with their room temperature thermal conductivities of 86 W/m.K and 317 W/m.K respectively are inherently the best materials.
“Pure indium or gold with their room temperature thermal conductivities of 86 W/m .K and 317 W/m .K respectively are inherently the best materials.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
Interpretationnone givenThermal contact resistance may be negligible if the amount of heat transfer across the contact is small.
“The thermal contact resistance may be negligible if the amount of heat transfer across the contact is small.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Premisenone givenIt is commonly practiced to fill the gap of contact surfaces with soft interstitial material such as indium, InGa, tin, lead, gold, Apiezon-N grease, Cryocon grease, GE7031 varnish, Polytec, Stycast 2850 epoxy, Araldite, Teflon, etc.
“It is commonly practiced to fill the gap of contact surfaces with soft interstitial material such as indium, InGa, tin, lead, gold, Apiezon-N grease, Cryocon grease, GE7031 varnish, , Polytec (thermally conductive epoxy), Stycast 2850 epoxy, Araldite, Teflon, etc.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
Interpretationnone givenIn general, the higher contact pressure, if possible, the lower the thermal contact resistance.
“In general, the higher contact pressure, if possible, the lower the thermal contact resistance.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
Interpretationnone givenThe soldering method may require a soldering flux to remove oxide layers on the surface.
“This method may require a soldering flux to remove oxide layers on the surface.”
Quote in the paperNot a substantial claimProbably not a substantial claim. It may be too vague to check against evidence. It may state two separate claims as one.
InterpretationreasoningIn the case of transient cooling or active cooling of cryogenic components where heat is significantly generated, the thermal contact problem becomes conspicuous and every effort should be made to minimize it.
“However, in the case of transient cooling or active cooling of cryogenic components where heat is significantly generated, the thermal contact problem becomes conspicuous and every effort should be made to minimize it.”
Quote in the paperNot a substantial claimProbably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenRepeating the assembly processes in order to correct unexpected errors with careful visual inspection would outcome a satisfactory result.
“Repeating the assembly processes in order to correct unexpected errors with careful visual inspection would outcome a satisfactory result.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
InterpretationreasoningSince the copper powder in Cryocon grease may hinder further reduction of the gap distance, it may result in poor performance than pure Apiezon-N.
“However, since this powder may hinder further reduction of the gap distance, it may result in poor performance than pure Apiezon-N.”
Quote in the paperSubstantial claimProbably not a substantial claim. It may be too vague to check against evidence. The paper may give no reason why it holds.
Interpretationnone givenThere should be only beneficial interstitial material between the mated surfaces.
“There should be only beneficial interstitial material between them.”
Quote in the paperNot a substantial claimProbably not a substantial claim. It may be too vague to check against evidence. It may state two separate claims as one.
Interpretationnone givenThe poor thermal contact situation is often encountered critically in various cryogenic practices and ruins the whole system performance.
“The poor thermal contact situation is often encountered critically in various cryogenic practices and ruins the whole system performance.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenThe extra amount of interstitial material in the gap of contact surfaces should not produce negative effect against efficient thermal conduction.
“The extra amount of interstitial material in the gap of contact surfaces should not produce negative effect against efficient thermal conduction.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
Interpretationnone givenThis cleaning and smoothing process shall ensure no contaminant is left between two mated surfaces.
“This process shall ensure no contaminant left between two mated surfaces.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
InterpretationreasoningThe extra amount of interstitial material needs to be easily drained out of the contact surface during assembly process.
“The extra amount of interstitial material needs to be easily drained out of the contact surface during assembly process.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
PremisecitationIn bulk copper, thermal conduction is dominated by phonon effect below liquid nitrogen temperature and the phonon scattering at bulk is continuously diminished until the mean free path becomes the order of sample length scale.
“In the case of bulk copper, thermal conduction is dominated by phonon effect below liquid nitrogen temperature and the phonon scattering at bulk is continuously diminished until the mean free path becomes the order of sample length scale [14,15].”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [14]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites [15]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
InterpretationreasoningFor the best result of thermal contact, the contact surface, whether copper or other metal, must be thoroughly cleaned and sufficiently smooth.
“For the best result of thermal contact, the contact surface either it is copper or other metal, must be thoroughly cleaned and sufficiently smooth.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
InterpretationreasoningOtherwise, the large temperature difference shall ultimately result in demanding a needlessly large cryogenic refrigeration system.
“Otherwise, the large temperature difference shall ultimately result in demanding a needlessly large cryogenic refrigeration system.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
Interpretationnone givenThe surface can be thinly covered by indium, gold, or Apiezon-N grease for securing sufficient direct contact area for best result.
“The surface can be thinly covered by indium, gold, or Apiezon-N grease for securing sufficient direct contact area for best result.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenMetallic solids are conveniently used in a variety of processes because they usually have higher thermal conductivities than most liquid interstitial materials.
“Metallic solids are conveniently used in a variety of processes because they usually have higher thermal conductivities than most liquid interstitial materials.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds.
Interpretationnone givenThe amount of coated interstitial material has to be minimized to avoid extra thermal resistance of the interlayer.
“The amount of coated interstitial material has to be minimized to avoid extra thermal resistance of the interlayer.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds. It may state two separate claims as one.
Interpretationnone givenThe rough solid surface is inherently not desirable for good thermal contact, but if it is in the micron-order range, the thermal contact resistance may be effectively reduced by proper interstitial material and adequate contact pressure.
“The rough solid surface is inherently not desirable for good thermal contact, but, if it is in the micron-order range, the thermal contact resistance may be effectively reduced by proper interstitial material and adequate contact pressure.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper may give no reason why it holds. It may state two separate claims as one.
Interpretationnone givenIt is commonly recommended that the contact surface must be flat and have sub-micron roughness level with no oxide layer.
“It is commonly recommended that the contact surface must be flat and have sub-micron roughness level with no oxide layer.”
Quote in the paperNot a substantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
Interpretationnone givenInterstitial material like indium, gold, or Apiezon-N grease can significantly reduce thermal contact resistance when it is minimally applied.
“Interstitial material like indium, gold, or Apiezon-N grease can significantly reduce thermal contact resistance when it is minimally applied.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
PremisereasoningThe temperature dependence of thermal contact resistance is different from that of bulk copper, which shows maximum thermal conductivity around 20 K.
“This temperature dependence characteristic is different from that of bulk copper which shows maximum thermal conductivity around 20 K.”
Quote in the paperNot a substantial claimProbably not a substantial claim.
Interpretationnone givenThe fundamental concept of utilizing soft interstitial material as a filler is to fill the unavoidable micro void between the mating surfaces.
“The fundamental concept of utilizing soft interstitial material as a filler is to fill the unavoidable micro void between the mating surfaces.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it.
InterpretationreasoningLiquid with small viscosity is an attractive filler because it can easily penetrate and fill the gap between the contacted surfaces.
“Liquid with small viscosity is an attractive filler because it can easily penetrate and fill the gap between the contacted surfaces.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
InterpretationreasoningThe thickness of the interstitial material has to be optimized because more polymer interstitial material tends to shrink more.
“The thickness of the interstitial material has to be optimized because more polymer interstitial material tends to shrink more.”
Quote in the paperSubstantial claimProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
InterpretationreasoningSince some applications may not allow direct heating of the contacted surfaces, the soldering method is limitable, but if possible it can produce excellent thermal contact conductance value.
“Since some application may not allow direct heating of the contacted surfaces, this method is limitable, but, if possible, it can produce excellent thermal contact conductance value.”
Quote in the paperNot a substantial claimIt may state two separate claims as one.
InterpretationreasoningThe exerted contact pressure may change or the gap between the contacted surfaces tends to increase due to thermal contraction mismatch.
“The exerted contact pressure may change or the gap between the contacted surfaces tends to increase due to thermal contraction mismatch.”
Quote in the paperSubstantial claim
The paper relies on this without support.
The thermal contact resistance data compiled from different studies are comparable enough to reveal general trends despite different preparation protocols and missing physical descriptions.
“Nevertheless, the data can present the essential characteristics of thermal contact resistance and suggest a practical way to overcome thermal contact problems in general.”
The paper relies on this without support.
The practical recommendations derived from the reviewed experiments apply to general cryogenic conduction-cooling systems.
“The general description of this technique has been widely perceived and reasonable engineering results have been achieved in most applications.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Thermal resistance is given in conductance units
MinorThe paper first gives the thermal resistance as 1 K/W, but later calls the same thermal resistance 1 W/K. W/K is the reciprocal unit.
“This is equivalent to the thermal resistance of 1 K/W and 0.1 K/W respectively with the contact area of 10 cm 2 .”
“the same thermal resistance of 1 W/K may bring a trouble for conduction cooling of superconducting magnet by creating phenomenological 10 K temperature difference.”
Different lower temperature limits for Fig. 3(c)
MinorThe same Fig. 3(c) apparatus is described as measuring from 77 K in one place and from 85 K in another.
“Fig. 3 (c).Experimental apparatus for measurement of thermal contact resistance using liquid nitrogen (N 2 ) between 77 K and 300 K [4].”
“Fig. 3 (c) is the rather simple experimental set-up using liquid nitrogen for the measurements between 85 K and 300 K.”
Citations
Cites
Swartz, E. T., & Pohl, R. O. (1989) · Reviews of Modern Physics · doi:10.1103/revmodphys.61.605 · Cited by 2,992
Oxidation of Polycrystalline Copper Thin Films at Ambient Conditions
Platzman, I., Brener, R., Haick, H., & Tannenbaum, R. (2008) · The Journal of Physical Chemistry C · doi:10.1021/jp076981k · Cited by 919
Thermal contact conductance; theoretical considerations
Mikic, B. B. (1974) · International Journal of Heat and Mass Transfer · doi:10.1016/0017-9310(74)90082-9 · Cited by 634
Temperature Dependence of Electrical and Thermal Conduction in Single Silver Nanowire
Cheng, Z., Liu, L., Xu, S., Lu, M., & Wang, X. (2015) · Scientific Reports · doi:10.1038/srep10718 · Cited by 236
Thermal boundary resistance of mechanical contacts between solids at sub-ambient temperatures
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Chen, K., Song, S., & Xue, D. (2012) · CrystEngComm · doi:10.1039/c2ce26544c · Cited by 94
Thermal contact resistance at low contact pressure: Effect of elastic deformation
Bahrami, M., Yovanovich, M. M., & Culham, J. R. (2005) · International Journal of Heat and Mass Transfer · doi:10.1016/j.ijheatmasstransfer.2005.02.033 · Cited by 93
Experimental investigation of thermal contact conductance for nominally flat metallic contact
Tariq, A., & Asif, M. (2015) · Heat and Mass Transfer · doi:10.1007/s00231-015-1551-1 · Cited by 92
The Art of Cryogenics: Low-Temperature Experimental Techniques
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Salerno, L. J., Kittel, P., & Spivak, A. L. (1994) · Cryogenics · doi:10.1016/0011-2275(94)90142-2 · Cited by 45
Thermal conductance of Cu/Cu and Cu/Si interfaces from 85 K to 300 K
Yu, J., Yee, A. L., & Schwall, R. E. (1992) · Cryogenics · doi:10.1016/0011-2275(92)90291-h · Cited by 44
Misra, P., & Nagaraju, J. (2010) · International Journal of Heat and Mass Transfer · doi:10.1016/j.ijheatmasstransfer.2010.06.052 · Cited by 23
Yovanovich, M. M. (1972) · AIAA Thermophysics Conference · doi:10.2514/6.1972-283 · Cited by 9
Thermal conductivity of hard anodized coatings on aluminum
Ogden, T. R. (1987) · AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · doi:10.2514/6.1987-2066 · Cited by 8
Thermal conductance measurements of bolted copper joints for SuperCDMS
Schmitt, R. L., Tatkowski, G. L., Ruschman, M., Golwala, S. R., Kellaris, N., Daal, M., Hall, J., & Hoppe, E. W. (2015) · Cryogenics · doi:10.1016/j.cryogenics.2015.04.006 · Cited by 7
Thermal Contact Resistance Measurement of Metal Interface at Cryogenic Temperature
Kim, M., & Choi, Y. S. (2014) · 설비공학논문집 · doi:10.6110/kjacr.2014.26.1.032 · Cited by 2
Flagged first, then by citations
Cited by
Sorted by citations
Siddappa, P. G., & Tariq, A. (2022) · Applied Thermal Engineering · doi:10.1016/j.applthermaleng.2022.119412 · Cited by 34
Esmeryan, K. D., Grakov, T., Vergov, L. G., Lazarov, Y., Fedchenko, Y. I., & Staykov, S. (2022) · Applied Thermal Engineering · doi:10.1016/j.applthermaleng.2022.119590 · Cited by 17
Tariq, A., & Siddappa, P. G. (2021) · International Journal of Thermal Sciences · doi:10.1016/j.ijthermalsci.2021.107031 · Cited by 9
Robust Nernst magnetothermoelectricity in the topological spin semimetal FeCrRh X ( X = Si , Ge)
Chanda, A., Nag, J., Schulz, N., DeTellem, D., Alam, A., Суреш, К. Г., Phan, M., & Srikanth, H. (2025) · Physical review. B./Physical review. B · doi:10.1103/physrevb.111.094416 · Cited by 8
Metadata
- Authors
- Jeong, S., & Park, C.
- Affiliations
- Korea Advanced Institute of Science and Technology (KR)
- Venue
- Progress in Superconductivity and Cryogenics
- Published
- 2015-12-31
- Volume
- 17
- Issue
- 4
- Pages
- 1-7
- ISSN
- 1229-3008 (ISSN-L)
- OpenAlex
- W2328566137
- Cited by
- 5
- References
- 16
- Citations by year
- 2025: 1 · 2022: 3 · 2021: 1
- FWCI
- 0.00
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Progress in Superconductivity and Cryogenics (publishedVersion)
- Funders
- National Research Foundation
- Ministry of Science, ICT and Future Planning
- National Research Foundation of Korea
- Topics
- Physical Sciences › Engineering › Aerospace Engineering › Spacecraft and Cryogenic Technologies
- Physical Sciences › Materials Science › Materials Chemistry › Thermal properties of materials
- Physical Sciences › Engineering › Computational Mechanics › Heat Transfer and Numerical Methods
- Keywords
- thermal contact resistance, cryogenic temperatures, thermal contact conductance, surface roughness, oxide layer, indium coating, gold coating, contact pressure
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-11-10, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-11-10 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Statistics and arithmetic are recomputed, not judged.
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