A review of the thermal contact conductance of junctions with metallic coatings and films

Lambert, M. A.; Fletcher, L. S.

doi:10.2514/6.1992-709

Cited by 14 publications

(14 citation statements)

References 3 publications

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“…The analysis of heat transfer at the interface is analogous to our problem of mass transport, especially when a convection boundary condition is present at these discrete regions instead of solid-solid contact. Determination of the constriction resistance is important for applications such as microelectronics where junctions are coated with metallic films to reduce the constriction resistance (Lambert & Fletcher 1993).…”

Section: Overview Of Applicationsmentioning

confidence: 99%

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

Shah

Shaqfeh

2015

J. Fluid Mech.

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Surfaces that include heterogeneous mass transfer at the microscale are ubiquitous in nature and engineering. Many such media are modelled via an effective surface reaction rate or mass transfer coefficient employing the conventional ansatz of kinetically limited transport at the microscale. However, this assumption is not always valid, particularly when there is strong flow. We are interested in modelling reactive and/or porous surfaces that occur in systems where the effective Damköhler number at the microscale can be O(1) and the local Péclet number may be large. In order to expand the range of the effective mass transfer surface coefficient, we study transport from a uniform bath of species in an unbounded shear flow over a flat surface. This surface has a heterogeneous distribution of first-order surface-reactive circular patches (or pores). To understand the physics at the length scale of the patch size, we first analyse the flux to a single reactive patch. We use both analytic and boundary element simulations for this purpose. The shear flow induces a 3-D concentration wake structure downstream of the patch. When two patches are aligned in the shear direction, the wakes interact to reduce the per patch flux compared with the single-patch case. Having determined the length scale of the interaction between two patches, we study the transport to a periodic and disordered distribution of patches again using analytic and boundary integral techniques. We obtain, up to non-dilute patch area fraction, an effective boundary condition for the transport to the patches that depends on the local mass transfer coefficient (or reaction rate) and shear rate. We demonstrate that this boundary condition replaces the details of the heterogeneous surfaces at a wall-normal effective slip distance also determined for non-dilute patch area fractions. The slip distance again depends on the shear rate, and weakly on the reaction rate, and scales with the patch size. These effective boundary conditions can be used directly in large-scale physics simulations as long as the local shear rate, reaction rate and patch area fraction are known.

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Section: Overview Of Applicationsmentioning

confidence: 99%

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

Shah

Shaqfeh

2015

J. Fluid Mech.

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“…A review of literature on the thermal conductance [8][9][10][11][12] has indicated a lack of experimental data of thermal contact resistance and total thermal conductance for honeycomb materials. Most of the previous studies on the thermal transport properties of honeycomb structures were analytically investigated.…”

Section: Introductionmentioning

confidence: 99%

Measurement of thermal contact resistance of aluminum honeycombs

Yeh

Chen

Wen

et al. 2003

Experimental Thermal and Fluid Science

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An experimental investigation of thermal contact resistance of the aluminum honeycomb (made of Al3104-H19 and Al3003-H16) sandwiched by two aluminum blocks was conducted with the honeycomb specimens aligned in either axial or lateral orientations. Honeycombs adopted in this study include two different cell diameters (d c ), 6.3 and 12.7 mm, as well as two different axial heights (H z ), 7.8 and 14.8 mm. For the axial tests, honeycomb sandwich specimens were jointed by four or eight pieces of bolts with an applied torque ranged from 1 to 6 N m. The interfacial contact pressures of axial honeycombs under different bolt-joined conditions were measured by the pressure-measuring films. For the lateral tests, the honeycomb was simply inserted between two aluminum blocks without using bolts to fasten. Results show that due to the anisotropic nature in heat conduction and the close contact provided by bolted joints, the total thermal conductance of axial honeycomb is greater than that of honeycomb in the lateral orientation under the condition with the same specimen height. An increase of either the cell diameter or specimen height of honeycombs leads to a decrease of the axial total conductance. Moreover, the axial total conductance was substantially enhanced by a double of the number of bolts used in the assembly of honeycomb specimens. However, the influence of bolt torque on the axial total conductance was observed only for the honeycomb with d c ¼ 6:3 mm and H z ¼ 7:8 mm. Due to the difference in specimen joint conditions, the thermal contact resistance between the solid aluminum surface and a lateral honeycomb is larger than that with an axial honeycomb. Under the conditions tested in this study, the thermal contact resistance of honeycombs in the axial direction appears to be one order of magnitude smaller than the total resistance. Nevertheless, the contribution of the lateral contact resistance of honeycombs to the total resistance was quite significant, especially for the specimen with a small height. It was found that the contact pressure of bolt-joined honeycombs in the interface increases evidently with an increase of either the bolt torque or the number of bolts. The empirical correlations between contact pressure and applied torque were also obtained for different joint conditions.

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“…Much of this work has been reviewed by Madhusudana [2] and Lambert and Fletcher [3]. Desirable coatings are generally soft, highly conductive metals deposited on one or both contact surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…Commonly studied metals include copper, gold, indium, lead, nickel, silver and tin. Optimum coating thicknesses have been found for each material [2,3]. Most researchers identified the ratio of thermal conductivity to microhardness as the most important factor in affecting the thermal contact conductance.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Constriction Resistance in Coated Joints

Olsen

Garimella

Madhusudana

2002

Journal of Thermophysics and Heat Transfer

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Metallic coatings applied to surfaces in contact have been shown to be effective at reducing thermal contact resistance. Contact resistance is primarily caused by the constriction of heat flo w as it passes through individual contact spots. Most analyses of coated constrictions have been limited to plane contacts of a semi-infinite cylinder, while an actual constriction terminates in a shape like the frustum of a cone. A numerical model has been developed to determine the constriction resistance of such a coated asperity. The gap between the cone and contact surface is considered to either be evacuated or filled with a gas, and the temperature jump phenomenon is included in the gas-gap model. The effects of radiation heat transfer are also included. The results indicate that an optimum coating thickness for minimizing constriction resistance exists in all cases. Most gases are found to reduce the coating effectiveness very slightly, especially compared to the effect of radiation. The effect of radiation on the model is shown to be highly dependent on the joint temperature, substrate and coating thermal conductivities, and constriction ratio. Contrary to current belief, radiation is shown to be important even for temperatures below 300°C when either the substrate conductivity or the constriction ratio is very low.

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A review of the thermal contact conductance of junctions with metallic coatings and films

Cited by 14 publications

References 3 publications

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

Measurement of thermal contact resistance of aluminum honeycombs

Modeling of Constriction Resistance in Coated Joints

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