Effects of Metallic Vapor Deposition Process and the Overall Coating Thickness on Thermal Contact Conductance

1995 ◽  
Vol 117 (4) ◽  
pp. 828-834 ◽  
Author(s):  
A. H. Howard ◽  
J. M. Ochterbeck ◽  
G. P. Peterson
Keyword(s):  
Coating Thickness ◽  
Vapor Deposition ◽  
Thermal Contact ◽  
Deposition Process ◽  
Thermal Contact Conductance ◽  
Maximum Enhancement ◽  
Test Set ◽  
Contact Conductance ◽  
Layered Coatings ◽  
Vapor Deposition Process

An investigation was conducted to determine the effects of the vapor deposition process and. the interstitial coating thickness on the overall joint conductance of metallic interfaces. Eight aluminum 6061-T6 test specimens were coated with indium and tested while in contact with uncoated aluminum 6061-T6 specimens. In the first test set, all specimens were coated to a thickness of 3.51 μm, but the vapor deposition process was varied to produce both single and multiple-layered coated specimens. In the second test set, the coating thickness was varied from 0.026 μm to 3.51 μm. The results indicated that when creating multiple layered coatings, oxidation and thermal cycling caused poor layer adhesion, and resulted in significantly reduced dimensionless contact conductance enhancement factors than for single-layered coatings with an equivalent thickness. Additionally, the results demonstrated that the thermal contact conductance could be enhanced to much greater levels than previously reported in the literature, and that the dimensionless enhancement factor asymptotically approached a maximum enhancement value. A theoretical maximum enhancement limit has been presented for comparison with the experimental data.

Thermal Contact Conductance of Metallic Coated BiCaSrCuO Superconductor/Copper Interfaces at Cryogenic Temperatures

1992 ◽  
Vol 114 (1) ◽  
pp. 21-29 ◽  
Author(s):  
J. M. Ochterbeck ◽  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Vapor Deposition ◽  
Thermal Contact ◽  
Deposition Process ◽  
Thermal Contact Conductance ◽  
Experimental Program ◽  
Contact Conductance ◽  
Nickel Substrates ◽  
Deposition Processes ◽  
Cold Pressed ◽  
And Control

The effects of vapor deposited coatings on the thermal contact conductance of cold pressed, normal state BiCaSrCuO superconductor/oxygen-free copper interfaces were experimentally investigated over a pressure range of 200 to 2000 kPa. Using traditional vapor deposition processes, thin coatings of indium or lead were applied to the superconductor material to determine the effect on the heat transfer occurring at the interface. The test data indicate that the contact conductance can be enhanced using these coatings, with indium providing the greater enhancement. The experimental program revealed the need for a better understanding and control of the vapor deposition process when using soft metallic coatings. Also, the temperature-dependent microhardness of copper was experimentally determined and found to increase by approximately 35 percent as the temperature decreased from 300 to 85 K. An empirical model was developed to predict the effect of soft coatings on the thermal contact conductance of the superconductor/copper interfaces. When applied, the model agreed well with the data obtained in this investigation at low coating thicknesses but overpredicted the data as the thickness increased. In addition, the model agreed very well with data obtained in a previous investigation for silver-coated nickel substrates at all coating thicknesses.

Measurement of the Thermal Contact Conductance and Thermal Conductivity of Anodized Aluminum Coatings

1990 ◽  
Vol 112 (3) ◽  
pp. 579-585 ◽  
Author(s):  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Coating Thickness ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Aluminum Surface ◽  
Anodized Aluminum ◽  
Contact Conductance ◽  
Surface Measurements

An experimental investigation was conducted to determine the thermal contact conductance and effective thermal conductivity of anodized coatings. One chemically polished Aluminum 6061-T6 test specimen and seven specimens with anodized coatings varying in thickness from 60.9 μm to 163.8 μm were tested while in contact with a single unanodized aluminum surface. Measurements of the overall joint conductance, composed of the thermal contact conductance between the anodized coating and the bare aluminum surface and the bulk conductance of the coating material, indicated that the overall joint conductance decreased with increasing thickness of the anodized coating and increased with increasing interfacial load. Using the experimental data, a dimensionless expression was developed that related the overall joint conductance to the coating thickness, the surface roughness, the interfacial pressure, and the properties of the aluminum substrate. By subtracting the thermal contact conductance from the measured overall joint conductance, estimations of the effective thermal conductivity of the anodized coating as a function of pressure were obtained for each of the seven anodized specimens. At an extrapolated pressure of zero, the effective thermal conductivity was found to be approximately 0.02 W/m-K. In addition to this extrapolated value, a single expression for predicting the effective thermal conductivity as a function of both the interface pressure and the anodized coating thickness was developed and shown to be within ±5 percent of the experimental data over a pressure range of 0 to 14 MPa.

Review of models for thermal contact conductance of metals

10.2514/3.870 ◽  
1997 ◽  
Vol 11 ◽  
pp. 129-140
Author(s):  
B. Merci ◽  
J. Steelant ◽  
J. Vierendeels ◽  
K. Riemslagh ◽  
E. Dick ◽  
...  
Keyword(s):  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Contact Conductance

Thermal contact conductance of adhesives for microelectronic systems

10.2514/3.871 ◽  
1997 ◽  
Vol 11 ◽  
pp. 141-145
Author(s):  
Andreas Haselbacher ◽  
Jiri Blazek ◽  
S. R. Mirmira ◽  
E. Marotta ◽  
L. S. Fletcher
Keyword(s):  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Contact Conductance
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