Discussion: “Thermal Contact Resistance of Silicone Rubber to AISI 304 Contacts” [ASME J. Heat Transfer, 121, pp. 700–702 (1999)]¹

The authors are to be complimented on this interesting and informative paper. I have, however, the following comments.

1 Elastomers are time sensitive and continue to deform under load (room temperature creep). Because of this, the contact resistance may be expected to vary with time. Were any attempts made to investigate the time-dependence of the resistance?

2 The Results and Discussion section of the paper appears to indicate that the conductivity, $kr,$ of the silicone rubber is accurately known. The bulk resistance, $Rb,$ then equals $t/kr,$ where t is the thickness of the rubber. How does this compare with the measured value of $Rb?$

3 In Tables 1 and 2, the mean asperity slopes are expressed in terms of [μm/m]. This means that the slopes for the metal surfaces range from $0.143×10−6$ to $0.427×10−6.$ These values seem to be extremely small. Our experience with similar metallic surfaces indicates that the slopes are of the order of 0.2. I believe, therefore, that the slopes should have been expressed in terms of [μm/μm] and not [μm/m].

4 In the second to last paragraph of the paper it is said that: “At the lower interface the heat flow is from metal to elastomer…”. This is incorrect. The heat flow is from elastomer to metal at the lower interface. (At the upper interface, the heat flow is from metal to elastomer, as correctly stated in the paper.)

I would appreciate the authors’ response to the above remarks.