Lateral heat flow method for thickness independent determination of thermal diffusivity

2007 ◽  
Vol 102 (8) ◽  
pp. 083522 ◽  
Author(s):  
Nilesh Tralshawala ◽  
Donald R. Howard ◽  
Bryon Knight ◽  
Yuri Plotnikov ◽  
Harry I. Ringermacher
Keyword(s):  
Thermal Diffusivity ◽  
Heat Flow ◽  
Flow Method ◽  
Independent Determination ◽  
Thickness Independent ◽  
Lateral Heat

LATERAL HEAT FLOW INFRARED THERMOGRAPHY FOR THICKNESS INDEPENDENT DETERMINATION OF THERMAL DIFFUSIVITY IN CFRP

2008 ◽  
Author(s):  
Nilesh Tralshawala ◽  
Don Howard ◽  
Bryon Knight ◽  
Yuri Plotnikov ◽  
Harry Ringermacher ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Heat Flow ◽  
Infrared Thermography ◽  
Independent Determination ◽  
Thickness Independent ◽  
Lateral Heat

Independent Determination of the Thermal Diffusivity and Conductivity of a Thin Metallic Layer Deposited on Silica

2008 ◽  
Author(s):  
Christian Fretigny ◽  
Jean Paul Roger ◽  
Li Liu ◽  
Danie`le Fournier
Keyword(s):  
Thermal Diffusivity ◽  
Careful Analysis ◽  
Thin Layers ◽  
Heat Diffusion ◽  
Bulk Materials ◽  
Thermal Insulator ◽  
Independent Determination ◽  
Lateral Temperature ◽  
Lateral Heat

It is well known that the thermal parameters of materials confined in thin layers may significantly differ from their bulk value. Lateral heat diffusion thermoreflectance experiment is a very powerful tool for determining directly the thermal diffusivity of bulk materials and of layered structure. Nevertheless, in the latter case, experimental data are fitted with the help of a heat diffusion model in which the layer thermal conductivity and thermal diffusivity are taken together into consideration. In this paper, we show that both parameters can be determined independently, in the case of a thermal conductive layer deposited on a thermal insulator, with a careful analysis of the amplitude and the phase of the lateral temperature field associated to a point source.

Thermal Properties of Thin Metallic Layer Deposited on Insulators: Effect of the Interface on the Independent Determination of the Thermal Diffusivity and Conductivity of the Layer

2008 ◽  
Author(s):  
Danie`le Fournier ◽  
Jean Paul Roger ◽  
Christian Fretigny
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Thermal Resistance ◽  
Thermal Contact ◽  
Heat Diffusion ◽  
Metallic Layer ◽  
Good Thermal Contact ◽  
Lateral Heat

Lateral heat diffusion thermoreflectance is a very powerful tool for determining directly the thermal diffusivity of layered structures. To do that, experimental data are fitted with the help of a heat diffusion model in which the ratio between the thermal conductivity k and the thermal diffusivity D of each layer is fixed, and the thermal properties of the substrate are known. We have shown in a previous work that it is possible to determine independently the thermal diffusivity and the thermal conductivity of a metallic layer deposited on an insulator, by taking into consideration all the data obtained at different modulation frequencies. Moreover, it is well known that to prevent a lack of adhesion of a gold film deposited on substrates like silica, an intermediate very thin (Cr or Ti) layer is deposited to assure a good thermal contact. We extend our previous work: the asymptotic behaviour determination of the surface temperature wave at large distances from the modulated point heat source for one layer deposited on the substrate to the two layers model. In this case (very thin adhesion coating whose thermal properties and thickness are known), it can be establish that the thermal diffusivity and the thermal conductivity of the top layer can still be determined independently. It is interesting to underline that the calculus can also be extended to the case of a thermal contact resistance which has often to be taken into account between two solids. We call thermal resistance a very thin layer exhibiting a very low thermal conductivity. In this case, the three parameters we have to determine are the thermal conductivity and the thermal diffusivity of the layer and the thermal resistance. We will show that, in this case, the thermal conductivity of the layer is always obtained independently of a bound of the couple thermal resistance – thermal diffusivity, the thermal diffusivity being under bounded and the thermal resistance lower bounded. Experimental results on thin gold layers deposited on silica with and without adhesion layers are presented to illustrate the method. Discussions on the accuracy will also be presented.

The Thermal Transport Properties of Polymers

1977 ◽  
Vol 50 (3) ◽  
pp. 480-522 ◽  
Author(s):  
D. Hands
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Heat Flow ◽  
Natural Rubber ◽  
Material Selection ◽  
Reliable Data ◽  
Large Scatter ◽  
Structure Property ◽  
Structure Property Relationships

Abstract Values of thermal diffusivity and thermal conductivity are needed for heat-flow calculations, for the determination of structure-property relationships, and for material selection and comparison. However, all aspects are hampered by a dearth of reliable data and anything more than a superficial glance at the literature is apt to be discouraging for the uninitiated. Hardly any thermal diffusivity data exist, and the reported values of thermal conductivity show very large scatter. The present state of confusion can be seen, for example, in Figures 1 and 2, which show the reported thermal conductivity values for polystyrene and gum natural rubber. Not only do the values differ at some temperatures by more than 100%, and in the case of rubber by almost 300%, but different trends are indicated throughout the temperature range. Discrepancies of this size cannot be due to sample variations, and they give some indication of the experimental difficulties associated with thermal property measurements.

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