Page 369 - Book Hosokawa Nanoparticle Technology Handbook

6.3 THERMOPHYSICAL PROPERTIES FUNDAMENTALS
Table 6.3.1
Program to develop thermal diffusivity standards by light pulse heating methods planned by NMIJ/AIST.
Light pulse heating methods Observable heat Planned year to start service
diffusion time
Metrological standard Reference material
Laser flash method
Conventional 1ms 10s FY2002 FY2005
Application to thin plates and coatings 1 s 10ms Under consideration Under consideration
Nanosecond thermoreflectance method 10ns 100 s FY2007 FY2007
Picosecond thermoreflectance method
Electrical delay 100ps 10ns FY2005 Under consideration
Optical delay 10ps 1ns

Bulk materials Thin plates and coatings Thin films

-2 -3 -4 -5 -6 -7 -8
10 10 10 10 10 10 10
Heat diffusion length / m
(l)

Laser flash method
Nanosecond thermoreflectance method

Picosecond thermoreflectance method
(Electrical delay)

Picosecond thermoreflectance method
(Optical delay)
Heat diffusion time / s
(τ) 10 0 10 -2 10 -4 10 -6 10 -8 10 -10 10 -12

2
2 −1
−5
(Thermal diffusivity, = 1×10 m s , = l / )
Figure 6.3.12
Observable heat diffusion time and observable thickness of the specimen covered by four types of light pulse heating
1
2
methods when the thermal diffusivity is 10 5 m s .
one-dimensional heat flow as shown in Fig. 6.3.12. change record disc is measured by the picosecond
Since the geometry is very simple, thermal diffusivity thermoreflectance method and the nanosecond
can be determined reliably with uncertainty evalua- thermoreflectance method. Reliability of thermal
tion based on GUM [7]. NMIJ/AIST has been design is improved drastically by heat-transfer
engaged in research for establishment of national simulation using those thermophysical property data
standard, international standard for thermal diffusiv- [15,16]. High-speed laser flash methods are also
ity measurements of thin films. applied to thermophysical property measurement of
Using these light pulse heating methods, thermal transparent conductive films used for a flat panel
diffusivity of each layer of multilayered thin films display [17] and hard coating films [18].
and boundary thermal resistance between the layers
can be determined from the observed transient tem-
perature curves based on the response function References
method [5,6,13,14].
Boundary thermal resistance between thin films [1] T. Baba, A. Ono: Improvement of the laser flash method
and thermal diffusivity of each layer of multilayer to reduce uncertainty in thermal diffusivity measure-
films constituting next generation light heating phase ments, Meas. Sci. Technol., 12, 2046–2057 (2001).

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