JPS54135589A - Thermal diffusivity measuring apparatus - Google Patents

Abstract

PURPOSE: To measure the tnermal diffusivity of substances accurately and promptly, by utilizing the proportional relationship between temperature changes by electromagnetic wave radiation to the electromagnetic absorption layer of the layer being measured which forms part of gas-sealed enclosed container wall and the standard specimen and pressure wave amplitudes.

CONSTITUTION: After passing through a chopper 7 and concave mirrors 13, 113, etc. the electromagnetic wave radiates an absorption layer 1b of standard speciemen having excellent absorption factor of electromagnetic wave which is disposed to form part of wall of gas-sealed enclosed containers 2, 102, and a specimen 101 of absorption layer only similar to the specimen of which is superposed a layer being measured 1a of which thickness varies from 5 to 20 μm, or 20 μm to 5 mm depending on the insulating material and the excellent thermal conductive material such as metal. Thus, the absorption layer generates heat to change in the temperature, and the surge wave amplitude generated in proportion to the temperature is detected by microphones 5, 105, and the logarithmic value of the ratio thereof is applied from an arithmetic circuit 10 into X-axis of X-Y recorder 11. On the other hand, the square root of the modulation frequency of electromagnetic wave due to chopper 7 is applied to Y-axis. And the thermal diffusivity may be obtained easily and accurately from the gradient of the recorded curve regardless of the kind of substance.

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