EP0419873A2
Expired / Lapsed
EP
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Method and apparatus for measuring thermal diffusivity by AC joule-heating
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1990-08-29
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Granted: —
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Expires: 2010-08-29
Abstract
Abstract Disclosed is a method for measuring the thermal diffusivity in the thickness direction of a thin sample plate (1), which has the steps of forming a conductive thin layer (3) on at least one surface of said thin sample plate (1) to allow the thin film to function as an ac heater (2) generating joule heat, applying an ac current modulated with a given modulation frequency to the ac heater (2) (conductive thin layer) so as to produce ac joule-heating, generating an oscillation response corresponding to said ac joule-heating on the opposite surface of the ac heater (2), and measuring the phase shift between said oscillation response, and the ac joule-heating, thereby obtaining the thermal diffusivity in the thickness direction of said sample plate (1). Apparatus useful for the method are also disclosed.
Inventors
- 👤 Toshimasa Hashimoto
- 👤 Akira Miyamoto
- 👤 Kohei Shizuka
- 👤 Teruo Hyugaji
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 23:26
CPC Classifications
G; G01; G01N; G01N25/00; G01N25/18
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
116 words
A method for measuring the thermal diffusivity in the thickness direction of a thin sample plate which comprises the steps of: forming a conductive thin layer on at least one surface of said thin sample plate to allow the thin film to function as an ac heater generating joule heat; applying an ac current modulated with a given modulation frequency to the ac heater (conductive thin layer) so as to produce ac joule-heating; generating an oscillation response corresponding to said at joule-heating on the opposite surface of the ac heater; and measuring the phase shift between said oscillation response and the ac joule-heating, thereby obtaining the thermal diffusivity in the thickness direction of said sample plate.
Claim 2
Independent Claim
116 words
A method for measuring the thermal diffusivity in the thickness direction of a thin sample plate which comprises the steps of: forming a conductive thin layer on at least one surface of said thin sample plate to allow the thin film to function as an ac heater generating joule heat; applying an ac current modulated with a given modulation frequency to the ac heater (conductive thin layer) so as to produce ac joule-heating; generating an oscillation response corresponding to said at joule-heating on the opposite surface of the ac heater; and measuring the phase shift between said oscillation response and the ac joule-heating, thereby obtaining the thermal diffusivity in the thickness direction of said sample plate.
Claim 3
Dependent Claim
29 words
The method of measuring the thermal diffusivity of the sample plate according to Claim 1 wherein the oscillation response is a temperature oscillation response or a periodic sound wave.
Claim 4
Dependent Claim
149 words
The method for measuring the thermal diffusivity according to Claim 2 which comprises the steps of: forming conductive thin layer on both surfaces of a thin sample plate to allow one of the thin layer to function as an ac heater generating joule heat and to allow another thin layer to function as a resistance thermometer making use of the variation of the resistance with temperature; applying an ac current modulated with a given modulation frequency to the ac heater so as to produce ac joule-heating; generating a temperature oscillation response corresponding to said ac joule-heating in said resistance thermometer; and measuring the phase shift between the temperature oscillation response and the ac joule heating for at least two points in said modulation frequency range, thereby obtaining the thermal diffusivity in the thickness direction of said sample plate from the relationship between the phase shifts and said modulation frequency.
Claim 5
Dependent Claim
35 words
The method for measuring thermal diffusivity according to Claim 3 wherein the sample plate is a plate of a hardly conductive material selected from high molecular materials (polymers), organic dyestuff, mineral ores, glasses and ceramics.
Claim 6
Dependent Claim
36 words
The method for measuring thermal diffusivity according to Claim 3 or 4 wherein the conductive thin layer functioning as the resistance thermometer is a thin layer made of a conductive material whose resistance varies with temperature.
Claim 7
Dependent Claim
40 words
The method for measuring thermal diffusivity according to Claim 3 or 4 wherein the thin layers functioning as the ac heater and the resistance thermometer are formed by a method selected from sputtering, vapor deposition, coating, adhesion and pressure application.
Claim 8
Independent Claim
34 words
The method for measuring thermal diffusivity according to any one of Claims 3 to 6 wherein the temperature dependence of the thermal diffusivity is measured at desired temperature by heating or cooling the sample.
Claim 9
Independent Claim
46 words
A method for measuring thermal conductivity of a thin sample plate comprising measuring the thermal diffusivity of the sample according to the method described in any one of Claims 3 through 7 and obtaining thermal conductivity using the specific heat and density of said sample plate.
Claim 10
Independent Claim
72 words
An apparatus for measuring thermal diffusivity in the thickness direction of a thin sample plate provided with conductive thin layers on both surfaces which comprises: an ac current generation means for applying an ac current with a given amplitude of modulation to one of the conductive thin layers; a dc current supplying means for applying a given dc current to another conductive thin film; and a lock-in amplifier for amplifying the voltage.
Claim 11
Independent Claim
72 words
An apparatus for measuring thermal diffusivity in the thickness direction of a thin sample plate provided with conductive thin layers on both surfaces which comprises: an ac current generation means for applying an ac current with a given amplitude of modulation to one of the conductive thin layers; a dc current supplying means for applying a given dc current to another conductive thin film; and a lock-in amplifier for amplifying the voltage.
Claim 12
Dependent Claim
19 words
The apparatus for measuring thermal diffusivity according to Claim 9 which further comprises a cell for accommodating the sample.
Claim 13
Dependent Claim
39 words
The apparatus for measuring thermal diffusivity according to Claim 10 which further comprises a means for heating or cooling the sample in the cell, thereby giving the temperature dependence of the thermal diffusivity by changing the measurement atmosphere temperature.
Claim 14
Dependent Claim
169 words
The method for measuring thermal diffusivity according to Claim 2 which comprises: providing for a cell equipped with a sound signal detector; incorporating a sample plate, on one surface of which being formed a conductive thin layer functioning as an ac heater and the opposite another surface of which serving as the measurement surface, into said cell in such a way that the measurement surface constitutes a part of the inner walls of said cell; applying an ac current modulated with a given modulation frequency to the conductive thin layer to produce ac joule-heating; generating a temperature oscillation response corresponding to said ac joule-heating on said measurement surface, thereby inducing a periodic sound wave; and measuring the phase shift between the ac joule heating and the corresponding periodic sound wave with said sound signal detector for at least two points in said modulation frequency range, thereby obtaining the thermal diffusivity in the thickness direction of the sample plate from the relationship between the phase shifts and said modulation frequency.
Claim 15
Dependent Claim
35 words
The method for measuring thermal diffusivity according to Claim 12 wherein the sample plate is a plate of a hardly conductive material selected from high molecular compounds (polymers), organic dyestuffs, mineral ores, glasses and ceramics.
Claim 16
Dependent Claim
36 words
The method for measuring thermal diffusivity according to Claim 12 or 13 wherein the thin layer functioning as the ac heater is formed by a method selected from sputtering, vapor deposition, coating, adhesion and pressure application.
Claim 17
Dependent Claim
32 words
The method for measuring thermal diffusivity according to Claim 12, 13, or 14, wherein the temperature dependence of the thermal diffusivity is measured at desired temperatures by heating or cooling the sample.
Claim 18
Independent Claim
46 words
A method for measuring thermal conductivity of a thin sample plate comprising measuring the thermal diffusivity of the sample according to the method described in any one of Claims 12 through 15 and obtaining thermal conductivity using the specific heat and density of said measurement sample.
Claim 19
Independent Claim
135 words
An apparatus for measuring thermal diffusivity in the thickness direction of a thin sample plate, on one surface of which is formed a conductive thin layer functioning as an ac heater and the opposite another surface of which serves as the measurement surface, which comprises: an ac current generation means for applying an ac current with a given amplitude of modulation to one of the conductive thin layers; a dc current supplying means for applying a given dc current to another conductive thin film; a cell having a sound signal detector in the interior and capable of incorporating the sample plate in such a way that the measurement surface of said sample plate composes a part of the inner walls thereof; and a lock-in amplifier for amplifying the output signals of said sound signal detector.
Claim 20
Independent Claim
135 words
An apparatus for measuring thermal diffusivity in the thickness direction of a thin sample plate, on one surface of which is formed a conductive thin layer functioning as an ac heater and the opposite another surface of which serves as the measurement surface, which comprises: an ac current generation means for applying an ac current with a given amplitude of modulation to one of the conductive thin layers; a dc current supplying means for applying a given dc current to another conductive thin film; a cell having a sound signal detector in the interior and capable of incorporating the sample plate in such a way that the measurement surface of said sample plate composes a part of the inner walls thereof; and a lock-in amplifier for amplifying the output signals of said sound signal detector.
Claim 21
Dependent Claim
39 words
The apparatus for measuring thermal diffusivity according to Claim 17 which further comprises a means for heating or cooling the sample in the cell, thereby giving the temperature dependence of the thermal diffusivity by changing the measurement atmosphere temperature.
References Cited (Backward Citations)
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