KR920007197B1 - Method and apparatus for measuring thermal diffusivity by ac joule-heating - Google Patents

Abstract

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Description

Apparatus for measuring heat diffusion rate by alternating current heating and measuring method thereof

1 and 1a are side views showing the structure of the sample plate under the present invention. FIG. 1 shows an example in which a conductive thin film is formed on one side and FIG. 1a on both sides.

2, 3 and 8 are schematic diagrams of an example of the measuring device of the present invention and a measuring method thereof.

2 and 3 are examples of using a temperature oscillation response, and FIG. 8 is an example of using a priodic sound wave.

4 is an example when the measuring device of the present invention is automated,

5 shows a measurement example of the change by the average root of the frequency of the phase difference of the output of the alternating current component of the alternating current heat source and the range thermometer measured by the sapphire plate.

6 shows an example of the measurement of the temperature dependence of the thermal diffusivity measured by the polystyrene film.

FIG. 7 is a diagram showing an example of temperature dependence of thermal conductivity obtained by using the measured values of thermal diffusion of a polystyrene film and the measured values of specific heat and density obtained by other methods.

FIG. 9 is a diagram showing a change measurement example based on a frequency square root of an output phase difference of an AC component of an AC heat source and a negative pressure detector measured by a PET (polyethylene terephthalate) film.

* Explanation of symbols for main parts of the drawings

1: Sample plate to be measured 2: AC heat source (conductive thin film)

3: resistance thermometer (conductive thin film) 4, 40: AC current generator (operating synthesis device),

5: DC power supply (battery) 6: resistance to prevent self-heating

7, 60: lock-in amplifier 8, 70: data processing window

9: cell for cooling sample plate heating 10: temperature controller

Δθ: Phase difference 50: Microphone

f: frequency of temperature change on the temperature measurement surface

T: measuring temperature α: thermal diffusivity

λ: thermal conductivity

The present invention relates to a device for measuring the thermal diffusivity of a material, a method for measuring the same, and a method for measuring the thermal conductivity, and in particular, an abnormal method for measuring the thermal diffusivity of a non-conductive material such as a polymer compound or a ceramic with good precision (temperature is uniform And a method for measuring the thermal conductivity using the measured value of the thermal diffusivity obtained by the measuring method.

The thermal diffusivity and thermal conductivity are one of important physical properties in determining the material design of various materials such as a high molecular compound, the processing conditions and product conditions when performing product design.

In recent years, with the development of computers, various simulation programs have been developed, and material design and product design using them are frequently performed. For example, structural analysis for analyzing stresses and deformations of processed products and structures, and thermal conductivity analysis for thermal movement phenomena are already widely used in the world, and in recent years, thermal flow for analyzing anomalies of resins in molds in injection molding Interpretations have also been used. The accuracy of analysis of these simulation programs is also the content of the program, which is more dependent on the precision of the physical property values used for the analysis.

Therefore, in order to improve their analysis accuracy and to perform material design and product design accurately, highly accurate physical property measurement of the target material is desired.

In fact, the processed products are not only used at room temperature but are often used at high temperatures, and polymer materials or the like are usually subjected to a molding process in which they are melted at high temperatures during processing and then cooled to room temperature.

For this reason, when material design and product design are carried out in consideration of the actual use conditions and processing conditions of the product, or when the analysis is performed based on actual phenomena, the physical properties in a wide temperature range above the melting temperature are known at room temperature. It is necessary.

In recent years, the processing material is frequently used as a composite form, and the jaws have been complicated by various branches. In many cases, it is difficult to obtain a large amount of measurement samples in measuring the physical properties for material development and material design of such a special processed material. In addition, it is necessary to know the physical properties quickly and to reflect the results in the development and design contents without delay in time, and as a result, it is required to measure the physical properties quickly with a small amount of samples. .

In the method of measuring the thermal diffusivity, there are two methods, a normal method and an abnormal method. The characteristic of the method of measuring the thermal diffusivity by the anomaly method is to obtain the thermal diffusivity by forcibly creating a state of thermal non-equilibrium in the sample and measuring the temperature change of the sample caused by the relaxation. There are advantages such as significantly shorter.

Typical examples of the measurement method of the thermal diffusion by the abnormal method are the Angstrom method, the flash method, and the PAS method. In the Angstrom method, a portion of a rod-like sample having a sufficiently small cross-sectional area compared to its length is brought into contact with a heat source that periodically heats and cools, causing periodic temperature changes at one end of the sample, resulting in temperature fluctuations in the sample. In the state where the wave of this temperature propagates the sample stage, the temperature is measured at two or more measuring points whose distance from the heating point is different with respect to the wave propagation direction, and the amplitude and phase of the wave of the temperature obtained at each measuring point are measured. To calculate the thermal diffusivity.

In the flash method, a light absorption film is provided on one surface of a sample of a flat plate, and for example, a laser pulse or the like is irradiated to perform temporal heating by light absorption, and the temperature rise in the absorption layer that occurs at this time is the thickness direction of the sample. Is a method of measuring the temperature change occurring on the sample surface opposite to the irradiation surface as a function of time after flash irradiation, and measuring the thermal diffusivity in the curve of temperature and time obtained at this time.

In the PAS method, a microphone for measuring sound pressure is installed in a sealed cell with a window that transmits light, and a light absorbing film is installed on one side of a sample of the flat plate in the cell to irradiate the modulated light beam through a window to periodically change temperature. As the wave of this temperature propagates, the opposite side of the sample causes periodic temperature change, and it measures the fluctuation of the pressure wave occurring in the cell and uses the phase and amplitude to calculate the thermal diffusion rate.

The conventional measuring method described above has the following problems.

Since the angstrom method needs to form a sample into a long rod shape, a large amount of sample material is required, and a single system for minimizing heat loss from the sample surface is large. In addition, the measurement requires a relatively long time, and the measurement object is limited to a material having a relatively high thermal diffusion rate.

Since the flash method heats by light absorption, when measuring a transparent sample or a sample with little light absorption, it is necessary to apply the absorption layer for light absorption to a sample surface. Therefore, a heat loss and a heating stain generate | occur | produce in the interface of an absorption layer and a sample, and become a cause of an error. In addition, since the measurement time is short, it is assumed that heat loss does not need to be considered. A large thermal diffusivity of a metal or the like satisfies this assumption well, but a smaller thermal diffusivity of a polymer compound or the like causes a larger error.

Since the PAS method also heats by light absorption, the same problem as in the flash method arises, and due to the measurement method of measuring sound pressure by the sound pressure detector, the influence of noise due to vibration and noise is great. Again, in these measurement methods, it is difficult to measure the temperature dependence of the thermal diffusion rate, and even if it is measured, a large-scale apparatus is required.

The present invention solves the above-mentioned problems, and can accurately measure a material having a low thermal diffusion rate, can finish even a small amount of sample to be measured, and can measure a thermal diffusion rate that can be quickly measured by a small-scale device. It is an object of the present invention to provide a method and apparatus, and to provide a method of measuring thermal conductivity that obtains thermal conductivity from the measured value of thermal diffusivity.

According to the present invention, there is provided a method for measuring thermal diffusivity in the thickness direction of a thin sample plate, wherein a conductive thin film is formed on at least one side of the thin sample plate to allow current to flow through the thin film. An AC heater that generates heat by flowing an AC current that is modulated at a predetermined modulation frequency to an alternating heat source of the sample plate to be measured, and generates AC alternating heat (AC joule-heating), The oscillation response corresponding to the alternating heat is generated on the opposite side of the sample plate to be measured, and the phase of the response curve is measured, so that the one in the thickness direction of the sample plate is measured. A method of measuring the thermal diffusion rate of a thin measurement sample plate for calculating the diffusion rate is provided.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The sample to be measured in the present invention is a non-conductive material which can be formed into a thin film, film or plate,

I. Phenol, urea, melamine, polyyl ester, epoxy, polyurethane, cellulose, polystyrene, polypropylene, polyethylene, vinylidene chloride, polyamide, polyacetal, polycarbonate, polysulfone, ABS, polyphenylene oxide, Polymer compounds, such as polyether sulfone, polyarylate, acryl, acrylonitrile, polyether ether ketone, polyether ketone, polyimide and polyolefin.

II. Cyanine, phthalocyanine, naphthalocyanine, nickel complex, spiro compound, ferrocene, polgiide, imidazole, berylene, phenazine, phenothiadine, polyene, azo compound, quinone, indigo, diphenylmethane, triphenylmethane Organic pigments such as polymethine, acridine, acridinone, carbostyryl, coumarin, diphenylamine, kinacridone, kinopraton, phenoxakidine, and phthaloplinone.

III. Quartz, diamond, garnet, kotandam, ruby, sapphire, camphor, fluorite, diatomaceous earth, mica, rock salt, apatite, kaolin, tumotite, quartzite, red tin, emotion stone, ko hee seok, moonstone, marble, serpentine, malachite, booki Site, benniite, quartz, olivine, gypsum, sulfur, barite, alum, fluorite, feldspar, talc, asbestos, limestone, roadmite, calcite, crystal, amber, spinel, alexandrite, emerald, topaz, seedlings, jade, opal Ore etc.

Ⅳ. Quartz glass, fluoride glass, soda glass, soda lime glass, barium. Glass, such as strontium glass, lead glass, alumino borosilicate glass, borosilicate glass, aluminosilicate glass, and silica glass.

Ⅴ. Al ₂ O ₃ , MgAl ₂ O ₄ , Beo, SiC, AIN, MgO, PLZT, Y ₂ O ₃ , Zro ₂ , TiO ₂ , CaF ₂ , GaAs, PbO, CaO, La ₂ O ₃ , Si ₃ N ₄ , It is a fugitive ceramic, such as (alpha) -Si: H, and its thickness is thin enough to neglect thermal diffusion of a surface direction, and it is thought that it is fully insulated in a surface direction.

The conductive material used for the alternating heat source is a current that flows and generates heat by Joule heat, for example, gold, silver, platinum, copper, grain, zinc, antimony, iridium, chromel, constantan, nichrome, aluminum, Chromium, nickel, carbon, and the like.

The conductive material used for a resistance thermometer changes resistance value with temperature, for example, gold, silver, platinum, copper, grain, zinc, antimony, iridium, chromel, constantan, nichrome, aluminum, chromium, nickel, Carbon.

In addition, the conductive thin film used for the alternating heat source and the resistance thermometer has a thickness thin enough that the interface with the sample plate can be neglected, and the heat capacity is thinner than that of the sample plate. Compared with this, it is cold and small and closely adhered to each other. Therefore, it is considered that one surface of the sample plate to be measured alternatingly generates heat at the modulation frequency of the alternating heat source and directly measures the alternating current component of the temperature change of the other surface.

The conductive thin film used for the AC heat source and the resistance thermometer is mounted on the sample plate to be measured.

I. Spatter which generates thin film by adsorbing onto surface by using phenomena of protruding atoms constituting solid while irradiating ions to solid surface.

II. Deposition that evaporates a material in vacuo and adsorbs it on a surface to produce a thin film.

III. Application to paint on the surface of liquid, semi-liquid substances.

Ⅳ. Bonding joining surfaces by adhesives of the same or double material.

Ⅴ. Although it adheres by pressing etc. which join by the pressing force which presses and does not use the contact | attachment agent of the same kind or a heterogeneous substance on the surface, the method by sputtering or vapor deposition is the most preferable.

When the sample plate and the conductive thin film are brought into close contact with each other using a spatter, for example, when gold is used, the sample plate to be measured is subjected to a mask with an epolyester film or the like, and is then subjected to vacuum at 1.2 KV and 3.5 mA. It is preferable to adsorb | suck gold on a sample to be measured over about 30 minutes with a voltage and an electric current, and to set it as the conductive thin film with a thickness of 10-5000 angstroms and a resistance of about 0.1-10 KPa.

When the sample plate and the conductive thin film are brought into close contact with each other by evaporation, for example, when gold is used, the sample plate is masked with a polyester film or the like, and then the gold is heated under electricity to its melting point or higher under vacuum. It is preferable to make an electroconductive thin film by evaporating and adsorb | sucking gold on a to-be-fined sample plate for about 30 minutes, and thickness of 10-5000 angstroms and resistance value of 0.1 kPa-10 KPa.

When the sample plate and the conductive thin film are brought into close contact with each other by coating, the conductive paste, such as silver paste, is coated on the surface sample plate uniformly so as to have a thickness of 10 to 5000 Angstroms of about 0.1O to 10KΩ. It is preferable.

When the sample plate and the conductive thin film are brought into close contact with each other by adhesion, an adhesive is applied to a conductive thin film such as a copper foil or a gold foil having a thickness of 10 to 5000 angstroms and a resistance value of 0.1 k to 10 K kPa to the conductive thin film and the sample plate to be measured. It is desirable to paint thin enough to ignore the interface and to make it completely adhered to the sample plate to be peeled off.

When the sample plate and the conductive thin film are brought into close contact with each other by crimping, a conductive thin film such as a copper foil or a gold foil having a thickness of 10 to 5000 angstroms and a resistance value of about 0.1 to 10 KΩ is formed on the interface between the conductive thin film and the coated sample plate. It is preferable to press and adhere to a to-be-crystallized sample board by the force more than the crimping force which can ignore an influence.

Hereinafter, the basic configuration of the present invention and its features will be described with reference to the drawings.

In FIGS. 1 and 1a, reference numeral 1 denotes a sample plate to be measured and its thickness is substantially constant, and is thin enough to disregard thermal diffusion in the plane direction, for example, to measure the thermal diffusion of the sample plate to be measured. In the case of this square, the ratio (1 / d) of the length l and the thickness d is 10 or more, preferably 50 or more, more preferably 100 or more, and the upper limit of the thickness l is It is 2000 micrometers or less, Preferably it is 1500 micrometers or less, More preferably, it is 1000 vm or less, The lower limit of thickness (d) is 0.10 micrometer or more, Preferably it is 0.1 micrometer in the range which can ignore the heat capacity of the conductive thin film contact | adhered to both surfaces. As mentioned above, More preferably, it is a film, a sheet, or plate shape of 1 micrometer or more. Further, the sample plate 1 to be measured is a non-conductive material such as a polymer compound, ceramic, etc., whose resistivity is 1 × 10 ⁴ cm or more, preferably 1 × 10 ⁶ cm or more, more preferably 1 × 10 ⁷ cm The upper limit of the resistivity may be any amount, but may be, for example, 1 × 10 ²¹ cm or less, preferably 1 × 10 ²² cm or less, and more preferably 1 × 10 ²³ cm or less. A conductive thin film serving as an alternating heat source for alternatingly heating one surface of a sample plate under application of an applied current, the resistance of which is 0.01O to 100KK, preferably 0.05K to 50KK, more preferably 0.1K to 10KK.

The conductive thin film serving as the alternating heat source is completely in contact with the sampled sample plate to the extent that the interface between the sample plate and the AC heat source can be ignored, and the thickness thereof is sufficiently thin compared to the sample plate to be measured, for example, 50000 Angstrom or less, preferably Preferably, it is 10000 angstrom or less, more preferably 5000 angstrom or less, and the lower limit of the thickness may be any amount as long as the alternating current passes through, for example, 1 angstrom or more, preferably 5 angstroms or more, and more preferably 10 angstroms or more.

(3) is a conductive thin film which serves as a resistance thermometer for measuring the alternating current component of the temperature change on the surface opposite to the alternating heat source, whose resistance value is 0.01 to 100 KPa, preferably 0.05 kPa to 50 KK, more preferably 0.1 kPa 10 KPa.

The conductive thin film, which is a resistance thermometer, is completely adhered to the sample plate under test so that the sample interface between the sample plate and the resistance thermometer can be ignored, and the thickness thereof is sufficiently thin compared to the sample plate under test, for example, 10000. One or less angstroms, preferably 5000 angstroms or less, more preferably 1000 angstroms or less, and the lower limit of the thickness through DC current can be used as long as possible to read the resistance change. 5 angstroms or more, more preferably 10 angstroms or more.

2, 3 and 8 are schematic diagrams of an example of the measuring method and apparatus of the present invention. FIGS. 2 and 3 are examples of using a heating wave as a response curve, and FIG. Yes.

First, an example of using electrons (heat wave) will be described.

As shown in FIG. 2 and FIG. 3, the alternating current source 2 flows through alternating current by the modulated alternating current generator (operating synthesis device) 4 and is heated by alternating heat. The resistive thermometer 3 flows a constant voltage DC current by the DC power supply (battery, etc.) of (5), and amplifies the voltage change which is changed by the temperature dependence of the resistance value with a lock-in amplifier, The AC amplifier of (7) is arranged in parallel with a resistor inserted in order to prevent self-heating of the resistance-type soil thermometer of (6) as shown in FIG. It is arranged in parallel with the meter and measures the alternating current component of the temperature change.

The lock amplifier 7 is also called a synchronous rectification circuit, and obtains a direct current by adding the reference AC wave and the shunt wave from the AC current generator 4. Since it has a predetermined equivalent bandwidth and has selectivity, noise between frequencies required is almost completely eliminated.

The output of this lock-in amplifier 7 is input to the data processing apparatus (e.g., personal computer) 8, and the thermal diffusion rate is obtained. The calculation method of this thermal diffusion rate is as follows.

Since the main heat sequence is the maximum at the peak point regardless of the current, the temperature change cycle is twice the cycle of the alternating current. Therefore, the AC component of the temperature of the heat source 2 changes to the frequency of f when the frequency of the modulated AC current is set to f / 2. The fluctuating temperature assumes that each frequency is ω (= 2πf),

Is indicated by.

Although the sample 1 is a non-conductive material, since its thickness is very thin, the work energy due to Joule heat of the alternating current source 2 is transferred only by the work conduction in the thickness direction, and the resistance-type thermometer side 3 on the opposite side is Cause periodic temperature changes at.

If the sample thickness is d and the thermal diffusivity is α, the fluctuation temperature is

If you only focus on the phase difference between them,

Becomes Where [Delta] [theta] is the phase at which the sample plate is delayed due to thermal diffusion, and [beta] is the device constant.

If Δθ = 2πf is substituted for Eq. (3),

Get

Therefore, with respect to the specimen to be measured whose thickness d is already known, the modulation frequency is changed by at least two points or more, and the phase difference Δθ of the AC component of the temperature measured by the AC heat source and the resistance thermometer is measured, and the modulation frequency f The rate of change of the phase difference with respect to the square root (tilt and tilt when graphing) can be obtained, and the thermal diffusivity α can be obtained using the equation (4).

)가 피측정시료판의 두께 d 이하로 되는 주파수이며, 상한은 저항식 온도계에 의해 측정되는 온도진폭(amplitude)이 노이즈보다 충분히 큰 범위이며, 피측정시료판이 두께 100μm의 고분자 필름인 경우, 0.01에서 1000Hz, 바람직하게는 0.5에서 700Hz, 더 바람직하게는 0.1에서 500Hz이다.The lower limit of the frequency range suitable for this measurement is the thermal diffusion length (μs =

Is the frequency at which the thickness of the sample plate is equal to or less than d, and the upper limit is a range in which the temperature amplitude measured by the resistance thermometer is sufficiently larger than noise, and the sample plate is a polymer film having a thickness of 100 μm. At 1000 Hz, preferably 0.5 to 700 Hz, more preferably 0.1 to 500 Hz.

The measurement target plate 1 is mounted on the heating and cooling cell 9, and the temperature of the measurement atmosphere of the measurement unit is controlled by the temperature controller 10. By varying the measurement atmosphere temperature, the temperature dependence of the thermal diffusivity can be measured at any temperature.

As shown in Fig. 4, all of these apparatuses are controlled by a personal computer, the measurement results are automatically processed, and a batch automated measurement system is achieved. By determining the measurement frequency range at the start of the measurement, the output frequency of the working synthesizing device, which is an alternating current generator, is automatically changed after the measurement as each frequency is finished. The measurement by the lock-in amplifier is sent to the personal computer at the end of the measurement as each frequency, so that after the end of the measurement as the determined measurement frequency range, their measurements are saved to the floppy disk. In addition, by determining the measurement temperature at the start of the measurement, after the measurement at each temperature is finished, the temperature is raised or lowered to the next temperature, and the measurement is automatically repeated until the measurement at the specified temperature is completed.

When the thermal diffusivity is expressed in relation to the thermal conductivity, the work conductivity is λ, the specific heat is Cp, and the density is p,

If you transform it,

Becomes Therefore, as a measurement of specific heat and density measured by another measuring method, the thermal conductivity can be obtained from the equation (6) by combining with the measurement of the thermal diffusivity according to the present invention.

Specific heat can be measured by differential scanning calorimeter, adiabatic calorimeter, density can be measured by volume dilatometer, P-V-T measuring device, etc., and their measured values are used to obtain thermal conductivity.

As described above, the present invention utilizes the phase difference and amplitude of the temperature change of the heating surface and the other surface caused by alternating current heating depending on the modulation frequency of the alternating current flowing through the surface of the microplate. The thermal diffusivity is obtained by forming a conductive thin film, generating heat by an alternating current, and electrically measuring the temperature change of the opposing surface. Since only a thin conductive thin film is formed on the small sample plate, it is easy to uniformly heat and cool the measurement environment, and the temperature dependence of the thermal diffusion rate can be measured by arbitrarily changing the measurement atmosphere temperature. .

Moreover, thermal conductivity can be calculated | required by obtaining the measured value of the specific heat and density calculated | required by another method. Next, an example of using the latter pressure wave will be described.

As shown in FIG. 8, the sample to be measured is mounted on the sealed container 30 so as to maintain the airtightness so that the surface to be measured forms a part of the wall surface of the sealed container, and the AC heat source 2 is modulated by an operation synthesizer or the like. The alternating current is heated by the generator 40 of the alternating current. The sealed container 30 is provided with a microphone 50 as a negative pressure detector so as to maintain airtightness, and its output is amplified by the lock-in amplifier of 60, and measures the AC component of the pressure wave in the sealed container.

The lock authentication amplifier 60 is also called a synchronous rectification circuit, and is obtained by adding the reference AC wave and the detection wave from the AC power generator 40 to obtain a DC component. Since it has a predetermined equivalent bandwidth and selectivity, noise other than the required frequency is almost completely eliminated.

The output of this lock amplifier 60 is input to the data processing apparatus (for example, a personal computer) 70, and the thermal diffusion rate is calculated | required. The calculation method of this thermal diffusion rate is as follows.

Since the main heat is irrespective of the current and the peak point, the period of change of the temperature is twice the period of the alternating current. Therefore, the alternating current component of the temperature of the heat source 2 is modulated alternating current. If the frequency of f / 2 is changed to the frequency of f. The fluctuation temperature assumes each frequency is ω (= 2πf), and as described above,

Is indicated by.

This work energy is transferred by heat conduction, causing periodic temperature changes in the gas in the sealed container in contact with the surface under measurement on the opposite side, and generating a pressure wave consistent with the phase of the temperature variation of the surface under measurement of the sample. If the thickness of the sample is d and the thermal diffusivity is α, the fluctuation temperature is

If you focus only on the costume car of both,

It becomes This Δθ coincides with the phase difference of the pressure wave.

Therefore, if ω = 2πf is put in Eq. (3) instead, as described above,

Get

Therefore, with respect to the sample to be measured whose thickness d is already known, the phase difference with respect to the square root of the modulation frequency f is measured by varying at least a two-point modulation frequency and measuring the phase difference Δθ of the pressure wave measured by the AC heat source and the sound pressure detector. At the slope of, the thermal diffusion rate can be obtained.

)가 피측정시료의 두께 d 이하로되는 주파수이며, 상한은 진폭이 노이즈보다 충분히 큰범위이며, 피측정시료판이 두께 1OOμm 정도의 고분자필름의 경우 0.01에서 1000Hz, 바람직하게는 0.1에서 700Hz, 더 바람직하게는 1에서 500Hz이다.The lower limit of the frequency range suitable for measurement is the thermal diffusion length (μs =

) Is the frequency below the thickness d of the sample under test, the upper limit is a range where the amplitude is sufficiently larger than the noise, and in the case of the polymer film having a sample thickness of about 100 μm, 0.01 to 1000 Hz, preferably 0.1 to 700 Hz, more preferably Preferably 1 to 500Hz.

As described above, the present invention utilizes that the phase difference and amplitude of the pressure wave in the sealed organic body induced by the temperature change of the heating surface and the other surface by alternating current heating depend on the modulation frequency of the alternating current flowing through the heating surface. A fine conductive thin film is formed on a small sample to be measured, is heated by an alternating current, and the temperature change of the opposite surface is measured using a pressure wave. Since only a micro conductive thin film is formed on the micro sample to be measured, it is easy to uniformly heat and cool the sample under test, and the equipment is simple and small.

Hereinafter, preferred embodiments of the present invention will be described by way of examples.

Example 1

It measures by the apparatus shown in FIG.

On the sample plate to be measured, a 98 µm-thick sapphire plate with a size of 15 mm x 15 mm, an alternating heating source of 500 angstroms and a resistance thermometer of 800 angstroms, and a polyester film masked 10 mm x 3 mm, respectively. In the thickness of 120μm and 15mm x 10mm, and the alternating heating source is 500 angstroms, the resistance thermometer is 800 angstroms, and like sapphire, 10mm x 3mm Rome And each of them was sputtered with gold.

5 shows the change by the square root of the frequency of the phase difference between the AC heat source by the sapphire plate and the AC component output of the resistance thermometer. In the inclination obtained in this figure, the thermal diffusivity is obtained using the above-described formula. According to this measuring method, noise of frequency difference required by using the lock-in amplifier is almost completely eliminated. By measuring the phase difference, measurement data can be obtained without the measurement error due to the absolute value of temperature, and the measurement data can be obtained with high accuracy and excellent reproducibility. . The thermal diffusivity obtained at this inclination coincides well with the calculated value of the thermal diffusivity of sapphire and the thermal diffusivity at other thermal properties at about 1.2 × 10 ⁻⁵ m ² / sec.

6 shows the results of measurement on the temperature dependence of the thermal diffusivity of the polystyrene film. Although the glass transition temperature of this sample plate is about 105 degreeC, the thermal diffusivity can be measured over the wide temperature range more than glass transition temperature as shown in the figure. Moreover, the interesting result of having a peak in the thermal diffusion rate near a glass transition point is obtained, and the big difference also appears in the thermal diffusion rate in a liquid state and a solid state.

As described above, according to the present invention, it is possible to capture in detail the change in thermal diffusivity due to the higher order structure of the substance and the molecular motion, and to reliably design a product at a high temperature, which has conventionally been difficult to evaluate.

In addition, in using various simulation programs, the analysis can be performed with better accuracy at the actual processing temperature and the use temperature.

7 shows the results of measuring the temperature dependence of the thermal diffusivity in the present invention of the polystyrene film and the thermal conductivity obtained from the measurement of specific heat and density by other methods. The specific heat used the differential scanning calorimeter and the density used the measured value obtained by the capillary-type P-V-T measuring apparatus. The thermal conductivity obtained has a peak near the glass transition point similarly to the thermal diffusivity, the overall behavior is similar to the thermal diffusivity, and the specific heat and density are also better, whereby the thermal diffusivity contributes significantly to the thermal conductivity. As a result of this, as in the case of the thermal diffusivity, it is possible to reliably design a product at a high temperature, which has been difficult to evaluate in the past, and also, by using various simulation programs, an analysis with better accuracy at the actual processing temperature and the use temperature can be obtained. can do.

And while the same measurement was attempted by the apparatus of FIG. 3, it confirmed that substantially the same result was obtained.

Example 2

The apparatus shown in FIG. 8 was used.

In the sample to be measured, a PET (polyethylene terephthalate) film having a thickness of 100 μm and a size of 10 mm × 10 mm was used, and an alternating heating source was one having a thickness of 300 angstroms deposited with a spatter.

9 shows the change by the square root of the frequency of the phase difference of the AC heat source and the output from the sound pressure detector by the sample to be measured.

In the inclination obtained in this figure, the thermal diffusivity is similarly calculated using the above-described formula.

As described above, according to the present invention, the following effects are obtained, and the present invention can be suitably applied to fields such as the development of various materials such as polymer materials and ceramics, product design, and analysis by simulation.

(1) Since the sample plate to be measured is very small (and thin in thickness), and the conductive thin film is brought into close contact with each other, only the phase difference of the AC component of the temperature is measured, so that the absolute value of the temperature is not a problem, and the accuracy is small. The measurement can be performed, and the apparatus can be downsized and the measurement speeded up.

Therefore, various problems that the conventional angstrom method has, namely, a large amount of samples are required, and a facility of a thermal insulation system for minimizing heat loss is large, and measurement takes a relatively long time. All problems of being limited to a material having a relatively high thermal diffusion rate can be eliminated.

(2) Since the conductive thin film is formed in close contact with the sample completely by a spatter or the like, and the contact interface is so thin that it can be ignored, heat loss is not a problem.

Therefore, it is possible to suppress the occurrence of heating stains and heat loss errors, such as a flash method using a light absorption or a PAS range, and to measure errors due to vibration or noise since the measurement is not performed using a sound pressure detector like the PAS method. no need.

(3) Since the sample is very small and the apparatus is simplified and miniaturized, the sample part in the cell equipped with the sample can be heated and cooled, and the measurement atmosphere temperature of the measurement part can be easily changed, and the temperature dependence of the thermal diffusion rate can be measured. Can be.

When examining the actual conditions of use of the product or analyzing based on actual phenomena, it is necessary to know the thermal properties over a wide temperature range above the melting temperature at room temperature, but according to the present invention, as in the conventional method, The device does not need to be complicated or enlarged for the treatment of perks or the sealing of cells, and it is possible to measure the thermal properties of the sample in other areas and to flexibly cope with the research and development of the versatile material properties in recent years.

(4) The thermal conductivity can be obtained from the measured values of specific heat and density determined by a method different from the measured value according to the present invention.

It is important to know not only the thermal diffusivity but also the thermal conductivity when researching and developing the properties in consideration of physical properties depending on the thermal movement of the material. However, according to the present invention, the multi-faceted material properties of both the thermal diffusivity and the thermal conductivity You can do research and development.

Claims (18)

A method for measuring the thermal diffusivity in the thickness direction of a thin sample plate, wherein an electrically conductive thin film is formed on at least one side of the thin sample plate and an electric current flows through the thin film to generate an alternating heat source generated by Joule heat. Alternating current is applied to an alternating heat source of one sample plate at a constant modulation frequency to generate alternating current, generating a response curve corresponding to the alternating heat generation on the other opposite side of the sample plate to be measured. A method for measuring the thermal diffusion rate by alternating heating of a thin measurement sample plate which calculates the thermal diffusion rate of the thickness term of the measurement sample plate by measuring the phase of the response curve. The method of measuring a thermal diffusivity according to claim 1, wherein the response curve is a heating wave or a pressure wave. The conductive thin film according to claim 2, wherein a conductive thin film is formed on both sides of the thin sample plate, and one side of the thin film is an alternating heat source that generates heat by the main heat while flowing a current, and the other thin film is subjected to temperature. Using a measuring system made of a resistance thermometer using a change in resistance, the alternating current is generated by flowing an alternating current that is modulated at a constant modulation frequency to the alternating heat source of the sample plate to be measured. A temperature change is generated in response to the heat generation, the phase of the temperature change is measured, and the modulation frequency transmitted at least two points or more in the range of the modulation frequency described for the sample plate to which it is described is changed. Thermal diffusion in the thickness direction of the sample plate to be measured in correlation with the phase difference of the temperature change measured by the temperature change and the resistance thermometer and the modulated frequency. Thermal diffusivity measurement method according to the heat exchange to produce a. The method of measuring thermal diffusivity by alternating heating according to claim 3, wherein the sample plate to be measured is a plate of a non-conductive material selected from a polymer compound, an organic pigment, an ore, glass, and a ceramic. 4. The method for measuring heat diffusion rate by alternating current heating according to claim 3, wherein the conductive thin film made of a resistive thermometer is a thin film made of a conductive material whose resistance changes with temperature. The method of measuring thermal diffusivity by alternating current heating according to claim 3, wherein formation of a thin film made of a thin film and a resistance thermometer other than the alternating heat source is performed by a method selected from among spatter, vapor deposition, coating, adhesion, and compression. 4. The method of measuring a thermal diffusivity by alternating current heating according to claim 3, wherein the heating temperature of the sample to be measured is changed to an appropriate temperature by heating or cooling the sample to be measured. The method for measuring thermal diffusivity according to any one of claims 3 to 7, wherein the thermal conductivity is calculated from the measurement of the thermal diffusivity of the sample to be measured and the specific heat and density of the sample to be measured. . A device for measuring the thermal diffusivity in the thickness direction of a thin sample plate having conductive thin films on both sides, comprising: an alternating current generator for supplying an alternating current having a constant amplitude modulation applied to one conductive thin film, and the other conductive thin film. An apparatus for measuring heat diffusion rate by alternating current heating, comprising: a DC current supply for supplying a constant DC current, and a lock-in amplifier for amplifying a voltage that changes due to a temperature dependency of the resistance of the other conductive thin film. 10. The heat diffusion rate measuring apparatus according to claim 9, further comprising a cell containing a sample to be measured. 11. An apparatus for measuring a thermal diffusivity by alternating current heating according to claim 10, further comprising a mechanism for heating or cooling a sample to be measured in the cell, and changing the measurement atmosphere temperature to an appropriate temperature so that the temperature dependence of the thermal diffusion rate can be measured. The measurement according to claim 2, wherein a container having a negative pressure detector is prepared inside, a conductive thin film to be formed as an alternating heat source is formed on one surface, and the other surface facing the one surface is the measurement surface. The sample plate is mounted in a container in which the skin surface of the thin film forms a part of the inner wall surface of the container, and an alternating current is applied to the conductive thin film of the sample plate to be measured at a predetermined modulation frequency. Heat is generated, thereby generating a temperature change in response to the alternating heat generation on the measured measurement surface, thereby inducing a pressure wave, and measuring the phase of the corresponding pressure wave by an electric pressure gauge that measures the electrical power. Change the modulation frequency of at least two points in the range of the modulation frequency described for one sample plate, and change the temperature of the alternating A method of measuring thermal diffusion by alternating current heating, which calculates a thermal diffusivity in the thickness direction of a sample plate under a correlation between a generated pressure wave phase difference and an electrical modulation frequency. The method according to claim 12, wherein the sample plate to be measured is a non-conductive material selected from a polymer compound, an organic pigment, an ore, glass, and a ceramic. The method for measuring the thermal diffusivity by alternating current heating according to claim 12, wherein formation of a thin film serving as an alternating heat source is performed by a method selected from sputtering, vapor deposition, coating, bonding, and compression. The method of measuring a thermal diffusivity by alternating current heating according to claim 12, wherein the measurement temperature of the sample to be measured is changed to an appropriate temperature by heating or cooling the sample to be measured, thereby measuring the temperature dependency of the thermal diffusion rate. The method according to any one of claims 12 to 15, wherein the thermal diffusivity of the sample to be obtained by the method described therein and the measured value of the specific heat and density of the sample to be measured are used to calculate the thermal conductivity of the sample to be measured. Method for measuring thermal diffusivity by heating. A device for measuring the thermal diffusivity in the thickness direction of a thin sample wave to be measured on one surface, the conductive thin film being formed as an alternating heat source and having the other surface facing the one surface as the measurement surface. An alternating current generator for supplying an alternating current with a constant amplitude modulation to the conductive thin film of An apparatus for measuring the thermal volatility rate by alternating current heating, comprising: a container capable of mounting the sample plate so that the surface to be measured is part of an inner wall, and a lock-in amplifier that amplifies the output from the detected negative pressure. 18. The apparatus for measuring the thermal diffusivity by alternating current heating according to claim 17, further comprising a mechanism for heating or cooling the sample to be measured in the cell, and changing the measurement atmosphere temperature to an appropriate temperature to measure the temperature dependency of the thermal diffusivity.

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