WO2008053735A1

WO2008053735A1 - Method and device for heating article

Info

Publication number: WO2008053735A1
Application number: PCT/JP2007/070558
Authority: WO
Inventors: Hiromichi Watanabe
Original assignee: National Institute Of Advanced Industrial Science And Technology
Priority date: 2006-11-02
Filing date: 2007-10-22
Publication date: 2008-05-08
Also published as: JP4953061B2; JP2008116285A; DE112007002614T5

Abstract

In the heating control for maintaining the sample temperature, conduction heating is performed while feedback-controlling the gate voltage of a conduction heating control transistor so that an article to be heated such as a sample is at a target temperature, and the gate voltage is held after stopping feedback-control. The gate voltage of the conduction heating control transistor to the sample is controlled to perform quick heating until the temperature reaches a target level in order to maintain the temperature at the target value with good repeatability at the time of holding the gate voltage. Then feedback control of the gate voltage is started to maintain the temperature at the target level. After continuing feedback control until it can be considered that the temperature is maintained, feedback control is stopped and the average control value at a plurality of moments in time immediately before stopping feedback control is held thus maintaining the sample temperature at the target value. When this heating method is employed in measurement of thermal properties of a matter, light heating is performed at the time of holding the gate voltage and a plurality of values of thermal properties are determined by measuring temperature variation and Joule heating value.

Description

Specification

Object heating method and apparatus

Technical field

[0001] The present invention relates to a method of heating a substance that can maintain a constant temperature at a predetermined temperature with good reproducibility and efficiency, particularly when various substances are heated to a predetermined temperature at a high speed and then maintained at a constant temperature. The present invention relates to an apparatus for carrying out the method, and further relates to a method and apparatus using the object heating method and apparatus.

Background art

[0002] In order to conduct heat transfer analysis of equipment that generates heat or equipment used at high temperatures, the thermal properties of heat transfer and accumulation of component materials (specific heat capacity, hemispherical total emissivity, heat Conductivity, thermal diffusivity). There is no accumulation of newly developed materials or reliable literature values! When using materials as component materials for equipment, the above-mentioned thermophysical values must be obtained experimentally. In general, the above four thermophysical values are measured by different devices, so there is a problem that costs and time are superimposed. In addition, if a thermophysical value at a high temperature of 1000 ° C or higher is required, heating the sample to a high temperature for each thermophysical value measurement may cause sample deterioration or degradation of the measuring device. .

[0003] In the 1970s, Cezairliyan et al. In the United States developed a method for measuring the specific heat capacity and hemispherical total emissivity of conductive materials at temperatures above 1000 ° C at high speed using a single measuring device. The characteristic of this measurement method is the method of heating the sample. The charge stored in a large-capacity battery or capacitor is passed through the conductive sample, and the sample is generated by Joule heat generated by a large pulsed current flowing in the sample. Was heated to 3000 ° C or higher within 0.2 seconds with force S.

[0004] In this measurement method, the temperature and electrical resistance of the sample are measured during the above-described energization heating or cooling of the sample after energization, and the heat balance relationship between the generated Joule heat, the heat capacity of the sample, and heat radiation. The above two thermophysical values were derived from the equation. Although this measurement method is limited to conductive materials, it has achieved high-speed measurement of thermophysical values at high temperatures of 2000 ° C and above, which has been very difficult to measure, resulting from sample deterioration and measurement device deterioration. Minimize measurement error It was an epoch-making method that allowed the measurement cost to be significantly reduced while limiting the measurement cost.

[0005] However, this measurement method cannot measure the thermal conductivity and thermal diffusivity necessary for heat transfer analysis, and it is necessary to measure these thermophysical values separately. Correspondingly, Righini et al. In Italy developed a method to measure the thermal conductivity at the same time by measuring the temporal change of the temperature distribution of the sample during pulsed heating, but the thermal conductivity is not necessarily self-evident. Because it is calculated! /, It has become popular! /, Nare.

[0006] In principle, thermal conductivity is defined as the product of specific heat capacity, density and thermal diffusivity. In many cases, the temperature dependence of the density of solids is very small compared to the temperature dependence of thermal conductivity and specific heat capacity, so in general, the thermal diffusivity at high temperatures is generally the same as the density value at room temperature. The thermal conductivity can be calculated from the measurement results of the thermal diffusivity and specific heat capacity. Currently, the thermal diffusivity of solids is generally measured by the flash method.

[0007] However, when measuring the thermal diffusivity of high-temperature materials by the flash method, the temperature of the sample is generally controlled using a resistance furnace! /, So the measurable temperature is limited to about 2700 ° C. At the same time, sample deterioration as described above and degradation of the measurement device may affect the measurement.

[0008] In solving the above-mentioned problems and measuring the thermal diffusivity of a high-temperature substance, physical property values such as specific heat capacity, hemispherical total emissivity, thermal conductivity, and thermal diffusivity can be measured at a time. In addition, it is impossible to measure with conventional methods! /, A multiple thermophysical property measurement method capable of measuring the physical property values even at high temperatures, and an apparatus for carrying out the method Is disclosed in Patent Document 1 below.

[0009] This technology has a system configuration as shown in FIG. 5, and a capacitor 32 in the figure stores electric charge used for sample heating, and serves as a control device for the gate electrode of a current switch 33 made up of a field effect transistor. By applying a control voltage signal from the data recording and control device computer 42 constituted by a computer, a heating current is supplied to a flat sample 35 having a thickness of 1 mm or less, and the generated Joule heat is generated. This causes sample 35 to self-heat.

[0010] A voltage signal after the potential difference between both ends of the standard resistor 34 is amplified by the signal adjustment amplifier 40 is input to the data recording and control computer 42 and the heating current flowing through the sample 35 Measure the size of. Further, the signal after the potential difference in the sample 35 is amplified by the signal adjustment amplifier 41 is inputted to the data recording and control computer 42, and the magnitude of the voltage applied to the sample 35 is measured. Calculate the product of the current and voltage, and the power required to heat the sample 5, and continuously measure the Joule heat per unit time generated in the sample.

The temperature of the sample 35 heated as described above is measured by a radiation thermometer 37 using a silicon photodiode having a time resolution of about several tens of microseconds as a detection element, and the signal is recorded and recorded. Input to computer 42 for control device. The vertical spectral emissivity required to convert the luminance temperature measured by the radiation thermometer 37 to the true temperature is determined at high speed by a 'statistic' parameter that represents the polarization state of light without a mechanical drive. Measure continuously using a DO AP type monochromatic ellipsometer.

[0012] The computer 42 for data recording and control monitors the temperature signal of the radiation thermometer 37 and adjusts the gate voltage of the current switch 33 so that the temperature of the sample 35 becomes the set temperature. Control the flowing current. A field-effect transistor is used as the current switch 33, and the gate voltage is feedback controlled to keep the sample temperature constant at the specified target value.

[0013] After the feedback control of the sample heating current is continued for a certain period, the feedback control is stopped, and the subsequent gate voltage value is held at the control value immediately before the feedback control is stopped. During the state, the sample surface of the sample 35 measured by the radiation thermometer 37 is irradiated with laser light from the Norse YAG laser 36 by the trigger signal output from the computer 42 for data recording and device control, and is heated. is doing. The surface temperature change of the sample 35 after irradiation with the laser beam for light heating is measured by a radiation thermometer 37, and the temperature change is fitted to a one-dimensional heat diffusion model by a computer 42 for data recording and control equipment, so that heat diffusion is achieved. Calculate the rate. In this apparatus, since the radiation temperature of the sample is measured at a sampling interval of several tens of microseconds, a silicon photodiode having a high response speed as described above is used as the light intensity detection element of the radiation thermometer. In order to reduce heat loss due to heat exchange between the sample and gas, the measurement atmosphere should be a vacuum below ImPa.

On the other hand, the surface of the sample 35 is irradiated with light from the light source 38 of the high-speed ellipsometer, and its reflection is reflected. The light is detected by a detector 39 of a high-speed ellipsometer, and the signal is input to a data recording and control computer 42 to measure the spectral emissivity of the sample surface.

Patent Document 1: JP-A-2005-249427

Non-Patent Document 1: A.Cezairliyan, J 丄 .McClure, C.W.Beckett: J.Res. National Bureau of Standards, Vol.75C-l (1971), pp.7-18

Disclosure of the invention

Problems to be solved by the invention

In the thermophysical property measurement method proposed by the present inventors as described above, for example, the sample is heated as shown in FIG. 6, and the temperature change of the sample due to the laserless laser irradiation is measured. Is called. That is, in the example shown in FIG. 6, in Step 1 where 0 <t <480 ms, the sample in the room temperature body is energized and heated while feedback controlling the gate voltage of the field effect transistor, and is maintained at the target temperature. . Next, in step 2 where t = 480 ms, the feedback control performed in step 1 is stopped. Next, in step 3 where 480 <t <800 ms, the last gate voltage value derived by feedback control is maintained. Next, in step 4 at t = 480.55 ms, the sample is irradiated with a pulse laser and the temperature change of the sample due to the pulse laser is measured. Finally, in step 5 of t> 800ms, set the gate voltage to zero and quickly return the sample temperature to room temperature.

[0016] By the conventional method as described above, the desired heating is actually performed, and there is a case where an accurate measurement may be performed. However, it was found that the sample temperature could not be kept constant with good reproducibility! /. Figure 7 shows an example of failure of sample heating using this conventional method. Fig. 7 (a) and Fig. 7 (b) show the results of two heating experiments performed continuously under the same heating conditions on the same tantalum sample. In both of these experiments, the target temperature was set to 2100K, and the time to continue feed knock control was set to 300ms. In the experiment of Fig. 7 (a), the temperature is not kept constant in step 3, ie, the step of maintaining the gate voltage value finally derived by feedback control, and the temperature gradually increases. On the other hand, in the example of Fig. 7 (b), the temperature drops to step 3! /, And then the temperature gradually drops! /.

[0017] As a result of examining various causes of sample heating failure as described above, It was found that the gate voltage of the field-effect transistor was heated while feedback controlling the gate voltage of a field-effect transistor, and the variation in the gate voltage control value in step 1 was maintained at the target temperature. Focusing on Fig. 8 (b), which shows the time change of the gate voltage control value of the field effect transistor during the heating experiment shown in Fig. 8 (a), which corresponds to Fig. 7 (b), the time from the start of heating to the time of 100ms It can be seen that there is a large difference in the gate voltage control value during rapid heating and after reaching the target temperature.

[0018] In the example shown in the figure, the gate voltage Vg is the saturation drain voltage value of the gate voltage of the field-effect transistor used this time when the temperature of the specimen temperature is kept constant from the rapid heating state. Therefore, it is shown that the voltage drops rapidly to about 2.7V. In the stage where the temperature is kept constant, the fluctuation range of Vg needs to be considerably smaller than the saturation drain voltage value. However, in the conventional method, feedback control is already performed at the stage of rapid heating, so the fluctuation range of the feedback control value of Vg set in advance is a wide range up to the saturation drain voltage value. It is necessary to. In addition, in order to perform rapid heating, it is necessary to increase the proportional variable (P value) of the PID control theory adopted in the feedback control algorithm. For this reason, in the above-mentioned prior art, it is necessary to make the fluctuation range and P value of Vg large, and inevitably, when the temperature is constant after rapid heating, Vg, that is, Joule heat generated per unit time. The amount varies greatly. In the above prior art, when the Vg value is maintained at the final control value after feedback control is stopped, the Joule heat generation corresponding to the final control value matches the heat loss due to radiation or heat transfer from the sample at the target temperature. By doing so, it is used to maintain a constant temperature for a short time after feedback control is stopped. However, if the fluctuation of Vg during feedback control is large, the final control value often becomes a value that does not correspond to the target temperature of the sample. When such inadequate heating is performed, the results of thermophysical measurements that need to initially hold the sample in a steady state will be inaccurate.

Therefore, the present invention performs energization heating while performing feedback control of the gate voltage of a transistor such as a field effect transistor so that the temperature of the object to be heated such as a sample becomes a target value. Feedback control after is maintained at the target value In heating control where the temperature is kept constant only by holding the gate voltage after that, so that the temperature constant state can be maintained with good reproducibility when the gate voltage is held after the feedback control is stopped. The main object is to provide a heating method and a heating device for the object.

Means for solving the problem

[0020] In order to solve the above problems, the object heating method according to the present invention controls the gate voltage of a transistor used to control the amount of current supplied to the conductive object to be heated, and the temperature of the object to be heated is a target value. After reaching the target value, the gate voltage feedback control is started so that the temperature of the object to be heated remains constant at the target value, and the temperature of the object to be heated remains constant at the target value. The feedback control is continued until the temperature is within the temperature amplitude range that can be substantially regarded as having been set, and the feedback control is stopped when the target value is held constant, and then the gate voltage value immediately before the feedback control is stopped. The temperature of the object to be heated is held constant at the target value by holding the average value of the gate voltage control value at any given time.

[0021] Further, according to another object heating method of the present invention, in the object heating method, a predetermined range in which a control range of the gate voltage is determined in a period during which the gout voltage is feedback-controlled. It is characterized by limiting to.

[0022] Further, according to another object heating method of the present invention, in the object heating method, the heated object is a conductive sample for measuring a thermophysical property, and immediately after the gate voltage is held. The sample is characterized by measuring the thermal properties by light heating the sample and measuring the subsequent temperature change of the sample.

[0023] Further, the object heating apparatus according to the present invention includes an energization heating unit that energizes and heats a conductive object to be heated, a transistor disposed in an energization circuit of the object to be heated, and a temperature of the object to be heated. Temperature control means for measuring the transistor, and a temperature control for controlling the gate voltage of the transistor so that the temperature of the object to be heated becomes a predetermined target value by inputting a temperature signal measured by the temperature measurement means In the temperature control means, the gate voltage is first rapidly heated by controlling the gate voltage, and once reaching the target value, the gate voltage is kept constant at the target value. Feedback control and feedback The feedback control is stopped after the temperature is maintained at the target value by the control, and then the gate voltage value is set to the average value of the gate voltage control values at a plurality of time points immediately before the feedback control is stopped. The sample temperature is kept constant at the target value even after feedback control is stopped.

[0024] Further, another object heating device according to the present invention provides a predetermined range in which a control range of the gate voltage is determined in advance during a period during which the gout voltage is feedback controlled by the object heating device. It is characterized by limiting to.

[0025] Further, in another object heating apparatus according to the present invention, in the object heating apparatus, the heated object is a conductive sample for measuring thermophysical properties, and immediately after the gate voltage is held. The sample is characterized by measuring the thermal properties by light heating the sample and measuring the subsequent temperature change of the sample.

[0026] Further, another object heating apparatus according to the present invention is characterized in that the object heating apparatus is used as a high-speed precision temperature heater that heats various objects.

[0027] Another object heating apparatus according to the present invention is characterized in that the object heating apparatus is used as a heat treatment method for a metal or alloy using direct current heating.

The invention's effect

[0028] Since the present invention is configured as described above, the gate voltage of a transistor such as a field effect transistor is not feedback controlled so that an object to be heated, such as a sample, reaches a target temperature. After that, in the heating control that keeps the temperature constant by simply holding the gate voltage, the temperature constant state can be continued with good reproducibility after the feedback control is stopped.

Brief Description of Drawings

[0029] [Fig. 1] Experimental data showing changes in luminance temperature when a sample is heated by the heating method of the present invention.

FIG. 2 is a diagram showing an example of a photoconductive hybrid 'pulse heating system to which the heating method of the present invention is applied.

[FIG. 3] Experimental data showing the fluctuation state of the gate voltage during the feedback control by the heating method of the present invention and the conventional example. [Fig. 4] Experimental data showing the state of luminance temperature change of the sample by the heating method of the present invention and the conventional example.

FIG. 5 is a system diagram of a conventional thermophysical property measuring apparatus previously proposed by the present inventors.

[Fig. 6] Experimental data showing changes in brightness temperature when a sample is heated by a conventional device.

[Fig. 7] Experimental data showing an example of failure when a sample is heated by a conventional apparatus.

[Fig. 8] Experimental data showing the cause of conventional sample heating failure.

Explanation of symbols

[0030] 1 Photoelectric hybrid 'pulse heating system

2 capacitors

3 Field effect transistor

4 Standard resistance

5 samples

6 No Noles Laser

7 Radiation thermometer

8 Semiconductor laser

9 High-speed ellipsometer

10 beam 'splitter

11 Voltage measurement probe

12 Temperature control · Signal recording computer

13 photodetector

BEST MODE FOR CARRYING OUT THE INVENTION

[0031] In order to solve the above problems, the present invention controls the gate voltage of a transistor used to control the amount of current supplied to the conductive object to be heated, and rapidly heats the object to be heated until the temperature reaches the target value. After reaching the target value, feedback control is continued until the temperature of the object to be heated converges to a temperature amplitude range that can be substantially regarded as being held at the target value. After the control is stopped, the gate voltage value of the gate voltage control value at multiple points immediately before the feedback control is stopped By holding the average value, the temperature of the object to be heated is held constant at the target value.

Example 1

[0032] An embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows the temperature change of the sample when the heating method of the present invention is used and the heating control is actually performed, and corresponds to the sample temperature change during the experiment by the conventional heating method shown in Fig. 6 above. is doing. The heating system for executing the heating method according to the present invention uses the same heating system as that of the previous application by the present inventors shown in FIG. 5, and the photoconductive hybrid pulse heating as shown in FIG. System 1 is used.

Capacitor 2 in FIG. 2 stores electric charge used for sample heating, and applies a control voltage signal from temperature control / signal recording computer 12 configured by a computer as a control device to the gate electrode of field effect transistor 3 Thus, a heating current is supplied to the flat sample 5 and the sample 5 is self-heated by the generated Joule heat.

[0034] The signal of the potential difference between both ends of the standard resistor 4 is input to the temperature control signal recording computer 12, and the magnitude of the heating current flowing through the sample 5 is measured. In addition, the potential difference signal in sample 5 is input to temperature control / signal recording computer 12 and the voltage applied to sample 5 is measured. Product of the above current and voltage Calculate the power required to heat sample 5, and continuously measure the Joule heat per unit time generated in the sample.

[0035] The temperature of the sample 5 heated as described above is measured by a radiation thermometer 7 using a silicon photodiode having a time resolution of about several tens of microseconds as a detection element, and the signal is controlled by a temperature control signal. Input to recording computer 12. The vertical spectral emissivity required to convert the luminance temperature measured with the radiation thermometer 7 to the true temperature is determined at a high speed with a 'statistics' parameter representing the polarization state of light without a mechanical drive. Measure continuously using a DOAP type monochromatic ellipsometer.

[0036] The temperature control 'signal recording computer 12 monitors the temperature signal of the radiation thermometer 7 and adjusts the gate voltage of the field effect transistor 3 so that the sample 5 has a set temperature, thereby adjusting the sample temperature. Is kept constant at the target value.

[0037] After the sample temperature is kept constant at the target value by the feedback control of the gate voltage, Radiation thermometer during a constant temperature state that is maintained for a short time by stopping the feedback control and holding the gate voltage value at the average value of the gate voltage control value at any time instant just before stopping the feedback control The back of the surface of the sample 5 to be measured by 7 is subjected to instantaneous light heating by irradiating optical noise from the laser 6 with a signal from the temperature control 'signal recording computer 12'. At that time, a part of the pulsed light beam is taken into the photodetector 13 by the beam splitter 10, and the signal from the detector is analyzed by a temperature control / signal recording computer to determine the irradiation time of the optical noise.

[0038] The surface temperature change of the sample 5 after irradiation with the light norms is measured by a radiation thermometer 7, and the temperature control and signal recording computer 12 is used to fit the temperature change to a one-dimensional heat diffusion model. Calculate the diffusion rate. In this device, since the radiation temperature of the sample is measured at a sampling interval of several tens of microseconds, a silicon photodiode having a high response speed is used as the light intensity detection element of the radiation thermometer as described above. In order to reduce heat loss due to heat exchange between the sample and gas, the measurement atmosphere should be a vacuum of ImPa or less.

[0039] On the other hand, the surface of the sample 5 is irradiated with light from the semiconductor laser 8, which is the light source of the high-speed ellipsometer, and the reflected light is detected by the high-speed ellipsometer 9, and the signal is controlled by a temperature control signal recording computer. Input to 12 and measure the spectral emissivity of the sample surface! The subsequent measurement of thermophysical properties is described in detail in the above-mentioned previous application, and since there is little direct relationship with the present invention, explanation here is omitted.

[0040] Using the apparatus as described above, in the present invention, the sample is heated as shown in FIG. In the heating experiment shown in Fig. 1, in the first step 1, rapid heating is performed in step 1 corresponding to the time region until the target temperature 2100K set in advance is reached. Once the target temperature is reached by rapid heating, feedback control of the gate voltage is started so that the target temperature is kept constant. This feedback control period corresponds to the time region of step 2 in FIG. 1. Unlike the above-described prior art, the sample temperature has already reached the target value before starting the feedback control. The fluctuation range of the voltage control value does not need to include such a large value as required during rapid heating. Therefore, fluctuations in the appropriate gate voltage control value to keep the target temperature constant Set the range in advance. In the experiment shown here, the control value fluctuation range of the gate voltage was limited to 2.8 to 2.9 V, and the fluctuation of the sample temperature and control gate voltage value in the time domain of Step 2 could be reduced.

[0041] The force S that will stop the feedback control after the end of step 3 after that, and the average value of the 20 gate voltage control values derived just before the stop of the feed knock control are temperature control and signal recording. The value of the gate voltage is held at this average value in the time domain in which the calculation is performed by the computer 12 and step 6 is completed after the start of step 4 after the feedback control is stopped. In this experiment, the time interval for deriving the 20 gate voltage control values used to calculate the average value is 2 ms, and this time domain corresponds to step 3 and corresponds to the 2 ms period immediately before the end of step 2. is doing.

[0042] After the feedback control is completed, an average value of the gate voltage control values at a plurality of times immediately before stopping the feedback control is obtained, and the gate voltage is held at that value from the start of step 4 to the end of step 6. To do. The time domain from the start of the gate voltage hold to the pulse laser irradiation shown as step 5 in the figure corresponds to step 4, which is 20 ms long in this experiment. In this experiment, pulse laser irradiation was not performed in order to confirm the continuity of the sample temperature after feedback control. In the time domain after laser irradiation shown in step 6, the temperature change of the sample is measured by the pulse laser to obtain various physical properties as detailed in the previous application. The period of step 6 is a period for acquiring data necessary for calculating the thermal diffusivity. Finally, the gate voltage is set to zero after the preset measurement work completion time, and the sample temperature is quickly returned to room temperature.

[0043] As a result of performing the control as described above, it is possible to maintain the temperature at the time of holding the gate voltage based on reproducibility. In addition, the feedback control time is shorter than before and the temperature can be kept constant when the gate voltage is held. Furthermore, the temperature fluctuation during feedback control can be reduced, and the magnitude force S of the overshoot of the sample temperature generated at the end of the rapid heating is reduced. These effects enable efficient and accurate thermophysical property measurement.

[0044] In order to confirm the above-mentioned effects of the present invention, a comparison between a conventional patent technique continuously performed using the same tantalum sample and a heating experiment performed by the technique of the present invention is shown in FIG. 3 and FIG. Fig. 3 (a) shows an example of the fluctuation range of the gate voltage by the same conventional heating method as in Fig. 8 (b). As mentioned above, Vg = 2.7 to 6 V, and the fluctuation range is large. It has been shown. On the other hand, according to the heating method of the present invention shown in FIG. 3 (b), the gate voltage Vg is maintained at 2.8 to 2.9V, and the allowable range of the gate voltage control value is narrowed. It is shown. By carrying out such control, the temperature can be kept constant with good reproducibility when holding the gate voltage after feedback control, and the temperature is kept at a predetermined constant value when holding the gate voltage with a shorter feedback control time than before. be able to. As a result, the experiment time is shortened, the contamination time of the sample is reduced, accurate measurement is possible, and the measurement cost S can be reduced.

[0045] FIGS. 4 (a) and 4 (b) show the temperature changes of the samples obtained during heating shown in FIGS. 3 (a) and (b), respectively. In Fig. 4 (a) showing the change in brightness temperature of the sample, it is shown that the temperature must be constant in step 3 after step 2 where feedback is stopped as described above! The On the other hand, in the heating method of the present invention shown in FIGS. 3 (b) and 4 (b), when the gate voltage is held after the feedback is stopped, the gate voltage during the feedback control in step 2 is stable as described above. In addition, since the average value of several tens of points immediately before the feedback control is stopped is used as the hold value, it can be maintained extremely stably at the same temperature as the predetermined temperature of the feedback control even after the feedback control. . This has the effect of improving the accuracy of thermal diffusivity and hemispherical total emissivity measurements.

Industrial applicability

[0046] The heating method of the present invention as described above mainly measures the thermophysical values such as specific heat capacity, hemispherical total emissivity, thermal conductivity and thermal diffusivity of various substances at high temperatures as described above. This heating method can be used for electrification heating of test specimens and various devices, for example. It can also be used as a high-speed precision temperature heater that requires

Furthermore, for example, in the heat treatment of metals and alloys, it is possible to reach the target temperature accurately and at high speed, and hold the temperature for an accurate time.

Claims

The scope of the claims

[1] After controlling the gate voltage of the transistor used to control the amount of current supplied to the conductive object to be heated, rapidly heating until the temperature of the object to be heated reaches a predetermined target value, and then reaching the target value ,

Start feedback control of the gate voltage so that the temperature of the object to be heated is maintained at the target value, until the temperature of the object to be heated converges to a temperature amplitude range that can be substantially regarded as being held at the target value. Continues feedback control, stops feedback control when it is held constant at the target value, and then holds the gate voltage value at the average value of the gate voltage control value at any time point immediately before stopping feedback control. The object heating method is characterized in that the temperature of the object to be heated is kept constant at a target value.

2. The object heating method according to claim 1, wherein a control range of the gate voltage is limited to a predetermined range in a period during which the gate voltage is feedback-controlled.

[3] The heated object is a conductive sample for measuring thermal properties,

Immediately after holding the gate voltage, the sample is photoheated,

The method for measuring a thermophysical property using the method for heating an object according to claim 1, wherein the thermophysical property is measured by measuring a subsequent temperature change of the sample.

[4] energization heating means for energizing and heating the conductive object to be heated;

A transistor disposed in the energization circuit of the heated object;

Temperature measuring means for measuring the temperature of the heated object;

A temperature control means for inputting a temperature signal measured by the temperature measurement means and controlling the gate voltage of the transistor so that the temperature of the object to be heated becomes a predetermined target value;

In the temperature control means, first, the gate voltage is controlled and rapidly heated, and once the target value is reached, the gate voltage is feedback controlled so that the temperature of the sample is kept constant at the target value. After the temperature is maintained at the target value by feedback control, stop the feed knock control, and then set the gate voltage value to the average value of the gate voltage control values at multiple points just before stopping the feedback control. The feedback The object heating device is characterized in that the sample temperature is kept constant at the target value even after the vacuum control is stopped.

5. The object heating device according to claim 4, wherein the gate voltage is limited to a predetermined range within a period during which the gate voltage is feedback controlled.

[6] The heated object is a conductive sample for measuring thermal properties,

Immediately after holding the gate voltage, the sample is photoheated,

5. The thermophysical property measuring apparatus using the object heating device according to claim 4, wherein the thermophysical property is measured by measuring a subsequent temperature change of the sample.

7. The object heating apparatus according to claim 4, wherein the apparatus is used as a high-speed precision temperature heater for heating various objects.

8. The object heating apparatus according to claim 4, wherein the apparatus is used as a heat treatment method for a metal or alloy using direct current heating.