JPS62231148A - Thermal analysis instrument - Google Patents

Abstract

PURPOSE:To improve the accuracy of temp. measurement while improving responsiveness by uniting a sample holder and heating furnace integrally, connecting a temp. detector to the center at the base of the sample holder and constructing the heating furnace in such a manner that the heat from said furnace is transmitted from the side wall of the sample holder to the base. CONSTITUTION:The sample holder 22 is integrally united with the side wall 24 and heating member 26. A bottom plate 30 which is the base of the sample holder 22 is inserted via mica 28 to the upper part of the heating member 26. The temp. detector 32 is joined to the central part of the bottom plate 30. The heat generated by a heater 36 flows mostly to the heating member 26. Since the thick mica 28 is interposed between the heating member 26 and the bottom plate 30, the greater part of the heat from the heating member 26 passes the metallic part of the sample holder 22 and flows in the central direction of the bottom plate 30 from the side wall 24 of the sample holder as shown by the arrow so as to arrive at a thermocouple 32. There is the sample 20 on the bottom plate 30 and therefore, a heat exchange is executed between the bottom plate 30 and the sample 20. The temp. of the sample 20 and the temp. of the bottom plate 30 are made equil. at approximately the same temp. at the place of the thermocouple 32.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is applicable to relatively simple applications such as melting point measuring devices, for example.
The present invention relates to a thermal analysis device that precisely measures the sample temperature while heating a sample of 1 (for example, about 0.1 to 100 mg).

The invention also relates to a thermally compensated differential scanning calorimeter.

(Prior Art) Examples of thermal analysis devices that measure the temperature of a trace sample while heating it are shown in FIGS. 6 and 7.

In the thermal analysis apparatus having the structure shown in FIG. 6, heat from the heater 2 is transmitted through the heat transfer plate 4 to the sample 6.

A thermocouple 8 as a temperature detector is attached to a heat exchanger plate 8 at the position of the sample 6.
It is set in. Although the heat transfer plate 4 is often fully bent, there is also a structure in which the heat transfer plate 4 is not provided and the sample 6 is heated by the heater 2 via an air layer. Alternatively, the thermocouple 8 may be directly immersed in the sample 6.

In the thermal analysis apparatus having the structure shown in FIG. 7, a heating furnace 12 is integrally provided at the bottom of the sample holder 10. In the heating furnace 12, a heater 16 and a platinum resistor 18 as a temperature detector are embedded in an insulating material 14. Sample holder 10
A sample 20 contained in a container is placed on top of the container.

(Problems to be Solved by the Invention) In the thermal analyzer shown in FIG.
The thermal resistance between them is large and the response is poor.

In the thermal analysis apparatus shown in FIG. 7, a temperature detector such as a platinum resistor 18 is provided near the heater 16 or is provided integrally with the heater 16.

Therefore, it is unclear whether the heater temperature or the sample temperature is detected, and it is necessary to calibrate the thermal analyzer each time.

For example, when heated at 10°C/min using the thermal analyzer shown in Figure 7, the melting point of indium (In) (156.5°C)
may appear about 3 to 4°C higher. This error varies depending on the heating rate, and increases as the heating rate increases.

The present invention provides a thermal analysis device that can rapidly raise the temperature of a sample while preventing the heat generated by the heater from directly transmitting to the temperature detector, and can also accurately measure the sample temperature. The purpose is to

(Means for Solving the Problems) In the thermal analysis apparatus of the present invention, a sample heating furnace is integrally provided at the lower part of the sample holder, a temperature sensor is bonded to the bottom surface of the sample holder, and the sample heating furnace An insulating material with high thermal resistance is interposed between the bottom surface of the sample holder and the sample holder, and the sample is placed in a path where heat flows from the side surface of the sample holder to the temperature sensor, and the sample is heated while the temperature sensor is heated. Measure the temperature.

Further, the thermal analysis device of the present invention is a differential scanning calorimeter, and a sample heating furnace is integrally provided at the lower part of each of the sample holder for a reference substance and the sample holder for a measurement sample, and An insulating material with high thermal resistance is interposed between each sample heating furnace and the bottom surface of each sample holder, and a reference substance and a measurement sample are placed in the path through which heat flows from the side surface of the sample holder and reaches the temperature detector. The temperature sensor is configured to measure the temperature of the reference substance and the measurement sample while heating the reference substance and the measurement sample.

(Example) FIG. 1 represents one embodiment of the invention.

22 is a cylindrical sample holder, and a side Ji 24 and a heating member 26 are integrally provided. A bottom plate 30 that becomes the bottom surface of the sample holder is attached to the top of the heating member 26 with mica 28 interposed therebetween.
is inserted, and the end surface of the bottom plate 30 and the inside of the sample holder side wall 24 are brought into close contact.

The sample holder side wall 24 and the bottom plate 30 are made of heat-resistant, fully bendable material such as stainless steel or platinum-iridium alloy.

The thickness of the mica 28 is approximately 200 to 300 μm, and the thermal resistance is sufficiently large.

A sample 20 placed in a container made of aluminum or the like is placed on the bottom plate 30 .

A thermocouple 32 as a temperature detector is bonded and attached to the center of the bottom plate 30.

Mica 34. The heater 36 and the mica 38 are inserted in this order, and the disc-shaped part of the support member 40, which has a cylinder whose tip is expanded into a disc-shape, is further inserted below. These members 34, 36, 38, 40 are fixed by bending the lower part of the sample holder side wall 24 inward.

Mica28. Heating member 26. Mica 34. Heater 6.
The mica 38 and the support member 40 have a hole in the center,
A thermocouple 32 protected by an insulator 33 is guided to the outside through these holes.

The thickness of the mica 34 provided between the heater 36 and the heating member 26 is about 20 to 30 μm, and this thickness is the same as that of the mica 38 provided between the heater 36 and the support member 40.
The heater 3 is sufficiently thinner than the
The heat generated in step 6 can be efficiently used for sample heating.

As the heater 36, a thin film heater with a thickness of approximately 15 μm is used, and is insulated by mica 34 and 38.

The sample holder, which also serves as a heating furnace, has an external diameter of approximately 7
It is possible to produce a material with a height H of approximately 4 mm. When configured in such a small size, the temperature is 100℃/
It is also possible to heat the sample for about a minute.

In this embodiment, most of the heat generated by the heater 36 flows to the heating member 26. Then, the heating member 26 and the bottom plate 30
Since the thick mica 28 is interposed between the heating member 2
Most of the heat from the sample holder 22 passes through the metal portion of the sample holder 22 and flows from the sample holder side wall 24 toward the center of the bottom plate 30, as indicated by the arrow, to the thermocouple 32. At this time, since the sample 20 is on the bottom plate 30, heat exchange occurs between the bottom plate 30 and the sample 20, and at the thermocouple 32, the temperature of the sample 20 and the temperature of the bottom plate 30 are equilibrated to almost the same temperature. .

According to this example, the temperature error in the melting point of indium was within about 0.3°C within a heating rate range of 1 to 20°C/min.

If the temperature range is below 400°C, mica 28°34.
In place of 38, a heat-resistant resin such as polyimide can be used. However, mica is preferred when heating to 500-600°C.

FIG. 2 shows an exploded perspective view of the embodiment shown in FIG. 1, and the manufacturing method thereof will be explained.

The sample holder main body 22 is formed into a shape in which the lower part of the side wall 24 is notched as shown in the figure.

Mica 28 is inserted into the side wall 24 from above the sample holder main body 22, and the bottom plate 30 to which the thermal lightning pair 32 is joined is press-fitted onto the mica 28. From below the sample holder 22, mica 34. Heater 36° mica 38 and support member 40
are inserted in this order, and the lower part of the side wall 24 is bent inward. Lead wires 37a and 37b of the heater 36 are taken out from the cut portion of the side wall 24.

FIG. 3 represents a second embodiment of the invention.

Comparing the embodiment shown in FIG. 1, the mica 34 as an insulating material interposed between the heater 36 and the heating member 26 in the heating furnace is replaced with a ceramic coating 42 mainly composed of alumina in this embodiment. They are different in that they are The other structure is the same as the embodiment shown in FIG. however,
The illustration of the insulator of the thermocouple 32 is omitted.

The thinner the ceramic coating 42 is, the better from a thermal standpoint, but the thinner it becomes, the worse the electrical insulation, so it should be 30~30.
Approximately 50 μm is appropriate.

Ceramic coating 42 is electrically insulating up to 500-600°C and has higher thermal conductivity than mica. Also,
Since the thickness can be made uniform and there are no air spaces like mica, it is easy to make products with uniform properties.

Such a ceramic coating 42 is applied to the heating member 26.
In order to form this on the back surface of the heating member 26, as shown in FIG. 2, a ceramic coating may be applied to the back surface of the heating member 26 with the lower part of the side wall 24 of the sample holder 22 being straight, and the heating member 26 may be wrapped.

In the embodiment shown in FIG. 3, mica 28 and 38 are used between the heating member 26 and the bottom plate 30 and between the heater 36 and the support member 40, respectively, as in the embodiment shown in FIG. In addition to reducing heat loss, this also serves as a cushioning material that absorbs differences in thermal expansion between each member due to temperature cycles and slight waviness of the ceramic coating surface, and evenly presses the heater 36 against the heating member 26. ing.

When the embodiment shown in FIG. 3 was used, both the baseline and noise level were improved by 2 to 3 times compared to the embodiment shown in FIG.

FIG. 4 represents a third embodiment of the invention.

Compared to the embodiment shown in FIG. 3, a ceramic coating 44 is also applied to the bottom surface of the bottom plate 30, and thermocouples 46 and 48 are also provided between the ceramic coating 44 and the mica 28.
The difference is that thermocouples 32, 46 and 48 are electrically connected to form a thermopile to increase the sensitivity of temperature measurement. Other structures are the same as those in FIG. Fourth
In the figure, the insulators of the thermocouples 32, 46, and 48 are not shown.

FIG. 5 shows an embodiment of the thermally compensated differential scanning calorimeter of the present invention.

Reference numerals 50a and 50b are sample holders integrated with the heating furnace, both of which are shown in FIG. 3.

A reference substance 52 is placed on the sample holder 50a, and a measurement sample 54 is placed on the sample holder 50b.

The sample holders 50a and 50b each have a support member 40a.
, 40b are integrally fixed to the support member 56.

Chromel alumel is used as the thermocouples 32a and 32b. The chromel wires (C) of the surface thermocouples 32a and 32b are commonly connected to each thermocouple 32a.

The Alumel wires (A) of 32b are connected to each input of the amplifier 58, respectively. As a result, the temperature difference ΔT between both sample holders 50a and 50b is input to the amplifier 58.

The temperature of each sample holder 50a, 50b can be measured by a respective thermocouple 32a, 32b.

60 is a power amplifier/switching circuit, and heaters 36a, 36b of the heating furnaces of both sample holders 50a, 50b.
The output signal of the amplifier 58 is inputted, and the heaters 36a, 36 are controlled so that the input signal of the amplifier 58 becomes 0, that is, the temperature difference ΔT=0.
Controls the amount of current applied to b.

In the differential scanning calorimeter shown in FIG. 5, the sample holder 50a,
50b shown in FIG. 1 or shown in FIG. 4 may be used.

(Effect of the invention) In the present invention, the sample holder and the heating furnace are integrated, and
A temperature sensor is connected to the center of the bottom of the sample holder so that the heat from the heating furnace is transmitted from the side wall of the sample holder to the bottom, improving temperature measurement accuracy and precisely controlling sample temperature according to a fixed program. become able to.

Furthermore, in the present invention, the temperature measurement accuracy does not depend greatly on the temperature increase. Therefore, when simply measuring the melting point, precise control of the heating rate is not required.

In addition, according to the present invention, the sample holder and the heating furnace can be integrated and made compact, and can be heated at high speeds, such as heating up to about 500°C at a heating rate of about 100°C/minute. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is an exploded perspective view of the same embodiment, FIGS. 3 and 4 are sectional views showing other embodiments, and FIG. A schematic cross-sectional view showing one embodiment of the differential scanning calorimeter of the invention, and FIGS. 6 and 7 are cross-sectional views showing an example of a conventional thermal analysis device, respectively. 22... Sample holder. 24...Sample holder side wall, 26...Heating member. 28.34.38... Mica, 36...
・Heater, 42.44...Ceramic coating. 50a, 50b... Sample holder.

Claims (4)

[Claims] (1) A sample heating furnace is integrally provided at the bottom of the sample holder, a temperature sensor is bonded to the bottom of the sample holder, and an insulating material with high thermal resistance is provided between the sample heating furnace and the bottom of the sample holder. A thermal analysis device that heats the sample and measures the temperature with the temperature detector by placing the sample in a path where heat flows in from the side of the sample holder and reaches the temperature detector. (2) The thermal analysis apparatus according to claim 1, wherein mica is used as the insulating material between the sample heating furnace and the bottom surface of the sample holder, and as the insulating material inside the sample heating furnace. (3) According to claim 1, wherein a ceramic coating is used as the insulating material between the sample heating furnace and the bottom surface of the sample holder and a part of the insulating material in the sample heating furnace. The thermal analysis device described. (4) A differential scanning calorimeter, in which a sample heating furnace is integrally provided at the bottom of each of a sample holder for a reference substance and a sample holder for a measurement sample, and a temperature detector is provided at the bottom of each sample holder. An insulating material with high thermal resistance is interposed between each sample heating furnace and the bottom surface of each sample holder, and a reference substance and a measurement material are provided in a path through which heat flows from the side surface of the sample holder and reaches the temperature sensor. A thermal analysis device that measures the temperature using each of the temperature detectors while heating a reference substance and a measurement sample by placing each sample thereon.