JPH0627060A - Heat measuring apparatus - Google Patents

Abstract

PURPOSE:To realize accurate measurement of heat by arranging a plurality of sample holders having identical shapes vertically in the axial direction along the wall face of an electric furnace thereby heating samples uniformly. CONSTITUTION:Sample holders 2a, 2b are arranged vertically in axial direction along the wall face of an electric furnace 1 and fixed through an electric insulating wall to a cylindrical isothermal wall 3. Each of the holders 2a, 2b has a bottom face fixed with a temperature sensor 5 such as a thermocouple connected with a temperature measuring circuit 6 and a differential thermal analysis(DTA) circuit 7 for detecting temperature difference between the holders 2a, 2b. A sample 9 is placed in the holder 2a whereas a reference substance 10 is placed in the holder 2b and the furnace 1 is controlled to heat the holders 2a, 2b at a constant temperature rise rate and then the temperature and temperature difference are recorded. The sample 9 can be identified and reaction characteristics thereof can be determined based on the temperature state of the sample 9 with respect to the substance 10. Overall diameter can be reduced through vertical arrangement of holders and accurate measurement with reduced noise can be realized through low power heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a differential thermal analysis (Differen
The present invention relates to a thermal measurement device used for tial thermal analysis (DTA) or differential scanning calorimetry (DSC).

[0002]

2. Description of the Related Art Conventionally, in the above-mentioned differential thermal analysis and differential scanning calorimetry, two samples of the same shape are usually placed in a cylindrical electric furnace a whose temperature rising rate is controlled as shown in FIG. The holders b and c are arranged in axially symmetrical positions, and one of the sample holders b
Is used to store a reference material such as α-alumina, the other sample holder c to store a sample to be measured, and temperature sensors d and e such as thermocouples are attached to each sample holder b and c. . When performing differential thermal analysis of a sample to be measured with this apparatus, first, the electric furnace a is heated at a constant rate. The reference material and the sample in the sample holders b and c rise in temperature slightly after the temperature of the electric furnace a due to their heat capacity and heat transfer resistance, and transfer, melting, reaction, etc. occur in the sample, and heat in and out occurs. If so, the sample temperature changes accordingly. When the temperature difference between the reference substance and the sample, that is, the differential temperature is measured by a temperature sensor e such as a temperature difference thermocouple, and the temperature change of the sample is measured by a temperature sensor d such as a thermocouple, when the sample is endothermic, The differential curve as shown in FIG. 2 is obtained. In this case, point A is an apparent transition start point, point B is a peak temperature, and point C is an apparent end point. By observing the low temperature state or the high temperature state with respect to the reference substance in this way and examining the number of peaks, the temperature at which it is located, the shape, etc.,
It becomes possible to know the identification of the sample and the reaction characteristics. Then, under certain conditions, the calorific value can be measured using the apparatus of FIG. When performing differential scanning calorimetry with this device, when a compensating heater is attached to the sample holders b and c and the electric furnace a is heated at a constant speed, a temperature difference occurs between the reference substance and the sample. , The compensating heater is activated to fill the temperature difference, and the energy required to fill the temperature difference is known, and the calorific value of the sample is measured. There is also known an apparatus in which the circumference of the sample holder is covered with a heat bath f made of ceramic or the like as shown by the chain line in FIG. 1 so that the heat is uniformly incident on the sample holder.

[0003]

When the sample holders b and c are arranged side by side in parallel with each other as described above, the heat incident from the electric furnace a is obstructed by the adjacent sample holder and the sample holder is not uniformly heated. This is not preferable because the reference substance and the sample cannot be heated uniformly and there is a slight difference in the measured value. Further, in order to arrange the sample holders in parallel in the electric furnace a, it is necessary to design the inner diameter of the electric furnace a large, so that a constant temperature rising rate cannot be obtained unless relatively large electric power is supplied, As the power increases, the output value of the temperature sensor may be affected by disturbance such as noise, which may prevent accurate measurement.

An object of the present invention is to provide a device capable of uniformly heating a sample holder, a sample and the like, obtaining a constant rate of temperature rise with a small amount of electric power, and performing accurate heat measurement with little disturbance. Is.

[0005]

According to the present invention, a plurality of sample holders having the same shape are provided in an electric furnace, and the temperature of each sample holder is detected while heating and raising the temperature of the electric furnace to measure the heat of the sample. In the above apparatus, the plurality of sample holders are arranged vertically in the axial direction along the wall surface of the electric furnace to achieve the above object. Further, the above object of the present invention is to provide one sample holder in an electric furnace,
This can also be achieved by covering the circumference of the sample holder with a heat bath made of a reference material used for heat measurement, and attaching a temperature sensor for measuring the respective temperature and differential temperature to the sample holder and the heat bath.

[0006]

[Operation] By arranging the sample holders vertically in the electric furnace, the radiant heat of the electric furnace does not directly enter the sample holders and is not blocked by other sample holders.
The entire circumference of each sample holder can be heated uniformly, and the reference substance and the sample to be measured can be heated uniformly.
Also, by arranging the sample holders vertically, the inner diameter of the electric furnace can be made small, and the electric power for heating can be reduced, so the influence of the disturbance due to the electric power on the output value of the temperature sensor is reduced. . Therefore, temperature unevenness does not occur, the error in the output value is reduced, and accurate measurement can be performed.

Further, by covering the circumference of the sample holder with a heat bath made of a reference substance and measuring the temperature of this heat bath and the differential temperature between the heat bath and the sample holder, differential thermal analysis can be carried out,
Since the sample holder that contains the reference material is not required, the internal volume of the electric furnace can be made smaller, and in this case as well, temperature unevenness does not occur, the electric power of the electric furnace can be reduced, and noise is reduced, resulting in an error in the output value. It is possible to perform accurate measurement with less.

[0008]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 3 shows an embodiment applied to DTA. In FIG.
Reference numeral 1 is an electric furnace that can control the temperature rising rate by controlling input power and has a substantially cylindrical space inside. The electric furnace 1
Inside, the two sample holders 2a and 2b were provided in the upper and lower sides in the axial direction along the wall surface. Each sample holder 2 is formed of the same material as the sample holder used in the conventional differential thermal analyzer, and is made of metal, glass, ceramic or the like.

Each of the sample holders 2a and 2b is to be mounted in a cylindrical isothermal wall 3 made of glass, metal or the like through an electrically insulating wall 4 such as glass or ceramic, and the bottom surface of each sample holder 2a or 2b. Temperature sensor 5 such as thermocouple,
I installed 5. These temperature sensors 5 and 5 include a temperature measuring circuit 6 that measures the temperature of each sample holder 2 itself,
It is connected to a DTA circuit 7 that detects a temperature difference (differential temperature) between both sample holders 2a and 2b. Reference numeral 8 is a lead wire outlet of the temperature sensor 5 which is opened in the isothermal wall 3 and the electric insulating wall 4.

The sample 9 to be measured is housed in one sample holder 2a, and the reference substance 10 is housed in the other sample holder 2b to perform thermal measurement of DTA of the sample 9. In the same manner as described above, by heating the sample holders 2a and 2b at a constant heating rate by controlling the electric power of the electric furnace 1, recording the temperature and temperature difference of each sample holder 2 and knowing the temperature state of the sample with respect to the reference substance. The identification and reaction characteristics of the sample 9 can be known. The sample holders 2a and 2b are connected to the electric furnace 1.
By arranging the electric furnace 1 in the axial direction up and down, the inner diameter of the electric furnace 1 can be reduced, and heating can be performed with a small amount of electric power at the same rate of temperature rise as in the conventional case. The value will be accurate. Further, since the heat from the electric furnace 1 reaches each sample holder 2 without being blocked, the sample holder 2 is uniformly heated over the entire circumference, and the temperature unevenness of the sample holder 2 is eliminated, and accurate measurement can be performed. If the conventional sample holder is installed in parallel, the inner diameter of the electric furnace is 10 cm.
When the sample holders 2 are arranged above and below as in the present invention, the inner diameter of the electric furnace 1 is about 5 cm, and the electric power for obtaining the same heating rate is about 1/5.

FIG. 4 shows an embodiment applied to a DSC. In this embodiment, a minute heater 11 is attached to each sample holder 2 and a differential amplifier circuit 12 and a differential calorific value compensation circuit 13 are provided. This is different from the third embodiment. This Figure 4
The method of performing the DSC measurement of the sample 9 using the apparatus of 1 is the same as the conventional case.

In FIG. 5, only one sample holder 2 is provided in the electric furnace 1, and the periphery of the sample holder 2 is covered with a heat bath 14 made of, for example, a reference material of α-alumina, and the sample holder 2 and the sample holder 2 are heated. A configuration in which temperature sensors 5 and 5 such as thermocouples are attached to the bath 14 is shown. When performing DTA measurement with this, the electric furnace 1 is heated at a constant speed and the sample holder 2
And the temperature of the hot bath 14 and their differential temperatures are detected. In this case, since the heat bath 14 shows the temperature change of the reference substance and also serves as an isothermal wall for the sample holder 2, the sample holder for containing the reference substance is not necessary and the vertical direction of the electric furnace 1 is shortened accordingly. It becomes possible to configure. Therefore, in this case as well, heating can be performed with a small heating power at the same rate of temperature rise as in the conventional case, and since the power is small, noise is reduced and the measured value becomes accurate, and each sample holder 2 is completely heated by the heat from the electric furnace 1. The sample can be heated uniformly over the circumference, and the uneven temperature of the sample holder 2 can be eliminated, and accurate measurement can be performed.

The heat bath 14 is formed in the shape of a container having an upper opening, and the temperature sensors 5 and 5 are provided on the inner surface of the heat bath 14 and a metal heat sensitive plate 15 on the lower surface of the sample holder 2. An electrical insulating wall 4 for insulating the components from each other was provided, and the sample holder 2 was placed via the heat insulating spector 16.

Calcium oxalate was placed in the sample holder 2 as a sample, the heat bath 14 was made of α-alumina as a reference substance, and DTA was measured at a temperature rising rate of 30 ° C./min. Results were obtained. This result is almost the same as the result measured by the conventional apparatus in which two sample holders are provided in parallel, and the electric power of the electric furnace 1 is about ⅕ of that of the conventional apparatus, and the measured value also has noise. Hardly appeared.

[0015]

As described above, according to the present invention, since a plurality of sample holders are arranged vertically in the electric furnace of the heat measuring apparatus in the axial direction along the wall surface of the electric furnace, the inner diameter of the electric furnace can be reduced. It can be made smaller and less electric power is needed to raise the temperature to reduce noise, and the sample holder can be heated uniformly so that accurate measurement can be performed, and it is economical because it consumes less power. , One sample holder is provided in the electric furnace, and the surroundings are covered with a heat bath made of a reference material used for heat measurement, and a temperature sensor for measuring the temperature and the differential temperature of each of the sample holder and the heat bath is provided. The effect similar to the above is acquired also by the structure attached.

[Brief description of drawings]

FIG. 1 is a cutaway side view of a conventional example.

FIG. 2 is a measurement diagram of a differential thermal analysis by the apparatus of FIG.

FIG. 3 is a cutaway side view of an embodiment of the present invention.

FIG. 4 is a cutaway side view of another embodiment of the present invention.

FIG. 5 is a cutaway side view of the embodiment of the present invention.

FIG. 6 is a measurement diagram of a differential thermal analysis by the apparatus of FIG.

[Explanation of reference numerals] 1 electric furnace 2, 2a, 2b sample holder 5 temperature sensor 9 sample to be measured 10 reference substance 11 micro heater 14 heat bath

Claims (4)

[Claims] 1. An apparatus for providing a plurality of sample holders having the same shape in an electric furnace and measuring the temperature of each sample by detecting the temperature of each sample holder while heating and raising the electric furnace. A heat measuring device, wherein a plurality of sample holders are arranged vertically in an axial direction along a wall surface of the electric furnace. 2. The heat measuring device according to claim 1, wherein the sample holders arranged above and below are covered with isothermal walls. 3. The heat measuring device according to claim 1, wherein each of the sample holders is provided with a heater. 4. A single sample holder is provided in an electric furnace, and the periphery of the sample holder is covered with a hot bath made of a reference material used for heat measurement, and the temperature and the difference of temperature of the sample holder and the hot bath are different from each other. A heat measuring device equipped with a temperature sensor for measuring temperature.