JP3134992U - Differential thermal analyzer - Google Patents

Abstract

【Task】
Without limiting the heating temperature range or operating atmosphere of the differential thermal analyzer, the difference in thermal expansion coefficient between the sensor plate and the heat sink or sensor presser plate surrounding the sensor plate can cause Provided is a means for preventing the sensor plate from being deformed or damaged and improving the life of the sensor plate.
[Solution]
As a path for transferring heat from the heat sink 3 surrounding the sensor plate 6N to the sample 2 and the reference material 1, the sensor plate 6N is connected to eight bridges 9N disposed between the notch 8N and the notch 8N. An arc-shaped bent portion projecting upward is provided, and lateral stress generated by heating is absorbed by the bent portion in the vertical direction.
[Selection] Figure 1

Description

  The present invention relates to a differential thermal analyzer for heating a reference material and a sample and measuring the thermal properties of the sample from the temperature difference between the two.

  A differential scanning analyzer (hereinafter referred to simply as a DSC) places a sample and a reference material in a heating furnace (hereinafter referred to as a heat sink), raises the temperature of the heat sink according to a predetermined program, and is on the rise This is an apparatus for detecting the temperature difference between the sample and the reference material and measuring the thermal reaction of the sample (see, for example, Patent Document 1).

  As the reference material, a material that has a constant heat capacity, is close to the heat capacity of the sample, has no phase transition within the temperature rising range, and rises smoothly as the heat sink temperature rises is selected. When there is no thermal change such as phase transition in the sample, both the reference material and the sample temperature change smoothly following the furnace temperature, but there is a phase transition such as melting in the sample, resulting in endotherm and heat generation. When a reaction occurs, the temperature difference between the sample temperature rise and the reference material changes with time.

  Therefore, the thermophysical property of the sample is measured from the detection of the temperature difference. The temperature difference converted into heat flow in and out of the sample and plotted against time or temperature is called a DSC curve. In order to detect a temperature difference, a DSC sensor using a thermocouple composed of a constantan plate (hereinafter referred to as a sensor plate) on which a reference material and a sample are placed, and a chromel wire and an alumel wire attached to the sensor plate ( Hereinafter, simply referred to as a sensor) is used.

  FIG. 3A shows the basic structure of DSC. The reference material 1 and the sample 2 are detachably mounted on the sensor plate 6 screwed by screws 5 from the inner and lower surfaces of the heat sink 3 surrounding the reference material 1 and the sample 2 through the sensor pressing plate 4. Yes. The heat sink 3 is heated by the heater 7 according to a prescribed program.

  FIG. 3B is a view of the sensor plate 6 as viewed from below. The sensor plate 6 is provided with eight notches 8 in total, four on the lower surface of the reference material 1 and four on the lower surface of the sample 2. By providing the notch 8, the amount of heat flowing from the heat sink 3 through the sensor plate 6 into the reference material 1 or the sample 2 is reduced to eight bridges provided between the notch 8 and the notch 8 adjacent thereto. Flows in through the bridge 9. Therefore, by appropriately determining the width and length of the bridge 9 in advance, the thermal resistance of the bridge 9 can be determined, and the inflow rate of the heat flow into the reference material 1 or the sample 2 can be limited to an appropriate amount. FIG. 4 is a diagram showing the inflow location of the heat flow in the sensor plate 6, and the heat flow flows between the notches 8 as indicated by arrows.

  As the material of the heat sink 3 and the sensor presser plate 4, silver having a high thermal conductivity is usually used. A constantan plate is used as the material of the sensor plate 6. As shown in FIG. 5A, a chromel wire and an alumel wire are respectively fixed to the lower surfaces of the reference material 1 and the sample 2 of the sensor plate 6 in the direction shown in the figure, and the sample is obtained by a chromel-alumel thermocouple on the sample 2 side. The temperature Ts of the reference material 1 is measured by a chromel-alumel thermocouple on the reference material 1 side, and the temperature Tr of the reference material 1 is formed by a chromel wire on the reference material 1 side-sensor plate 6-chromel wire on the sample 2 side. The temperature difference ΔT = Tr−Ts between the sample 2 and the reference material 1 is measured by the pair. In FIG. 5A, the chromel wire is indicated by a symbol + and the alumel wire is indicated by a symbol-.

  FIG. 5B shows an example of the relationship between the temperature and time of each part during DSC operation. As shown in the figure, when the temperature of the heat sink is increased at a constant gradient with respect to time, the temperature Tr of the reference material 1 increases monotonously following the temperature of the heat sink. The temperature Ts of the sample 2 also increases following the temperature of the heat sink. However, if the sample 2 has a change in thermal characteristics (endothermic reaction, exothermic reaction, etc.) due to phase transition or the like, the temperature gradient changes at that temperature. The figure shows the case where there is an endothermic reaction. By analyzing this change, the thermophysical property of the sample 2 is measured.

JP-A-11-201924

  The structure of a conventional DSC is as described above. However, this structure has a problem that the sensor has a short life or the heating temperature range and the working atmosphere of the DSC are limited. That is, since the heat sink 3 and the sensor pressing plate 4 are usually made of silver having a high thermal conductivity, the thermal expansion coefficient is different from that of the constantan material of the sensor plate 6. The linear expansion coefficient of constantan is smaller than the linear expansion coefficient of silver. In this combination, tensile stress is generated in the sensor plate 6 when the temperature is raised. In general, DSC is repeatedly heated to a temperature of 700 ° C. or higher, and this difference in thermal expansion becomes a problem.

  As described above, the sensor plate 6 is provided with the notch 8 and the bridge 9 between the notch 8 and the bridge 9 (hereinafter referred to as a heat path), which is a limited heat transfer path. Since it is structured to flow into the sample 2 or the reference material 1 through the arrowed portion in FIG. 3, the stress generated by the difference in thermal expansion of each component is concentrated in a heat path that is weak in strength, and by repeated heat cycles Since the heat path is deformed or broken, the life of the sensor plate 6 and thus the sensor is shortened.

  Conventionally, as a structure for preventing the above-described shortening of the sensor life, (1) a method in which a material such as the heat sink 3 is made of copper, which is a material similar to the sensor plate 6, or (2) a space between the sensor plate 6 and the heat sink 3 is used. However, these methods limit the upper limit temperature or the working atmosphere of the heat sink 3. That is, in the case of (1), the upper limit temperature is limited to about 600 ° C. due to the problems of copper strength and oxidation, and in the case of (2), the graphite sheet burns in the air, so that the DSC is not in an inert gas atmosphere. Cannot be used. An object of the present invention is to provide means for solving such problems.

  In order to solve the above problems, a differential thermal analyzer provided by the present invention is a differential thermal analyzer that heats a sample placed on a sensor plate and a reference material and measures the thermal properties of the sample from the temperature difference between the two. A bent portion is provided in the heat transfer path to the sample of the sensor plate and the reference material. Therefore, this bent part becomes an absorption site for the difference in thermal expansion. Further, the bent portion includes a portion protruding upward or downward of the sensor plate disposed in the horizontal direction.

  According to the present invention, since the thermal expansion difference between the sensor plate and the heat sink or the sensor plate and the sensor holding plate is absorbed by the bent portion provided in the heat path, the heat path is prevented from being deformed or damaged by the heat cycle. The sensor life can be improved without the limitation of the heating temperature range and the working atmosphere when the sensor life improvement method is applied.

  This will be described with reference to the illustrated example. 1A, a sensor plate 6N corresponding to the sensor plate 6 of FIG. 3 is provided with a notch 8N corresponding to the notch 8 of FIG. As shown in FIG. 1B, the eight bridges 9N corresponding to the bridge 9 in FIG. 3 are bent upward from the sensor plate 6N, and the bent shape is a shape protruding upward. It can also project downward. The heat flow passes through each bent bridge 9N and reaches the reference substance 1 or the sample 2. The lateral stress accompanying heating is absorbed by the bent portion in the vertical direction.

  The present invention is not limited to the above-described embodiments, and various modifications can be given. For example, in FIG. 1, the cross section of the bridge 9N is a semicircular arc shape protruding upward, but the shape of the bridge 9N is a three-dimensional shape protruding beyond the upper surface of the sensor plate 6N toward the upper surface or beyond the lower surface toward the lower surface. It suffices to have a bent portion, and the cross-sectional shape may be any shape such as a bellows shape, a wave shape, or a triangular shape. It is obvious that the number of bridges 9N is not limited to eight in FIG. In the above description, the vertical bent portion provided for the sensor plate 6N in the horizontal direction has been described. However, the bent portion of the present invention does not necessarily have to be in the vertical direction. For example, as shown in FIG. 2, a bridge 9P having a redundant heat transfer path by bending in the horizontal direction may be provided in the surface of the sensor plate 6P provided with the notches 8P. The present invention encompasses all of these.

  The present invention can be applied to a differential thermal analyzer that heats a reference material and a sample and measures the thermal properties of the sample from the temperature difference between the two.

It is a figure which shows the Example of this invention. It is a figure which shows the other Example of this invention. It is a figure which shows an example of a structure of the conventional differential thermal analyzer. It is a figure which shows the heat flow of the sensor board of the conventional differential thermal analyzer. It is a figure which shows the temperature measurement means of the conventional differential thermal analyzer, and the relationship between the temperature and time of a reference substance and a sample.

Explanation of symbols

1 Reference Material 2 Sample 3 Heat Sink 4 Sensor Holding Plate 5 Screw 6 Sensor Plate 6N Sensor Plate 6P Sensor Plate 7 Heater 8 Notch 8N Notch 8P Notch 9 Bridge 9N Bridge 9P Bridge

Claims (2)

  In a differential thermal analyzer that heats a sample placed on a sensor plate and a reference material and measures the thermal properties of the sample from the temperature difference between the two, a bent portion is provided in the heat transfer path to the sample and reference material on the sensor plate. A differential thermal analyzer characterized by being provided.   The differential thermal analyzer according to claim 1, wherein the bent portion includes a portion protruding upward or downward of the sensor plate disposed in the horizontal direction.

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