JPS6018747A - Apparatus for measuring coefficient of linear expansion - Google Patents

Abstract

PURPOSE:To make it possible to measure the coefficient of linear expansion even with respect to a minute material with good accuracy, by heating or cooling the material to be measured received in a vacuum container by a thermoelectric cooling element to impart uniform temp. distribution to said material, and detecting the generated minute displacement amount. CONSTITUTION:A heating and cooling thermoelectric cooling element 7 is fixed to a fixed base plate 8 and a material 2 to be measured is placed on said element 7 while a quartz glass rod 11 and a minute displacement measuring apparatus 9 are further set. These apparatuses are received in a vacuum vessel 10 which is, in turn, evacuated by a vacuum exhaust apparatus 13. When a current is supplied to the thermoelectric cooling element 7, the material 2 is heated or cooled and the gap of the displacement measuring apparatus 9 changes and the change in a current is generated in a converter 16 to be detected by an ammeter 17. As mentioned above, by evacuating the vessel 10 to obtain a heat insulating state, and, by using the thermoelectric cooling element 7, the temp. distribution of the material 2 becomes uniform and coefficient of linear expansion can be measured even with respect to a minute material with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a linear expansion coefficient measuring device, and particularly to a measuring device suitable for measuring the linear expansion coefficient of minute materials.

[Background of the invention]

As shown in FIG. 1, the conventional linear expansion coefficient measuring device winds a heating coil 3 around a measurement sample 2 placed on a substrate 1, surrounds it with a heat insulating material 4, and wraps the measurement sample 2 around the heating coil. 2, and the deformation of the measurement sample 2 caused by this heating is transmitted through the entire quartz glass 5 to the minute displacement measuring device 6, and the amount of relative displacement from the substrate 1 is measured. In the above structure, there are many factors such as coil diameter, number of turns, and winding spacing in order to create a heating coil 3 with a uniform temperature distribution, and it has been difficult to obtain a uniform heating coil 3. From the above point, in order to obtain relatively uniform results, the measurement sample 2 must have a length of at least 30 m, and samples shorter than this have the disadvantage of large measurement variations. Furthermore, measurements are limited to measurements at high temperatures above room temperature, and a separate device is required to measure the coefficient of linear expansion from room temperature to about -40c, which is a problem with semiconductor components, for example.

[Purpose of the invention]

In view of the above points, it is an object of the present invention to provide a linear expansion coefficient measuring device having a structure for heating and cooling a minute material to a uniform temperature distribution and accurately measuring the amount of displacement generated by the heat. be.

[Summary of the invention]

The characteristics of the present invention are that the measurement sample is stored in a vacuum container, the inside of the container is evacuated to a vacuum of 10-" Torr or less to create an adiabatic state, and the sample is expanded by heating and cooling with a thermoelectric cooling element.・This was an attempt to measure contraction.

[Embodiments of the invention]

Hereinafter, one embodiment of the linear expansion coefficient measuring device of the present invention will be described with reference to FIG. First, the thermoelectric cooling element 7 for heating and cooling the measurement sample 2 is adhesively fixed onto the fixed substrate 8. Next, the measurement sample 2 is placed on the thermoelectric cooling element 7, and the quartz glass rod 11 and minute displacement measuring device 9 are further set. The minute displacement measuring device 9 and the fixed substrate 8 are fixed so as not to cause relative displacement, and the quartz glass rod 11 is supported so as to move with the deformation of the measurement sample 2. All these devices are vacuum containers10
Put it inside and evacuate using the vacuum evacuation device i ¥13. The power supply 12 for the thermoelectric cooling element, the thermometer 15, the converter 16 for the minute displacement measuring device, and the ammeter 17 are each provided outside the vacuum container for measurement. Measurement using this device begins with the power supply 12 for the thermoelectric cooling element.
When the thermoelectric cooling element 7 is energized, the carrier 11 fixed sample 2 is heated or cooled. At this time, the measurement sample 2 expands or contracts, and the quartz glass rod 11 responds to this movement.
goes up and down. Corresponding to this vertical movement, the gap between the top surface member 14 such as an At material bonded to the top of the quartz glass rod 11 and the minute displacement measuring device 9 changes, and the current changes through the minute displacement measuring device converter 16. Output. The relationship between the amount of current change and the amount of displacement of the minute displacement measuring device 9 is determined in advance, and the coefficient of linear expansion is calculated from the relationship between the sample temperature measured by the thermocouple 15' and the amount of sample displacement.

By the way, when the thermoelectric cooling element 7 used in the present invention is energized with DC current, due to the Beltier effect, for example, as shown in FIG.
The a side cools and %7b7b generates heat. Therefore, 7
A temperature difference occurs between the a side and the 7b side, and the thermoelectric cooling element 7 deforms based on this temperature difference. Therefore, when using this device, it is first necessary to establish the relationship between the displacement amount of the thermoelectric cooling element 7 itself and the temperature. FIG. 3 shows the results of measuring the relationship between the displacement amount and temperature of the thermoelectric cooling element 7 itself using this device. Based on this result, for example, when measuring the entire At material (vertical 5 x width 5 x length 10) as measurement sample 2, the results shown in FIG. 4 are obtained. First, the measured value is the relationship between temperature and displacement based on plane 7b, that is, the measured value tAt material + thermoelectric element shown by the dashed line A in the figure, and the relationship shown in Figure 3 is subtracted from this value. The amount of displacement is similar to that of the true At material. (Indicated by a solid line B in the figure.) In addition, a broken line C in the figure indicates a calculated value. If we calculate the linear expansion coefficient of the At material based on the bending, we get 23. I x 10= (tr')
Therefore, the linear expansion coefficient 'k of general At material is 23.6
When Xl 0-' (C-1), it is possible to measure a length of 10 sea breams with an accuracy of 98%.

According to this embodiment, trial heating can be performed using a smaller thermoelectric cooling element than in the conventional indirect heating using a coil heater, so that the apparatus becomes smaller. Furthermore, in addition to heating, cooling can be achieved by switching the electrodes, and in the conventional case, it would be necessary to use a refrigerator or the like for cooling, and the manufacturing cost of the device can be reduced.

Since the device can be miniaturized in this way, heating and cooling can be performed more easily than in the past, and testing can be performed in a shorter time.

In addition, with conventional coil heater heating, the sample cannot be observed because it covers the outer periphery of the sample, but according to the present invention, it is sufficient to heat and cool only one side of the sample, and it is possible to heat and cool only one side of the sample from the outside. This has the advantage of allowing for sample observation.

〔Effect of the invention〕

As explained above, according to the present invention, the coefficient of linear expansion of an object with minute dimensions can be measured accurately and efficiently.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of an example of a conventional linear expansion coefficient measuring device.
Fig. 2 is a vertical cross-sectional view of one embodiment of the linear expansion coefficient measuring device of the present invention, Fig. 3 is a diagram showing the amount of displacement of a thermoelectric cooling element with respect to temperature change, and Fig. 4 is a linear expansion coefficient measuring device of the present invention. A with the device
It is a figure showing the result of measuring T material. 2... Measurement sample, 7... Thermoelectric cooling element, 8... Fixed substrate, 9... Minute displacement measuring device, 10... Vacuum container% 11... Quartz glass rod, 12... Power supply for thermoelectric cooling element, 15... Thermometer, 16... Converter for minute displacement measuring device, 17... Ammeter. Sono 1 map

Claims (1)

[Scope of Claim] A linear expansion coefficient measuring device for measuring expansion and contraction of a microscopic part or microscopic material due to temperature changes, wherein the material is housed in a vacuum container and a thermoelectric cooling element is used. A linear expansion coefficient measuring device characterized in that a uniform temperature distribution is given to the material by heating and cooling, and the amount of displacement generated is detected by a minute displacement measuring device.