RU1786412C - Device for measuring integral radiating power of metals - Google Patents

Abstract

The invention can be used to measure the emissivity of metals or their alloys. An object of the invention is to improve the accuracy of measuring emissivity. The installation contains a substrate with a recess filled with the studied metal. When heated, the distance between the surface and the integral heat radiation detector changes. From the output of the distance measuring device, a signal is input to the input of the thermocouple moving device and the integral heat radiation detector, which raises or lowers the thermocouple and the thermal radiation receiver. In this case, the integral thermal radiation and the surface temperature of the metal are continuously measured. 1 tablet, 1 ill. in

Description

The invention relates to the field of physicochemical analysis and can be used to measure the integral emissivity of metals and their alloys. Advantageously, the invention is intended to construct a temperature dependence of the emissivity of metals and their alloys.

A device for measuring the integral emissivity of metals and their alloys is known, containing cooled current leads in which the test sample is mounted with thermocouples attached to it, and an integral thermal radiation detector 1 is located opposite the sample.

A disadvantage of the known device is the inability to simultaneously measure the emissivity and temperature of the sample.

The closest in technical essence and the achieved result to the invention is a device for measuring the integral emissivity of metals, including a substrate with a recess for the metal to be studied, an integrated thermal radiation detector located above it and a thermocouple placed in a case. The thermocouple is in direct contact with the bottom of the substrate.

A disadvantage of the known device is that it does not provide an accurate measurement of the integral radiative

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abilities of metals. This drawback is due to the fact that when the temperature of a substance changes, it changes its volume and at the same time, the level of the substance in the substrate changes. In addition, due to thermal inertia, an uneven distribution of temperature over the volume occurs, which prevents the exact determination of the crystallization (melting) temperature of the substance from the jump-like change in the thermal radiation of the substance from its surface at the moment of the solid-liquid phase transition.

An object of the invention is to improve the accuracy of measuring the emissivity of metals.

To achieve objective B, a device for measuring the integral emissivity of metals, including a substrate with a recess for the metal under investigation, an integrated thermal radiation detector located above it and an thermocouple placed in a case, according to the invention, a through hole is made in the substrate in which the thermocouple is located in the case with the possibility of movement , a device for measuring the distance to the surface of a substance and an associated device for moving an integral receiver of thermal radiation and so on were introduced thermocouples.

Distinctive features of the proposed device are a through hole in the substrate, in which the thermocouple is located in the case with the possibility of movement, and the presence of a device for measuring the distance to the surface of the substance and the associated device for moving the integral radiation detector and thermocouple. Due to this, depending on the temperature change in the volume of the metal, the integral heat radiation detector and thermocouple are simultaneously moved, which improves the accuracy of measuring the integral emissivity of the metal and, in addition, provides simultaneous measurement of the integral heat flux and temperature of the surface layer of the substance.

The drawing shows a diagram of the device.

The device comprises a substrate 1 with a recess 2. In the substrate 1 there is a through hole 3 in which the thermocouple 4 is located in the case with the possibility of vertical movement in the recess 2 filled with the metal under study 5. An integral thermal radiation detector 6 is located above the substrate 1. Distance measurement

between the surface of the metal 5 and the integral heat radiation detector 6 is carried out by a distance measuring device 7. The output of the distance measuring device 7 is connected to the input of the thermocouple moving device 8 and the integral heat radiation detector. A device for measuring the integral emissivity of metals is placed in a vacuum chamber, the test metal is heated by induction (not shown in the diagram).

The device operates as follows.

5 Substrate 1, together with thermocouple 4, is filled with test metal 5 and heated, followed by cooling. After crystallization of the test metal 5, its surface is ground to a thermocouple

0 4 followed by polishing the surface of the investigated metal 5 to grade 14.

After evacuation to Pa, a gel atmosphere is introduced, followed by induction heating

5 of the test metal 5, while the device 7 continuously monitors the distance between the surface of the test metal 5 and the integral heat radiation detector 6. When increasing or decreasing

0 distance due to a change in the volume of the studied metal 5 from the output of the device 7, a corresponding signal is supplied to the input of the device 8, which carries out the raising or lowering of the thermocouple 4 and

5 receiver 6 for heat radiation. In this case, the values of the thermocouple 4 and the integral receiver 6 of thermal radiation are measured. Thus, when the integral emissivity of the surface of the investigated metal 5 is abruptly changed, the temperature of the emitting metal layer 5 is determined. This makes it possible to increase the accuracy of measuring the integral emissivity of metals.

5After measuring the melting temperature of the test metal, its crystallization temperature is measured with the induction heating switched off. The crystallization process begins with

0 of the surface layer of the metal 5, in which the thermocouple 4 is located, due to the thermal inertia of the massive substrate 1. The movement of the thermocouple 4 and the integral heat radiation detector 6 when changing

5 volume of the investigated metal occurs in the same way as when heated.

Due to the fact that the integral emissivity of the metal depends on temperature, advantageously the device according to the invention is illustrated by the following specific embodiment.

A laboratory version of the proposed device was manufactured. A substrate with a diameter of 20 mm and a depth of 25 mm was placed in a 10-liter vacuum chamber with an integral thermal radiation detector located above it, made in the form of a direct-vision radiometer with a thermocouple from a Rapir-2 optical pyrometer. Heating was carried out by induction. During operation, a dynamic vacuum of the order of Pa was achieved or a gel atmosphere of 99.99% was used depending on the vapor pressure conditions of the metal under study. The distance between the surface of the metal under study and the integrated radiation detector was measured with a MI-1 measuring microscope with a resolution of 10 μm. To raise or lower both the thermocouple and the integral heat radiation detector, a micrometer screw installed in the vacuum rotation inlet was used. A platinum-rhodium thermocouple with a wire thickness of 0.5 mm was used to measure temperatures. As control samples in accordance with the International Temperature Scale, constant melting points of silver of 960.8 ° C were used; as well as secondary constant melting points of tin 231.9 ° C; cadmium 320.9 ° C; lead 327.3 ° C; zinc 419.5 ° C; antimony 630.5 ° C;

aluminum 660.1 ° C; copper 1083 ° C; nickel 1453 ° С, cobalt 1492 ° С.

The research results are summarized in table. The table shows that the melting points of the metals obtained on the installation of the prototype, are at variance with the reference points of the International temperature scale. When comparing the temperature melting points obtained on the proposed device with the reference temperature points of the International Temperature Scale, full correspondence between them is seen. This improves the accuracy of measuring the integral emissivity of metals.

Claims (1)

SUMMARY OF THE INVENTION A device for measuring the integral emissivity of metals, including a substrate with a recess for the metal under investigation, an integrated thermal radiation detector located above it, and a thermocouple placed in a case, in order to increase the accuracy of measurements, a through a hole in which the thermocouple is located in the case with the possibility of movement, an additional device for measuring the distance from the integrated receiver of thermal radiation to the surface STI and substance associated therewith integral unit movable heat radiation receiver and the thermocouple.