Vacuum variable-temperature tube furnace

Abstract

The invention discloses a vacuum variable-temperature tube furnace, which comprises an inner glass tube and an outer glass tube. The inner glass tube and the outer glass tube form a hollow sealed cylindrical tube. A vacuum layer is reserved between the inner glass tube and the outer glass tube. An electric heating layer is coated to the outside of the inner glass tube. Electrode connecting wires penetrating through the outer glass tube are led out from two ends of the electric heating layer. A hollow area inside the inner glass tube is a heating area. The vacuum variable-temperature tube furnace is provided with the inner glass tube and the outer glass tube, the vacuum thermal-insulation layer is arranged between the inner glass tube and the outer glass tube, and accordingly samples are continuously variable in temperature and available for continuous measurement, and abrupt change of linear expansion can be conveniently observed through the transparent glass tubes. The electric heating material is coated to the inner glass tube instead of an existing resistance wire, so that the temperature field of a linear expansion coefficient measurer is even and stable, the range of obtained temperature is wide, power is only tens of watts, stability is higher, and measurement results are low in error and high in precision.

Description

technical field [0001] The invention relates to a tube furnace, in particular to a vacuum variable temperature tube furnace. Background technique [0002] The coefficient of linear expansion, sometimes called the coefficient of linear elasticity, refers to the percentage change in the length of a material for every 1°C change in temperature. Most substances have the characteristic of "expanding with heat and contracting with cold", which is caused by the intensification or weakening of the thermal motion of molecules inside the substance. This property should be taken into account in the design of engineering structures, in the manufacture of machinery and instruments, in the processing of materials, such as welding, otherwise, it will affect the stability of the structure and the accuracy of the instrument. The linear expansion of a material is the elongation in one dimension when the material expands when heated. The coefficient of linear expansion is an important indica...

AI Technical Summary

Problems solved by technology

The operation of this linear dilatometer is cumbersome, and the measured substance needs to be moved back and forth in the hot and cold environment, resulting in large errors and low test efficiency, which can easily affect the accuracy of the operator's judgment and cause the experiment to fail. Even if the experiment is successful, other Experimental accuracy is often not high

The constant temperature control during the test is often realized by the operator adding dry ice to the methanol in the pre-cooling tank in time according to the temperature change displayed by the thermometer. On the one hand, the operation is inconvenient. On the other hand, a large amount of methanol and dry ice are used in the laboratory. Bring out, affect human health

In addition, keeping the cold and hot bath constant during the measurement is very difficult in technical operation, and the temperature range obtained by each measurement is very limited

[0003] It can be seen from the above that although the existing resistance wire heating can obtain a wide temperature range and is easy to change the temperature, the power consumption is large and the temperature field is uniform and stable.

Although the temperature field is uniform and stable by using two cold and hot constant temperature baths, it has the following defects: 1) only for cold and hot two constant temperature baths, that is, the temperature of the cold constant temperature bath is between -32 ° C and -28 ° C, The temperature of the thermal constant temperature bath is measured in the two temperature ranges of +28°C to +32°C relative to the original temperature of the sample (usually room temperature) to measure the linear expansion coefficient at a constant temperature; 2) It is impossible to change the temperature, let alone observe the sudden change of the linear expansion

3) The equipment is complex and huge, and its price is high

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