Heat-resisting ceramic-armored high-temperature thermocouple and manufacturing method thereof

Abstract

The invention discloses a heat-resisting ceramic-armored high-temperature thermocouple and a manufacturing method thereof. The thermocouple is composed of a junction box, a cover shell, wiring columns, a protection bushing, a sealing tape, an insulation layer, a lead, a thermocouple wire and insulators, wherein the protection bushing is made of alumina high-temperature ceramic, a carbon fiber basket is integrated inside the ceramic body, and one surface, facing the inner part of the protection bushing, of the carbon fiber basket exceeds the insulation layer on the inner surface of the protection bushing; a heat conduction block made of pure titanium is also arranged, the working end is connected with the carbon fiber basket extending end, and the center of the opening end is connected with the lead; silicon carbide-based ceramic fiber is braided to form the lead; the sealing tape is made by adopting a high-temperature adhesive HN-767A; the sealing space formed by the protection bushing, the high-temperature adhesive and the junction box is a protective atmosphere environment; and the thermocouple wire is the nickel-chromium-silicon / nickel-silicon thermocouple wire. The thermocouple of the invention can replace an expensive platinum rhodium thermocouple, and has the advantages of good economics, high reliability and long service life.

Description

technical field [0001] The invention relates to the field of temperature sensors, in particular to a heat-resistant ceramic armored high-temperature thermocouple and a manufacturing method thereof. Background technique [0002] When used for heat treatment of heat-resistant tool steel such as heat-resistant steel and high-speed steel (the treatment temperature is generally between 1100 ° C and 1350 ° C), currently only platinum-rhodium thermocouples (B couple, S couple or R couple) can be used as heat treatment. Using thermocouples, according to the requirements of the US military standard AMS2750E, a total of three thermocouples are required for high-temperature heat treatment as normal couples. As we all know, platinum-rhodium thermocouples are expensive (the minimum wholesale price of armored platinum-rhodium couples is 1,500 yuan, and there are also It is only 10% rhodium-containing S even), thus further increasing the economic cost. It should be pointed out that, in fa...

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Problems solved by technology

[0002] When used for heat treatment of heat-resistant tool steel such as heat-resistant steel and high-speed steel (the treatment temperature is generally between 1100 ° C and 1350 ° C), currently only platinum-rhodium thermocouples (B couple, S couple or R couple) can be used as heat treatment. Using thermocouples, according to the requirements of the US military standard AMS2750E, a total of three thermocouples are required for high-temperature heat treatment as normal couples. As we all know, platinum-rhodium thermocouples are expensive (the minimum wholesale price of armored platinum-rhodium couples is 1,500 yuan, and there are also It is only S even containing 10% rhodium), thus further increasing the economic cost

It should be pointed out that, in fact, the domestic platinum-rhodium thermocouple can only reach 1200°C in general, and its service life and performance will be greatly reduced if it is used for a long time at overtemperature; while the nickel-chromium-silicon- Nickel silicon, although cheap, durable, high reliability, theoretical use temperature, but its easy oxidation failure characteristics at high temperature make it impossible to use in conventional high temperature heat treatment, generally only used for temperature measurement below 1100 °C

[0003] Among the relevant patents that have been applied in China, there is no patent information on the use of nickel-chromium-silicon-nickel-silicon wires for high-temperature measurement. Among similar patent documents, the patent "A High-temperature Thermocouple" (application number: 201610136518.7, publication date: 2016-07-20), disclosed a high-temperature thermocouple structure that is also a ceramic protective sleeve, but there are two problems: ① platinum-rhodium thermocouple is still used, and the economy is not good; ② the outer protective tube adopts Silicon carbide ceramics, although the thermal conductivity of silicon carbide ceramics is better than other ceramics, only its high brittleness, difficulty in forming and large porosity make it easy to damage when used as a protective sleeve, poor reliability, and easy to have tiny Particles penetrate and damage the platinum-rhodium precious metal structure inside, and the service life is short

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