Ceramic armored high-temperature thermocouple and manufacturing method thereof

Abstract

The invention discloses a ceramic armored high-temperature thermocouple and a manufacturing method thereof. The thermocouple consists of a junction box, a cover case, terminals, a protective casing pipe, a sealing tape, an insulation layer, a lead, a thermocouple wire, and insulators. Specifically, the protective casing pipe is prepared from alumina based high-temperature ceramic, a carbon fiber basket is integrated in the ceramic, and one carbon fiber basket side facing the inside of the protective casing pipe is beyond the insulation layer on the inner surface of the protective casing pipe. The protective casing pipe is also provided with a glue sealing body, which is made of high temperature glue HN-767A. A carbon fiber basket central bundle wire is connected to the lead and fixed in the glue sealing body. The sealing tape is made of high temperature glue HN-767A. The protective casing pipe, the high temperature glue and the junction box form an airtight space, which is a 1Pa-10Pa vacuum environment. The thermocouple wire is nickel chromium silicon-nickel silicon thermocouple wire. The thermocouple provided by the invention that can replace expensive platinum rhodium thermocouple has the advantages of good economical efficiency, high reliability and long service life.

Description

technical field [0001] The invention relates to the field of temperature sensors, in particular to a 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 fact, the domesti...

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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, high theoretical use temperature, but its easy oxidation failure characteristics at high temperature make it can not be used in conventional high temperature heat treatment, generally only used for temperature measurement below 1100 ℃

[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 very good, only its high brittleness, difficulty in molding and large porosity make it easy to be damaged when used as a protective sleeve, and its reliability is poor. At the same time, it is easy for tiny particles to invade and damage its internal parts. Platinum-rhodium precious metal construction for short service life

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