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

Abstract

The invention discloses a heat-resistant ceramic armored high-temperature thermocouple and a manufacturing method thereof. The protective sleeve is made of alumina-based high-temperature ceramics, and a carbon fiber basket is integrated in the ceramic body, and the side of the carbon fiber basket facing the inside of the protective sleeve exceeds the insulating layer on the inner surface of the protective sleeve; a heat conduction block is also provided. The heat conduction block is made of pure titanium, its working end is connected with the excess end of the carbon fiber mesh basket, and the center of the open end is connected with the lead wire; the lead wire is braided with silicon carbide-based ceramic fiber; the sealing tape is made of high temperature glue HN‑767A; the protective cover The airtight space formed by tube, high-temperature glue and junction box is a protective atmosphere environment; the thermocouple wire is nickel-chromium-silicon-nickel-silicon thermocouple wire; the thermocouple of the present invention can replace expensive platinum-rhodium thermocouple, and has good economy and high reliability ,long lasting.

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 a thermocouple, 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 wholesale price of armored platinum-rhodium couples is as low as 1,500 yuan per piece, Also only be containing rhodium 10% S even), therefore further increased economic cost. It should be pointed out that, in fact, ...

AI Technical Summary

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 a thermocouple, 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 wholesale price of armored platinum-rhodium couples is as low as 1,500 yuan per piece, It is only S even containing 10% rhodium), so it further increases 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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