Protective atmosphere encapsulated ceramic sheathed high temperature thermocouple and manufacturing method thereof

Abstract

The invention discloses a protective atmosphere packaged ceramic armored high-temperature thermocouple and a manufacturing method thereof. The thermocouple consists of a junction box, a casing, a terminal post, a protective sleeve, a sealing tape, an insulating layer, a lead wire, a thermocouple wire, and an insulator. The protective sleeve is made of alumina-based high-temperature ceramics and has a flat-bottomed cylindrical hollow structure. The ceramic body of the protective sleeve is integrated with a pure titanium wire mesh basket. The central bundle line of the pure titanium wire mesh basket is the lead wire from the flat-bottomed cylinder The center of the bottom surface of the body-shaped hollow structure protrudes, and its working end is connected to the protruding end of the pure titanium wire mesh basket, and the center of the opening end is connected to the lead wire; the lead wire is woven with silicon carbide-based ceramic fibers; the sealing tape is made of high-temperature glue HN‑767A; The airtight space formed by the protective sleeve, high-temperature glue and junction box is a protective atmosphere; the thermocouple wire is nickel-chromium-silicon-nickel-silicon thermocouple wire; the thermocouple of the present invention can replace the expensive platinum-rhodium thermocouple, and is economical and reliable High performance and long service life.

Description

Technical field [0001] The invention relates to the field of temperature sensors, in particular to a protective atmosphere packaging ceramic armored high temperature thermocouple and a manufacturing method thereof. Background technique [0002] When used for the heat treatment of heat-resistant steel and high-speed steel and other heat-resistant tool steels (the treatment temperature is generally between 1100℃-1350℃), currently only platinum-rhodium thermocouples (B couple, S couple or R couple) can be used as heat treatment Use a thermocouple. According to the requirements of the US military standard AMS2750 E, a total of three thermocouples are required as normalized couples during high temperature heat treatment. As we all know, platinum and rhodium thermocouples are expensive (the minimum wholesale price of armored platinum and rhodium couples is 1500 yuan, It is only the S couple containing 10% rhodium, so the economic cost is further increased. It should be pointed out tha...

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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 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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