High temperature sensitive ceramic armored high-temperature thermocouple and manufacture method thereof

Abstract

The invention discloses a high temperature sensitive ceramic armored high-temperature thermocouple and a manufacture method thereof. The thermocouple is composed of a conjunction box, a cover casing, terminals, a protective bushing, a sealing strip, an insulating layer, a lead wire, a thermocouple wire and insulators; the protective bushing of a cylindrical hollow structure is made of alumina based high temperature ceramics, a carbon fiber basket is integrated in a ceramic body of the protective bushing, a central wire bundle of the carbon fiber basket extends out of the center of the bottom of the cylindrical hollow structure, a work end is connected with the exceeding end of the carbon fiber basket, and the center of an opening end is connected with the lead wire; the lead wire is formed by braiding silicon carbide based ceramic fibers; the sealing strip is made of a high-temperature adhesive HN-767A; an enclosed space formed by the protective bushing, the high temperature adhesive and the conjunction box is of a vacuum environment ranging from 1Pa to 10Pa; and the thermocouple wire is a nickel chromium silicon-nickel silicon thermocouple wire. The thermocouple of the invention can replace an expensive platinum rhodium thermocouple, the economic performance and the reliability are high, and the service life is long.

Description

technical field [0001] The invention relates to the field of temperature sensors, in particular to a high-temperature-sensitive ceramic sheathed 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 ou...

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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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