Novel high-temperature erosion-resistant thermocouple protection sleeve and production method thereof

Abstract

The invention discloses a novel high-temperature anti-erosion thermocouple protection sleeve and a preparation method thereof. Austenitic stainless steel is selected as a substrate, and a layer of AlFeNi composite coating with an atomic ratio of 3:1:1 is sprayed on the surface of a workpiece. Then keep it in the temperature range of 670°C-700°C for 0.5-1 hour, raise the temperature to 950°C-1000°C, keep it for 3-4 hours, then cool it to 300°C with the furnace, take it out and air-cool it, so as to obtain austenitic stainless steel The surface of the thermocouple protection sleeve substrate is attached with a single-phase coating of FeAl intermetallic compound with B2 structure. The present invention obtains a columnar crystal B2-FeAl intermetallic compound coating with directional growth characteristics on the surface of the austenitic stainless steel thermocouple protection sleeve, which greatly improves the high temperature wear resistance and corrosion resistance, and is especially suitable for circulating fluidized bed boilers Surface protection with thermocouples.

Description

technical field [0001] The invention relates to a preparation technology of a novel high-temperature anti-erosion thermocouple protective casing, which is mainly aimed at the thermocouple protective casing used in high-temperature erosive atmospheres such as circulating fluidized bed boilers. Background technique [0002] In the power industry, thermocouples for temperature measurement are widely used in circulating fluidized bed boilers. Due to the complex working environment in the furnace, special requirements are put forward for the thermocouple protection sleeve, namely wear resistance, high temperature resistance, erosion resistance and corrosion resistance. Due to the high temperature of the measurement point in the furnace and the large amount of corrosive gas, a large number of fuel particles in the furnace have the effect of scouring, wearing and corroding the thermocouple, the surface material of the thermocouple protection sleeve is seriously lost, and the servic...

AI Technical Summary

Problems solved by technology

Because the temperature of the measurement point in the furnace is too high and contains a large amount of corrosive gas, a large number of fuel particles in the furnace have the effect of scouring, wearing and corroding the thermocouple, the surface material loss of the thermocouple protection sleeve is serious, and the service life is short

Traditional stainless steel protective sleeves, such as 1Cr18Ni9Ti, 0Cr25Ni20 sleeves, etc., have low manufacturing cost and high temperature resistance can meet the requirements, but the high temperature erosion resistance is insufficient

Applied to circulating fluidized bed boilers, the service life is only 30-90 days, which has a great impact on the long-term safe operation of the boiler

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