Method for improving electric performance uniformity of insulation filling material in tube electric heating part

Abstract

The invention relates to a method for improving the uniformity of the electrical property of an insulated filling material for a tubular electrothermal element, and is characterized in: grinding a solid additive used for improving electrical property into powder with a grain diameter less than 0.045 mm; spreading the powder of the solid additive into an organic solution of silicon; coating the organic solution of silicon on electrically fused magnesia particles with proper grain size distribution; subjecting the electrically fused magnesia particles coated with organic solution of silicon to solidification at a temperature of between 200 DEG C and 400 DEG C, roast in an oxidizing atmosphere at a temperature of between 800 DEG C and 1500 DEG C and cooling to obtain products. The method can also fixe the additive on the surfaces of the magnesia particles, which allows the magnesia particles to be layered during transportation and the filling process, and ensures the products have an equal content of the additive everywhere, thereby guaranteeing the uniformity of electrical property of the product.

Description

technical field [0001] The invention relates to a method for improving the electrical performance uniformity of an insulating filling material for a tubular electric heating element. Background technique [0002] Tubular heating elements are usually composed of three parts: metal shell, heating wire and insulating filling material. Among them, the insulating filling material plays the roles of fixing the heating wire, transferring heat and providing sufficient electrical insulation performance. Because of its good thermal conductivity and high temperature electrical insulation, fused magnesia is widely used as an insulating filling material for tubular heating elements. [0003] In order to obtain suitable processing performance, block fused magnesia is usually crushed into granular powder (commonly known as magnesium oxide powder or magnesia) with a particle size between 0.425mm and 0.045mm, and the particle size of each particle size is adjusted according to requirements....

AI Technical Summary

Problems solved by technology

However, a high content of additives will have side effects on other properties of the product (such as causing a decrease in high-pressure resistance)

[0007] 2. Usually, when the additives are broken, a large part of the particle size is less than 0.045mm, but due to the fluidity of the product, this part of the additives cannot be used in production, which greatly reduces the yield of the additives;

[0008] 3. The most serious problem is: due to the bumping of the product during transportation and the vibration of the filling machine during the production of tubular heating elements, magnesia particles of different particle sizes will inevitably be stratified

Stratification will lead to inconsistencies in the content of additives in various parts of magnesia, which will affect the uniformity of the electrical properties of magnesia: excessive additive content will cause some side effects (such as causing a decline in high-voltage resistance), and insufficient additive content It will directly lead to insufficient thermal insulation resistivity, and finally show that the manufactured tubular heating elements cannot meet the requirements and are scrapped.