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Silicon carbon rods main purpose and the use of precautions


Nov 20,2023

Silicon-carbon rods are mainly used in float glass baths, optical glass melting furnaces, glass deep-adding furnaces; they are widely used in high-temperature resistance furnaces, high-temperature electric kilns, low-temperature electric kilns, ceramics industry, magnetic industry, aluminum industry, rare-earth industry and so on.
Main Function Characteristics

Feature one
Electrified heat, fast heating speed, uniform temperature field; oxidizing atmosphere in the normal use of temperature up to 1450 ℃, continuous use up to 2000 hours;

Features two
And good chemical stability, high temperature resistance, oxidation resistance, corrosion resistance;

Feature three
The three cold ends of the rod body uniformly sprayed with high-quality aluminum layer, greatly improving the conductivity; three cold ends can be directly connected to the three-phase power supply, but also in the top of the furnace single wiring;

Feature four
Equal diameter silicon-carbon rods in the production process to arrange a special process to strengthen and transform the rod body, so that the rod body according to the different environments in which it is used (or acidic or alkaline) and add different specific production materials and layer technology to achieve the purpose of improving the ability to resist and service life.

Properties of Silicon Carbon Rods
Silicon-carbon rods are made of high-purity green hexagonal silicon carbide as the main raw material, according to a certain ratio of material processing billet, 2200 ℃ high-temperature siliconization and recrystallization sintering and made of rods, tubes and non-metallic high-temperature electric heating elements. Oxidizing atmosphere in the normal use of temperature up to 1450 ℃, continuous use up to 2000 hours.
Carbon rods with high operating temperature, high temperature resistance, oxidation, corrosion resistance, fast heating, long life, high temperature deformation is small, easy to install and maintain, etc., and has good chemical stability.

Physical Properties
Component texture: hard and brittle, resistant to rapid cold and heat, high temperature deformation is not easy, other physical properties are as follows:
Thermal conductivity: 20 Daca/m-hr-degree.
Coefficient of linear expansion: 5×10-6(1/℃) .

Chemical properties
Silicon-carbon rods have good chemical stability and strong resistance to acid. Alkaline substances have an erosive effect on it under high temperature conditions.
Silicon carbon rod components used above 1000 ℃ can interact with oxygen and water vapor as follows:
①SiC+2O2→SiO2(click the link for product details)+CO2
② SiC + 4H2O = SiO2 (click on the link to learn more about the product) + 4H2 + CO2
The content of SiO2 in the component increases gradually, and the resistance increases slowly as it ages. If too much water vapor, will promote the oxidation of SiC, by ② reaction of H2 and O2 in the air combined with H2O and then react to produce a vicious cycle. Reduce component life. Hydrogen (H2) can reduce the mechanical strength of components. Nitrogen (N2) below 1200 ℃ can prevent SiC oxidation above 1350 ℃ and SiC reaction, so that SiC decomposition of chlorine (Cl2) can make Sic decomposition.

Precautions for use:

1, silicon carbon rods are hard and brittle, easily broken by violent vibration and impact. Therefore, we should be extra careful when transporting, and put it down gently when handling.

2、The length of the heating part of the silicon carbon rod should be equal to the width of the furnace. If the heating part extends into the furnace wall, it is easy to burn the furnace wall.

3, the length of the cold end of the silicon carbon rod should be equal to the thickness of the furnace wall plus the length of the cold end out of the furnace wall. The general length of the cold end is 50~150mm, so as to cool the cold end and connect the clamps.

4, wear silicon carbon rods of the furnace should be the inner diameter of the cold end of the outer diameter of 1.4 ~ 1.6 times, the furnace hole is too small or hole filler stuffed too tight, high temperature will hinder the free expansion and contraction of the silicon carbon rods and lead to broken rods. When installing, the silicon carbon rod should be able to freely rotate 360 degrees.

5, the distance between the silicon carbon rod and the heated object and the furnace wall should be greater than or equal to 3 times the diameter of the heating part. The center distance between the silicon carbon rod and the silicon carbon rod should be not less than 4 times the diameter of its heating part.

6. The cold end part of the silicon carbon rod is connected to the main circuit with aluminum braid or aluminum foil. The fixture of the cold end part should be clamped tightly.

7, the new furnace or a long time not to use the furnace to be baked before use, should use the old rod or other heat source baking furnace.

8, silicon carbon rods should be stored to prevent moisture. Because moisture is easy to make the cold end of the aluminum layer decomposition, fall off, resulting in the cold end of the contact resistance with the fixture increases, and silicon carbon rods are easy to collapse after power.

9, silicon carbon rods should be used before the matching resistance. The first resistance value of the same or close to the silicon carbon rods connected together.

10, for the silicon carbon rod equipped with voltage regulator. The voltage at the beginning of power supply is half of its normal working voltage, and then gradually increase the voltage after stabilizing for a period of time. In this way, the silicon carbon rod will not cause breakage due to rapid heating.

11, silicon carbon rod continuous service life is long; intermittent use of short life.

12, the use of silicon carbon rods to choose a reasonable surface load density and use of temperature. Use temperature should not be greater than 1650 ℃; in the harmful gas environment to prevent the use of silicon carbon rods and harmful gases occurring chemical reaction.