What are the precautions for using silicon carbide rods of equal diameter?

What are some considerations for silicon carbide rods of the same diameter? Let's analyze them together.

1. Silicon carbide rods of the same diameter are hard and brittle, and easily break when subjected to severe vibrations and impacts. Therefore, they must be handled with care during transportation.

2. The length of the heating element of the silicon carbide rod of the same diameter should be equal to the width of the furnace. The heating element should be integrated into the furnace wall for easy combustion.

3. The length of the cold end of the silicon carbide rod of the same diameter should be equal to the furnace wall thickness plus the length of the cold end extrusion wall. Generally, the cold end extrusion is between 50 and 150 mm to cool the cold air and facilitate insertion.

4. The inner diameter of the furnace containing the silicon carbide rod should be 1.4 to 1.6 times the outer diameter of the cold end. If the furnace opening is too small or the filling material inside is too tight, it will hinder the free stretching of the silicon carbide rod at high temperatures, causing the entire rod to break. During installation, the silicone strip should be allowed to rotate freely 360 degrees.

5. The distance between the silicon carbide rod of equal diameter and the heated object and furnace wall temperature should be greater than or equal to three times the diameter of the non-heating part. The center-to-center distance between wires must be greater than four times the diameter of the heating zone.

6. The cold end of the silicon carbide rod and the main circuit should be connected using aluminum braid or aluminum foil. Clamps must be installed in cold areas.

7. Use new electricity or electricity that has not been used for a long time. Prepare the oven before use. Use old rods or other heat sources.

8. Prevent moisture from affecting the silicon carbide rod during storage. Moisture can easily cause the aluminum layer on the cold end to decompose and peel off, increasing the contact resistance between the cold end and the clamp, leading to easy breakage of the silicon carbide rod after startup.

9. Before using the silicon carbide rod, a matching resistor must be used. Connect silicone rods with equal or close resistance values together.

10. The silicon carbide rod is equipped with a pressure regulating control device. The initial voltage is half of the normal operating voltage. After a period of stable operation, the voltage can be gradually increased. This prevents the silicon carbide rod from breaking due to rapid heating.

11. Silicon carbide rods have a long service life; intermittent operation results in a shorter service life.

12. When using silicon carbide rods, a reasonable surface load density and operating temperature should be selected. The ambient temperature must be below 1650°C. In environments with harmful gases, further precautions should be taken to prevent chemical reactions between the silicon carbide rods and the harmful gases.

13. When replacing silicon carbide rods of the same diameter, silicone rubber with a resistance similar to that of the rods used in the furnace should be used. If necessary, the entire furnace of silicon carbide rods should be replaced to extend the service life of the silicon carbide rods and to utilize rods that cannot be removed by hand. If the resistance value is correct, replacement can also be performed in the later stages of furnace operation.

14. Prevent silicon carbide rods of the same diameter from splashing onto molten metal. If molten metal splashes onto the rods, they will easily break.

15. Prevent alkali, alkaline earth metals, and alkali oxides from corroding the silicon carbide rods.