Precautions for the use and maintenance of carbon silicon rods
1. The quality of silicon carbide rod is hard and brittle, and it is easy to break when subjected to severe vibration and impact. Therefore, during transportation, unpacking, installation and replacement, it is required to handle with care, and to prevent mechanical knocks to avoid breaking the rod.
2. The length of the heating part of the silicon carbide rod should be equal to the width of the high temperature furnace. If the heating part goes deep into the furnace wall, it is easy to burn the furnace wall.
3. The length of the cold end of the silicon carbide rod should be equal to the thickness of the furnace wall plus the extension length of the cold end of 50~150mm in order to cool the cold end and the connecting fixture.
4. The distance between the silicon carbide 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 carbide rod and the silicon carbide rod should not be less than 4 times the diameter of the heating part.
5. Newly built box-type high-temperature furnaces or furnaces that have not been used for a long time should be baked before use, and old rods or other heat sources should be used.
6. The cold end of the silicon carbide rod is connected to the main circuit with aluminum braid or aluminum foil, and the clamp at the cold end must be clamped tightly.
7. The silicon carbide rod has a long continuous service life and a short intermittent service life.
8. Before installing and using the silicon carbide rod, check the resistance (Ω) value marked on the cold end. If the writing is unclear, it must be re-tested. The test method is the voltage measured when the silicon carbide rod is energized and heated to a high temperature of 1050°C. , Current, resistance calculated by Ohm's law.
9. When silicon carbide rods are used, each group of rods should be matched with high temperature resistance. First connect silicon carbide rods with the same or similar resistance values together, and the allowable difference in resistance value is: ≥φ12mm rod with resistance, resistance value tolerance is ≤0.2Ω, ≤φ8mm rod with resistance, resistance value tolerance is ≤ 0.5Ω.
10. Equipped with a pressure regulating device for silicon carbide rods. When the new furnace starts to transmit power, the initial voltage of power transmission should be half of its normal working voltage, and then gradually increase the voltage after a period of stability. In this way, the silicon carbide rod will not be broken due to the rapid temperature rise.
11. The silicon carbide rods should be protected from moisture when they are stored. Because it is easy to decompose and fall off the aluminum layer at the cold end after being exposed to moisture, the contact resistance between the cold end and the fixture is increased, and the silicon carbide rod is prone to cracking after being energized; if it is found that the aluminum sprayed on the rod end is deteriorated and deliquescent, it can be treated after surface treatment. Re-spray aluminum. If there is no aluminum spray condition, you can wrap several layers of aluminum foil on the rod spray aluminum section. If the deliquescence is serious, replace the stick in time to ensure normal use.
12. When using silicon carbide rods, choose a reasonable surface load density and operating temperature. The operating temperature should not be greater than 1650 degrees Celsius; it is necessary to prevent the chemical reaction between the silicon carbide rod and the harmful gas when used in a harmful gas environment.
13. Prevent the molten metal from splashing on the silicon carbide rod. Splashing on the molten metal may easily cause the rod to break.
14. Prevent alkali and alkaline oxides from corroding silicon carbide rods.
15. During the long-term operation of the furnace, when individual silicon carbide rods are damaged due to some reason and need to be replaced, the silicon carbide rods with suitable resistance value should be selected according to the growth of the resistance value of the silicon carbide rods at that time, and new silicon carbide rods should not be arbitrarily taken. Rod replacement. If the silicon carbide rods are damaged more or the resistance increases too much, and the required furnace temperature cannot be reached, all the silicon carbide rods are replaced with new ones. The replaced silicon carbide rod is re-measured (using a pressure meter, ammeter) to measure its resistance value, and the resistance is used in the low temperature area.
16. The use of silicon carbide rods must be equipped with voltage regulator or thyristor voltage regulator and voltage, ammeter and temperature automatic control instruments. The resistance value gradually increases due to the oxidation of the rod during use. In order to keep the furnace temperature normal, the operating voltage should be increased. When the voltage is increased to the maximum limit of the voltage transformer used and still cannot meet the requirements, the furnace can be stopped to change the wiring method of the rod. continue to use.
17. It is strictly forbidden to use the silicon carbide rods with overload. If the rods are broken for some reason or the rods are found to be unevenly heated, and the parts are incandescent or dark red for a period of time, this indicates that the rod body is inconsistent with age, and the resistance of the segments is too different. Check and replace the rods, and replace all rods with new rods. For example, when replacing some new rods or single rods, the resistance of the new rods and the used rods are not matched properly, resulting in unbalanced load and uneven furnace temperature. Due to the large resistance difference, the rod temperature is also highly correlated, which will seriously affect the service life.