Reasons for turning back of graphite electrode in use
Most of the problems in the use of electrode paste are caused by the overlapping of multiple factors. Among them, there are many U-turns.
Here, two situations are not discussed for the time being.
1; Operational factors during use (e.g., carbon deficiency, silkworm erosion, etc.)
II; Loopholes in the production process (such as different batches, inclusions, etc.)
Starting from the rationality of process formulation design, we focus on the following situations:
Let’s start with a phenomenon in our daily life. I think everyone has experienced such a thing; In the cold winter, we take a cold glass and pour boiling hot water into it. What happens? Why?
The result is well known. If it is light, the glass wall becomes cracked; Most importantly, the bottom of the glass is completely detached.
In fact, this is because when the glass is subjected to thermal stress, the heated bottom of the glass and the non heated wall of the glass will produce temperature instantaneously. At this time, if the glass material has poor thermal strain capacity and cannot take away the heat in time, the thermal stress is too concentrated, so the glass will crack and even the bottom end will fall off.
Some people will ask, this has nothing to do with electrode paste!
After all, the glass and the electrode paste belong to inorganic non-metal and have similarities.
We return our thinking to the submerged arc furnace. The electrode is like a glass, and the strong current is like hot water. However, there is another important factor that exacerbates the U-turn.
So we introduced a physical quantity: effect.
In order to improve the thermal shock resistance of electrode paste, it should be considered from three aspects: reducing the generation of thermal stress, buffering the development of thermal stress and enhancing the ability of thermal stress.
1、 Reducing the generation of thermal stress. Measures: high thermal conductivity, low linear expansion coefficient and high strength (controversial)
2、 Buffering the development of thermal stress. Methods: low elastic modulus (controversial)
3、 The ability to enhance thermal stress. Ways: increase the addition and proportion of graphite material, increase the particle size and proportion of large particle aggregate appropriately, increase the bulk density, properly improve the softening point of asphalt, and add additives with good thermal conductivity.