The sliding nozzle consists of an upper and lower nozzle and an upper and lower sliding plate. It is a key functional component that controls the flow of molten steel from the ladle to the tundish or from the tundish to the crystallizer. Among them, the sliding plate is the key carbon composite functional component in the sliding nozzle system, which has the function of controlling and injecting the steel flow. At present, the skateboards for ordinary ladles mainly use aluminum carbon skateboards, while the skateboards for large refined ladles mainly use aluminum zirconium carbon skateboards.
During the service of skateboards, their use environment is extremely harsh, so most of them are damaged after being used several times. The damage methods mainly include:
- Thermomechanical erosion
The temperature difference before and after the skateboard is used is as high as 1,400°C, forming extremely strong internal stress inside the skateboard, leading to the formation of large cracks, and the repeated erosion of the material inside the cast hole of the skateboard by molten steel will cause the material to peel off.
- Thermochemical attack
Various elements (oxygen, iron, manganese, calcium, etc.) in molten steel or slag will react with various components in the slide plate, causing chemical erosion of the slide plate and deteriorating the material structure. Ultimately, the thermomechanical strength and erosion resistance of the material are significantly reduced.
- Wear and sticking to steel
The viscosity of some special steel types (stainless steel and steel containing titanium and chromium) is higher than that of ordinary carbon steel, which is prone to steel sticking, causing wear and tear on the skateboard and greatly reducing the service life of the skateboard.
It can be seen that the skateboard not only has high mechanical strength and thermal shock stability, but also has good erosion resistance and peeling resistance. At the same time, in order to cope with the increasingly demanding new requirements for steel smelting, especially to meet the smelting needs of steel types such as calcium-treated steel and clean steel. Refractory materials workers in various countries continue to discuss and research the materials of skateboards. One of the main research directions is to reduce the carbon content in skateboards while ensuring sufficient service life.
