Sliding Nozzle System Refractory
Sliding Nozzle System Refractory Description
Sliding nozzle system are mainly used in two places, one is at the bottom of steel ladle, plays the role of steel liquid flowing rate control unit, the other is at the bottom of tundish, controlling steel liquid flowing rate from tundish to crystallizer. Sliding gate’s movement is controlled by operation unit, so the hole of up-sliding gate and down-sliding plate can be opened and closed at will, steel liquid flow rate is adjusted in this way.
Sliding nozzle system is composed of well bricks, sprue bricks and sliding gate. As to ladle sliding gate, high quality alumina zirconia carbon sliding gate and alumina carbon sliding gate’s service life is about 2~4 times. For tundhish sliding gate, it should serve a continuous casting cycle, which means the service life is usually below 8 times. For ordinary steel casting, alumina carbon sliding gate and alumina zirconia carbon sliding gate can meet production requirement. For up-long nozzle, corundum bricks, alumina carbon bricks and chrome corundum bricks are usually adopted. Their service life is between 20~30 times.
Ordinary casting sliding gate system refractory
| Item | Alumina carbon up nozzle | Alumina carbon mortar | Alumina zirconia carbon sliding gate | Alumina carbon down nozzle | Alumina down nozzle |
| Application | Steel ladle sliding nozzle | Sliding nozzle masonry | Steel ladle | Steel ladle | Steel ladle |
| Al2O3 % | 90 | ≥65 | ≥70 | 75.6 | ≥60 |
| F·C % | 4.7 | 4.7 | ≥7 | 4.87 | / |
| Fe2O3 % | / | 1.60 | ZrO2≥6 | / | / |
| Apparent porosity % | 4.7 | / | 2 | 5.7 | 13.6 |
| Bulk density g/cm3 | 3.18 | / | 3.07 | 2.86 | 2.40 |
| Crushing strength MPa | 112.3 | / | 117 | 105.5 | 65 |
| Modulus of rupture Mpa | / | 3.8(1500℃, 3h) | |||
| Refractoriness under load(T2) ℃ | >1700 | / | ≥1700 | ≥1700 | / |
| Reheating linear change rate % | / | Setting time: 60~150min |
| Item | Up nozzle well block | Well block | Up nozzle | AC sliding gate | AZC sliding gate | Sliding gate mortar |
| Material | Corundum | High alumina | Chrome corundum | Alumina carbon | Alumina zirconia carbon | Alumina chrome |
| Al2O3 % | 97 | 81.5 | 87 | 93 | 77.7 | 84 |
| Cr2O3 % | / | / | 10 | / | / | 4.5 |
| SiO2 % | / | 11 | / | 6.2 | / | 4 |
| CaO % | 2.4 | TiO2: 3.3 | / | / | / | / |
| ZrO2 % | / | P2O5: 2.2 | P2O5: 2.0 | / | 6.5 | P2O5: 5 |
| C % | / | / | / | 9 | 8.2 | / |
| Apparent porosity % | / | 22 | 17.5 | 16 | 9 | / |
| Bulk density g/cm3 | 3.0 | 2.75 | 3.25 | 2.79 | 3.07 | / |
| Crushing strength MPa | >50 | 80 | / | >30 | 200 | / |
| Modulus of rupture Mpa(1450℃) | 2.8 | / | / | >7 | 12 | / |
| Refractoriness under load(T2) ℃ | / | >1430 | >1700 | ≥1700 | / | / |
| Reheating linear change rate %(1450℃,3h) | / | 1.0 | / | / | / | / |
Main Damage Reasons of Sliding Gate
- Carbon boning sliding gate can be oxidized in middle temperature oxidizing condition and lose strength, the surface of sliding gate will be abraded irregularly. It is the main damage reason of sliding gate.
- Another damage reason is thermal shock. Sliding gate will endure strong thermal shock and generate great thermal stress, which can induce sliding gate crack or crushing.
- The third damage reason is steel liquid scouring and abrasion. Steel liquid flowing speed is very quick, can take away oxide granule and dissolve carbon in sliding gate, so the diameter of sliding gate’s hole is enlarged.
High Oxygen Steel Casting Sliding Gate
For high oxygen steel casting, alumina carbon sliding gate and alumina zirconia carbon sliding gate’s service life can greatly decline. Sliding nozzle system must have good oxidization resistance, good iron oxide corrosion resistance, as well as thermal shock resistance and abrasion resistance. Through numerous research and application cases, alumina magnesia spinel carbon sliding gate, magnesia spinel carbon sliding gate and magnesia carbon sliding gate are tested to have good service life.
High Oxygen Steel Casting Sliding Gate Index
| Item | Alumina magnesia spinel carbon sliding gate | Magnesia spinel carbon sliding gate | Magnesia carbon sliding gate |
| Al2O3 % | 80 | 10 | / |
| MgO % | 8 | 84 | 89.7 |
| C % | 8 | 5 | 3.5 |
| Apparent porosity % | 6 | 6 | 7 |
| Bulk density g/cm3 | 3.05 | 2.98 | 2.78 |
| Crushing strength MPa | 150 | 100 | 160 |
| Modulus of rupture Mpa(1400℃) | 12 | 15 | 18 |
| Thermal expansion rate(800℃) | 0.90 | 0.92 | 0.82 |