MgO-C, MgO-Al2O3-C and Al2O3-MgO-C Carbon Bricks: Grade Selection by Vessel and Zone
A refractory engineer selecting carbon-bonded refractories is not simply comparing three competing products — they are matching specific chemical and physical formulations to localized thermal-chemical wear zones. MgO-C, MgO-Al2O3-C, and Al2O3-MgO-C bricks share the core metallurgical principle of resin bonding and flake graphite protection, yet occupy distinctly calibrated positions along the basic slag resistance versus thermal shock resilience curve. Operating temperatures, molten slag basicity (CaO/SiO₂ ratio), iron oxide content (FeO), and thermal cycling frequency strictly govern which refractory formulation ensures uncompromised campaign longevity.
We manufacture, hydraulic-press, and thermal-temper all three carbon-bonded brick grades with tailored residual carbon fractions, high-potency metallic antioxidant packages, and tight-tolerance custom wedge/arch shapes. Our linings are engineered specifically for high-stress zones: steel ladle slag lines and sidewalls, BOF trunnions and cones, EAF hot spots and lower panels, and Ladle Furnace (LF) synthetic slag lines.
Three Carbon-Bonded Refractory Grades: Core Chemistries & Wear Mechanisms
MgO-C Brick (Magnesia-Carbon): Superior Basic Slag & Hot-Spot Resistance
Formulated from ultra-high-purity dead-burned and fused magnesia (MgO ≥ 78%) bonded with crystalline natural flake graphite and active metallic antioxidants (Al, Si, or Mg alloys) to suppress hot-face carbon oxidation. MgO-C provides industry-standard refractoriness against corrosive high-basicity slags and aggressive slag foaming. It serves as the primary working lining for steel ladle slag lines, BOF trunnions and charge impact pads, EAF arc hot spots, and LF secondary refining slag zones.
MgO-Al2O3-C Brick (Magnesia-Alumina-Carbon): Enhanced Thermal Shock Resistance for Transition Zones
Engineered by introducing electrofused or tabular alumina aggregates into the magnesia-carbon matrix. Controlled in-situ spinel (MgAl₂O₄) formation during high-temperature service imparts high micro-structural elasticity and spalling resistance while preserving slag corrosion resistance. This grade is targeted at severe transition zones exposed to fluctuating temperature swings, including BOF cone-to-barrel junctions and high-stress ladle slag-line transition courses.
Al2O3-MgO-C Brick (Alumina-Magnesia-Carbon): Economical Steel-Line & Spalling Resistance
Formulated with high-grade alumina as the predominant aggregate (Al₂O₃ 60–75%) combined with high-purity magnesia and flake graphite. This grade delivers superior resistance to liquid steel washing, high thermal shock tolerance, and controlled residual expansion that tightens joint seams during operation. It represents a cost-effective, high-integrity lining for zones below the slag line, including ladle sidewall barrels and EAF lower panels.
Zone-by-Zone Application Reference Across Steelmaking Vessels
Three-Vessel Working Lining Zonation: schematic cross-section of Steel Ladle, BOF Converter, and EAF indicating optimal brick grade distribution.
| # | Vessel / Lining Zone | Recommended Grade | Primary Wear Mechanism & Selection Rationale |
|---|---|---|---|
| 1 | Steel Ladle — Slag Line | MgO-C | High-basicity slag corrosion, synthetic refining slag washing, and intense thermal radiation. |
| 2 | Steel Ladle — Sidewall / Metal Line | Al2O3-MgO-C | Molten steel scouring and static ferrostatic pressure with moderate slag contact; cost-effective durability. |
| 3 | BOF Converter — Trunnion & Slag Line | MgO-C | Intense mechanical stress during rotation, high-velocity slag splashing, and oxidation during oxygen blowing. |
| 4 | BOF Converter — Cone-to-Barrel Transition | MgO-Al2O3-C | Severe thermal fatigue and cyclic temperature swings across scrap charging, blowing, and tapping phases. |
| 5 | EAF — Electrode Hot Spot | MgO-C | Extreme electric arc flare radiation, localized superheating, and aggressive chemical slag washing. |
| 6 | EAF — Lower Sidewall Panel | Al2O3-MgO-C | Liquid steel contact, chemical wear, and thermal fatigue under continuous melt cycles. |
Working Lining vs. Permanent Lining: Placement in Vessel Wall Architecture
Modern metallurgical vessel walls are constructed in distinct concentric shells from the outer steel casing inward: the permanent safety lining (high-alumina brick or low-cement insulating castables providing structural thermal containment), an optional intermediate safety barrier, and the working lining (the sacrificial hot face directly exposed to molten metal and slag). MgO-C, MgO-Al2O3-C, and Al2O3-MgO-C bricks are engineered exclusively for the working lining. For backup safety linings, explore our integrated Steel Ladle, BOF Converter, and EAF Refractory Solutions.
Technical Data Sheets (TDS): Chemical Composition & Physical Properties
MgO-C Brick — Typical Technical Data Sheet (TDS)
| Property | Typical Specification |
|---|---|
| MgO Content (%) | ≥ 78 |
| Fixed Carbon (C) (%) | 10 – 18 |
| Fe₂O₃ Content (%) | ≤ 1.2 |
| Bulk Density (g/cm³) | ≥ 2.95 |
| Apparent Porosity (%) | ≤ 5.0 |
| Cold Crushing Strength (CCS) (MPa) | ≥ 35 |
| Hot Modulus of Rupture (HMOR, 1400°C × 0.5h) | ≥ 6.0 MPa |
| Oxidation Layer Depth (1400°C × 3h) | ≤ 4.0 mm |
| Maximum Service Temperature (°C) | ~1750 |
MgO-Al2O3-C Brick — Typical Technical Data Sheet (TDS)
| Property | Typical Specification |
|---|---|
| MgO Content (%) | 55 – 65 |
| Al₂O₃ Content (%) | 8 – 15 |
| Fixed Carbon (C) (%) | 10 – 14 |
| Bulk Density (g/cm³) | ≥ 2.90 |
| Apparent Porosity (%) | ≤ 6.0 |
| Cold Crushing Strength (CCS) (MPa) | ≥ 30 |
| Hot Modulus of Rupture (HMOR, 1400°C × 0.5h) | ≥ 5.5 MPa |
| Thermal Shock Resistance (1100°C Water Quench) | ≥ 20 Cycles |
| Maximum Service Temperature (°C) | ~1700 |
Al2O3-MgO-C Brick — Typical Technical Data Sheet (TDS)
| Property | Typical Specification |
|---|---|
| Al₂O₃ Content (%) | 60 – 75 |
| MgO Content (%) | 5 – 12 |
| Fixed Carbon (C) (%) | 8 – 12 |
| Bulk Density (g/cm³) | ≥ 2.85 |
| Apparent Porosity (%) | ≤ 7.0 |
| Cold Crushing Strength (CCS) (MPa) | ≥ 32 |
| Hot Modulus of Rupture (HMOR, 1400°C × 0.5h) | ≥ 5.0 MPa |
| Thermal Shock Resistance (1100°C Water Quench) | ≥ 25 Cycles |
| Maximum Service Temperature (°C) | ~1650 |
*Standard production laboratory data. Every export consignment is dispatched with lot-traceable EN 10204 3.1 Mill Test Certificates (MTC).
Carbon Content, Antioxidant Systems & Engineering Considerations
Fixed Carbon Levels & Thermal Conductivity Trade-offs
Higher residual carbon improves slag-corrosion and thermal-spalling resistance, but increases thermal conductivity toward the vessel shell. We balance fixed carbon between 8% and 18% based on shell temperature limits and localized wear severity.
Metallic Antioxidant Systems Matched to Tap-to-Tap Furnace Cycles
Rapid tap-to-tap cycles impose different oxidation stresses compared to prolonged secondary refining holds. We calibrate metallic antioxidant additions (Al, Si, Mg-Al alloys) to synthesize protective in-situ ceramic phases at operational temperatures.
Interface with Tap Hole Sleeves & Ladle Flow Control Refractories
Working linings must integrate smoothly with vessel bottom outlet assemblies. For flow components, explore our guides on Ladle Nozzle Filler Sand, Ladle Well Blocks, and Slide Gate Plates.
Custom Drawing Machining & Joint Geometry Tolerance
We press standard key, wedge, and arch bricks as well as complex custom shapes to customer drawings, ensuring tight mortarless or mortared joints that eliminate molten steel finning.
Industrial Manufacturing Gallery: 2500-ton CNC hydraulic pressing, high-temperature tempering, and rigorous dimensional tolerance inspection.
Technical Procurement Specifications & Quality Checkpoints
Meltshop Technical RFQ Input Parameters
Vessel Operating Condition Inputs:
Standard Quality Review Checkpoints:
- Vessel Duty & Slag Basicity: Operating temperature range, slag CaO/SiO₂ ratio, FeO percentage, and refining hold times.
- Zonal Lining Geometry: Radial shell curvature, taper dimensions, and expansion allowance joints.
- Target Campaign Heats: Current specific consumption records and planned reline turnaround schedules.
- Packaging & Protection: Palletized moisture-barrier shrink wrapping for long-distance maritime transit.
Frequently Asked Technical Questions: Carbon Bricks (FAQ)
What is the practical difference between MgO-C and MgO-Al2O3-C brick?
MgO-C features higher magnesia content and provides peak resistance to corrosive basic slags. MgO-Al2O3-C incorporates alumina to form in-situ spinel during service, sacrificing a small degree of slag resistance to achieve superior thermal shock resistance in cycling transition zones.
Can Al2O3-MgO-C brick be used at a steel ladle slag line?
Al2O3-MgO-C is not recommended for primary slag lines due to corrosive attack by high-basicity refining slags. It is specifically formulated for ladle sidewalls and bottoms where steel scouring and thermal spalling dominate.
Why does fixed carbon content range from 8% to 18% across these grades?
Carbon content is calibrated to service severity: critical slag lines and arc hot spots require 14–18% carbon to prevent slag wetting and erosion, whereas lower sidewalls use 8–12% carbon to reduce thermal shell conductivity and procurement costs.
Is MgO-C brick suitable for Ladle Furnace (LF) synthetic slag refining?
Yes. The LF slag line encounters highly reactive, basic desulfurizing slags and arc flare. Premium fused magnesia MgO-C bricks are the standard solution. For full LF configurations, see our Ladle Furnace (LF) Refractory Solutions.
Do you supply custom brick geometries, or standard DIN/GOST/ISO sizes only?
We supply both international standard sizes (DIN, GOST, ISO) and customized pre-assembled ring shapes engineered to your CAD drawings, OEM part numbers, or physical refractory samples.
Related Steelmaking Refractory Solutions & Flow Control Systems
- Steel Ladle Refractory Solutions — Complete zoned lining systems, purging plugs, and slide gate refractory assemblies.
- BOF Converter Refractory Solutions — Zoned magnesia-carbon bricks and trunnion repair systems.
- EAF Refractory Solutions — High-durability MgO-C hearth, sidewall, and delta roof lining.
- Ladle Furnace (LF) Refractory Solutions — Slag line MgO-C brick and delta roof high-alumina castables.
- Complete Steel Plant Refractory Solutions — Turnkey refractory engineering from primary furnace to continuous caster.
Request an Engineering Grade Recommendation & Technical Quotation
Provide your vessel specifications, campaign life targets, and operating slag chemistry. Our metallurgical engineering team delivers a tailored MgO-C, MgO-Al2O3-C, or Al2O3-MgO-C brick recommendation and quotation within 24–48 hours.
Direct Engineering Email: sales@ykchanshine.com | Plant Line: +86-139-9807-2158