What Is Refractory Slide Gate?

A refractory slide gate is a sliding valve device made of high-performance refractory materials, mainly used for flow control of high-temperature molten metal (such as molten steel and molten iron) in the metallurgical industry. Its core function is to adjust the water inlet opening by sliding, so as to achieve precise opening and closing and flow regulation of the metal flow, and is an indispensable key component in the continuous casting process.

Structure and composition

Core components:

Upper slide gate (moving plate): connected to the drive mechanism, and the water inlet opening is adjusted by lateral sliding.

Lower slide gate (fixed plate): fixed to the bottom of the ladle or tundish, and docked with the water inlet.

Sealing mechanism: metal edging, ceramic sealing pad or spring pressure device to ensure close fit between slide gates (gap <0.1mm) to prevent steel leakage.

Auxiliary system:

Drive device: hydraulic, pneumatic or mechanical drive to control the movement of the slide gate.

Cooling system: water-cooled or air-cooled design to protect non-refractory components (such as hydraulic cylinders) from high-temperature radiation.

Material properties

The performance of refractory slide plates depends on their material system and must meet the following core requirements:

Performance requirements Material solutions Typical components

1. High temperature resistance (>1600℃) High melting point oxides (Al₂O₃, ZrO₂) and carbon composite Al₂O₃ (60-80%), C (5-15%)
2. Thermal shock resistance Graphite or silicon carbide (SiC) buffers thermal stress SiC (10-20%), graphite layer
3. Chemical corrosion resistance Add ZrO₂, Si₃N₄ to resist slag corrosion ZrO₂ (15-25%), Si₃N₄ coating
4. High strength and wear resistance Isostatic pressing + high temperature sintering, densified structure Porosity <12%, compressive strength >50MPa
5. Core functions
6.  

Precise flow control:

A(h): opening corresponding area;

H: molten steel static pressure head)

Dynamic response: Hydraulic drive can achieve millisecond-level adjustment, suitable for high-speed continuous casting (such as thin slab 6m/min).

High temperature sealing:

The contact pressure between the slide plates reaches 5-20MPa to prevent high-temperature molten steel from penetrating.

Emergency shutdown function: In case of sudden failure, the steel flow is cut off within 0.5 seconds to avoid steel leakage accidents.

Long life and reliability:

Gradient material design: surface corrosion resistance (ZrO₂), middle layer thermal shock resistance (Al₂O₃-C), bottom layer reinforcement (metal fiber).

Typical life: 8-12 heats for ordinary steel grades, 4-6 heats for high-corrosion steel grades (such as stainless steel).

Industrial application scenarios

1. Core flow control of continuous casting process

Ladle → tundish:

The slide plate is installed at the bottom of the ladle to control the flow rate of molten steel injected into the tundish and maintain the stability of the tundish liquid level (fluctuation ±5mm).

Tundish → crystallizer:

In some processes, it replaces the stopper rod to directly adjust the molten steel flow rate of the crystallizer and reduce the defects of the ingot caused by liquid level fluctuation.

2. Adapt to different steel grades and processes

 

Raw material preparation:

Mixed oxide powder (Al₂O₃, ZrO₂), graphite, binder (phenolic resin).

Molding:

Isostatic pressing (200-300MPa) or compression molding to ensure uniform density of the billet.

Sintering:

High temperature sintering (1600-1800℃, 10-24 hours) in a reducing atmosphere to form a dense ceramic-carbon composite structure.

Post-processing:

Precision grinding (surface roughness <1.6μm), coating (such as SiC anti-oxidation layer).
 

Technology frontier and future trends

Intelligent skateboard system:

Embedded sensors: Real-time monitoring of skateboard temperature and wear, and data transmission through the Internet of Things (IoT).

AI predictive maintenance: Predict life based on historical data and optimize replacement cycle (such as warning when 10% of life is left).

Green material innovation:

Carbon-free skateboard: Develop MgO-CaO-ZrO₂ system to reduce graphite use and reduce carbon emissions.

Recyclable design: Modular structure to achieve skateboard material separation and recycling (such as ceramic and metal component separation).

Breakthrough in extreme working conditions:

Ultra-high temperature alloy smelting: Use Y₂O₃ to stabilize ZrO₂ skateboard, and withstand >1800℃ environment (such as titanium alloy continuous casting).

Electromagnetic assisted drive: Combine electromagnetic force rapid response and hydraulic high thrust to improve adjustment accuracy.

Ladle refractory is the core consumable in the steelmaking process, and its performance directly affects the quality of molten steel, production safety and cost. Compared with the tundish refractory, the ladle material needs to withstand longer molten steel residence time, more complex slag-steel reaction and higher mechanical load.