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Magnesia Insulation Board – Product Overview

Sep 11, 2026

Magnesia Insulation Board – Product Overview

Magnesia insulation boards are basic refractories manufactured from magnesia sand and fibrous reinforcement. They offer low thermal conductivity, high flexural strength, excellent slag resistance, and low permanent linear change at elevated temperatures. Widely used as impact pads, bottom plates, and sidewall panels in continuous casting tundish working linings, Magnesia insulation boards also demonstrate superior resistance to slag. In this regard, they significantly outperform their silica-based counterparts.

Main Technical Specifications

MgO (%)

SiO₂ (%)

Al₂O₃ (%)

Density (g/cm³)

Porosity (%)

Flexural Strength (MPa)

Cold Crushing Strength (MPa)

Thermal Conductivity (W/m·K)

Thermal Expansion (1000℃×3h, %)

Residual Moisture (%)

85-87

7-8

< 4

1.8-1.9

35-45

4-5

13-14

0.4-0.5

0.7-0.8

< 1.0

2. Product Description

Magnesia insulation board is a basic refractory product known for its high-temperature performance. It is manufactured from magnesia sand and fibrous materials through scientific proportioning, high-pressure forming, and high-temperature heat treatment. The resulting product exhibits low bulk density, good mechanical strength, and low thermal conductivity, along with outstanding slag corrosion resistance. Magnesia insulation board is non-radioactive, odorless, and non-toxic, making it an environmentally friendly material for both production and application.

The combination of magnesia sand and fibrous components forms an interlocking skeleton structure that significantly contributes to the product's mechanical strength, particularly in flexural performance.

The production process begins with mixing the raw materials into a slurry, followed by vacuum pressure filtration forming, drying, and high-temperature heat treatment, culminating in the desired density, strength, thermal conductivity, and other physical properties.

Manufacturing process of magnesia insulation boards As a wet processing method, this route enables precise control over product performance and ensures batch-to-batch consistency and uniformity.

3. Main Features

Excellent slag corrosion resistance, outperforming silica-based insulation boards.

Low bulk density, ranging from 1.8 to 1.9 g/cm³.

Low thermal conductivity, approximately 0.4–0.5 W/m·K.

High mechanical strength, particularly in flexural strength.

4. Main Applications

Magnesia impact pads applications: impact pads, bottom plates, and sidewall panels in tundish working linings.

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