Fused Mullite

Product Overview

Fused mullite is a high-purity synthetic refractory raw material made from high-purity industrial alumina and silica, or quality bauxite, by arc melting above 2000℃ followed by cooling and crystallization. Its main phase is mullite (3Al₂O₃·2SiO₂). Large crystals, a dense structure, good high-temperature volume stability and excellent thermal shock resistance suit high-performance refractories.

Fusion produces fully developed crystals up to several millimeters long, with little intergranular glass and high purity. Compared with sintered mullite, fused mullite has larger crystals and better thermal shock resistance.

Sized aggregate grades include 0-1, 1-3, 3-5 and 5-8 mm; fine powders include 100, 200 and 325 mesh. Other specifications can be customized.

Core Advantages

1. High purity and stable performance

High-purity industrial alumina and silica provide 70%-77% Al₂O₃, low impurities and ≥93% mullite phase for stable refractory performance.

2. High refractoriness and temperature resistance

Refractoriness ≥1850℃ and a melting point of approximately 1840-1900℃ suit various industrial furnaces.

3. Good thermal shock resistance

Low thermal expansion and excellent thermal shock resistance help prevent cracking under rapid temperature changes. Its anisotropy factor A is much lower than that of sintered mullite, giving more uniform expansion that improves resistance to thermal stress and overall stability.

4. Good high-temperature volume stability

Large crystals, a dense structure and low high-temperature creep help resist cracking and spalling in furnace walls and roofs exposed to repeated heating and cooling.

5. Strong corrosion resistance

Balanced resistance to slag and combustion gases, with greater resistance to molten glass than sintered refractories.

6. Strong chemical stability

Excellent acid and alkali resistance suits varied chemical environments.

Technical Specifications

Physical Properties

Applications

Steelmaking: hot-blast stove roofs, blast-furnace shafts and hearths, and ladle linings

Glass: regenerators and linings in glass-melting furnaces

Ceramics: sintering kilns and high-temperature fixtures, including locating frames, saggers, base plates and supports for electronic components

Petrochemicals: linings in dead zones of petroleum cracking systems

Monolithic refractories: high-performance castables, ramming mixes, plastic refractories and precast shapes

Precision casting: molding sand, lost-foam coatings and refractory coatings

Fused mullite combines low weight with high strength and is widely used in steelmaking, kiln industries and heat-treatment furnaces. Its addition improves castable flow, penetration resistance, corrosion resistance and spalling resistance, extending service life and reducing refractory consumption per ton of steel.

Packaging

Packaging type

25 kg plastic woven bags / 25 kg per bag / Small orders and samples

Bulk bags / 1000 kg (1 ton) per bag / Large industrial orders

25 kg bags in a bulk bag / 40 × 25 kg bags per bulk bag / Flexible handling and efficient transport

25 kg bags on pallets / 25 kg per bag / Forklift handling and warehouse stacking

Custom Packaging Service

Custom packaging can include specific capacities, labels and branding.

Use and Storage Recommendations

1. Combine sized aggregate and fine powder

In refractory castables, aggregate forms the structural skeleton and fine powder fills the matrix voids. Select a suitable grading according to the formulation.

2. Storage Conditions

Store in a dry, ventilated place. Protect against moisture and contamination during transport and do not exceed specified stacking heights.

3. Operating Precautions

Above 1450℃, mullite bricks should not contact alkalis, which can decompose mullite. In reducing atmospheres above 1370℃, mullite also decomposes, with some SiO₂ converting to gaseous SiO and leaving the brick.

Frequently Asked Questions

How does fused mullite differ from sintered mullite?

Fusion fully melts the raw materials before cooling and crystallization, producing larger crystals, a denser structure, higher purity and better thermal shock resistance. Sintering uses solid-state reactions, producing finer, more reactive grains. Fused mullite can contain 76%-80% Al₂O₃, while sintered mullite normally does not exceed the theoretical 72.8%.

How do M75 and M70 differ?

M75 is a high-purity grade with 70%-77% Al₂O₃, Fe₂O₃≤0.2% and refractoriness ≥1850℃ for demanding purity requirements. M70 is a natural grade with 60%-70% Al₂O₃ and lower cost for most high-temperature industrial applications.

Can the product be used in high-temperature steelmaking environments?

Yes. Fused mullite has refractoriness ≥1850℃ and excellent thermal shock and slag resistance, supporting hot-blast stove roofs, blast-furnace shafts and ladle linings.

Are custom particle sizes available?

Yes. Aggregate from 0-1 to 5-8 mm and fine powder from 100 to 325 mesh are available, with other specifications on request.

What is the minimum order quantity?

Standard orders start from one 25 kg bag. Bulk bags are normally shipped as complete units.