Insulation Refractory

What are the classifications and characteristics of lightweight insulation materials?

Release Time: 2024-10-30
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Lightweight insulating materials can be categorized by installation method, operating temperature, physical state, microstructure, and production process.

1. By Usage

Installed in Insulating Layer: General type, non-direct flame contact.
Installed in Both Insulating and Working Layers: Advanced type, direct flame contact.

2. By Operating Temperature

Low Temperature: Suitable for temperatures below 600°C, such as slag wool.
Medium Temperature: Suitable for 600-1200°C, including calcium silicate boards, ceramic fiber boards, and silica insulation bricks.

Medium Temperature
High Temperature: Suitable for over 1200°C, such as anorthite insulating firebrick and mullite insulating bricks.

High Temperature

3. By Physical State

Powdered Lightweight Insulating Materials: Examples include alumina hollow spheres, expanded perlite, and diatomite.

Bubble Alumina Brick

Fixed-Form Lightweight Insulating Materials: Examples include lightweight refractory mortar and castables.
Fibrous Lightweight Insulating Materials: Includes ceramic fiber boards, blankets, and other products.

ceramic fiber board

Mixed-Type Lightweight Insulating Materials: Includes insulating boards and thermal insulation coatings.

4. By Microstructure

By Microstructure

Gas-Connected Lightweight Materials: Dominated by interconnected open pores, such as refractory powders.
Solid-Connected Lightweight Materials: Contains primarily closed pores, where gas is encapsulated by the solid phase, ensuring isolated closed pores. Examples include calcium silicate boards and bubble alumina bricks produced by foaming.

ceramic fiber board

Interwoven Gas-Solid Structure: Features continuous gas and solid phases interwoven, as seen in refractory fiber products and composite fiber materials.

5. By Production Method

Burnout Method: Organic pore-forming agents like sawdust, coal powder, or polystyrene balls are added, creating highly porous, open-pore insulating materials upon burning out. This method can yield lightweight bricks with high porosity and low density, though excessive pore-forming agents may cause cracks during drying and sintering.
Foaming Method: Adding foaming agents or blowing agents creates lightweight insulation materials through casting, curing, drying, and sintering. Compared to the burnout method, foaming produces uniformly distributed, primarily closed pores with controlled sizes.

Formulated with a blend of clay, calcium carbonate (CaCO₃), and an organic foaming agent, Firebird‘s GMK23  Anorthite Insulating Firebricks undergo a high-temperature firing process that forms both anorthite (CaO • Al₂O₃ • 2 SiO₂) and mullite (3Al₂O₃ • 2SiO₂) phases. This process enhances the bricks’ insulating and thermal properties while preventing sulfur dioxide (SO₂) emissions.

GMK23 Anorthite Insulating Firebrick

Chemical Method: Volatile or decomposable materials like CaCO₃ or Ca(OH)₂ are added to create pores upon decomposition at high temperatures. This method produces materials with low porosity and fine slit-like pores, yielding products with high strength and low thermal conductivity.
Directly Porous Materials: Examples include diatomite, vermiculite, or perlite, which are naturally porous but lose structural integrity above 900°C.

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