Insulating Firebrick (IFB) FJM23–FJM32 | 1260–1760°C

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FJM Series Mullite Insulation Brick | Lightweight Refractory Bricks

Firebird FJM Series Insulating Firebricks (IFBs) are high-quality, lightweight refractory bricks made from pure refractory clays, alumina, and specially graded organic fillers that burn out during production to create a consistent pore structure.

Classification temperature 1260℃ - 1760℃

Grade FJM23, FJM25, FJM26, FJM28, FJM30, FJM32

Capacity 1,000,000pcs NF1 bricks per month

Customized branding and packaging accepted

Free samples can be provided upon request

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Introduction

Features

Photo Gallery

Product Knowledge

Technology Parameters

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Introduction of Mullite Insulation Brick

Manufactured through casting, extrusion, or foaming methods, the mullite insulation bricks are sintered in natural gas-powered tunnel kilns. After undergoing meticulous grinding for accurate dimensions, the refractory bricks are securely packed on ISPM15 or non-fumigation plywood pallets.

Firebird Insulating Firebricks are provided according to different classification standard:
(1) ASTM Standard FJM 23, FJM25. FJM26, FJM28, FJM30, FJM32 Grades;
(2) JIS Classification Standard A, B, C Group;
(3) We can offer Sillimanite Brick, High Alumina Brick, Bubble Alumina Brick, Fireclay Brick, Silica Brick etc.

From standard straight, arch, and block shapes to bespoke designs, our manufacturing capabilities cater to your unique project needs.

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Features of Mullite Insulation Brick

Exceptional Permanent Linear Change (PLC):

Produced using high-purity raw materials and subject to prolonged high-temperature sintering, FJM mullite insulation bricks exhibit minimal PLC for safe, long-lasting application.
Low Thermal Conductivity:

Superior thermal insulation enables thinner furnace walls, reducing operational costs and boosting efficiency.
Low Density & Heat Storage:

Lightweight and thermally insulating, mullite insulation brick absorb minimal heat, offering fuel savings and rapid heat-up in cyclical heating equipment.
High Purity:

Minimal impurities like iron and alkali flux ensure consistent refractory performance in specified atmospheres.
High Strength:

Strong compressive strength allows for self-supporting structures at elevated temperatures, enhancing construction stability.
Precise Dimensions:

Machine-calibrated bricks enable quick and easy laying, creating stronger and tighter refractory linings that minimize heat loss.

Photo Gallery of Mullite Insulation Brick

Mullite Insulation Brick production equipment 1

Mullite Insulation Brick production equipment 2

Application of Mullite Insulation Brick

FJM Series Insulating Firebricks are versatile and ideal for hot face refractory lining or back-up insulation in various industries, including:• Chemical & Petrochemical: Kilns, flues, refining vessels, heaters, reactor chambers.
• Glass: Melters, regenerators, tin baths, distributors, tempering furnaces.
• Ceramics: Roller kilns, tunnel kilns, shuttle kilns, electricity furnace.• Aluminum: Anode baking furnaces, primary electrolytic cells.• Lithium-ion Battery: Cathode and anode furnaces.
• Iron & Steel: Coke ovens, blast furnaces, hot blast stoves, reheating furnaces, bright metal annealing furnaces.
• Industrial Furnaces: Carburizing furnaces, heat treating furnaces, electronic product furnaces, refractory sintering furnaces

Size is no longer a limitation

Most Firebird IFBs are available in large sizes, eliminating the need for mortar joints and allowing for dimensions up to 600*500*100mm. This flexibility removes the design limitations associated with traditional brick shapes and sizes. The nominal cost of block sizes is offset by significant labor savings and fewer mortar joints, making them a cost-effective solution. Additionally, the reduced number of joints improves the structural integrity and thermal efficiency of installations, providing long-term benefits.

Customizing insulating firebricks for your project

Firebird offers versatility beyond standard shapes. They can be custom fabricated to meet specific needs. This allows for intricate designs in high-heat applications like furnaces, kilns, and fireplaces. Imagine a brick with special hole or cutouts to improve air circulation or heat flow! These special shapes can be made with features like:

Holes,Flycuts,Channels,Tapers,Rounded edges,Tongue & Grooves,Notches and chord cuts

By using custom insulating fire bricks, builders can create unique and efficient heating equipments.

Technology Parameters

FJM Series Insulating Firebrick
Grade		Standard	Unit	FJM23L	FJM23	FJM24	FJM25	FJM26	FJM26-60	FJM26H
Classification Group		ISO 2245		125-0.5-L	125-0.6-L	130-0.8	135-0.8-L	140-0.8-L	140-0.8-L	140-0.9
Classification Group		ASTM C155		23	23	24	25	26	26	26
Classification Temperature			℃	1260	1260	1300	1350	1430	1430	1430
Bulk Density		ASTM C134	g/cm³	0.5	0.6	0.8	0.8	0.8	0.8	0.9
Cold Crushing Strength		ASTM C133	MPa	1.2	1.6	2	2	2.5	2.4	2.8
Modulus of Rupture		ASTM C133	MPa	0.7	0.9	1.2	1.2	1.4	1.3	1.5
Permanent Linear				-0.3	-0.2	-0.5	-0.5	-0.4	-0.2	-0.2
Change Thermal	@ ℃×24h conductivity	ASTM C210	%	1230	1230	1300	1350	1400	1400	1400
400℃		ASTM C182	W/m.K	0.17	0.19	0.26	0.21	0.21	0.23	0.3
600℃				0.19	0.23	0.28	0.27	0.27	0.28	0.32
800℃				0.22	0.24	0.3	0.3	0.3	0.31	0.35
1000℃				0.24	0.25	0.34	0.32	0.32	0.33	0.38
1200℃				—	—	—	—	0.35	0.36	0.39
Chemical Composition
Al2O3			%	42	42	45	50	55	60	55
SiO2				54	54	48	46	41.5	37	41.5
Fe2O3				0.8	0.8	1	0.9	0.8	0.7	0.8
TiO2				1.2	1.2	1.2	1.3	1	0.7	1
Cao+MgO				0.7	0.7	0.7	0.7	0.7	0.5	0.7
Na2O+K2O				1.3	1.3	1.2	1.1	1	1.2	1

Grade	Standard	Unit	FJM27	FJM28	FJM30	FJM30S	FJM32	FJM32A
Classification Group	ISO 2245 ASTM C155		145-0.9-L 27	150-0.9- L	160-1.0-L 30	160-1.0-L 30	165-1.2-L 32	170-1.3-L 32
Classification Temperature	℃		1450	1540	1600	1600	1650	1760
Bulk Density	ASTM C134	g/cm3	0.9	0.9	1	1	1.2	1.3
Cold Crushing Strength	ASTM C133	MPa	3	2.8	3	4.5	4.5	4
Modulus of Rupture	ASTM C133	MPa	1.5	1.5	1.8	2	2.5	2
Permanent Linear Change @ ℃×24h	ASTM C210	%	-0.5 1450	-0.8 1510	-0.8 1600	-0.2 1600	-0.7 1650	-0.9 1730
Thermal Conductivity
400℃	ASTM C182	W/m.K	0.3	0.3	0.4	0.4	0.43	0.49
600℃			0.32	0.32	0.42	0.42	0.5	0.5
800℃			0.35	0.35	0.44	0.44	0.51	0.51
1000℃			0.38	0.38	0.45	0.45	0.53	0.53
1200℃			0.39	0.39	0.47	0.47	0.55	0.55
Chemical Composition
Al2O3		%	60.5	65	72	64	75	77
SiO2			36	32.3	25.7	33.5	23	21
Fe2O3			0.8	0.6	0.5	0.5	0.4	0.4
TiO2			0.7	0.7	0.7	0.7	0.6	0.6
Cao+MgO			0.5	0.5	0.3	0.3	0.3	0.3
Na2O+K2O			1.2	0.9	0.8	0.8	0.7	0.7

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Frequently asked questions (FAQs)

What’s the difference between insulating firebrick (IFB) and dense firebrick?

IFB is lightweight and porous, designed mainly to reduce heat loss with low thermal conductivity. Dense firebrick is heavier and stronger, used for the hot face where wear and slag resistance matter. Many furnaces use dense brick hot face + IFB backup insulation.

How do I choose the right IFB grade (23/26/28/30/32)?

Choose based on your continuous operating temperature (not peak only). Pick a grade with a safe temperature margin, then confirm PLC stability and thermal conductivity for your lining zone. Share your furnace type + temps + lining layers, and we can recommend the grade quickly.

Can you supply custom sizes/shapes, and what’s needed for a quote?

Yes—standard sizes and custom cuts/shapes (bevels, grooves, special profiles) are available. To quote, we need grade (or service temp), drawing/dimensions, quantity, application, and destination. This helps confirm feasibility, cost, and lead time.

What’s the typical MOQ and lead time for insulating firebrick (IFB)?

MOQ depends on grade, size, and whether it’s standard or custom shape. Standard sizes are usually faster, while custom cuts/molds need extra time. Share your required grade + size + quantity, and we can confirm MOQ and lead time quickly.

Can insulating firebrick be used as the hot-face lining?

Sometimes, but it depends on temperature, abrasion, and atmosphere. IFB is mainly for backup insulation; hot-face zones often need denser, more wear/slag-resistant refractories. If you tell us the furnace zone and conditions, we can advise whether IFB is suitable or recommend a better hot-face option.