Description

Due to its unique crystal structure, sintered mullite exhibits excellent mechanical properties and thermal stability at high temperatures. In refractory material formulations, sintered mullite is not only used as an aggregate or matrix material, but it can also form a stable crystalline phase network during firing or use, significantly improving the thermal shock resistance and volume stability of the products.

Sintered mullite is a refractory mineral material with 3Al₂O₃·2SiO₂ as its main crystalline phase. It is typically produced by sintering high-purity alumina–silica raw materials at high temperatures. Its crystal structure is highly stable, allowing it to maintain good mechanical properties and volume stability even under high-temperature conditions. It is widely used in medium- to high-grade refractory material systems.

Sintered mullite is a high-grade refractory raw material with advantages such as uniform thermal expansion, good thermal shock resistance, high refractoriness under load, low creep, high hardness, and excellent chemical corrosion resistance. Because natural mullite resources are limited, the production of sintered mullite and fused mullite has become widely adopted.

Synthetic Sintered Mullite (synthetic dense aluminum silicate aggregate)

Indicators Grade	Al₂O₃ min	Fe₂O₃ max	SiO₂ %	TiO₂ %	K₂O %	Na₂O %	CaO %	MgO %	Apparent porosity% max	Fire resistance ℃ max	Bulk density g/m³min	Mullite phase% min
M45	45.5	1.3	51.0	1.0	0.10	0.10	0.35	0.15	2.5	1770	2.62	65
M47	47.0	1.0	50.0	0.90	0.08	0.08	0.30	0.10	2.0	1770	2.64	65
M60	58.0	1.35	36.25	2.0	0.10	0.08	0.35	0.10	2.8	1790	2.78	78
M60-1	58.0	1.0	35.0	1.8	0.10	0.10	0.35	0.10	2.8	1790	2.78	78
M60-II	58.0	0.5	38.0	0.8	0.10	0.10	0.35	0.10	2.8	1790	2.78	78

Synthetic Silica-rich Kaolinite

Burning %

SiO₂

Al₂O₃

TiO₂

CaO

MgO

K₂O

Na₂O

Fe₂O₃

% max

True density g/cm³

Mullite phase%

Fire resistance℃

Apparent porosity%

0.05

53.48

43.54

(42.0min)

0.06

0.03

0.27

2.10

0.06

0.40

(0.50max)

2.64

1750-

1770

1.8

(2.0max)

High-quality synthetic refractory raw materials

Brand

Project

Mullai stone

Magnesium aluminum spinel

Cordierite

Zirconium corundum sintered mullite

Sintered corundum

M75

M70

M70M

M70L

M60

M60M

M60L

MA-90

MA-70

Al₂O₃%

≥75

≥70

≥60

≥90

≥70

≥35

≥40

≥98

Mg0 %

≥7

≥25

≥12.5

Zr0₂%

≥33

TiO₂%

≤0.5

≤0.6

≤1.5

≤2.65

≤0.8

≤1.8

≤2.0

Fe₂O₃%

≤0.5

≤0.6

≤1.0

≤1.35

≤0.8

≤1.0

≤1.35

≤0.8

≤1.2

≤1.0

K₂0+Na₂0 %

≤0.5

≤0.6

Fire resistance ℃

≥1790

≥1750

≥1850

Bulk density g/cm³

≥2.85

≥2.75

≥2.85

≥2.75

≥3.30

≥3.20

≥1.70

≥3.30

≥3.60

Apparent porosity %

≤3

≤4

≤3

Mineral phase content %

≥90

≥80

≥90

≥80

≥90

≥95

Use

High-quality raw materials for refractory materials, special ceramics, casting molds, etc.

The synthesis methods of sintered mullite can be divided into sintering and electrofusion.

●Sintered sintered mullite is made from high-quality natural raw materials, refined and homogenized through multiple processes, and then calcined at high temperatures. Sintered sintered mullite products have stable quality and are widely used in the production of various high-temperature, low-creep products with excellent thermal shock resistance. Sintered sintered mullite can be processed into fine powders of: 0-1mm, 1-3mm, 3-5mm, 5-8mm, and 0-50mm: 180#-0, 200#-0, 240#-0, and 325#-0.

●The electric melting method involves adding the batch materials into an electric arc furnace, where they melt in the high temperature generated by the electric arc, and then cool and crystallize. When using natural raw materials (such as bauxite), the lumpy raw materials can be directly crushed to particles <1.5mm without grinding, and then mixed evenly with other powdered raw materials in a mixer.

1.Mineral beneficiation is performed, and a suitable formula is determined based on the chemical composition of the raw materials. The mixing formula for various mineral raw materials varies depending on the product grade. Examples include sintered mullite with 47% alumina, sintered mullite with 60% alumina, and sintered mullite with 70% alumina.

2.After crushing all the necessary raw materials, mix them evenly and wet grind them into a 325-mesh slurry with a water content of about 60%.

3.Most of the moisture is removed using a filter press and then preliminarily dried to reduce the moisture content to below 10%.

4.Remove the metallic impurities and squeeze the dried mud into sticks, then dry it until the moisture content is below 1%.

5.The dried, rod-shaped slurry is calcined in a rotary kiln or tunnel kiln. The calcination temperature varies depending on the product grade, such as 1500 degrees Celsius for 47% sintered mullite, 1650 degrees Celsius for 60% sintered mullite, and 1750 degrees Celsius for 70% sintered mullite.

6.After calcination reaches its peak temperature, the temperature is slowly reduced to form the sintered mullite mineral phase.

7.After complete cooling, it can be crushed, screened, and bagged.