Multi-Purpose Refractory Materials Mullite Sand and Powder

MULLITE

Introduction:

Mullite sand is an aluminum-silicate refractory material, typically used in stainless-steel investment-casting processes. It withstands temperatures around 1,750 ºC; the higher the Al₂O₃ content, the lower the Fe content and the smaller the dust fraction, the better its quality. Produced by high-temperature sintering of kaolin, it produces castings that strip easily, stay dimensionally stable, resist shrinkage, have good surface finish and give high casting yields.

Product pictures:

Applications:
 

Magnesia-based ceramics have high shell strength and excellent air permeability, making them an essential molding material for precision casting. They are particularly suitable for the production of high-temperature alloy castings.

1.Mold casting (lost-wax casting)
It is used to make refractory molds for casting parts. Usually, it is mixed with magnesia powder in a certain ratio (such as sand: powder = 3:1), and combined with sodium silicate or silica sol as the binder to form multi-layer molds.
Applicable scenarios: turbine blades in the aerospace field, precision gears in the machinery industry, complex parts in the weapons industry, etc. It can withstand the erosion of metal liquids (such as stainless steel, titanium alloy) at temperatures above 1500 degrees, prevent mold cracking or sand sticking, and ensure the surface finish of the castings.

2. V-shaped molding and vacuum suction casting
As a dry sand filling material, the mullite sand is fixed and shaped by using negative vacuum pressure, without the need for adhesives or only using a small amount of adhesives.
Applicable scenarios: The production of large cast steel parts (such as machine tool beds, wind turbine flanges), and cast copper parts. It can reduce casting defects such as pores and sand holes, and the sand material can be recycled and reused, thereby reducing production costs.
 

Mullite is the core raw material for manufacturing high-performance refractory products. Due to its high refractory temperature and excellent thermal shock resistance, it is suitable for the key parts of high-temperature industrial kilns.

1.Fire-resistant bricks and molding materials
Mixed with high alumina powder, corundum, etc., they are used to make mullite-based fire-resistant bricks or molding materials, which are applied as the inner lining of kilns (such as the belly of metallurgical blast furnaces and the wall of glass kilns).
Advantages: They can withstand temperatures above 1700°C for a long time, and have a low thermal expansion coefficient (about 5.3×10^-8/), and are less likely to crack after repeated heating and cooling, thereby extending the service life of the kilns.

2. Furnace Liner and Insulation Materials
Fine-grained mullite (80-120 mesh) can be used as the aggregate for lightweight insulation bricks, or directly as the filling insulation layer in the kiln (such as the interlayer of a ceramic sintering kiln).
Applicable scenarios: High-temperature kilns in the ceramic and building materials industries, which can reduce heat loss, lower energy consumption, and prevent the insulation layer from shrinking and deforming under high temperatures.

The corrosion-resistant and high-temperature-resistant properties of mullite make it indispensable in metallurgical auxiliary applications and special scenarios.

1.Metallurgical auxiliary materials
As a covering agent or drainage sand for the continuous casting tundish, it can isolate the air and prevent the secondary oxidation of molten steel, while ensuring the smooth drainage of molten steel during pouring.
Applicable scenarios: The continuous casting production line of steel mills, which can reduce inclusions in molten steel and improve the quality of steel (such as high-strength steel plates for automobiles, pipeline steel).

2. Special Ceramics and Electronic Materials
As a sintering aid for alumina ceramics, adding a small amount of mullite (5%-10%) can lower the sintering temperature of the ceramics while enhancing their density and mechanical strength.
Applicable scenarios: Ceramic substrates for the electronics industry (such as ceramic filters for 5G base stations), special industry wear-resistant ceramic parts (such as water pump impellers).

3. Other Special Applications
As a grinding material, it is used for fine polishing of metal surfaces (such as mirror finish treatment of stainless steel products), due to its high hardness (Mohs hardness 6-7) and uniform particle size, resulting in a smooth surface without scratches after polishing.
As a filler for sodium silicate, it enhances the high-temperature resistance and compressive strength of sodium silicate concrete, and is used for pouring the floors and walls in high-temperature workshops.

Test Report

Application Adaptation of Different Specifications of Mollite Quartz

The classification of mullite quartz generally includes 8-16 mesh, 16-30 mesh, 30-60 mesh, 60-80 mesh, and 80-120 mesh; mullite powder generally includes 200 mesh and 300 mesh, etc.

8-16 Mesh
Mullite: Bottom layer of mold casting shell, large-scale casting V-method molding (such as turbine blade shell, wind power flange casting)
Reinforcement layer sand: Mullite 16-30 mesh (combined with mullite powder 200 mesh + silica sol)
16-30 Mesh
Mullite: Bottom layer of mold casting shell, large-scale casting V-method molding (same as 8-16 mesh application scenarios)
Reinforcement layer sand: Mullite 16-30 mesh (combined with mullite powder 200 mesh + silica sol)
30-60 Mesh
Mullite: Middle layer of mold casting shell, refractory casting material aggregate (such as precision gear shell, kiln furnace casting material)
Back layer sand: Mullite 30-60 mesh (combined with mullite powder 200 mesh + silica sol)
60-80 Mesh
Mullite: Middle layer of mold casting shell, refractory casting material aggregate (same as 30-60 mesh application scenarios)
80-120 Mesh
Mullite: Surface layer of mold shell, lightweight insulation material aggregate (such as surface refinement of castings, insulation brick production)
Surface layer sand: Zircon sand 120 mesh (combined with zircon powder 325 mesh + silica sol, not mullite)
200 Mesh (powder)
Mullite powder: Back layer slurry (mixed with silica sol), reinforcement layer (mixed with silica sol), sealing slurry (mixed with silica sol)
Other applications: Mold binder mixture, ceramic sintering aid, polishing materials (such as improvement of mold strength, ceramic substrate sintering, metal polishing)
300 Mesh (powder)
Mullite powder: Same as 200 Mesh, used in mold binder mixture, ceramic sintering aid, polishing materials, etc. scenarios.

FAQ:

Q: Do you provide samples ? is it free or extra ?
A: Yes, we can offer the sample for free but the freight is on client's account.

Q:How about the price and quanlity?
A:We provide ex-factory price, good and steady quality products and we are widely recognised by clients for our steady quanlity.

Q:How many years of experience in supply?
A:Our company has a professional trade team, serving in the trade industry for nearly 20 years.

Q:Do you accept customization?
A:We can give you the right advice according to your specific application.