16-200 Mesh Mullite Sand and Powder for Investment Casting

Product Overview

Our premium Mullite Sand is high-purity aluminosilicate refractory exclusively developed for lost-wax investment casting, perfectly matched with supporting Mullite Flour to build robust, dimension-stable ceramic shell molds. Produced via high-temperature calcination of premium bauxite raw ore, this mullite grain features low thermal expansion, outstanding thermal shock resistance and ultra-low impurity content. It is a cost-effective alternative to zircon sand for stainless steel, alloy steel and carbon steel precision casting, drastically cutting casting defects and improving finished casting surface smoothness.

Raw Material & Chemical Composition

Raw Source

High-quality flint bauxite clinker, sintered above 1500℃ to form stable mullite crystal phase (3Al₂O₃·2SiO₂), then crushed, screened and dedusted strictly to obtain uniform Mullite Sand grains.

Core Physical & Refractory Performance

Ultra High Refractoriness ≥1750℃：Withstands high temp pouring of stainless steel, alloy and carbon steel, no shell softening or collapse under molten metal heat.

Ultra-Low Thermal Expansion Coefficient：Minimal expansion & shrinkage during heating/cooling, keep casting dimensional tolerance within standard range, effectively reduce mold cracking, deformation and size deviation.

Excellent Thermal Shock Resistance：Resist sharp temperature jumps in dewaxing, sintering and pouring processes; shell not easy to crack, lower scrap rate.

Good Breathability & High Shell Hardness：Uniform spherical grain structure ensures smooth gas discharge during pouring, eliminate pores & blowholes; fired shell hardness over 8MPa for complex thin-wall castings.

Easy Shakeout Performance：Brittle mullite shell after cooling, simple knockout without sticking metal; save post-processing polishing labor & time.

Stable Chemical Inertness：No chemical reaction with molten steel alloy, avoid sand sticking, scab and inclusion defects on casting surface.

Available Mesh Sizes

We supply full-size series of Mullite Sand and matched fine Mullite Flour for different shell coating layers:

Mullite Sand (Grit for stucco layer)

8–16mesh / 16–30mesh / 30–60mesh / 60–80mesh / 80–120mesh

Coarse grit (8–30mesh): Back-up layer, strengthen whole shell structure

Medium-fine grit (30–120mesh): Intermediate layer, balance strength & breathability

Mullite Flour (Powder for prime slurry layer)

200mesh / 300mesh / 325meshFine powder mixed with silica sol to make prime coating, deliver mirror-smooth casting surface.

Custom mesh grading & chemical index adjustment available for special casting craft.

FAQ

Q1: Can Mullite Sand fully replace zircon sand for stainless steel casting?

A: Yes. Our high-purity Mullite Sand with matched Mullite Flour meets dimensional precision requirements of most stainless steel castings, with much lower material cost. Only ultra-high precision aerospace single crystal parts still adopt zircon sand.

Q2: Which mesh size should I choose for my shell making?

A: 16–30mesh /30–60mesh Mullite Sand is the universal intermediate layer; 200/300mesh Mullite Flour for prime coating. Tell us your casting wall thickness and metal material, we recommend matched grit combination.

Q3: Will mullite sand cause sand sticking defects?

A: Our product strictly controls iron and alkaline impurities, stable high-temperature chemical inertness. Correct shell-making operation with matched mullite flour can completely avoid sand sticking.