Excellent Performance of White Fused Alumina in Precision Investment Casting

1. High-Quality Shell Building Material

White fused alumina (WFA) is produced by melting high-purity alumina at temperatures above 2000 °C. With an α-Al₂O₃ content of over 99–99.6% and a refractoriness of 2050–2100 °C, it is an ideal replacement for traditional zircon sand as a face coat material in investment casting. Its low thermal expansion coefficient (~8×10⁻⁶/°C) helps maintain shell integrity during rapid temperature changes. The high particle uniformity (over 95% within target size) and excellent dispersibility result in denser, stronger molds that significantly improve the surface finish and dimensional accuracy of castings while reducing defects.

2. Enhanced Mold Durability

Thanks to its Mohs hardness of 9.0 and stable strength at temperatures above 1900 °C, WFA strengthens molds and cores for cast iron, cast steel, and non-ferrous alloy applications. It provides excellent resistance to molten metal erosion, extending mold life by 30–50% and reducing maintenance needs.

Key Performance Advantages

High Thermal Stability

WFA maintains stable thermochemical properties during casting. Its thermal expansion rate is only about one-third of that of conventional materials, which minimizes cracking or deformation caused by thermal shock. With a very low gas evolution (< 3 ml/g), WFA also reduces the risk of gas-related casting defects such as pinholes.

Superior Surface Finish

When used as micro powder (0.5–45 μm) for fine polishing, WFA delivers uniform cutting action, achieving surface roughness as low as Ra < 0.8 μm. Its self-sharpening ability (breakage rate < 5%) ensures consistent polishing performance over extended use.

Flexible Process Adaptability

Our white fused alumina is available in a wide range of grain sizes (F12 to F10000) to meet various casting needs:

Coarse grades (F12–F100): Improve mold release for complex shapes, increasing demolding success by over 25%.

Fine grades (F220–F1000): Enable high-precision ceramic cores with dimensional accuracy of ±0.1 mm.

3. Value in Process Optimization

Cost Savings

Replacing zircon sand with WFA can reduce raw material costs by 30–40%. It also allows for a 15–20% reduction in shell thickness (typical shell thickness: 0.8–1.2 mm) and shortens the shell building cycle.

Environmental Benefits

WFA is free from heavy metal contamination (heavy metal content < 0.01%) and complies with ISO 14001 environmental standards. Used sand can be fully recycled for refractory applications, supporting circular production and sustainability goals.

Proven Applications in High-End Industries

White fused alumina has been widely used in aerospace turbine blade casting, precision medical device components, and other demanding applications. Case studies show that its use can increase product yield from 85% to 97%.