1. Core advantages
(1) High refractoriness and thermal stability
The refractoriness can reach above 1900℃, which is much higher than silica sand (about 1600℃). It can withstand the erosion of high-temperature molten metal (such as stainless steel and nickel-based alloy), reducing sand sticking and sintering defects of castings.
Low thermal expansion coefficient (~8×10⁻⁶/℃), small volume change when heated, avoiding the expansion of the molding sand and causing surface cracks or dimensional deviations of the castings.
(2) Excellent resistance to metal penetration
**High density (4.5-4.8 g/cm³)** and dense structure effectively prevent the metal liquid from penetrating into the pores of the sand mold and improve the surface finish of the casting (Ra can be optimized to 6.3-12.5μm).
Inert chemical properties, extremely low reactivity with alloy elements such as Fe, Cr, and Ni, avoiding chemical sand sticking or pores.
(3) Rapid heat conduction and cooling control
The thermal conductivity (2-3 W/m·K) is twice that of silica sand, which accelerates the solidification of castings, refines the grain structure, and improves mechanical properties (such as tensile strength increased by 10%-15%).
Combined with the gradient sand mold design (surface chromium ore sand + back layer silica sand), the cooling rate can be controlled in a directional manner to reduce shrinkage and shrinkage defects.
(4) Environmental protection and economy
Reusability: After magnetic separation and water washing, the recovery rate can reach more than 80%, and the long-term cost is lower than zirconium sand.
No free SiO₂ hazard: Avoid the risk of silicosis caused by high-temperature crystallization of silica sand, and meet occupational health standards (such as OSHA).
2. Typical application scenarios
High alloy steel casting: stainless steel valve body, turbine blades and other complex thin-walled parts, reduce surface defects.
Large castings: rollers, marine crankshafts, using their high heat storage capacity to achieve uniform cooling.
Lost foam casting: Used for coating sand in key areas to prevent molten metal from penetrating the foam mold.
Vacuum casting (V method): Compounded with zircon sand (ratio 1:1) to balance cost and performance.
