White Fused Alumina for Investment casting
In precision investment casting, casting sand works to make the shell. There are several types of casting sand such as Mullite, Fused Aluina, Clay, and Zircon sand. The main goal is to meet different metal pouring temperatures. Thus it will achieve ideal performance and cost-effectiveness. The thermal resistance of white fused alumina is better than that of fused silica, mullite, and clay. So it is more suitable for metal and alloy castings with higher pouring temperatures.
1. Surface sand for precision castings such as stainless steel and ferroalloys.
The surface layer sand of precision casting should have high thermal shock resistance and high-temperature resistance. It contacts with high-temperature metal melt directly. The melting point of white fused alumina is as high as 2250 °. That is much higher than the temperature of stainless steel casting at 1400-1500 °. Meanwhile, white fused alumina also has high mechanical strength and creep resistance, which is conducive to obtaining a smooth surface for castings.
2. Surface sand and back sand for investment casting of nickel alloys, manganese alloys, etc.
The pouring temperature of this type of alloy is about 1530-1580 ° C. In the meantime, the thermal shrinkage rate of the alloy melt is relatively high. Therefore, it is necessary to choose refractory materials with good permeability and low coefficient of thermal expansion as the back sand. Zircon sand can meet the requirements of this application. However, its high cost and quality stability also depend on the grade of the zircon ore. Suspension-treated White Fused Alumina F240, F280, and F400 have good fluidity and particle uniformity as the back sand. The content of fine powder is also low. It can replace zircon sand and reduce manufacturing costs.
In addition, white fused alumina sand with high packing density and low sodium content is also used as precision casting shell sand for stainless steel and nickel-based alloys. The permeability and strength of the shell mold are adjusted by packing density. Low sodium white corundum has better creep resistance and higher thermodynamic properties, making it widely used in investment casting.
