A Grade vs. B Grade Fused Silica

A Grade and B Grade are two typical fused silica specifications. The buyer matches the grade to the acceptance limits already written for the process. Neither grade is automatically suitable for every process. The lot still has to be confirmed on the COA.

Typical A Grade chemistry

Typical A Grade figures, confirmed on the COA for the lot and on the quotation, are SiO2 99.9% min, Fe2O3 ≤100 ppm, Al2O3 ≤200 ppm, Na2O/K2O ≤100 ppm, MgO ≤200 ppm, CaO ≤100 ppm, and magnetic material ≤50 ppm. The page for A Grade fused silica sets out that tighter typical chemistry. A typical table is not itself the result of the lot.

Typical B Grade chemistry

Typical B Grade grains are SiO2 99.8% min. Typical B Grade powder is SiO2 99.7% min. Typical impurity figures for B Grade are Fe2O3 ≤200 ppm, Na2O ≤200 ppm and magnetic material ≤100 ppm. These figures are also confirmed on the COA for the lot. See B Grade fused silica for that wider typical range.

Physical figures often quoted for both

Both grades are often described with the same typical physical range: bulk density 2.18-2.20 g/cm3, pH about 6, melting point 1750°C, softening point 1650°C, linear expansion 5×10^-7 /°C, amorphous content above 99%, and crystalline content below 1%. Confirm the lot on the COA and on the quotation. These typical figures are not a standing result for every shipment.

Match the grade to your own limits

Compare the figures above with the limits your process already uses. Place the COA for the offered lot beside those limits. If the plant specification is tighter than typical B Grade, ask for A Grade and check that lot. If the plant accepts the wider limits, B Grade may be the grade to request. The choice stays with the buyer.

Shenzhen Zhixin New Materials Co., Ltd. supplies both grades for shipment to Europe, the United States, Brazil and other export destinations. Send the grade, the particle size, the quantity and the destination so the quotation can name the lot basis.