Fused Silica Chemical Limits: SiO2 and Impurities

Read chemical limits as your own acceptance limits, then check them against the COA for the quoted lot. The figures below are typical values for discussion. They describe the result for a lot only when the COA or the quotation says so.

Typical A Grade figures

Typical A Grade values, confirmed on the COA or the quotation for the quoted lot, 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 A Grade note states those figures as typical values for discussion.

Typical B Grade figures

Typical B Grade values, confirmed the same way, are SiO2 99.8% min for grains, SiO2 99.7% min for powder, Fe2O3 ≤ 200 ppm, Na2O ≤ 200 ppm and magnetic material ≤ 100 ppm. the B Grade note states those figures as typical values, not as a result already measured on your lot.

Items a buyer may limit

Fe2O3, Al2O3, alkalis (Na2O and K2O), MgO, CaO and magnetic material are items a buyer may limit. Your specification decides which limits matter. A typical list is not a rejection list for every plant. Compare the reported analysis with the limits you wrote down.

Physical figures sometimes recorded with chemistry

Buyers sometimes record physical figures beside the chemistry. Typical values for A Grade and B Grade are bulk density 2.18-2.20 g/cm3, pH about 6, melt point 1750°C, softening point 1650°C, thermal expansion 5×10^-7 per °C, amorphous content above 99% and crystalline content below 1%. Confirm these on the COA or the quotation for the quoted lot.

Shenzhen Zhixin New Materials Co., Ltd. reports the chemical result for the quoted lot on the COA. Use that document when you accept the material.