Requirements for the purity of silica sol in different fields
Generally speaking, silica sol is a dispersion of nano silica in water, with a relatively simple composition, mainly consisting of nano silica, water, and a small amount of stabilizers (Na+, K+, NH4+, etc.). However, there are also metal impurities such as Fe2+, Ca2+, AI3+, as well as acid radical impurities such as SO42-, CI -, NO3-, etc. in silica sol.
Different application fields have different requirements for the purity of silica sol.
(1) As a low-end application of silica sol, there are no special requirements for the purity of silica sol in fields such as casting, refractory materials, and coatings. The sodium content of silica sol used in these fields can reach 1000-2000ppm.
(2) The application field of catalysts has certain requirements for the metal content of silica sol, and excessive metal impurity content can affect catalytic efficiency. Generally, the Na content is required to be less than 1000ppm. But there are many types of catalysts and there are also high requirements, such as requiring the sodium ion content in the silica sol to be less than 100ppm.
(3) The field of chip polishing has the highest requirement for silica sol, which requires multiple polishing processes during chip manufacturing. For certain occasions, the content of metal impurities in silica sol is required to be less than 1ppm.