... surface is covered by hydroxyl(-OH), its inner contains 2.5% - 3.0% weight of hydroxyl, this percentage is ... up to 1.8ml/g, the particle size is 5.6um base on D50 average particle,let the coatings and ... effection.The main chemical indexItemsBV809Average Particle size (μm, Malvern)5.0-6.0Pore volume (ml/g)1.8Surface TreamentorganicPH ... cauterization (950°C,2hr%)10-12SiO2 content %,≥98.5 BV809 Matting agent