1.high purity 99.99% 2.abrasion resistance 3.anti-corrosion 4.protect electrode 5.high voltage resistance High purity&heating-resistanceOD range 1.2mm-360mm, Silicon Dioxide>99.995%Transmittance of visible light>90% a ) except the incorporation of impurity content of trace titanium, aluminium, iron outside, calcium, magnesium, potassium, sodium, lithium seven impurity elements of the total ...