There will be bubbles, nodules, crystals, stones and other inclusions in the vitreous body. These defects in the glass body greatly reduce the quality of the glass. Forhigh borosilicate glassStones are dangerous defects in the vitreous body. They are crystalline solid inclusions that appear in the glass body, and they have a great influence on the glass. When borosilicate glass fiber precursors are stretched, they are more likely to cause. Broken ends and flying wires for drawing. Even if these stones do not cause breakage, they will greatly reduce the strength of the glass fiber.

high boron siliconglass electric melting cellarThe main causes of middle stones are as follows:

　　（1) Raw material stones are mainly caused by the high concentration of mineral raw materials and insufficient contact with molten glass due to uneven batch mixing. The incompletely melted particles flow out with the molten glass to form granular or flocculent stones.

　　（2) The stones introduced by the clinker, the clinker of the high borosilicate glass electric melting cellar comes from the defective ball, the clinker produced by the ball making and the glass block of the furnace removed. Defective balls and glass blocks in the kiln are usually clean and do not cause stones. The clinker produced by pelletizing will inevitably be mixed with other impurities, so some knots will be produced.

　　（3) Refractory stones, refractory materials interact with high borosilicate glass liquid or volatile products for a long time, and are corroded and enter the high borosilicate glass liquid to produce stones. In the high borosilicate glass electric melting cellar, this is mainly caused by the corrosion of quartz bricks. When the quartz brick is corroded by high temperature borosilicate glass liquid, the quartz brick will become cristobalite, metastable cristobalite, and a large number of scaly cracks will appear. When metastable cristobalite is corroded by glass, large particles gradually decompose into small particles, which enter the molten glass and form stones, which are mostly opaque white.

　　（4) Crystalline stone is mainly caused by the existence of "dead corners" in the kiln, and the temperature of the dead corners is within the crystal growth temperature range for a long time.

　　（5) The heating of foreign impurity stone and high borosilicate glass electric melting cellar is heated by carbon rod. When the carbon rod is broken due to arc discharge, the resulting carbon rod slag will enter the molten glass, causing the product to appear black stone. In addition, platinum electrodes are used in high borosilicate glass electric furnaces. When the liquid level of the glass is low, molybdenum will be oxidized at high temperature, and black stones will also appear. The number of stones caused by these two phenomena is also relatively small, but if abnormalities occur, a large number of stones will continue to be produced.