(1) The gas in the material particle gap and the gas adsorbed on the material surface
At the initial stage of blending material melting, this kind of gas volatilizes or evaporates unceasingly, forms the big bubble in the rising process to float but escapes the glass liquid, generally will not directly cause the visible bubble in the glass product. Unless the raw material particle size is not properly controlled, the blending material cluster is not fully melted, the gas cannot be discharged.
(2) The gas released by the decomposition of salts
Mixtures in the presence of large amounts of carbonate, sulfate and nitrate, these salts thermal decomposition, produce a large number of tiny air bubbles, the gas generated in the salt decomposition quantity, accounts for about 20% of the weight of the batch of 15 a, and the formation of the glass liquid ratio, large size out many times, the release of gases and moving, promoting the improvement of the heat exchange efficiency, accelerate the melting of the batch, improved the uniformity of glass composition and temperature uniformity, but, this kind of gas bubbles not promptly eliminate will form glass bubbles.
(3) The gas generated by external factors
The glass bubbles formed by the gases precipitated from refractory materials, harmful impurities and glass liquid, have a long time to disappear in normal production and are difficult to disappear, but this kind of situation is rare.
The temperature of the glass drops too fast or the temperature fluctuates greatly, or due to various reasons, the REDOX state of glass fluctuates greatly, these factors combine to make the solubility of various gases in glass fluctuates, releasing a large number of tiny secondary bubbles. These bubbles are characterized by small diameters and large Numbers.
Sometimes, due to wrong calculation or wrong feeding in the process of execution, the composition of glass in the furnace fluctuates greatly, the solubility of the gas in the glass fluctuates, and a large number of glass bubbles are generated.
There are two ways for glass bubbles to disappear in the process of clarification: one is that the small bubbles grow into big bubbles, and the bubbles keep rising due to the density difference and finally disappear out of the glass liquid. The other is a tiny air bubble, with lower temperature, the gas solubility in the glass, because the surface tension, the bubble exists in several kinds of gas composition, due to the small air bubble diameter, high pressure, gas quickly absorbed by the glass, with the decrease of diameter, the bubble pressure rising, in the end all the gases in the air bubbles into the glass. The little bubbles completely disappear.