Borosilicate glass forming technology

Float glass forming technology is to melt, clarify, and homogenize the molten glass in the melting furnace, and float on the surface of the molten tin in the tin bath at high temperature, using the surface tension of the molten glass and the surface between the molten glass and the molten tin. The combined action of tension and gravity of molten glass completes the process of flattening, thinning, polishing, cooling, and solidification of molten glass, making it a high-quality flat glass superior to polished glass. The main decisive factors for the formation of float glass are the viscosity, surface tension and gravity of the glass. Among these three factors, the viscosity of the glass liquid mainly plays the role of glass shaping, the surface tension of the glass liquid mainly plays the role of glass polishing, and the gravity of the glass liquid mainly plays the role of glass flattening. These three effects the flattening and polishing of the glass liquid. Both have a certain effect, and they can be combined with each other to produce float glass.

The amount of tin infiltration, the valence state and the depth of tin infiltration on the lower surface of float glass have a greater impact on the quality of float glass and the deep processing of the glass. The amount of tin penetration on the lower surface of float glass is usually expressed by the CPM value. It is the characteristic spectral line count of tin per minute per unit area of the lower surface of the float glass, called the number of tin counts per minute. Generally speaking, the lower the curve, the flatter it represents. The tin penetration of the whole board is less and uniform. There is still a big gap in the CPM value of glass between domestic and foreign countries and joint ventures. The amount of tin in the glass is serious. Deep processing of glass

According to the information, the vapor pressure of tin increases sharply with the temperature of the tin liquid. As shown in Table 6, the vapor pressure of tin is 1.35×10 Pa at 730 ℃, and the vapor pressure of tin is 133.32 Pa at 1 440 ℃. It can be seen that the temperature- 4 Increased by 1 time, the vapor pressure increased by 7.04×10 times. Therefore, comparing high borosilicate glass and soda-lime silica glass, if the temperature at the tip of the tin bath is increased by about 300°C, the vapor pressure of tin is increased by 142 times. In this way, when the float process produces high borosilicate glass, the glass liquid seems to be in a tin vapor bath. At the same time, because the temperature of producing high borosilicate glass is increased by several hundred degrees, the activity of tin ions is greatly enhanced, and tin ions penetrate into the glass electrode. The surface capacity is greatly enhanced, and the possibility of increasing the amount of tin infiltration is greatly increased. The influence of tin infiltration on the change of the glass surface properties is greater. This is one of the problems that need to be solved by the float glass process.