The Oxidation State of Sulfur Detected in Na_2O-CaO-SiO_2 Float Glass by X-ray Absorption Near Edge Structure Spectra

The oxidation state of sulfur is detected in Na20-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure （XANES） spectra at the sulfur K edge. The measured spectra show the only presence of S^6＋ in the Na20-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S^6＋ is the dominant species, but S^2- is also present on both surfaces. It is not certain whether cation bonds to S^2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated.

Temperature Modeling of the Molten Glass in Tin Bath

Based on the experimental investigation by quantitative analysis, temperature fields of the molten glass in tin bath were numerically simulated by the finite elememt method. The experimental results show that the cooling rate of glass is directly proportional to the draught speed, but inversely proportional to the thickness of the glass. This model lays the foundation for computer simulation system about float glass.

The Effect of Bi_2O_3 on the Structure and Properties of Float Glass

CaO-Al2O3-SiO2 system float glasses were melted at an elevated temperature, and about 60% of the total energy was occupied by melting and clarification stage. In order to reduce the melting temperature of the float glasses, Bi2O3 was added as fluxing agent. The structure and some melting properties such as the influence of the addition of the oxidation bismuth on the properties of float glass melt, melting temperature, and the structure of glass were studied. The results showed that the basic structure was not changed with the addition of Bi2O3 from 0.5% to 2%. The viscosity of the glass melt decreased with the addition of Bi2O3 obviously, as the viscosity of the glass melt was 1.35 Pa.s, the temperature was reduced by about 30 ℃ from sample A1 to sample A5. With the increasing of Bi2O3, the bending strength of glass was reduced and the transmisivity of glass samples had no change in visible light range, and the transmissivity of the glass samples was more than 88%. The ultraviolet cut-off length showed red shift with the addition of Bi2O3. With the increasing of Bi2O3, the water resistance of the glass samples was improved.

KINETIC FACTORS AFFECTING THE CORROSION OF SiO_2 IN SILICATE GLASSES CAUSED BY ALKALINE SOLUTIONS

The corrosion of a ZrO2 containing alkali re-sistant silicate glass, float glass and silica glass caused by the aqueous solution of NaOH was studied by use of correlation method with spectrophotometry. Effects of the corroding tem-perature, time and solution concentration on the rate of reac-tion and the degree of corrosion were investigated; effects of the apparent activation energy and the experimental value of frequency factor on the rate constant were discussed.

Effect of Temperature on Polishing and Flatting Time of Float-formed Li_2O-Al_2O_3-SiO_2 Glass

Li2O-Al2O3-SiO2 glass prepared from traditional melting and cooling process was investigated.The surface characteristic of LAS glass was studied by simulating tin bath with different temperature and time,and the effect of surface tension/viscosity ratio on flatting time was analyzed.The results demonstrated that LAS glass can polish effectively when polishing at 1 300 ℃ for 8 min,and the optimum flatting and polishing temperature was 1 250-1 300 ℃.

THE RELATIONSHIP BETWEEN BATCH REDOX AND SULPHUR BUBBLE DEFECT OF GLASS

Bubble defects of glass were studied by Ruman spectrum, C equivalent of glass raw materials were analyzed by chemical method, and the solubility of sulphur in glass was determined with SC-132 Sulphur Determination.. Then, the relationship between glass bubble, the redox numbers of glass batch and the solubility of sulphur in float glass were discussed. The way that can improve the quality of float glass was found.

Analysis and comparison of laser cutting performance of solar float glass with different scanning modes

Cutting quality and efficiency have always been important indicators of glass laser cutting.Laser scanning modes have two kinds,namely,the spiral and concentric circle scanning modes.These modes can achieve high-performance hole cutting of thick solar float glass using a 532-nm nanosecond laser.The mechanism of the glass laser cutting under these two different scanning modes has been described.Several experiments are conducted to explore the effect of machining parameters on cutting efficiency and quality under these two scanning modes.Results indicate that compared with the spiral scanning mode,the minimum area of edge chipping(218340µm)and the minimum Ra(3.01µm)in the concentric circle scanning mode are reduced by 9.4%and 16.4%respectively.Moreover,the best cutting efficiency scanning mode is 14.2%faster than that in the spiral scanning mode.The best parameter combination for the concentric circle scanning mode is as follows:Scanning speed:2200 mm/s,number of inner circles:6,and circle spacing:0.05 mm.This parameter combination reduces the chipping area and sidewall surface roughness by 8.8%and 9.6%respectively at the same cutting efficiency compared with the best spiral processing parameters.The range of glass processing that can be achieved in the concentric circle scanning mode is wider than that in the spiral counterpart.The analyses of surface topography,white spots,microstructures,and sidewall surface element composition are also performed.The study concluded that the concentric circle scanning mode shows evident advantages in the performance of solar float glass hole cutting.

Simulation of tin penetration process in the surface layer of soda-lime-silica float glass

Based on the analysis of tin penetration mechanism in the float glass process, the oxidation model of stannous ion is constructed considering the oxygen activity and the redox reaction in the glass surface layer. The calculation of stannous ion's oxidation rate makes it possible to predict both stannous and stannic ion's concentrations independently. And it is also the necessary precondition for the numerical verification of tin penetration mechanism. Coupled diffusion simulation method is established to simulate the penetration process of both stannous and stannic ions simultaneously. The result shows that when the green glass is formed in the reducing atmosphere in tin bath, the stannic ion is accumulated at the position where oxygen activity changes sharply. Satellite peak (internal local concentration maximum) occurs in the tin concentration profile of green glass, which is quite different from that in low iron glass. Compared with gradually cooling temperature regulation, the tin penetrated shifts to greater depth and the depth and magnitude of the satellite peak also increase when reheating temperature regulation is applied. In order to reduce the amount of penetrated tin, the residual time in the high temperature region should be shortened.