Effect Of Temperature Parameters On Structure And Properties Of Borosilicate Foam Glass

The purpose of this paper is to research the effect of temperature parameters on bubble structure and properties of borosilicate foam glass by changing the parameters such as temperature, holding time and heating-up speed.In this experiment, SiO2 and H3BO3 powders were adopted as main raw materials, carbon was used as foaming agent. Low silica content system and high silica content system borosilicate foam glass were fabricated by powder sintering method. The size, shape and distribution of bubbles were observed by optical microscope and scanning electronic microscope. The phase components of the samples were tested by X-ray diffraction. The bulk densities, coefficient of thermal expansion, water absorption and acid corrosion resistance of the samples were also measured.The results show that, to low silica system, with temperature increasing the bubbles will be swell. At 1200℃, the mixture hadn't been well fused and there are much crystal in glass. At 1300℃, the pressure in bubbles is too high while the viscosity and surface tension are too low, the bubbles connected or break up. The temperature 1250℃is the best. With prolonging of holding time, the bigger bubbles will swallow up the smaller ones to grow. When the holding time is 30min, the bubbles did not well develop. When the holding time is 90min, the bubbles grew excessively, connected each other, and even break. It was proper to hold the time 60min. The bubble diameter of samples prepared at 1250℃for 60min is between 1mm to 2mm, and the thickness between bubbles is about 0.1mm. The lowest density is 0.483g/cm3 and the smallest water absorption is 0.87%. The average coefficient of heat expansion is 8.2826×10-6/℃. The weight of samples which had been corroded for 2 months in 0.1mol/L H2SO4 changed from 0.46% to 1.51%.To high silica system, the tendency of bubbles with temperature and holding time is similar to that in low silica system. The best temperature and holding time were 1450℃and 60min separately. Samples are also influenced by heating-up rate. In the case of 6℃/min , the uniformity of bubbles was worse than that in the case of 10℃/min or 8℃/min, because there are too much gas in the body which would lead to foaming badly if the heating-up rate is too slow. The bubble diameter of samples prepared at 1450℃for 60min with heating-up rate of 8℃/min is about 1mm to 2mm, and the thickness between bubbles is about 50μm. The properties of samples in high silica system are much better than low silica system. The lowest density is 0.201g/cm3 and the smallest water absorption is 0.19%. The average coefficient of heat expansion is 1.3557×10-6/℃. The weight of samples changed from 0% to 0.72% after tested in H2SO4 , whose concentration from 1wt% to 5wt%,at 100℃。...