Effects of Molding Pressure and Sintering Temperature on Properties of Foamed Glass without Blowing Agent

A process of fabricating the foamed glass that has closed pores with 8 similar to 580 mu m sizes without a blowing agent by sintering 10 mu m boron-free glass powder composed of CaO, MgO, SO3, Al2O3-83 wt% SiO2 at a molding pressure of 0 similar to 120 MPa and a sintering temperature of 750 similar to 1000 degrees C was investigated. To analyze the glass transition temperature of glass powder, thermogravi-metric analysis-differential thermal analysis (TGA-DTA) method were used. The microstructure and pore size of foamed glass were examined using the optical microscopy and field emission scanning electron microscopy (FE-SEM). For the thermal diffusivity and color of the fabricated samples, a heat flow meter and ultraviolet-visible-near-infrared (UV-VIS-NIR)-colormetry were used, respectively. In the TGA-DTA result, the glass transition temperature of glass powder was confirmed to be 626 degrees C. In the microstructure result, closed pores of 7 similar to 20 mu m were formed at 750 similar to 900 degrees C, and they were not affected by the molding pressure and sintering temperature. However, at 1,000 degrees C, when there was 0 MPa molding pressure, closed pores of 580 mu m were confirmed, and the pore size decreased as the molding pressure increased. Moreover, at a molding pressure of 30 MPa or higher, closed pores of approximately 400 mu m were formed. The porosity showed an increasing trend of smaller molding pressure and larger sintering temperature, and it was controllable in the range of 5.69 similar to 68.45%. In the thermal diffusivity result, there was no change according to the molding pressure, and, by increasing the sintering temperature, up to 0.115 W/m.K could be obtained. The Lab color index (CIE-Lab) results all showed a similar translucent white color regardless of molding pressure and sintering temperature. Therefore, based on the foamed glass without boron and blowing agent, it was confirmed that white foamed glass, which has closed pores of 8 similar to 580 mu m and a thermal diffusivity characteristic of 0.115 W/m.K, can be fabricated by changing the molding pressure and sintering temperature.