Surface And Interface Modifications Of Silicate Glass Via Supercritical Water

The reaction between supercritical water and silicate glasses was analysed using various surface analysis methods. The alkali silicate glasses with a diameter of one inch were treated over 300 deg C inside the chamber and cooled into room temperature after the treatment. The surface of the glasses was severely etched especially over 400 deg C, which is near the supercritical point of water; 374 deg C, 221.MPa. Not only the formation of pores but also the precipitation of alkali int he glass were observed from teh image of secondary electron microscopy (SEM) and EPMA analysis. An optical interferometry microscope revealed that the average roughness after the treatment dramatically increased depending on the increase of treatment temperature. The polishing test of the treated glass indicated that the mechanical properties at the surface of the treated glass dramatically decreased due to the reaction between supercritical water and glass.